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Sample records for planetary nebula gc

  1. The remarkably high excitation planetary nebula GC 6537.

    PubMed

    Aller, L H; Hung, S; Feibelman, W A

    1999-05-11

    NGC 6537 is an unusually high excitation point symmetric planetary nebula with a rich spectrum. Its kinematical structures are of special interest. We are here primarily concerned with the high resolution spectrum as revealed by the Hamilton echelle Spectrograph at Lick Observatory (resolution approximately 0.2 A) and supplemented by UV and near-UV data. These extensive data permit a determination of interstellar extinction, plasma diagnostics, and ionic concentrations. The photoionization models that have been used successfully for many planetary nebulae are not entirely satisfactory here. The plasma electron temperature of a photoionization model cannot much exceed 20,000 K, but plasma diagnostics show that regions emitting radiation of highly ionized atoms such as [NeIV] and [NeV] are much hotter, showing that shock excitation must be important, as suggested by the remarkable kinematics of this object. Hence, instead of employing a strict photoionization model, we are guided by the nebular diagnostics, which reveal how electron temperature varies with ionization potential and accommodates density effects. The predictions of the photoionization model may be useful in estimating ionization correction factor. In effect, we have estimated the chemical composition by using both photoionization and shock considerations. PMID:10318889

  2. Planetary nebulae

    NASA Astrophysics Data System (ADS)

    Gieseking, F.

    1983-02-01

    The first planetary nebula (PN) was discovered by Darquier in 1779. In 1981, a compilation of galactic PN listed a total of 1455 objects. Outside the Milky Way Galaxy, PN are currently known in the Magellanic Clouds and in several members of the local group of galaxies. The PN have a rich emission-line spectrum, which makes it possible to recognize them at large distances. A central stellar object can be observed within the nebula. In 1927, spectral lines at 4959 A and 5007 A emitted by the PN could finally be identified as 'forbidden lines' of O(++). The life expectancy of a PN, estimated on the basis of the observed expansion rate, is only about 30,000 years. The PN have a number of interesting characteristics which are partly related to the high effective temperature and luminosity of the central stars, the presence of a particle system under extreme physical conditions, and the stellar material provided by the PN for the interstellar medium. Attention is given to the determination of the distance of PN, the Shklovsky distances, and two mysterious aspects related to the spectrum

  3. Orion Nebula and Planetary Nebulae

    NASA Technical Reports Server (NTRS)

    Dufour, Reginald J.

    1998-01-01

    This report summarizes the research performed at Rice University related to NASA-Ames University consortium grant NCC2-5199 during the two year period 1996 September 1 through 1998 August 31. The research program, titled Orion Nebula and Planetary Nebulae, involved the analysis of Hubble Space Telescope (HST) imagery and spectroscopy of the Orion Nebula and of the planetary nebulae NGC 6818 and NGC 6210. In addition, we analyzed infrared spectra of the Orion Nebula taken with the Infrared Space Observatory (ISO) The primary collaborators at NASA-Ames were Drs. R. H. Rubin, A. G. C. M. Tielens, S. W. J. Colgan, and S. D. Lord (Tielens & Lord has since changed institutions). Other collaborators include Drs. P. G. Martin (CITA, Toronto), G. J. Ferland (U. KY), J. A. Baldwin (CTIO, Chile), J. J. Hester (ASU), D. K. Walter (SCSU), and P. Harrington (U. MD). In addition to the Principal Investigator, Professor Reginald J. Dufour of the Department of Space Physics & Astronomy, the research also involved two students, Mr. Matthew Browning and Mr. Brent Buckalew. Mr. Browning will be graduating from Rice in 1999 May with a B.A. degree in Physics and Mr. Buckalew continues as a graduate student in our department, having recently received a NASA GSRP research fellowship (sponsored by Ames). The collaboration was very productive, with two refereed papers already appearing in the literature, several others in preparation, numerous meeting presentations and two press releases. Some of our research accomplishments are highlighted below. Attached to the report are copies of the two major publications. Note that this research continues to date and related extensions of it recently has been awarded time with the HST for 1999-2000.

  4. Misclassified planetary nebulae

    NASA Astrophysics Data System (ADS)

    Sabbadin, F.

    1986-08-01

    The classifications of 130 objects as planetary nebulae (PNs) in the catalogs of Kohoutek (1965, 1969, and 1972) are reexamined by analyzing their images on the IR (755-885-nm) and red (610-690-nm) plates of the NIR photographic survey of the Galactic plane of Hoessel et al. (1985). Factors affecting the IR and red brightness of normal stars and emission-line objects are discussed, and it is shown that PNs should be brighter in the red than in the IR. Thirty-six supposed PNs for which this is not the case are identified, and it is suggested that they have been improperly classified.

  5. Atomic hydrogen in planetary nebulae

    NASA Technical Reports Server (NTRS)

    Schneider, Stephen E.; Silverglate, Peter R.; Altschuler, Daniel R.; Giovanardi, Carlo

    1987-01-01

    The authors searched for neutral atomic hydrogen associated with 22 planetary nebulae and three evolved stars in the 21 cm line at the Arecibo Observatory. Objects whose radial velocities permitted discrimination from Galactic H I were chosen for observation. Hydrogen was detected in absorption from IC 4997. From the measurements new low limits are derived to the mass of atomic hydrogen associated with the undetected nebulae. Radio continuum observations were also made of several of the nebulae at 12.6 cm. The authors reexamine previous measurements of H I in planetary nebulae, and present the data on a consistent footing. The question of planetary nebula distances is considered at length. Finally, implications of the H I measurements for nebular evolution are discussed and it is suggested that atomic hydrogen seen in absorption was expelled from the progenitor star during the final 1000 yr prior to the onset of ionization.

  6. Kinematics of planetary nebulae. II

    NASA Astrophysics Data System (ADS)

    Purgathofer, A.; Perinotto, M.

    1981-08-01

    In a program of study of radial velocities of planetary nebulae, 84 spectra of eight planetary nebulae in the direction of the galactic anticenter have been obtained at the L. Figl Observatory near Vienna with an image tube spectrograph giving a reciprocal dispersion of 26 A/mm. With this material, the kinematical behavior of the objects was studied, and it is shown that most of them deviate significantly from circular motion in the Galaxy.

  7. HUBBLE'S PLANETARY NEBULA GALLERY

    NASA Technical Reports Server (NTRS)

    2002-01-01

    [Top left] - IC 3568 lies in the constellation Camelopardalis at a distance of about 9,000 light-years, and has a diameter of about 0.4 light-years (or about 800 times the diameter of our solar system). It is an example of a round planetary nebula. Note the bright inner shell and fainter, smooth, circular outer envelope. Credits: Howard Bond (Space Telescope Science Institute), Robin Ciardullo (Pennsylvania State University) and NASA [Top center] - NGC 6826's eye-like appearance is marred by two sets of blood-red 'fliers' that lie horizontally across the image. The surrounding faint green 'white' of the eye is believed to be gas that made up almost half of the star's mass for most of its life. The hot remnant star (in the center of the green oval) drives a fast wind into older material, forming a hot interior bubble which pushes the older gas ahead of it to form a bright rim. (The star is one of the brightest stars in any planetary.) NGC 6826 is 2,200 light- years away in the constellation Cygnus. The Hubble telescope observation was taken Jan. 27, 1996 with the Wide Field and Planetary Camera 2. Credits: Bruce Balick (University of Washington), Jason Alexander (University of Washington), Arsen Hajian (U.S. Naval Observatory), Yervant Terzian (Cornell University), Mario Perinotto (University of Florence, Italy), Patrizio Patriarchi (Arcetri Observatory, Italy) and NASA [Top right ] - NGC 3918 is in the constellation Centaurus and is about 3,000 light-years from us. Its diameter is about 0.3 light-year. It shows a roughly spherical outer envelope but an elongated inner balloon inflated by a fast wind from the hot central star, which is starting to break out of the spherical envelope at the top and bottom of the image. Credits: Howard Bond (Space Telescope Science Institute), Robin Ciardullo (Pennsylvania State University) and NASA [Bottom left] - Hubble 5 is a striking example of a 'butterfly' or bipolar (two-lobed) nebula. The heat generated by fast winds causes

  8. Molecular Hydrogen in Planetary Nebulae

    NASA Astrophysics Data System (ADS)

    Speck, Angela K.; Baldridge, Sean; Matsuura, Mikako

    2015-08-01

    Planetary Nebulae (PNe) have long played the role of laboratories for investigating atomic, molecular, dust and plasma physics, which have applications to diverse other astrophysical environments. In this presentation we will discuss clumpy structures within planetary nebulae that are the hosts to, and protectors of molecular gas in an otherwise forbidding ionized zone. We will present new observations of the molecular hydrogen emission from several PNe and discuss their implications for the formation, evolution and survival/demise of such molecular globules. The science behind dust and molecule formation and survival that apply to many other astronomical objects and places.

  9. Ultraviolet photometry of planetary nebulae

    NASA Technical Reports Server (NTRS)

    Holm, A. V.

    1972-01-01

    Nine of the planetary nebulae observed by the Wisconsin filter photometers are compared with 15 Monocerotis in the spectral region 1430-4250 A. The data are corrected for the degradation of the filters of stellar photometer number four with time. Comparisons with simple models indicate that most of the observed nebulae are subject to some interstellar extinction in the far ultraviolet. However, NGC 246 and NGC 1360 appear to be nearly unreddened. Thus far no unexpected features have been found in the observations.

  10. The Formation of a Planetary Nebula.

    ERIC Educational Resources Information Center

    Harpaz, Amos

    1991-01-01

    Proposes a scenario to describe the formation of a planetary nebula, a cloud of gas surrounding a very hot compact star. Describes the nature of a planetary nebula, the number observed to date in the Milky Way Galaxy, and the results of research on a specific nebula. (MDH)

  11. Abundance patterns in planetary nebulae

    NASA Astrophysics Data System (ADS)

    Henry, Richard B. C.

    1990-06-01

    Abundances of He, N, O, and Ne have been uniformly calculated for 192 planetary nebulas residing in the Galactic disk and halo, the LMC, the SMC, and M31. Direct correlations appear to exist for type I as well as non-type I objects for the following pairs of parameters: N/O-He/H, N/O-N/H, and Ne/H-O/H. Separately, type I planetaries show a weak anticorrelation between N/O and O/H, while non-type I's exhibit direct correlations between N/H and O/H and between N/O and O/H. From these patterns, it is inferred that non-type I's synthesize N via the CN cycle. Type I planetaries, on the other hand, manufacture N at least partially via the ON cycle, destroying O in the process. Neither type appears to synthesize O or Ne.

  12. Planetary nebulae and stellar evolution

    NASA Technical Reports Server (NTRS)

    Maran, S. P.

    1983-01-01

    Newly defined characteristics of planetary nebulae (PN) derived from analysis of a photometric survey of 57 PN are reported. The data were combined with measurements of 27 other PN made since 1918 and were found to indicate core masses ranging from 0.55-1.0 solar mass. N/O elemental abundance ratios observed were correlated with the planetary nuclei masses, and were in direct proportion. IUE data on PN that overlapped a large part of the survey indicated that the PN in the galactic disk are more massive than PN in the halo. It is suggested that PN evolve into white dwarfs, a hypothesis supported by astrometric solutions for three nearby visual binaries featuring white dwarfs with well-determined masses. It is noted, however, that PN with masses exceeding one solar mass have been sighted in the Magellanic Clouds.

  13. MHD Solutions for Proto-Planetary Nebulae

    NASA Astrophysics Data System (ADS)

    García-Segura, G.; López, J. A.; Franco, J.

    2004-07-01

    This paper provides solutions for the origin of post-AGB winds, their acceleration up to high speed, and the subsequent formation of extremely collimated proto-planetary nebulae. Several wind models with terminal velocities from a few tens of kms up to 103 kms are calculated, which produce proto-planetary nebulae with linear momentum in the range 1036-1040 gcms and with kinetic energies in the range 1042-1047 erg. These results match available observations of proto-planetary nebulae. In the present simplistic scheme, the driver of the wind is just the magnetic pressure at the stellar surface. Other forces are not taken into account in this study, except gravity. We conclude that mass-loss rates of post-AGB stars and transition times from late AGB up to planetary nebula central stars could be directly linked with the production of magnetic field at the stellar core.

  14. 3-D structures of planetary nebulae

    NASA Astrophysics Data System (ADS)

    Steffen, W.

    2016-07-01

    Recent advances in the 3-D reconstruction of planetary nebulae are reviewed. We include not only results for 3-D reconstructions, but also the current techniques in terms of general methods and software. In order to obtain more accurate reconstructions, we suggest to extend the widely used assumption of homologous nebula expansion to map spectroscopically measured velocity to position along the line of sight.

  15. Several evolutionary channels for bright planetary nebulae

    NASA Astrophysics Data System (ADS)

    Richer, Michael G.; McCall, Marshall L.

    2016-08-01

    The populations of bright planetary nebulae in the discs of spirals appear to differ in their spectral properties from those in ellipticals and the bulges of spirals. The bright planetary nebulae from the bulge of the Milky Way are entirely compatible with those observed in the discs of spiral galaxies. The similarity might be explained if the bulge of the Milky Way evolved secularly from the disc, in which case the bulge should be regarded as a pseudo-bulge.

  16. Zinc abundances of planetary nebulae

    NASA Astrophysics Data System (ADS)

    Smith, C. L.; Zijlstra, A. A.; Dinerstein, H. L.

    2014-07-01

    Zinc is a useful surrogate element for measuring Fe/H as, unlike iron, it is not depleted in the gas phase media. Zn/H and O/Zn ratios have been derived using the [Zn IV] emission line at 3.625 μm for a sample of nine Galactic planetary nebulae, seven of which are based upon new observations using the Very Large Telescope (VLT). Based on photoionization models, O/O++ is the most reliable ionization correction factor for zinc that can readily be determined from optical emission lines, with an estimated accuracy of 10 per cent or better for all targets in our sample. The majority of the sample is found to be subsolar in [Zn/H]. [O/Zn] in half of the sample is found to be consistent with solar within uncertainties, whereas the remaining half are enhanced in [O/Zn]. [Zn/H] and [O/Zn] as functions of Galactocentric distance have been investigated and there is little evidence to support a trend in either case.

  17. GALEX Observations of Planetary Nebulae

    NASA Astrophysics Data System (ADS)

    Panda, Swayamtrupta

    2016-05-01

    The first ultraviolet (UV) photometric observations of planetary nebulae (PNe) are presented using observations made by the Galaxy Evolution Explorer (GALEX). We have found 108 PNe detected by GALEX and resolved their angular diameters in near-UV (NUV) and also in far-UV (FUV) for 28 PNe considering a 3σ emission level beyond the background. Of the PNe, 57 are elliptical, 41 are circular and the rest 10 are bipolar in NUV. The emission lines that contribute to the NUV intrinsic flux are C III] and He II. The measured intrinsic luminosities considering the sole contribution from the central stars have been found to lie in the range of 10^37-10^51 erg/s. The comparative study of the angular sizes against effective wavelengths in 5 distinct regimes has shown that the listed PNe are bright in NUV which opens up the discussion related to the extent of hotness, the very high temperatures of the CSPNe and the exact nature of it. The intensity contour plots of the PNe have also provided us with over 10 well-defined candidates having bipolar morphological signatures, the origin and evolution of whose can be traced back to the dynamics of stellar winds in the post-AGB stage.

  18. Reconstruction and visualization of planetary nebulae.

    PubMed

    Magnor, Marcus; Kindlmann, Gordon; Hansen, Charles; Duric, Neb

    2005-01-01

    From our terrestrially confined viewpoint, the actual three-dimensional shape of distant astronomical objects is, in general, very challenging to determine. For one class of astronomical objects, however, spatial structure can be recovered from conventional 2D images alone. So-called planetary nebulae (PNe) exhibit pronounced symmetry characteristics that come about due to fundamental physical processes. Making use of this symmetry constraint, we present a technique to automatically recover the axisymmetric structure of many planetary nebulae from photographs. With GPU-based volume rendering driving a nonlinear optimization, we estimate the nebula's local emission density as a function of its radial and axial coordinates and we recover the orientation of the nebula relative to Earth. The optimization refines the nebula model and its orientation by minimizing the differences between the rendered image and the original astronomical image. The resulting model allows creating realistic 3D visualizations of these nebulae, for example, for planetarium shows and other educational purposes. In addition, the recovered spatial distribution of the emissive gas can help astrophysicists gain deeper insight into the formation processes of planetary nebulae. PMID:16144246

  19. COMPARING SYMBIOTIC NEBULAE AND PLANETARY NEBULAE LUMINOSITY FUNCTIONS

    SciTech Connect

    Frankowski, Adam; Soker, Noam E-mail: soker@physics.technion.ac.i

    2009-10-01

    We compare the observed symbiotic nebulae (SyN) luminosity function (SyNLF) in the [O III] lambda5007 A line to the planetary nebulae (PN) luminosity function (PNLF) and find that the intrinsic SyNLF (ISyNLF) of galactic SyNs has-within its uncertainty of 0.5-0.8 mag-very similar cutoff luminosity and general shape to those of the PNLF. The [O III]/(Halpha+[N II]) line ratios of SyNs and PNs are shown to be also related. Possible implications of these results for the universality of the PNLF are briefly outlined.

  20. Physical Structure of Planetary Nebulae. I. The Owl Nebula

    NASA Astrophysics Data System (ADS)

    Guerrero, Martín A.; Chu, You-Hua; Manchado, Arturo; Kwitter, Karen B.

    2003-06-01

    The Owl Nebula is a triple-shell planetary nebula with the outermost shell being a faint bow-shaped halo. We have obtained deep narrowband images and high-dispersion echelle spectra in the Hα, [O III], and [N II] emission lines to determine the physical structure of each shell in the nebula. These spatiokinematic data allow us to rule out hydrodynamic models that can reproduce only the nebular morphology. Our analysis shows that the inner shell of the main nebula is slightly elongated with a bipolar cavity along its major axis, the outer nebula is a filled envelope coexpanding with the inner shell at 40 km s-1, and the halo has been braked by the interstellar medium as the Owl Nebula moves through it. To explain the morphology and kinematics of the Owl Nebula, we suggest the following scenario for its formation and evolution. The early mass loss at the TP-AGB phase forms the halo, and the superwind at the end of the AGB phase forms the main nebula. The subsequent fast stellar wind compressed the superwind to form the inner shell and excavated an elongated cavity at the center, but this has ceased in the past. At the current old age the inner shell is backfilling the central cavity. Based on observations made with the William Herschel Telescope, operated on the island of La Palma by the Isaac Newton Group in the Spanish Observatorio del Roque de Los Muchachos of the Instituto de Astrofísica de Canarias, and with the Burrell Schmidt telescope of the Warner and Swasey Observatory, Case Western Reserve University.

  1. MHD Solutions for Proto-Planetary Nebulae

    NASA Astrophysics Data System (ADS)

    García-Segura, G.; López, J. A.; Franco, J.

    2003-09-01

    This paper provides solutions for the origin of post-AGB winds, their acceleration up to high speed, and the subsequent formation of extremely collimated proto-planetary nebulae. Several wind models with terminal velocities from a few tens of voidb @xkms-1 up to 10^3 voidb @xkms-1 are calculated, which produce proto-planetary nebulae with linear momentum in the range 10^36 - 10^40 voidb @xgcms-1 and with kinetic energies in the range 10^42 - 10^47 erg. These results match available observations of proto-planetary nebulae. In the present simplistic scheme, the driver of the wind is just the magnetic pressure at the stellar surface. Other forces are not taken into account in this study, except gravity. We conclude that mass-loss rates of post-AGB stars and transition times from late AGB up to planetary nebula central stars could be directly linked with the production of magnetic field at the stellar core. As an example, mass-loss rates as large as 8×10^-5 M[ scriptstyle sun ]yr-1 and transition times as short as 5,000 years are predicted.

  2. Nebular UV Absorption Lines in Planetary Nebulae

    NASA Astrophysics Data System (ADS)

    Dinerstein, Harriet

    We propose to continue our Cycle 1 program of studying the Lyman and Werner bands of H_2, seen in absorption against the UV continua of planetary nebula central stars, which arise within neutral-molecular envelopes surrounding the ionized gas. These are the pump lines for a fluorescent cascade of near-infrared emission lines which are observed in many planetary nebulae. By observing the UV lines we can probe the chemical and thermal structure of the envelopes, as well as measure molecular column densities and clarify the excitation processes for the infrared lines. In Cycle 1 we were granted time for three targets, one of which was successfully observed shortly before submission of this proposal. Although the data were not yet available for examination, similar target observed by the project team revealed a rich set of H_2 circumstellar absorption features, demonstrating the feasibility of our program. FUSE spectra also include absorption features from atomic species such as O I and C II, which give rise to important far-infrared fine-structure cooling lines that likewise have been observed from planetary nebulae. In Cycle 2, we add as a secondary goal a search for nebular components of the O VI 032, 1038 AA absorption lines, which trace the presence of hot shocked gas, in nebulae with anomalously strong optical recombination lines of ions of oxygen and nitrogen. This will test a plausible hypothesis for the origin of this anomaly.

  3. Heat conduction fronts in planetary nebulae

    NASA Technical Reports Server (NTRS)

    Soker, Noam

    1994-01-01

    We present arguments which suggest that many of the x-ray, some optical, and some UV observations of planetary nebulae, can be explained by the presence of heat conduction fronts. The heat flows from the hot bubble formed by the shocked fast wind to the cool shell and halo. Heat conduction fronts are likely to account for emission of x rays from plasma at lower temperature than the expected temperature of the hot bubble. In the presence of magnetic fields, only a small fraction of the fast wind luminosity emerges as radiation. Heat conduction fronts can naturally produce some unusual line flux ratios, which are observed in some planetary nebulae. Heat conduction fronts may heat the halo and cause some material at the inner surface of the shell to expand slower than the rest of the shell. In the presence of an asymmetrical magnetic field, this flow, the x-ray intensity, and the emission lines, may acquire asymmetrical structure as well.

  4. Molecular line mapping of (young) planetary nebulae

    NASA Astrophysics Data System (ADS)

    Bujarrabal, Valentín

    2016-07-01

    In this contribution, I will review recent results obtained from high-resolution observations of molecular emission of planetary nebulae in the millimeter and submillimeter waves, stressing the easy interpretation of the data and the great amount of quantitative results obtained from them. Radio interferometers have been shown to be very efficient in the observation of our objects and, particularly since the arrival of ALMA, the amount of results is becoming impressive. We will deal mainly with young planetary nebulae or protoplanetary nebulae, since, as we will see, molecular lines tend to be weak in evolved objects because of photodissociation. In relatively young nebulae, the molecular gas represents most of the nebular material and can be well observed in line emission in mm- and submm-waves. Those observations have yielded many quantitative and accurate results on the structure, dynamics, and physical conditions of this largely dominant nebular component. In more evolved sources, we can follow the evolution of the chemical composition, although the data become rare.

  5. A newly discovered compact planetary nebula

    NASA Astrophysics Data System (ADS)

    Cappellaro, E.; Turatto, M.; Sabbadin, F.

    1989-07-01

    An H-alpha emission object is identified in a 103a-E + RG1 objective prism plate taken with the 92/67-cm Schmidt telescope of the Astronomical Observatory of Padua at Asiago (Italy). The object turns out to be a compact planetary nebula located at alpha(1950.0) = 18 h 4.3 min and delta(1950.0) = -8 deg 56.4 arcmin (classification code: 19 + 5 deg 1).

  6. Abundances, planetary nebulae, and stellar evolution

    NASA Technical Reports Server (NTRS)

    Aller, Lawrence H.

    1994-01-01

    Among Henry Norris Russell's many achievements were his contributions to solar and stellar spectroscopy, in particular, to an analysis of the chemical composition of the solar atmosphere. The question of composition differences between stars was hotly debated; some distinguished astronomers argued that all stars had the solar composition. Some early challenges to this doctrine are described. Determinations of chemical compositions of gaseous nebulae were much more difficult. If we observe the lines of a given chemical element in one ionization stage in a stellar spectrum, we can deduce readily the abundance of that element. No such luxury is available for a planetary or diffuse gaseous nebula. We must measure lines of as many ionization stages as we can. Furthermore, a nebula is an extended object. Often detailed spectroscopy is at hand only for narrow pencil columns taken through the image. Different observers use a variety of apertures. Fortunately it is possible to calculate theoretical spectra for any arbitrary cross section taken through a symmetrical model, so UV, optical, and IR observations all can be compared properly with a prediction. The value of high-resolution spectra obtained with instruments such as the Hamilton Echelle Spectrograph at Lick Observatory is emphasized. Improved fluxes for weak but important transitions are found. Close blends of lines of different ions can be resolved, and checks can be made on predictions of atomic parameters such as Einstein A-values and collision strengths. High spectral resolution data have been obtained and reduced for 22 planetary nebulae of varying size, structure, stellar population membership, dustiness, level of excitation, evolutionary status, and chemical compositions. The promise seems justified that with such extensive, high quality data, additional insights on nebular genesis and late states of stellar evolution can be found. The present survey is confined to nebulae of high surface brightness, but

  7. Abundances, planetary nebulae, and stellar evolution

    NASA Astrophysics Data System (ADS)

    Aller, Lawrence H.

    1994-09-01

    Among Henry Norris Russell's many achievements were his contributions to solar and stellar spectroscopy, in particular, to an analysis of the chemical composition of the solar atmosphere. The question of composition differences between stars was hotly debated; some distinguished astronomers argued that all stars had the solar composition. Some early challenges to this doctrine are described. Determinations of chemical compositions of gaseous nebulae were much more difficult. If we observe the lines of a given chemical element in one ionization stage in a stellar spectrum, we can deduce readily the abundance of that element. No such luxury is available for a planetary or diffuse gaseous nebula. We must measure lines of as many ionization stages as we can. Furthermore, a nebula is an extended object. Often detailed spectroscopy is at hand only for narrow pencil columns taken through the image. Different observers use a variety of apertures. Fortunately it is possible to calculate theoretical spectra for any arbitrary cross section taken through a symmetrical model, so UV, optical, and IR observations all can be compared properly with a prediction. The value of high-resolution spectra obtained with instruments such as the Hamilton Echelle Spectrograph at Lick Observatory is emphasized. Improved fluxes for weak but important transitions are found. Close blends of lines of different ions can be resolved, and checks can be made on predictions of atomic parameters such as Einstein A-values and collision strengths. High spectral resolution data have been obtained and reduced for 22 planetary nebulae of varying size, structure, stellar population membership, dustiness, level of excitation, evolutionary status, and chemical compositions. The promise seems justified that with such extensive, high quality data, additional insights on nebular genesis and late states of stellar evolution can be found. The present survey is confined to nebulae of high surface brightness, but

  8. HUBBLE CAPTURES UNVEILING OF PLANETARY NEBULA

    NASA Technical Reports Server (NTRS)

    2002-01-01

    This Wide Field and Planetary Camera 2 image captures the infancy of the Stingray nebula (Hen-1357), the youngest known planetary nebula. In this image, the bright central star is in the middle of the green ring of gas. Its companion star is diagonally above it at 10 o'clock. A spur of gas (green) is forming a faint bridge to the companion star due to gravitational attraction. The image also shows a ring of gas (green) surrounding the central star, with bubbles of gas to the lower left and upper right of the ring. The wind of material propelled by radiation from the hot central star has created enough pressure to blow open holes in the ends of the bubbles, allowing gas to escape. The red curved lines represent bright gas that is heated by a 'shock' caused when the central star's wind hits the walls of the bubbles. The nebula is as large as 130 solar systems, but, at its distance of 18,000 light-years, it appears only as big as a dime viewed a mile away. The Stingray is located in the direction of the southern constellation Ara (the Altar). The colors shown are actual colors emitted by nitrogen (red), oxygen (green), and hydrogen (blue). The filters used were F658N ([N II]), F502N ([O III]), and F487N (H-beta). The observations were made in March 1996. Credit: Matt Bobrowsky, Orbital Sciences Corporation and NASA

  9. Planetary nebulae and the interstellar medium

    NASA Technical Reports Server (NTRS)

    Aller, L. H.

    1986-01-01

    In addition to available published data on planetary nebulae (PN), some 40 objects largely concentrated towards the galactic center and anticenter regions were included. All were observed with the Lick 3(sup m) telescope and image tube scanner. Abundances of C, N, O, Ne, Cl, and Ar were determined by a procedure in which theoretical models were used to obtain ionization correction factors (ICF). Of the 106 PN, 66 are N-rich and 40 are N-poor. There appear to be no significant differences between the average compositions in the solar neighborhood and the average taken over the entire observable portion of the galaxy.

  10. NGC 2242 - A newly discovered planetary nebula

    NASA Astrophysics Data System (ADS)

    Maehara, H.; Okamura, S.; Noguchi, T.; He, X. T.; Liu, J. Y.; Huang, Y. W.; Feng, X.-C.

    1987-05-01

    Photometric and spectroscopic analyses are made for the object NGC 2242, which was detected in a survey of emission-line galaxies by Liu et al. (1986). Luminosity and color distributions and a small heliocentric velocity (-30 km s-1) are all inconsistent with previous classifications as a galaxy. NGC 2242 is probably a planetary nebula located at ≡2 kpc from the sun and at ≡500 pc above the galactic plane. Characteristics and physical parameters of NGC 2242 are discussed in some detail.

  11. The expansion velocity field within the planetary nebula NGC 7008

    NASA Astrophysics Data System (ADS)

    Sabbadin, F.; Ortolani, S.; Bianchini, A.; Hamzaoglu, E.

    1983-06-01

    The forbidden O III, H-alpha, and forbidden N II expansion velocity fields within the planetary nebula NGC 7008 have been obtained from high dispersion spectrograms. The photographic and spectroscopic data indicate that this nebula is very inhomogeneous. A rough model consists of two coaxial prolate spheroids of moderate ellipticity. Evidence is presented that K 4-44 (93 + 5 deg 1), classified as a distinct planetary nebula in the Catalogue of Galactic Planetary Nebulae of Perek and Kohoutek (1967) is a condensation within NGC 7008.

  12. Hierarchies of Models: Toward Understanding Planetary Nebulae

    NASA Technical Reports Server (NTRS)

    Knuth, Kevin H.; Hajian, Arsen R.; Clancy, Daniel (Technical Monitor)

    2003-01-01

    Stars like our sun (initial masses between 0.8 to 8 solar masses) end their lives as swollen red giants surrounded by cool extended atmospheres. The nuclear reactions in their cores create carbon, nitrogen and oxygen, which are transported by convection to the outer envelope of the stellar atmosphere. As the star finally collapses to become a white dwarf, this envelope is expelled from the star to form a planetary nebula (PN) rich in organic molecules. The physics, dynamics, and chemistry of these nebulae are poorly understood and have implications not only for our understanding of the stellar life cycle but also for organic astrochemistry and the creation of prebiotic molecules in interstellar space. We are working toward generating three-dimensional models of planetary nebulae (PNe), which include the size, orientation, shape, expansion rate and mass distribution of the nebula. Such a reconstruction of a PN is a challenging problem for several reasons. First, the data consist of images obtained over time from the Hubble Space Telescope (HST) and spectra obtained from Kitt Peak National Observatory (KPNO) and Cerro Tololo Inter-American Observatory (CTIO). These images are of course taken from a single viewpoint in space, which amounts to a very challenging tomographic reconstruction. Second, the fact that we have two disparate and orthogonal data types requires that we utilize a method that allows these data to be used together to obtain a solution. To address these first two challenges we employ Bayesian model estimation using a parameterized physical model that incorporates much prior information about the known physics of the PN. In our previous works we have found that the forward problem of the comprehensive model is extremely time consuming. To address this challenge, we explore the use of a set of hierarchical models, which allow us to estimate increasingly more detailed sets of model parameters. These hierarchical models of increasing complexity are akin

  13. Hierarchies of Models: Toward Understanding Planetary Nebulae

    NASA Technical Reports Server (NTRS)

    Knuth, Kevin H.; Hajian, Arsen R.; Clancy, Daniel (Technical Monitor)

    2002-01-01

    Stars like our sun (initial masses between 0.8 to 8 solar masses) end their lives as swollen red giants surrounded by cool extended atmospheres. The nuclear reactions in their cores create carbon, nitrogen and oxygen, which are transported by convection to the outer envelope of the stellar atmosphere. As the star finally collapses to become a white dwarf, this envelope is expelled from the star to form a planetary nebula (PN) rich in organic molecules. The physics, dynamics, and chemistry of these nebulae are poorly understood and have implications not only for our understanding of the stellar life cycle but also for organic astrochemistry and the creation of prebiotic molecules in interstellar space. We are working toward generating three-dimensional models of planetary nebulae (PNe), which include the size, orientation, shape, expansion rate and mass distribution of the nebula. Such a reconstruction of a PN is a challenging problem for several reasons. First, the data consist of images obtained over time from the Hubble Space Telescope (HST) and spectra obtained from Kitt Peak National Observatory (KPNO) and Cerro Tololo Inter-American Observatory (CTIO). These images are of course taken from a single viewpoint in space, which amounts to a very challenging tomographic reconstruction. Second, the fact that we have two disparate and orthogonal data types requires that we utilize a method that allows these data to be used together to obtain a solution. To address these first two challenges we employ Bayesian model estimation using a parameterized physical model that incorporates much prior information about the known physics of the PN. In our previous works we have found that the forward problem of the comprehensive model is extremely time consuming. To address this challenge, we explore the use of a set of hierarchical models, which allow us to estimate increasingly more detailed sets of model parameters. These hierarchical models of increasing complexity are akin

  14. Abundances in the Planetary Nebula IC 5217

    NASA Technical Reports Server (NTRS)

    Hyung, Siek; Aller, Lawrence H.; Feibelman, Walter A.; Lee, Woo-Baik; Fisher, Richard R. (Technical Monitor)

    2001-01-01

    High resolution optical wavelength spectroscopic data were secured in the optical wavelengths, 3700A - 10,050A, for the planetary nebula IC 5217 with the Hamilton Echelle Spectrograph at Lick Observatory. These optical spectra have been analyzed along with the near-UV and UV archive data. Diagnostic analyses indicate a nebular physical condition with electron temperature of about 10,700 K (from the [O III] lines) and the density of N(sub epsilon) = 5000/cm. Ionic concentrations have been derived with the representative diagnostics, and with the aid of a photoionization model construction, we derived the elemental abundances. Contrary to the previous studies found in the literature, He and C appear to be depleted compared to the average planetary nebula and to the Sun (and S marginally so), while the remaining elements appear to be close to the average value. IC 5217 may have evolved from an O-rich progenitor and the central star temperature of IC 5217 is likely to be 92,000 K.

  15. CRL 618: A Nascent Planetary Nebula

    NASA Astrophysics Data System (ADS)

    Tafoya, D.; Loinard, L.; Fonfría, J. P.; Vlemmings, W. H. T.; Martí-Vidal, I.; Pech, G.

    2014-04-01

    CRL 618 is an object that exhibits characteristics of both AGB and post-AGB star. It also displays a spectacular array of bipolar lobes with a dense equatorial region, which makes it an excellent object to study the development of asymmetries in evolved stars. In the recent decades, an elliptical compact HII region located in the center of the nebula has been seen to be increasing in size and flux. This seems to be due to the ionization of the circumstellar envelope by the central star, and it would be indicating the beginning of the planetary nebula phase for CRL 618. We analyzed interferometric radio continuum data at ~5 and 22 GHz from observations carried out at seven epochs with the VLA. We traced the increase of the flux of the ionized region over a period of ~26 years. We measured the dimensions of the HII region directly from the brightness distribution images to determine the increase of its size over time. For one of the epochs we analyzed observations at six frequencies from which we estimated the electron density distribution. We carried out model calculations of the spectral energy distribution at two different epochs to corroborate our observational results. We found that the radio continuum flux and the size of the ionized region have been increasing monotonically in the last three decades. The size of the major axis of the HII region shows a dependance with frequency, which has been interpreted as a result of a gradient of the electron density in this direction. The growth of the HII region is due to the expansion of an ionized wind whose mass-loss rate increased continuously for a period of ~100 years until a few decades ago, when the mass-loss rate experienced a sudden decline. Our results indicate that the beginning of the ionization of the circumstellar envelope began around 1971, which marks the start of the planetary nebula phase of CRL 618.

  16. Ultraviolet spectra of planetary nebulae. X - Physical conditions in the compact planetary nebula Sw St 1

    NASA Technical Reports Server (NTRS)

    Flower, D. R.; Goharji, A.; Cohen, M.

    1984-01-01

    Photoelectric visual and ultraviolet observations of the compact planetary nebula Sw St 1 are analyzed. The electron density, determined from the C III 1907/1909 A line ratio, is N(e) = (1.1 + or - 0.1) x 10 to the 5th/cu cm, consistent with the high emission measure and high critical frequency determined from observations of the thermal radio emission. The C/O abundance ratio in the nebula is found to be N(C)/N(O) = 0.72 + or - 0.1, i.e. the envelope is oxygen-rich, as suggested by the identification of the silicate feature in the 8-13 micron infrared spectrum. Difficulties remain in accurately determining the reddening constant to the nebula and its electron temperature.

  17. THE ROTTEN EGG NEBULA A PLANETARY NEBULA IN THE MAKING

    NASA Technical Reports Server (NTRS)

    2002-01-01

    The object shown in these NASA/ESA Hubble Space Telescope images is a remarkable example of a star going through death throes just as it dramatically transforms itself from a normal red giant star into a planetary nebula. This process happens so quickly that such objects are quite rare, even though astronomers believe that most stars like the Sun will eventually go through such a phase. This star, with the prosaic name of OH231.8+4.2, is seen in these infrared pictures blowing out gas and dust in two opposite directions. So much dust has been cast off and now surrounds the star that it cannot be seen directly, only its starlight that is reflected off the dust. The flow of gas is very fast, with a velocity up to 450,000 mph (700,000 km/h). With extreme clarity, these Hubble Near Infrared Camera and Multi-Object Spectrometer (NICMOS) images reveal that the fast-moving gas and dust are being collimated into several thin streamers (on the right) and a jet-like structure (on the left), which can be seen extending away from the centers of both pictures. On the right, wisps of material in jet-like streamers appear to strike some dense blobs of gas. This interaction must produce strong shock waves in the gas. The pictures represent two views of the object. The color image is a composite of four images taken with different NICMOS infrared filters on March 28, 1998. It shows that the physical properties of the material, both composition and temperature, vary significantly throughout the outflowing material. The black-and-white image was taken with one NICMOS infrared filter. That image is able to show more clearly the faint detail and structure in the nebula than can be achieved with the color composites. Observations by radio astronomers have found many unusual molecules in the gas around this star, including many containing sulfur, such as hydrogen sulfide and sulfur dioxide. These sulfur compounds are believed to be produced in the shock waves passing through the gas

  18. Atlas of monochromatic images of planetary nebulae

    NASA Astrophysics Data System (ADS)

    Weidmann, W. A.; Schmidt, E. O.; Vena Valdarenas, R. R.; Ahumada, J. A.; Volpe, M. G.; Mudrik, A.

    2016-08-01

    We present an atlas of more than one hundred original images of planetary nebulae (PNe). These images were taken in a narrow-band filter centred on the nebular emission of the [N ii] during several observing campaigns using two moderate-aperture telescopes, at the Complejo Astronómico El Leoncito (CASLEO), and the Estación Astrofísica de Bosque Alegre (EABA), both in Argentina. The data provided by this atlas represent one of the most extensive image surveys of PNe in [N ii]. We compare the new images with those available in the literature, and briefly describe all cases in which our [N ii] images reveal new and interesting structures. The reduced images as FITS files are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/592/A103

  19. Radial velocities of Planetary Nebulae revisited

    NASA Astrophysics Data System (ADS)

    Vázquez, Roberto; Ayala, Sandra A.; Wendolyn Blanco Cárdenas, Mónica; Contreras, María E.; Gómez-Muñoz, Marco Antonio; Guillén, Pedro F.; Olguín, Lorenzo; Ramos-Larios, Gerardo; Sabin, Laurence; Zavala, Saúl A.

    2015-08-01

    We present a new determination of radial velocities of a sample of Galactic Planetary Nebulae (PNe) using a systematic method and the same instrumental setting: the long-slit high-dispersion Manchester Echelle Spectrograph (MES) on the 2.1-m telescope at the San Pedro Mártir Observatory (OAN-SPM; Mexico). This project was inspired by the work of Schneider et al. (1983, A&AS, 52, 399), which has been an important reference during the last decades. Radial velocities of gaseous nebulae can be obtained using the central wavelength of a Gaussian fit, even when there is an expansion velocity, as expected in PNe, but with not enough resolution to see a spectral line splitting. We have used the software SHAPE, a morpho-kinematic modeling and reconstruction tool for astrophysical objects (Steffen et al. 2011, IEEE Trans. Vis. Comput. Graphics, 17, 454), to prove that non-uniform density or brightness, on an expanding shell, can lead to mistaken conclusions about the radial velocity. To determine radial velocities, we only use the spectral data in which a spectral line-splitting is seen, avoiding thus the problem of the possible biased one-Gaussian fit. Cases when this method is not recommended are discussed.This project has been supported by grant PAPIIT-DGAPA-UNAM IN107914. MWB is in grateful receipt of a DGAPA-UNAM postdoctoral scholarship. MAG acknowledges CONACYT for his graduate scholarship.

  20. Temperature Scale of Central Stars Planetary Nebulae

    NASA Technical Reports Server (NTRS)

    Kruk, Jeffry

    2005-01-01

    The goal of this project was to gain new insight into both the true temperatures of the central stars of planetary nebulae and their evolutionary histories. The temperature scale of the hottest central stars of planetary nebulae is poorly known. The temperature diagnostics available at visible wavelengths are not useful for these very hot stars, or suffer from as-yet unresolved systematic uncertainties. However, the combination of FUSE FUV spectra and HST NUV spectra allows precise temperature determinations by utilizing ionization balances of C III, C IV and O V, O VI lines. The sample comprises hot hydrogen-rich central stars covering the hottest phase of post-AGB evolution (T_eff greater than 70,000K). The spectra were analyzed with fully metal line blanketed NLTE model atmospheres in order to determine T_eff, surface gravity, and chemical composition. In addition to the temperature scale, the spectra help address the question of metal abundances at the surface of these stars. Depending on the particular star, the metal abundances are either dominated by ongoing diffusion processes or they originate from dredge-up phases during previous AGB evolution. The sample was selected so as to include objects that were expected to exhibit both processes, in order to assess their relative importance and to gain insight into the evolutionary history of the stars. The objects that show qualitatively a metal abundance pattern which points at dredge-up phases, can be used to quantitatively check against abundance predictions of stellar evolution theory. The other objects, where gravitational diffusion and radiative acceleration determine the photospheric metal abundances, will be used to check our NLTE models which for the first time include diffusion processes self-consistently.

  1. Estimating the Binary Fraction of Central Stars of Planetary Nebulae

    NASA Astrophysics Data System (ADS)

    Douchin, Dimitri

    2015-01-01

    Planetary nebulae are the end-products of intermediate-mass stars evolution, following a phase of expansion of their atmospheres at the end of their lives. Observationally, it has been estimated that 80% of them have non-spherical shapes. Such a high fraction is puzzling and has occupied the planetary nebula community for more than 30 years. One scenario that would allow to justify the observed shapes is that a comparable fraction of the progenitors of central stars of planetary nebula (CSPN) are not single, but possess a companion. The shape of the nebulae would then be the result of an interaction with this companion. The high fraction of non-spherical planetary nebulae would thus imply a high fraction of binary central stars of planetary nebulae, making binarity a preferred channel for planetary nebula formation. After presenting the current state of knowledge regarding planetary nebula formation and shaping and reviewing the diverse efforts to find binaries in planetary nebulae, I present my work to detect a near-infrared excess that would be the signature of the presence of cool companions. The first part of the project consists in the analysis of data and photometry acquired and conducted by myself. The second part details an attempt to make use of archived datasets: the Sloan Digital Sky Survey Data Release 7 optical survey and the extended database assembled by Frew (2008). I also present results from a radial velocity analysis of VLT/UVES spectra for 14 objects aiming to the detection of spectroscopic companions. Finally I give details of the analysis of optical photometry data from our observations associated to the detection of companions around central stars of planetary nebulae using the photometric variability technique. The main result of this thesis is from the near-infrared excess studies which I combine with previously published data. I conclude that if the detected red and NIR flux excess is indicative of a stellar companion then the binary

  2. ISO Spectroscopy of Proto-Planetary Nebulae

    NASA Technical Reports Server (NTRS)

    Hrivnak, Bruce J.

    2000-01-01

    The goal of this program was to determine the chemical properties of the dust shells around protoplanetary nebulae (PPNs) through a study of their short-wavelength (6-45 micron) infrared spectra. PPNs are evolved stars in transition from the asymptotic giant branch to the planetary nebula stages. Spectral features in the 10 to 20 gm region indicate the chemical nature (oxygen- or carbon-rich), and the strengths of the features relate to the physical properties of the shells. A few bright carbon-rich PPNs have been observed to show PAH features and an unidentified 21 micron emission feature. We used the Infrared Space Observatory (ISO) to observe a sample of IRAS sources that have the expected properties of PPNs and for which we have accurate positions. Some of these have optical counterparts (proposal SWSPPN01) and some do not (SWSPPN02). We had previously observed these from the ground with near-infrared photometry and, for those with visible counterparts, visible photometry and spectroscopy, which we have combined with these new ISO data in the interpretation of the spectra. We have completed a study of the unidentified emission feature at 21 micron in eight sources. We find the shape of the feature to be the same in all of the sources, with no evidence of any substructure. The ratio of the emission peak to continuum ranges from 0.13 to 1.30. We have completed a study of seven PPNs and two other carbon-rich objects for which we had obtained ISO 2-45 micron observations. The unidentified emission features at 21 and 30 micron were detected in six sources, including four new detections of the 30 micron feature. This previously unresolved 30 micron feature was resolved and found to consist of a broad feature peaking at 27.2 micron (the "30 micron" feature) and a narrower feature peaking at 25.5 micron (the "26 micron" feature). This new 26 micron feature is detected in eight sources and is particularly strong in IRAS Z02229+6208 and 16594-4656. The unidentified

  3. The Very Fast Evolution of Bi-Lobed Planetary Nebulae

    NASA Astrophysics Data System (ADS)

    Gesicki, K.; Zijlstra, A. A.; Morisset, C.

    2015-12-01

    We study the kinematical ages of six Galactic bulge planetary nebulae selected purely on their bi-lobed morphology. The ages are derived from pseudo-3D photoionization and kinematical models, using HST images and UVES spectra and assuming axial symmetry. The bi-lobed nebulae show similar kinematical ages (˜1500 yrs), despite of their different sizes, expansion velocities and stellar temperatures.

  4. The Variable Central Star of Planetary Nebula NGC2346

    NASA Astrophysics Data System (ADS)

    Kohoutek, L.

    1983-06-01

    NGC 2346, known already to Sir William Herschel, has been classified as a planetary nebula by R. Minkowski (1946) on the basis of its appearance on direct photographs. Morphologically it POssesses a distinct axial symmetry and belongs to the class of bipolar nebulae

  5. Asymmetry of planetary nebulae: Collimated ionized jets in butterfly nebulae and dust extinction effects in compact planetary nebulae

    NASA Astrophysics Data System (ADS)

    Lee, Ting-Hui

    Planetary Nebulae (PNe) are the transition phase between asymptotic giant branch (AGB) stars and white dwarfs for stars with masses between 1 and 8 [Special characters omitted.] . Though originally thought to be explainable with simple models, the shapes of PNe have been found to be much more complex in striking images taken with the Hubble Space Telescope ( HST ). I have investigated two possible causes of the asymmetric appearances of PNe: collimated ionized winds and dust extinction. Narrow-waist bipolar nebulae (butterfly nebulae) may be sculpted by a collimated ionized wind from the central binary star system (Livio & Soker 2001). The system consists of a mass-losing AGB star that is responsible for the nebular material and a white dwarf companion star that is responsible for the ionizing flux. Motivated by the discovery of an ionized jet in the bipolar nebula M 2-9 (Lim & Kwok 2003) that may be responsible for sculpting the nebula's mirror-symmetric structure, I have searched for optically thick cores at radio wavelengths--a characteristic signature of collimated ionized winds-- in sixteen butterfly nebulae. 11 northern nebulae were observed with the Very Large Array (VLA) at 1.3 cm and 0.7 cm, and 5 southern nebulae were observed with the Australia Telescope Compact Array (ATCA) at 6 cm and 3.6 cm. Two northern objects, 19W32 and M 1-91, and two southern objects, He 2-84 and Mz 3, were found to exhibit a compact radio core with a rising spectrum consistent with an ionized jet. Here I present an analysis of these four radio cores and discuss the implications of the results. The shape of PNe is predominantly axisymmetric. However, many PNe also exhibit non-axisymmetric structures. Non-axisymmetry, such as unequal intensity or size at the two sides, could be caused by the two sides having different amounts of dust extinction along the line of sight. To investigate whether dust extinction might cause the observed asymmetry, I use an indirect method to probe the

  6. Planetary Nebulae with Supporting IR Data

    NASA Technical Reports Server (NTRS)

    Harrington, J. Patrick

    1999-01-01

    We present new HST/WFPC2 imagery for the planetary nebula (PN) NGC 6818. Observations were made in line filters F437N, F487N, F502N, and F656N plus continuum filter F547M. The primary goal was to develop a high spatial resolution (approx. 0.1 in.) map of the intrinsic line ratio [O III] 4363/5007 and thereby evaluate the electron temperature (T(sub e)) and the mean-square T(sub e) variation (t(sup 2) across the PN. In this process we developed an extinction map from the F487N (H(beta)) and F656N (H(alpha)) images by comparing the observed line ratios in each pixel to the theoretical ratio and computing a c(H(beta)) map which was used to correct the observed 4363/5007 ratios for reddening. We also adjust for the continuum contribution to the line filter data. We present color-coded pictures of the reddening (c(H(beta))) map, the [O III] T(sub e) map, as well as our determinations of t(sup 2). The T(sub e) map shows a decline from approx. 14000 K in the inner regions to approx. 11000 K at the outer edge. Such a radial T(sub e) gradient is expected for a high-excitation nebula with a prominent He(++) zone such as NGC 6818. A composite of images taken in 3 filters (F656N, red; F487N, blue; and F502N, [O III] 5007, green) shows a roughly spherical outer envelope as well as a brighter vase-shaped interior "bubble". There is a prominent orifice to the North and a smaller one to the South, along the major axis, possibly caused by a blow-out from a fast wind. This nebula has an appearance remarkably similar to that of the PN NGC 3918 previously imaged with HST by H. Bond. We note from the continuum images (F547M) two stars in the nebular field that are fainter than the prominent central star; these are roughly 2-4 sec. N and NE of the central star. Further study is needed to establish whether or not there may be a physical association of either star with the central star.

  7. A survey for PAH emission in H II regions, planetary and proto-planetary nebulae

    NASA Technical Reports Server (NTRS)

    Demuizon, M.; Cox, P.; Lequeux, J.

    1989-01-01

    The results of a systematic investigation of polycyclic aromatic hydrocarbon (PAH) emission in H II regions, planetary nebulae (PN), and proto-planetary nebulae (PNN), are reported. Data is obtained from the low resolution spectra (LRS) of IRAS. The results show that: PAHs are formed in carbon rich objects; and PAH emission is ubiquitous in general interstellar medium and requires the presence of ultraviolet photons, in planetary and proto-planetary nebulae, PAH emission is seen only where an ionizing flux is present and in carbon rich objects.

  8. A Study of the Planetary Nebula M57

    NASA Technical Reports Server (NTRS)

    Archie, Deithra; Moore, Brian

    2000-01-01

    We present an overview of the objects known as planetary nebulae. These emission nebulae are the end-product of the evolution of a dying star. our ground-based imagery is of the most famous of these objects, M57, also known as the Ring Nebula. Taken with the 2.12-meter telescope at San Pedro Matir in Baja, Mexico, these seeing-limited images show variations in ionization, density and temperature as a function of position in the nebula. Our ground-based imagery is compared to similar HST archival images.

  9. Planetary nebulae in the Small Magellanic Cloud

    NASA Astrophysics Data System (ADS)

    Ventura, P.; Stanghellini, L.; Di Criscienzo, M.; García-Hernández, D. A.; Dell'Agli, F.

    2016-08-01

    We analyse the planetary nebulae (PNe) population of the Small Magellanic Cloud (SMC), based on evolutionary models of stars with metallicities in the range 10-3 ≤ Z ≤ 4 × 10-3 and mass 0.9 M⊙ < M < 8 M⊙, evolved through the asymptotic giant branch (AGB) phase. The models used account for dust formation in the circumstellar envelope. To characterize the PNe sample of the SMC, we compare the observed abundances of the various species with the final chemical composition of the AGB models: this study allows us to identify the progenitors of the PNe observed, in terms of mass and chemical composition. According to our interpretation, most of the PNe descend from low-mass (M < 2 M⊙) stars, which become carbon rich, after experiencing repeated third dredge-up episodes, during the AGB phase. A fraction of the PNe showing the signature of advanced CNO processing are interpreted as the progeny of massive AGB stars, with mass above ˜6 M⊙, undergoing strong hot bottom burning. The differences with the chemical composition of the PNe population of the Large Magellanic Cloud is explained on the basis of the diverse star formation history and age-metallicity relation of the two galaxies. The implications of this study for some still highly debated points regarding the AGB evolution are also commented.

  10. Abundances in Eight M31 Planetary Nebulae

    NASA Astrophysics Data System (ADS)

    Hensley, Kerry G.; Kwitter, Karen B.; Corradi, Romano; Galera-Rosillo, R.; Balick, Bruce; Henry, Richard B. C.

    2014-06-01

    As part of a continuing project using planetary nebulae (PNe) to study the chemical evolution and formation history of M31 (see accompanying poster by Balick et al.), we obtained spectra of eight PNe in the fall of 2013 with the OSIRIS spectrograph on the GTC. All of these PNe are located outside M31’s inner disk and bulge. Spectral coverage extended from 3700-7800Å with a resolution of ~6 Å. Especially important in abundance determinations is the detection of the weak, temperature-sensitive auroral line of [O III], at 4363Å, which is often contaminated by Hg I 4358Å from streetlights; the remoteness of the GTC eliminated this difficulty. We reduced and measured the spectra using IRAF, and derived nebular diagnostics and abundances with ELSA, our in-house five-level-atom program. Here we report the chemical abundances determined from these spectra. The bottom line is that the oxygen abundances in these PNe are all within a factor of 2-3 of the solar value, (as are all the other M31 PNe our team has previously measured) despite the significant range of galactocentric distance. Future work will use these abundances to constrain models of the central star to estimate progenitor masses and ages. In particular we will use the results to investigate the hypothesis that these PNe might represent a population related to the encounter between M31 and M33 ~3 Gy ago. We gratefully acknowledge support from Williams College.

  11. Spectroscopy of planetary nebulae in M 33

    NASA Astrophysics Data System (ADS)

    Magrini, L.; Perinotto, M.; Corradi, R. L. M.; Mampaso, A.

    2003-03-01

    Spectroscopic observations of 48 emission-line objects of M 33 have been obtained with the multi-object, wide field, fibre spectrograph AF2/WYFFOS at the 4.2 m WHT telescope (La Palma, Spain). Line intensities and logarithmic extinction, cbeta , are presented for 42 objects. Their location in the Sabbadin & D'Odorico diagnostic diagram (Hα /[S II] vs. Hα /[N II]) suggests that >70% of the candidates are Planetary Nebulae (PNe). Chemical abundances and nebular physical parameters have been derived for the three of the six PNe where the 4363 Å, [O II]i emission line was measurable. These are disc PNe, located within a galactocentric distance of 4.1 kpc, and, to date, they are the farthest PNe with a direct chemical abundance determination. No discrepancy in the helium, Oxygen and Argon abundances has been found in comparison with corresponding abundances of PNe in our Galaxy. Only a lower limit to the sulphur abundance has been obtained since we could not detect any [S III] line. N/H appears to be lower than the Galactic value; some possible explanations for this under-abundance are discussed. Based on observations obtained at the 4.2 m WHT telescope operated on the island of La Palma by the Isaac Newton Group in the Spanish Observatorio del Roque de Los Muchachos of the Instituto de Astrofisica de Canarias.

  12. Planetary nebulae in the Small Magellanic Cloud

    NASA Astrophysics Data System (ADS)

    Ventura, P.; Stanghellini, L.; Di Criscienzo, M.; García-Hernández, D. A.; Dell'Agli, F.

    2016-08-01

    We analyse the planetary nebulae (PNe) population of the Small Magellanic Cloud (SMC), based on evolutionary models of stars with metallicities in the range $10^{-3} \\leq Z \\leq 4\\times 10^{-3}$ and mass $0.9 M\\odot < M < 8M\\odot$, evolved through the asymptotic giant branch (AGB) phase. The models used account for dust formation in the circumstellar envelope. To characterise the PNe sample of the SMC, we compare the observed abundances of the various species with the final chemical composition of the AGB models: this study allows us to identify the progenitors of the PNe observed, in terms of mass and chemical composition. According to our interpretation, most of the PNe descend from low-mass ($M < 2 M\\odot$) stars, which become carbon rich, after experiencing repeated third dredge-up episodes, during the AGB phase. A fraction of the PNe showing the signature of advanced CNO processing are interpreted as the progeny of massive AGB stars, with mass above $\\sim 6 M\\odot$, undergoing strong hot bottom burning. The differences with the chemical composition of the PNe population of the Large Magellanic Cloud (LMC) is explained on the basis of the diverse star formation history and age-metallicity relation of the two galaxies. The implications of the present study for some still highly debated points regarding the AGB evolution are also commented.

  13. Planetary nebula progenitors that swallow binary systems

    NASA Astrophysics Data System (ADS)

    Soker, Noam

    2016-01-01

    I propose that some irregular messy planetary nebulae (PNe) owe their morphologies to triple-stellar evolution where tight binary systems evolve inside and/or on the outskirts of the envelope of asymptotic giant branch (AGB) stars. In some cases, the tight binary system can survive, in others, it is destroyed. The tight binary system might break up with one star leaving the system. In an alternative evolution, one of the stars of the broken-up tight binary system falls towards the AGB envelope with low specific angular momentum, and drowns in the envelope. In a different type of destruction process, the drag inside the AGB envelope causes the tight binary system to merge. This releases gravitational energy within the AGB envelope, leading to a very asymmetrical envelope ejection, with an irregular and messy PN as a descendant. The evolution of the triple-stellar system can be in a full common envelope evolution or in a grazing envelope evolution. Both before and after destruction (if destruction takes place), the system might launch pairs of opposite jets. One pronounced signature of triple-stellar evolution might be a large departure from axisymmetrical morphology of the descendant PN. I estimate that about one in eight non-spherical PNe is shaped by one of these triple-stellar evolutionary routes.

  14. Absolute spectrophotometry of northern compact planetary nebulae

    NASA Astrophysics Data System (ADS)

    Wright, S. A.; Corradi, R. L. M.; Perinotto, M.

    2005-06-01

    We present medium-dispersion spectra and narrowband images of six northern compact planetary nebulae (PNe): BoBn 1, DdDm 1, IC 5117, M 1-5, M 1-71, and NGC 6833. From broad-slit spectra, total absolute fluxes and equivalent widths were measured for all observable emission lines. High signal-to-noise emission line fluxes of Hα, Hβ, [Oiii], [Nii], and HeI may serve as emission line flux standards for northern hemisphere observers. From narrow-slit spectra, we derive systemic radial velocities. For four PNe, available emission line fluxes were measured with sufficient signal-to-noise to probe the physical properties of their electron densities, temperatures, and chemical abundances. BoBn 1 and DdDm 1, both type IV PNe, have an Hβ flux over three sigma away from previous measurements. We report the first abundance measurements of M 1-71. NGC 6833 measured radial velocity and galactic coordinates suggest that it is associated with the outer arm or possibly the galactic halo, and its low abundance ([O/H]=1.3× 10-4) may be indicative of low metallicity within that region.

  15. Planetary nebulae in galaxies beyond the Local Group.

    NASA Astrophysics Data System (ADS)

    Ford, H. C.; Ciardullo, R.; Jacoby, G. H.; Hui, X.

    Planetary nebulae can be used to estimate the distances to galaxies and to measure stellar dynamics in faint halos. The authors discuss surveys which have netted a total of 665 candidate planetary nebulae in NGC 5128 (Cen A), NGC 5102, NGC 3031 (M81), NGC 3115, three galaxies in the Leo Group (NGC 3379, NGC 3384, NGC 3377), NGC 5866, and finally, in NGC 4486 (M87). The highly consistent distances derived from the brightnesses of the jth nebula and the median nebula in different fields in the same galaxy and from different galaxies in the same group lend strong support to the suggestion that planetaries are an accurate standard candle in old stellar populations. Comparison of theoretical luminosity functions to be observed PNLFs shows that there is a very small dispersion in the central star masses.

  16. The Chemical Diversity of Planetary Nebulae

    NASA Astrophysics Data System (ADS)

    Dinerstein, Harriet L.; Geballe, T. R.; Sterling, N. C.

    2014-01-01

    The metallicity of the progenitor star of a planetary nebula (PN) can be inferred from measurements of elements whose abundances are unaffected by nucleosynthesis during the star’s evolution. In practice, nearly all of the observable elements that qualify, such as O, Ne, S, and Ar, are α species (built up by α-capture reactions). On the other hand, the total elemental abundances of the Fe-group nuclei are not directly measurable in ionized nebulae due to the highly refractory character of Fe and most other Fe-group elements. Although emission lines of several Fe ions are seen in many PNe, they generally indicate mildly to severely subsolar gas-phase abundances that are interpreted as the consequence of depletion into dust. The identification of a near-infrared emission line of Zn, the least refractory (by far) Fe-group element, by Dinerstein & Geballe (2001, ApJ, 562, 515) provided the first practical tracer of Fe/H in PNe. In this poster, we recap results to date from observations of Zn in 21 PNe from a range of Milky Way populations including the thin and thick disk and three Local Group dwarf galaxies. Combined with the results of Smith, Zijlstra, & Dinerstein (2013, MNRAS, submitted) for several objects in the Galactic Bulge, we find that PNe echo the abundance patterns of their parent populations: PNe with spatio-kinematic properties of Fe-poor stellar populations (e.g. the thick disk and bulge) tend to have subsolar zinc (<[Zn/H]> ≈ -0.6 dex) accompanied by elevated [O/Zn]. This conforms to the composition profile of the corresponding stars, if [Zn/H] and [O/Zn] can be taken as proxies for [Fe/H] and [α/Fe] respectively. Deducing the Fe/H metallicity of a PN from an α element alone is inadvisable, as a low-[Fe/H], high-[α/Fe] pattern is indistinguishable from one of solar [Fe/H] and [α/Fe]. To estimate [Fe/H] in a PN for which Zn measurements are unavailable or not feasible, the best approach is to measure an α species and scale by [α/Fe] typical

  17. On planetary nebulae as sources of carbon dust: Infrared emission from planetary nebulae of the galactic halo

    NASA Technical Reports Server (NTRS)

    Dinerstein, Harriet L.; Lester, Daniel F.

    1990-01-01

    Planetary nebulae of the galactic disk are generally seen to emit a thermal continuum due to dust grains heated by stellar and nebular photons. This continuum typically peaks between 25 and 60 micron m, so that the total power emitted by the dust is sampled well by the broad-band measurements made by IRAS. Researchers examine here the characteristics of the infrared emission from the four planetary nebulae which are believed on the basis of their low overall metallicities to belong to the halo population. These nebulae are of particular interest because they are the most metal-poor ionized nebulae known in our Galaxy, and offer the opportunity to probe possible dependences of the dust properties on nebular composition. Researchers present fluxes extracted from co-addition of the IRAS data, as well as ground-based near infrared measurements. Each of the four halo objects, including the planetary nebula in the globular cluster M15, is detected in at least one infrared band. Researchers compare the estimated infrared excesses of these nebulae (IRE, the ratio of measured infrared power to the power available in the form of resonantly-trapped Lyman alpha photons) to those of disk planetary nebulae with similar densities but more normal abundances. Three of the halo planetaries have IRE values similar to those of the disk nebulae, despite the fact that their Fe- and Si-peak gas phase abundances are factors of 10 to 100 lower. However, these halo nebulae have normal or elevated C/H ratios, due to nuclear processing and mixing in their red giant progenitors. Unlike the other halo planetaries, DDDM1 is deficient in carbon as well as in the other light metals. This nebula has a substantially lower IRE than the other halo planetaries, and may be truly dust efficient. Researchers suggest that the deficiency is due to a lack of the raw material for producing carbon-based grains, and that the main bulk constituent of the dust in these planetary nebulae is carbon.

  18. Abundances of Planetary Nebula NGC 5315

    NASA Technical Reports Server (NTRS)

    Pottasch, S. R.; Beintema, D. A.; Koorneef, J.; Salas, J. Bernard; Feibelman, W. A.; Oegerle, William R. (Technical Monitor)

    2002-01-01

    The ISO and IUE spectra of the elliptical nebula NGC 5315 is presented. These spectra axe combined with the spectra in the visual wavelength region to obtain a complete, extinction corrected, spectrum. The chemical composition of the nebulae is then calculated and compared to previous determinations. The HST Nicmos observations of the nebula in 3 emission lines are also presented. These observations are used to determine the helium abundance as a function of position in the nebula. A discussion is given of possible evolutionary effects.

  19. Asymmetric Planetary Nebulae VI: the conference summary

    NASA Astrophysics Data System (ADS)

    De Marco, O.

    2014-04-01

    The Asymmetric Planetary Nebulae conference series, now in its sixth edition, aims to resolve the shaping mechanism of PN. Eighty percent of PN have non spherical shapes and during this conference the last nails in the coffin of single stars models for non spherical PN have been put. Binary theories abound but observational tests are lagging. The highlight of APN6 has been the arrival of ALMA which allowed us to measure magnetic fields on AGB stars systematically. AGB star halos, with their spiral patterns are now connected to PPN and PN halos. New models give us hope that binary parameters may be decoded from these images. In the post-AGB and pre-PN evolutionary phase the naked post-AGB stars present us with an increasingly curious puzzle as complexity is added to the phenomenologies of objects in transition between the AGB and the central star regimes. Binary central stars continue to be detected, including the first detection of longer period binaries, however a binary fraction is still at large. Hydro models of binary interactions still fail to give us results, if we make an exception for the wider types of binary interactions. More promise is shown by analytical considerations and models driven by simpler, 1D simulations such as those carried out with the code MESA. Large community efforts have given us more homogeneous datasets which will yield results for years to come. Examples are the ChanPlaN and HerPlaNe collaborations that have been working with the Chandra and Herschel space telescopes, respectively. Finally, the new kid in town is the intermediate-luminosity optical transient, a new class of events that may have contributed to forming several peculiar PN and pre-PN.

  20. Planetary Nebula Kinematics in M101

    NASA Astrophysics Data System (ADS)

    Herrmann, Kimberly A.; Ciardullo, Robin

    2011-02-01

    Look at a spiral; what do you see? Stars zooming `round in the galaxy! Their motions indicate total mass, but how much is DM, stars, and gas? Study motions in and out; first find monochromatic stars- that's my kind. Find us, get our velocities, then: determine disk mass! I'm a PN! Rotation curves indicate the total mass of spirals, but halo mass profiles cannot be decoupled from the visible disk mass using rotation curves alone. To break this disk-halo degeneracy, we have been using planetary nebulae (PNe) to measure the z-component of the stellar velocity dispersion in the disks of face-on spirals. These measurements of σ_z, coupled with straightforward assumptions, have yielded disk surface mass estimates over several scale lengths (h_R) in 6 spirals. We find that in the inner regions of galaxies (R < 3.5 h_R), the values of σ_z are consistent with those expected from a constant mass-to-light ratio (M/L), constant scale-height disk and this trend continues into the outer regions of M74 and IC 342. However, in M83 and M94, σ_z flattens and becomes constant with radius. We have interpreted this as evidence for satellite accretion with disk flaring, but an increasing disk M/L may also contribute to the behavior. To investigate this phenomenon more thoroughly, we are proposing to extend the survey of an additional galaxy, M101, to R > 8 h_R. Last year we imaged M101 with the wide-field Mosaic camera on the KPNO 4-m telescope. This proposal is to perform follow-up spectroscopy on ~240 PNe in M101 with WIYN/Hydra.

  1. Molecular chemistry and the missing mass problem in planetary nebulae

    NASA Astrophysics Data System (ADS)

    Kimura, R. K.; Gruenwald, R.; Aleman, I.

    2012-05-01

    Context. Detections of molecular lines, mainly from H2 and CO, reveal molecular material in planetary nebulae. Observations of a variety of molecules suggest that the molecular composition in these objects differs from that found in interstellar clouds or in circumstellar envelopes. The success of the models, which are mostly devoted to explain molecular densities in specific planetary nebulae, is still partial however. Aims: The present study aims at identifying the influence of stellar and nebular properties on the molecular composition of planetary nebulae by means of chemical models. A comparison of theoretical results with those derived from the observations may provide clues to the conditions that favor the presence of a particular molecule. Methods: A self-consistent photoionization numerical code was adapted to simulate cold molecular regions beyond the ionized zone. The code was used to obtain a grid of models and the resulting column densities are compared with those inferred from observations. Results: Our models show that the inclusion of an incident flux of X-rays is required to explain the molecular composition derived for planetary nebulae. We also obtain a more accurate relation for the N(CO)/N(H2) ratio in these objects. Molecular masses obtained by previous works in the literature were then recalculated, showing that these masses can be underestimated by up to three orders of magnitude. We conclude that the problem of the missing mass in planetary nebulae can be solved by a more accurate calculation of the molecular mass.

  2. The Stingray nebula: watching the rapid evolution of a newly born planetary nebula.

    NASA Astrophysics Data System (ADS)

    Bobrowsky, M.; Sahu, K. C.; Parthasarathy, M.; García-Lario, Pedro

    The formation and early evolution of planetary nebulae represent one of the most poorly understood phases of stellar evolution ( Kwok, 1987; Maddox, 1995). One of the youngest, the Stingray Nebula (He3-1357) ( Henize, 1967; Henize, 1976), shows all the tell-tale signs of a newly born planetary nebula: it has become ionized only within the past few decades ( Parthasarathy et al., 1993); the mass-loss from the central star has ceased within the past few years; and the central star is becoming hotter and fainter as expected from a star on its way to becoming a DA white dwarf ( Parthasarathy et al., 1995). The Stingray Nebula thus provides the ideal laboratory for examining the early structure and evolution of this class of objects. Images of the Stingray Nebula, obtained with the Hubble Space Telescope, show for the first time that its multiple expulsions of matter are focused by an equatorial ring and bubbles of gas located on opposite sides of the ring ( Bobrowsky et al., 1995). The position angle of the outflows has changed, possibly as a result of precessional motion induced by the presence of a companion star. This is consistent with the precessing jet model by Livio & Pringle (1996). Indeed, we have reported the discovery of a companion star in the Stingray Nebula ( Bobrowsky et al., 1998). Finally, we present evidence of the companion star dynamically distorting the gas in this newly-born planetary nebula.

  3. A search for planetary nebulae on the 'POSS'

    NASA Astrophysics Data System (ADS)

    Dengel, J.; Hartl, H.; Weinberger, R.

    1980-05-01

    Results of a search for new planetary nebulae on a quarter of the Palomar Observatory Sky Survey (POSS) E plates are reported. A total of 218 prints evenly scattered over all accessible galactic longitudes and latitudes was examined, in addition to the entire region between longitudes 33 and 213 deg and latitudes + or - 2 deg. Five objects satisfying the criteria of emission nebulosity characteristic of planetary nebulae and/or a central blue star were detected, as well as another three dozen very faint, roundish unlisted objects. The coordinates, dimensions, central star magnitudes, surfaces brightnesses, nebular magnitudes, volumes and estimated distances of the five probable planetary nebulae are presented, and it is noted that all but one of them are of considerably low surface brightness.

  4. On the formation of ansae in planetary nebulae

    NASA Technical Reports Server (NTRS)

    Soker, Noam

    1990-01-01

    Formation mechanisms for the two optical bright knots in planetary nebulae, 'ansae', are investigated. Adiabatic two-dimensional numerical simulations of the interacting winds flow at early stages of the planetary nebulae evolution are performed. It is found that no real focusing of the shocked fast wind material toward the symmetry axis occurs, and thus the interaction of winds by itself will not form the ansae. A model is proposed, in which jets from the central star form the ansae. These jets are presumably being formed during the few hundred years in the period between the end of the slow wind and the beginning of the fast wind. It is shown that a companion to the progenitor red giant can lead to the degree of asymmetry observed in elliptical planetary nebulae.

  5. The abundances of neon, sulfur, and argon in planetary nebulae

    NASA Technical Reports Server (NTRS)

    Beck, S. C.; Lacy, J. H.; Townes, C. H.; Aller, L. H.; Geballe, T. R.; Baas, F.

    1981-01-01

    New infrared observations of Ne II, Ar III, and S IV are used in optical observations of other ionization states of the considered elements to evaluate the abundances of neon, argon, and sulfur in 18 planetary nebulae. Attention is also given to one or more of the infrared lines in 18 other nebulae. It is pointed out that S IV was detected in approximately 90% of the observed objects, while Ar III was found in about 80%, and Ne II in roughly one-third. It is noted that optical observations typically include only a limited region of the nebula, while the infrared measurements frequently involve integration over the entire nebular image.

  6. Planetary Nebulae in the Magellanic Clouds

    NASA Astrophysics Data System (ADS)

    Dopita, M. A.

    The relative closeness, the low reddening, and accurately known distance to the Magellanic Clouds give the ideal set of circumstances to pursue quantitative examinations of individual stellar at metallicities lower than solar. Our understanding of the population of PN in the Magellanic Clouds has been much enhanced recently by imaging and spectroscopic studies using the HST. With the HST, details of the internal nebular structure are resolved as well as ground-based telescopes resolve galactic PN. In the UV, the low line of sight reddening ensures that high signal to noise nebular and central star spectra can be obtained; sufficient to examine the P-Cygni profiles of the mass-losing central stars in some cases. In conjuction with ground-based spectrophotometry, absolute flux, expansion velocity and density information, this data set permits fully self consistent diameters, ages, masses, and abundances to be derived for the nebulae, and the central stars can be accurately placed on the H-R Diagram. Thus, we can examine the details of the evolution, and of the mass- and age-dependent dredge-up processes in a way which is just not possible in the case of Galactic PN. A brief summary of the highlights of the results: * The younger, low excitation, compact planetary nebulae appear to have a central reservoir of dense atomic and molecular gas. This gas lies close to the central star and is undergoing ionisation and being accelerated into outflow, consistent with the "two-wind" model of PN evolution and shaping. * The PN previously classified as nitrogen-rich objects (Peimbert Type I), show the bipolar "butterfly" symmetry that is also a characteristic of their Galactic counterparts. These have been shown to have the most massive precursor stars, as had been long suspected for the Galactic Type I PN. * The PN divide into two evolutionary groups according to kinematic age / size relationships, which may be identified with stars which leave the AGB as He- or as H- burners

  7. Planetary nebulae in 2014: A review of research

    NASA Astrophysics Data System (ADS)

    Zijlstra, A. A.

    2015-10-01

    Planetary nebulae had a double anniversary in 2014, 250 years since their discovery and 150 years since the correct spectroscopic identification. This paper gives an overview of planetary nebula research published in 2014. Topics include surveys, central stars, abundances, morphologies, magnetic fields, stellar population and galactic dynamics. An important continuing controversy is the discrepancy between recombination-line and forbidden-line abundances. A new controversy is the relation between symbiotic stars and [WC] stars. PN of the year is undoubtedly CRL 618, with papers on its binary symbiotic/[WC] nucleus, rapid stellar evolution, expanding jets and magnetic fields.

  8. Interacting winds and the shaping of planetary nebulae

    NASA Technical Reports Server (NTRS)

    Soker, Noam; Livio, Mario

    1989-01-01

    Using two-dimensional hydrodynamics, the problem of shaping of planetary nebulae by the interacting winds model is studied. The shock structure is obtained and it is shown that interacting winds are capable of producing morphologies similar to the ones observed in planetary nebulae, provided that a density contrast exists between the equatorial and polar directions. This confirms recent suggestions by Balick. Mechanisms that can produce the required density contrast are discussed and it is shown that binary central stars provide the most natural mechanism, especially via common envelope evolution. It is not yet entirely clear whether stellar rotation is sufficient to generate the required contrast in the case of single central stars.

  9. Investigating potential planetary nebula/cluster pairs

    NASA Astrophysics Data System (ADS)

    Moni Bidin, C.; Majaess, D.; Bonatto, C.; Mauro, F.; Turner, D.; Geisler, D.; Chené, A.-N.; Gormaz-Matamala, A. C.; Borissova, J.; Kurtev, R. G.; Minniti, D.; Carraro, G.; Gieren, W.

    2014-01-01

    Context. Fundamental parameters characterizing the end-state of intermediate-mass stars may be constrained by discovering planetary nebulae (PNe) in open clusters (OCs). Cluster membership may be exploited to establish the distance, luminosity, age, and physical size for PNe, and the intrinsic luminosity and mass of its central star. Aims: Four potential PN-OC associations were investigated to assess the cluster membership for the PNe. Methods: Radial velocities were measured from intermediate-resolution optical spectra, complemented with previous estimates in the literature. When the radial velocity study supported the PN/OC association, we analyzed whether other parameters (e.g., age, distance, reddening, central star brightness) were consistent with this conclusion. Results: Our measurements imply that the PNe VBe 3 and HeFa 1 are not members of the OCs NGC 5999 and NGC 6067, respectively, and that they very likely belong to the background bulge population. Conversely, consistent radial velocities indicate that NGC 2452/NGC 2453 could be associated, but our results are not conclusive so additional observations are warranted. Finally, we demonstrate that all the available information point to He 2-86 being a young, highly internally obscured PN member of NGC 4463. New near-infrared photometry acquired via the Vista Variables in the Via Lactea ESO public survey was used in tandem with existing UBV photometry to measure the distance, reddening, and age of NGC 4463, finding d = 1.55 ± 0.10 kpc, E(B - V) = 0.41 ± 0.02, and τ = 65 ± 10 Myr, respectively. The same values should be adopted for the PN if the proposed cluster membership is confirmed. Based on observations gathered with ESO-VISTA telescope (program ID 172.B-2002).Based on observations gathered at Las Campanas observatory (program ID CN2012A-080).The spectra as FITS files are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc

  10. Infrared Study of Fullerene Planetary Nebulae

    NASA Astrophysics Data System (ADS)

    García-Hernández, D. A.; Villaver, E.; García-Lario, P.; Acosta-Pulido, J. A.; Manchado, A.; Stanghellini, L.; Shaw, R. A.; Cataldo, F.

    2012-12-01

    We present a study of 16 planetary nebulae (PNe) where fullerenes have been detected in their Spitzer Space Telescope spectra. This large sample of objects offers a unique opportunity to test conditions of fullerene formation and survival under different metallicity environments because we are analyzing five sources in our own Galaxy, four in the Large Magellanic Cloud (LMC), and seven in the Small Magellanic Cloud (SMC). Among the 16 PNe studied, we present the first detection of C60 (and possibly also C70) fullerenes in the PN M 1-60 as well as of the unusual ~6.6, 9.8, and 20 μm features (attributed to possible planar C24) in the PN K 3-54. Although selection effects in the original samples of PNe observed with Spitzer may play a potentially significant role in the statistics, we find that the detection rate of fullerenes in C-rich PNe increases with decreasing metallicity (~5% in the Galaxy, ~20% in the LMC, and ~44% in the SMC) and we interpret this as a possible consequence of the limited dust processing occurring in Magellanic Cloud (MC) PNe. CLOUDY photoionization modeling matches the observed IR fluxes with central stars that display a rather narrow range in effective temperature (~30,000-45,000 K), suggesting a common evolutionary status of the objects and similar fullerene formation conditions. Furthermore, the data suggest that fullerene PNe likely evolve from low-mass progenitors and are usually of low excitation. We do not find a metallicity dependence on the estimated fullerene abundances. The observed C60 intensity ratios in the Galactic sources confirm our previous finding in the MCs that the fullerene emission is not excited by the UV radiation from the central star. CLOUDY models also show that line- and wind-blanketed model atmospheres can explain many of the observed [Ne III]/[Ne II] ratios using photoionization, suggesting that possibly the UV radiation from the central star, and not shocks, is triggering the decomposition of the

  11. INFRARED STUDY OF FULLERENE PLANETARY NEBULAE

    SciTech Connect

    Garcia-Hernandez, D. A.; Acosta-Pulido, J. A.; Manchado, A.; Garcia-Lario, P.; Stanghellini, L.; Shaw, R. A.; Cataldo, F. E-mail: amt@iac.es E-mail: Pedro.Garcia-Lario@sciops.esa.int E-mail: letizia@noao.edu

    2012-12-01

    We present a study of 16 planetary nebulae (PNe) where fullerenes have been detected in their Spitzer Space Telescope spectra. This large sample of objects offers a unique opportunity to test conditions of fullerene formation and survival under different metallicity environments because we are analyzing five sources in our own Galaxy, four in the Large Magellanic Cloud (LMC), and seven in the Small Magellanic Cloud (SMC). Among the 16 PNe studied, we present the first detection of C{sub 60} (and possibly also C{sub 70}) fullerenes in the PN M 1-60 as well as of the unusual {approx}6.6, 9.8, and 20 {mu}m features (attributed to possible planar C{sub 24}) in the PN K 3-54. Although selection effects in the original samples of PNe observed with Spitzer may play a potentially significant role in the statistics, we find that the detection rate of fullerenes in C-rich PNe increases with decreasing metallicity ({approx}5% in the Galaxy, {approx}20% in the LMC, and {approx}44% in the SMC) and we interpret this as a possible consequence of the limited dust processing occurring in Magellanic Cloud (MC) PNe. CLOUDY photoionization modeling matches the observed IR fluxes with central stars that display a rather narrow range in effective temperature ({approx}30,000-45,000 K), suggesting a common evolutionary status of the objects and similar fullerene formation conditions. Furthermore, the data suggest that fullerene PNe likely evolve from low-mass progenitors and are usually of low excitation. We do not find a metallicity dependence on the estimated fullerene abundances. The observed C{sub 60} intensity ratios in the Galactic sources confirm our previous finding in the MCs that the fullerene emission is not excited by the UV radiation from the central star. CLOUDY models also show that line- and wind-blanketed model atmospheres can explain many of the observed [Ne III]/[Ne II] ratios using photoionization, suggesting that possibly the UV radiation from the central star, and

  12. PLANETARY NEBULAE IN FACE-ON SPIRAL GALAXIES. II. PLANETARY NEBULA SPECTROSCOPY

    SciTech Connect

    Herrmann, Kimberly A.; Ciardullo, Robin E-mail: rbc@astro.psu.ed

    2009-09-20

    As the second step in our investigation of the mass-to-light ratio of spiral disks, we present the results of a spectroscopic survey of planetary nebulae (PNe) in five nearby, low-inclination galaxies: IC 342, M74 (NGC 628), M83 (NGC 5236), M94 (NGC 4736), and M101 (NGC 5457). Using 50 setups of the WIYN/Hydra and Blanco/Hydra spectrographs, and 25 observations with the Hobby-Eberly Telescope's Medium Resolution Spectrograph, we determine the radial velocities of 99, 102, 162, 127, and 48 PNe, respectively, to a precision better than 15 km s{sup -1}. Although the main purpose of this data set is to facilitate dynamical mass measurements throughout the inner and outer disks of large spiral galaxies, our spectroscopy has other uses as well. Here, we co-add these spectra to show that, to first order, the [O III] and Balmer line ratios of PNe vary little over the top {approx}1.5 mag of the PN luminosity function. The only obvious spectral change occurs with [N II], which increases in strength as one proceeds down the luminosity function. We also show that typical [O III]-bright planetaries have E(B - V) {approx} 0.2 of circumstellar extinction, and that this value is virtually independent of [O III] luminosity. We discuss the implications this has for understanding the population of PN progenitors.

  13. Probing Early-Type Galaxy Halos Using Planetary Nebulae

    NASA Astrophysics Data System (ADS)

    Merrifield, Michael; Arnaboldi, Magda; Coccato, Lodovico; Gerhard, Ortwin; Napolitano, Nicola; Pulsoni, Claudia; Planetary Nebula Spectrograph Collaboration

    2016-01-01

    Planetary nebulae offer an invaluable probe of the stellar kinematics at very large radii in early-type galaxies, reaching regimes where we can learn about both the dark matter halo of the system and the formation history of the stellar component. We present results from the largest kinematic survey to-date of extragalactic planetary nebulae in the outer halos early-type galaxies, obtained using the custom Planetary Nebula Spectrograph instrument. The survey currently comprises validated homogeneous catalogs for 33 early-type galaxies, with data typically extending to beyond 5 effective radii.This survey confirms that planetary nebulae trace the bulk stellar population very closely, allowing these data to be combined with more conventional absorption-line spectral studies at smaller radii. Analysis shows that: (1) there is a kinematic dichotomy amongst the galaxies between those that display rapidly-falling velocity disperson profiles and those where the dispersion remains roughly constant with radius - a distinction that reflects both orbital and mass profile differences; (2) rotation in outer regions correlates strongly with rotation in inner regions - they are fairly monolithic systems; (3) the velocity field usually contains symmetries that indicate triaxiality; (4) some systems have outer velocity fields that imply these regions are not in any sort of equilibrium.

  14. Optical Spectrum of the Compact Planetary Nebula IC 5117

    NASA Technical Reports Server (NTRS)

    Hyung, Siek; Aller, Lawrence H.; Feibelman, Walter A.; Lee, Seong-Jae; Fisher, Richard R. (Technical Monitor)

    2001-01-01

    High resolution spectroscopic data of the very compact planetary nebula IC 5117 are obtained in the optical wavelengths, 3700A - 10050A, with the Hamilton Echelle Spectrograph at Lick Observatory, and which have been analyzed along with the International Ultraviolet Explorer (IUE) UV archive data. Although a diagnostic diagram shows significant density and temperature fluctuations, our analysis indicates that the nebular gas may be represented by a homogeneous shell of extremely high density gas, N(sub epsilon) approx. 90 000 /cu cm. The average electron temperatures, e.g. indicated by the [OIII] diagnostics, are around 12 000 K. We construct a photoionization model to represent most of the observed line intensities, and the physical condition of this compact nebulosity. Based on the semi-empirical ionization correction approach, and model indications, we derived the elemental abundances: He, C, N, O, Ne, and Ar appear to be normal or marginally depleted compared to the average planetary nebula, while the remaining elements, S, Cl, and K appear to be enhanced. IC 5117 is perhaps a very young compact planetary nebula, slightly more evolved than the other well-known compact planetary nebula IC 4997. The central stellar temperature is likely to be around 120 000 K, evolved from a C-rich AGB progenitor.

  15. The spectrum of planetary nebula K 1-27

    NASA Technical Reports Server (NTRS)

    Henize, K. G.; Fairall, A. P.

    1981-01-01

    The spectrum of K 1-27 shows He II 4686 stronger than either H-beta or forbidden O III 4959. K 1-27 therefore appears to belong to the small group of old, very hot planetary nebulae which also includes NGC 246, NGC 4361, and Abell 36.

  16. The Extended Region Around the Planetary Nebula NGC 3242

    NASA Technical Reports Server (NTRS)

    2009-01-01

    This ultraviolet image from NASA's Galaxy Evolution Explorer shows NGC 3242, a planetary nebula frequently referred to as 'Jupiter's Ghost.'

    The unfortunate name of 'planetary nebula' for this class of celestial object is a historical legacy credited to William Herschel during the 18th century a time when telescopes where small and objects like these, at least the central region, looked very similar to gas-giant planets such as Saturn and Jupiter. In fact, NGC 3242 has no relation to Jupiter or any other planet.

    Telescopes and their detectors have dramatically improved over the past few centuries. Our understanding of what planetary nebulae truly are has improved accordingly.

    When stars with a mass similar to our sun approach the end of their lives by exhausting supplies of hydrogen and helium fuel in their cores, they swell up into cool red-giant stars. In a last gasp before death, they expel the layers of gas in their outer atmosphere. This exposes the core of the dying star, a dense hot ball of carbon and oxygen called a white dwarf. The white dwarf is so hot that it shines very brightly in the ultraviolet. The ultraviolet light from the white dwarf, in turn, ionizes the gaseous material expelled by the star causing it to glow. A planetary nebula is really the death of a low-mass star.

    Although low-mass stars like our sun live for billions of years, planetary nebulae only last for about ten thousand years. As the central white dwarf quickly cools and the ultraviolet light dwindles, the surrounding gas also cools and fades.

    In this image of NGC 3242 from the Galaxy Evolution Explorer, the extended region around the planetary nebula is shown in dramatic detail. The small circular white and blue area at the center of the image is the well-known portion of the famous planetary nebula. The precise origin and composition of the extended wispy white features is not known for certain. It is most likely material ejected during the star's red

  17. Carbon Chemistry in Planetary Nebulae: Observations of the CCH Radical

    NASA Astrophysics Data System (ADS)

    Schmidt, Deborah Rose; Ziurys, Lucy

    2015-08-01

    The presence of infrared (IR) emission features observed in interstellar environments is consistent with models that suggest they are produced by complex organic species containing both aliphatic and aromatic components (Kwok & Zhang 2011). These IR signals change drastically over the course of the AGB, proto-planetary, and planetary nebulae phases, and this dramatic variation is yet to be understood. The radical CCH is a potential tracer of carbon chemistry and its evolution in dying stars. CCH is very common in carbon-rich circumstellar envelopes of AGB stars, and is present in the proto-planetary nebulae. It has also been observed at one position in the very young planetary nebula, NGC 7027 (Hasegawa & Kwok 2001), as well as at one position in the Helix Nebula (Tenenbaum et al. 2009) - a dense clump east of the central white dwarf. In order to further probe the chemistry of carbon, we have initiated a search for CCH in eight PNe previously detected in HCN and HCO+ from a survey conducted by Schmidt and Ziurys, using the telescopes of the Arizona Radio Observatory (ARO). Observations of the N=1→0 transition of CCH at 87 GHz have been conducted using the new ARO 12-m ALMA prototype antenna, while measurements of the N=3→2 transition at 262 GHz are being made with the ARO Sub-Millimeter Telescope (SMT). We also have extended our study in the Helix Nebula. Thus far, CCH has been detected at 8 new positions across the Helix Nebula, and appears to be widespread in this source. The radical has also been identified in K4-47, M3-28, K3-17, and K3-58. These sources represent a range of nebular ages. Additional observations are currently being conducted for CCH in other PNe, as well as abundance analyses. These results will be presented.

  18. The Chandra planetary nebula survey (CHANPLANS). II. X-ray emission from compact planetary nebulae

    SciTech Connect

    Freeman, M.; Kastner, J. H.; Montez, R. Jr.; Balick, B.; Frew, D. J.; De Marco, O.; Parker, Q. A.; Jones, D.; Miszalski, B.; Sahai, R.; Blackman, E.; Frank, A.; Chu, Y.-H.; Guerrero, M. A.; Zijlstra, A.; Bujarrabal, V.; Corradi, R. L. M.; Nordhaus, J.; and others

    2014-10-20

    We present results from the most recent set of observations obtained as part of the Chandra X-ray observatory Planetary Nebula Survey (CHANPLANS), the first comprehensive X-ray survey of planetary nebulae (PNe) in the solar neighborhood (i.e., within ∼1.5 kpc of the Sun). The survey is designed to place constraints on the frequency of appearance and range of X-ray spectral characteristics of X-ray-emitting PN central stars and the evolutionary timescales of wind-shock-heated bubbles within PNe. CHANPLANS began with a combined Cycle 12 and archive Chandra survey of 35 PNe. CHANPLANS continued via a Chandra Cycle 14 Large Program which targeted all (24) remaining known compact (R {sub neb} ≲ 0.4 pc), young PNe that lie within ∼1.5 kpc. Results from these Cycle 14 observations include first-time X-ray detections of hot bubbles within NGC 1501, 3918, 6153, and 6369, and point sources in HbDs 1, NGC 6337, and Sp 1. The addition of the Cycle 14 results brings the overall CHANPLANS diffuse X-ray detection rate to ∼27% and the point source detection rate to ∼36%. It has become clearer that diffuse X-ray emission is associated with young (≲ 5 × 10{sup 3} yr), and likewise compact (R {sub neb} ≲ 0.15 pc), PNe with closed structures and high central electron densities (n{sub e} ≳ 1000 cm{sup –3}), and is rarely associated with PNe that show H{sub 2} emission and/or pronounced butterfly structures. Hb 5 is one such exception of a PN with a butterfly structure that hosts diffuse X-ray emission. Additionally, two of the five new diffuse X-ray detections (NGC 1501 and NGC 6369) host [WR]-type central stars, supporting the hypothesis that PNe with central stars of [WR]-type are likely to display diffuse X-ray emission.

  19. SOFIA Observations of the Planetary Nebula NGC7027

    NASA Astrophysics Data System (ADS)

    Spuck, Timothy; Werner, M. W.; Sahai, R.; Hartley, M.; Herter, T. L.; Horner, J.; Keller, L. D.; Livingston, J.; Morris, M.

    2013-01-01

    NGC7027 is one of the brightest and best-studied planetary nebulae. The nebula is 2900 light years from earth, and approximately 0.08 parsec in physical size making it one of the youngest known planetary nebula with an estimated age of just 600 years. NGC7027’s central 16th magnitude star is pumping out the energy of 6000 suns, and at 185,000 Kelvin the star is one of the hottest known. NGC7027 was imaged using the FORCAST instrument on SOFIA at 6.4, 6.6, 11.1, 19.7, 24.2, 33.6, and 37.1 microns. The HBPW of the measurements is 4-to-6 pixels 3 to 4.5 arc sec] across the bands. Analysis indicates a bright well-resolved nebula with an overall angular size of ~10 X 13 arc sec. The morphology is similar to what is seen in ground-based infrared and radio continuum images. The size varies little with wavelength. The SED derived from the SOFIA observations varies moderately but systematically across the nebula, with the longer wavelengths becoming relatively brighter at the edges. Analysis of the images has been carried out under the NASA-IPAC Teacher Archive Research Program with portions of the work being carried out at the Jet Propulsion Laboratory, operated by the California Institute of Technology under a contract with NASA.

  20. The planetary nebula system and dynamics of NGC 5128. I - Planetary nebulae as standard candles

    NASA Technical Reports Server (NTRS)

    Hui, Xiaohui; Ford, Holland C.; Ciardullo, Robin; Jacoby, George H.

    1993-01-01

    We present the result of a planetary nebula (PN) survey of the nearby giant elliptical galaxy NGC 5128 performed with CCD cameras at the prime focus of the CTIO 4 m telescope. By comparing CCD images centered on the characteristic emission line forbidden O III 5007 A and on the adjacent continuum, we identify a total of 785 PNs in areas extending 20 kpc along the photometric major axis and covering the whole galaxy to 10 kpc. From these data, we form a complete sample of 224 PNs extending to a dereddened limiting magnitude of m5007 = 24.8, which extends 1.5 mag down the PN luminosity function (PNLF). Adopting a foreground extinction of E(B-V) = 0.1, we derive a distance to the galaxy of 3.5 +/- 0.2 Mpc, in excellent agreement with the surface brightness fluctuation method. No population effect on the bright cutoff of PNLF is observed in the isophotal radius range of 2-16 kpc, but the luminosity specific PN density seems to increase with radius inside of 7 kpc, in agreement with the alpha(2.5)-color relation observed for other galaxies.

  1. PLANETARY NEBULAE IN FACE-ON SPIRAL GALAXIES. III. PLANETARY NEBULA KINEMATICS AND DISK MASS

    SciTech Connect

    Herrmann, Kimberly A.; Ciardullo, Robin E-mail: rbc@astro.psu.ed

    2009-11-10

    Much of our understanding of dark matter halos comes from the assumption that the mass-to-light ratio (Y) of spiral disks is constant. The best way to test this hypothesis is to measure the disk surface mass density directly via the kinematics of old disk stars. To this end, we have used planetary nebulae (PNe) as test particles and have measured the vertical velocity dispersion (sigma{sub z}) throughout the disks of five nearby, low-inclination spiral galaxies: IC 342, M74 (NGC 628), M83 (NGC 5236), M94 (NGC 4736), and M101 (NGC 5457). By using H I to map galactic rotation and the epicyclic approximation to extract sigma{sub z} from the line-of-sight dispersion, we find that, with the lone exception of M101, our disks do have a constant Y out to approx3 optical scale lengths (h{sub R} ). However, once outside this radius, sigma{sub z} stops declining and becomes flat with radius. Possible explanations for this behavior include an increase in the disk mass-to-light ratio, an increase in the importance of the thick disk, and heating of the thin disk by halo substructure. We also find that the disks of early type spirals have higher values of Y and are closer to maximal than the disks of later-type spirals, and that the unseen inner halos of these systems are better fit by pseudo-isothermal laws than by NFW models.

  2. Two new evolved neighbouring planetary nebulae in Aquila

    NASA Astrophysics Data System (ADS)

    Ali, A.; Pfleiderer, J.

    1997-08-01

    In the course of a search for faint new non-stellar objects in the Northern Galactic Plane, two neighbouring planetary nebula (PNe) candidates have been detected on film copies of the POSS II. Whereas the morphology of the smaller of the two objects (v = 15 arcsec) is typical for PNe, the nature of the larger one (34 x 18 arcsec^2) defied an even provisional classification, on its photographic appearance alone. Optical spectra, however, allowed both sources, which are separated by 20 arcmin only, to be classified as highly obscured PNe. Both nebulae obviously are rather old, i.e. they are evolved representatives of their kind.

  3. The Herschel Planetary Nebula Survey (HerPlaNS)

    NASA Astrophysics Data System (ADS)

    Ueta, T.; Ladjal, D.; HerPlaNS Team

    2012-12-01

    The Herschel Planetary Nebula Survey (HerPlaNS, PI: T. Ueta) is one of the largest Herschel Open Time 1 program in which we explore the far-infrared aspects of 11 planetary nebulae (PNs) with the Herschel Space Observatory, exploiting its unprecedented capabilities in broadband photometry mapping, spectral mapping, and integral-field spectroscopy. We perform (1) deep PACS/SPIRE broadband mapping to account for the coldest dust component of the nebulae and determine the spatial distribution of the dusty haloes in the target PNs, (2) exhaustive PACS/SPIRE line mapping in far-IR atomic and molecular lines in two representative PNs to diagnose the energetics of the nebulae as a function of location in the nebulae, and (3) PACS/SPIRE spectral-energy-distribution spectroscopy at several positions in the target PNs to understand variations in the physical conditions as a function of location in the nebulae, to build a more complete picture of the interplay between the dust and gas components as a function of location in the nebulae. The HerPlaNS survey is distinguished from the existing guaranteed-time Key Program (KPGT), "Mass Loss of Evolved StarS" (MESS, PI: M. Groenewegen, including 10 PNs) by the extra dimension added by spectral mapping and integral-field spatio-spectroscopy that permit simultaneous probing of the gas and dust component in the target PNs. Through these investigations, we will consider the energetics of the entire gas-dust system as a function of location in the nebulae, which is a novel approach that has rarely been taken previously. HerPlaNS is conducted in collaboration with the Chandra Planetary Survey (ChanPlaNS, PI: J.H. Kastner) to furnish substantial PN data resources that would allow us—a community of PN astronomers—to tackle a multitude of unanswered issues in PN physics, from the shaping mechanisms of the nebulae to the energetics of the multi-phased gas-dust system surrounding the central white dwarf. These PN surveys, combined with

  4. Weak magnetic fields in central stars of planetary nebulae?

    NASA Astrophysics Data System (ADS)

    Steffen, M.; Hubrig, S.; Todt, H.; Schöller, M.; Hamann, W.-R.; Sandin, C.; Schönberner, D.

    2014-10-01

    Context. It is not yet clear whether magnetic fields play an essential role in shaping planetary nebulae (PNe), or whether stellar rotation alone and/or a close binary companion, stellar or substellar, can account for the variety of the observed nebular morphologies. Aims: In a quest for empirical evidence verifying or disproving the role of magnetic fields in shaping planetary nebulae, we follow up on previous attempts to measure the magnetic field in a representative sample of PN central stars. Methods: We obtained low-resolution polarimetric spectra with FORS 2 installed on the Antu telescope of the VLT for a sample of 12 bright central stars of PNe with different morphologies, including two round nebulae, seven elliptical nebulae, and three bipolar nebulae. Two targets are Wolf-Rayet type central stars. Results: For the majority of the observed central stars, we do not find any significant evidence for the existence of surface magnetic fields. However, our measurements may indicate the presence of weak mean longitudinal magnetic fields of the order of 100 Gauss in the central star of the young elliptical planetary nebula IC 418 as well as in the Wolf-Rayet type central star of the bipolar nebula Hen 2-113 and the weak emission line central star of the elliptical nebula Hen 2-131. A clear detection of a 250 G mean longitudinal field is achieved for the A-type companion of the central star of NGC 1514. Some of the central stars show a moderate night-to-night spectrum variability, which may be the signature of a variable stellar wind and/or rotational modulation due to magnetic features. Conclusions: Since our analysis indicates only weak fields, if any, in a few targets of our sample, we conclude that strong magnetic fields of the order of kG are not widespread among PNe central stars. Nevertheless, simple estimates based on a theoretical model of magnetized wind bubbles suggest that even weak magnetic fields below the current detection limit of the order of 100

  5. HST Search for Planetary Nebulae in Local Group Globular Clusters

    NASA Astrophysics Data System (ADS)

    Bond, Howard E.

    2015-01-01

    If every star of about solar mass produces a planetary nebula (PN) near the end of its life, there should be several dozen PNe in the globular clusters (GCs) of the Local Group. However, ground-based surveys of Milky Way GCs have revealed only 4 PNe. A converse argument is that it is likely that the remnants of stars now evolving in ancient GCs leave the AGB so slowly that any ejected PN dissipates long before the star becomes hot enough to ionize it. Thus there should not be any PNe in Milky Way GCs--but there are four! It has been suggested that these PNe are the result of binary mergers of binary stars within GCs, i.e., that they are descendants of blue stragglers. To explore these issues and extend them beyond the Milky Way, I carried out a Snapshot imaging survey of GCs throughout the Local Group with the Hubble Space Telescope. Observations were made with the WFPC2 camera in 2007-2008, and with WFC3 in 2009-2011. Frames were obtained in a narrow-band [O III] 5007 filter and in a broad V filter (F555W). In this filter combination, a PN will have a comparable signal in both bandpasses, but stars will be much brighter in the V filter. I surveyed 41 GCs in M31, 4 in M33, 8 in the Magellanic Clouds, 2 in Fornax, and 1 each in NGC 6822, WLM, and NGC 147. Only one candidate PN was found, in the M31 GC B086. My results appear to be consistent with a ground-based spectroscopic survey for PNe in the M31 GCs by Jacoby et al. (2013), which found only 3 PN candidates in 274 clusters. PNe are very rare in GCs, but a few do exist, and they may require binary interactions for their formation.

  6. Ultraviolet observations of close-binary and pulsating nuclei of planetary nebulae; Winds and shells around low-mass supergiants; The close-binary nucleus of the planetary nebula HFG-1; A search for binary nuclei of planetary nebulae; UV monitoring of irregularly variable planetary nuclei; and The pulsating nucleus of the planetary nebula Lo 4

    NASA Technical Reports Server (NTRS)

    Bond, Howard E.

    1992-01-01

    A brief summary of the research highlights is presented. The topics covered include the following: binary nuclei of planetary nebulae; other variable planetary nuclei; low-mass supergiants; and other IUE-related research.

  7. Kinematic study of planetary nebulae in NGC 6822

    NASA Astrophysics Data System (ADS)

    Flores-Durán, S. N.; Peña, M.; Hernández-Martínez, L.; García-Rojas, J.; Ruiz, M. T.

    2014-08-01

    Context. The kinematics of planetary nebulae in external galaxies and in our own is a clue for understanding the behavior of the low- and intermediate-mass stars and their relation with other components of the galaxies. Aims: By measuring precise radial velocities of planetary nebulae (which belong to the intermediate-age population), H ii regions and A-type supergiant stars (which are members of the young population) in NGC 6822, we aim to determine whether both types of population share the kinematics of the disk of H i found in this galaxy. Methods: Spectroscopic data for six planetary nebulae were obtained with the high spectral-resolution spectrograph Magellan Inamori Kyocera Echelle (MIKE) on the Magellan telescope at Las Campanas Observatory. Data for another three PNe and one H ii region were obtained from the SPM Catalog of Extragalactic Planetary Nebulae, which employed the Manchester Echelle Spectrometer attached to the 2.1m telescope at the Observatorio Astronómico Nacional, México. An additional PN and one H ii region were observed with this same telescope-spectrograph in 2013. Thus, in total we have high-quality data for 10 of the 26 PNe detected in this galaxy. In the wavelength calibrated spectra, the heliocentric radial velocities were measured with a precision better than 5-6 km s-1. Data for two additional H ii regions and two A-type supergiant stars were collected from the literature. The heliocentric radial velocities of the different objects were compared to the velocities of the H i disk at the same position. Results: From the analysis of radial velocities we found that H ii regions and A-type supergiants do share the kinematics of the H i disk at the same position, as expected for these young objects. In contrast, most planetary nebula velocities differ significantly (more than 12 km s-1) from that of the H i at the same position. The kinematics of planetary nebulae is different from the young population kinematics and is more similar to

  8. MULTIPOLAR PLANETARY NEBULAE: NOT AS GEOMETRICALLY DIVERSIFIED AS THOUGHT

    SciTech Connect

    Chong, S.-N.; Imai, H.; Chibueze, J.; Kwok, Sun; Tafoya, D. E-mail: sunkwok@hku.hk

    2012-12-01

    Planetary nebulae (PNe) have diverse morphological shapes, including point-symmetric and multipolar structures. Many PNe also have complicated internal structures such as tori, lobes, knots, and ansae. A complete accounting of all the morphological structures through physical models is difficult. A first step toward such an understanding is to derive the true three-dimensional structure of the nebulae. In this paper, we show that a multipolar nebula with three pairs of lobes can explain many such features, if orientation and sensitivity effects are taken into account. Using only six parameters-the inclination and position angles of each pair-we are able to simulate the observed images of 20 PNe with complex structures. We suggest that multipolar structure is an intrinsic structure of PNe and the statistics of multipolar PNe have been severely underestimated in the past.

  9. [Fe iii] lines in the planetary nebula NGC 2392

    NASA Astrophysics Data System (ADS)

    Zhang, Yong; Fang, Xuan; Chau, Wayne; Hsia, Chin-Hao; Liu, Xiao-Wei; Kwok, Sun

    2012-08-01

    The Eskimo Nebula (NGC 2392) is a young double-shell planetary nebula (PN). Its intrinsic structure and the responsible shaping mechanism are still not fully understood. We present new optical spectroscopy of NGC 2392 at two different locations to obtain the spectra of the inner and outer shells. Several [Fe iii] lines are clearly detected. We find that these [Fe iii] lines mostly originate from the inner shell. Therefore, we suggest that NGC 2392 might have an intrinsic structure similar to the Ant Nebula Mz 3, which exhibits a number of [Fe iii] lines from the central dense regions. In this scenario, the inner and outer shells correspond to the central emission core and the outer lobes of Mz 3, respectively.

  10. Spatial studies of planetary nebulae with IRAS

    NASA Technical Reports Server (NTRS)

    Hawkins, G. W.; Zuckerman, B.

    1991-01-01

    The infrared sizes at the four IRAS wavelengths of 57 planetaries, most with 20-60 arcsec optical size, are derived from spatial deconvolution of one-dimensional survey mode scans. Survey observations from multiple detectors and hours confirmed (HCON) observations are combined to increase the sampling to a rate that is sufficient for successful deconvolution. The Richardson-Lucy deconvolution algorithm is used to obtain an increase in resolution of a factor of about 2 or 3 from the normal IRAS detector sizes of 45, 45, 90, and 180 arcsec at wavelengths 12, 25, 60, and 100 microns. Most of the planetaries deconvolve at 12 and 25 microns to sizes equal to or smaller than the optical size. Some of the planetaries with optical rings 60 arcsec or more in diameter show double-peaked IRAS profiles. Many, such as NGC 6720 and NGC 6543 show all infrared sizes equal to the optical size, while others indicate increasing infrared size with wavelength. Deconvolved IRAS profiles are presented for the 57 planetaries at nearly all wavelengths where IRAS flux densities are 1-2 Jy or higher.

  11. Spatial studies of planetary nebulae with IRAS

    SciTech Connect

    Hawkins, G.W.; Zuckerman, B. )

    1991-06-01

    The infrared sizes at the four IRAS wavelengths of 57 planetaries, most with 20-60 arcsec optical size, are derived from spatial deconvolution of one-dimensional survey mode scans. Survey observations from multiple detectors and hours confirmed (HCON) observations are combined to increase the sampling to a rate that is sufficient for successful deconvolution. The Richardson-Lucy deconvolution algorithm is used to obtain an increase in resolution of a factor of about 2 or 3 from the normal IRAS detector sizes of 45, 45, 90, and 180 arcsec at wavelengths 12, 25, 60, and 100 microns. Most of the planetaries deconvolve at 12 and 25 microns to sizes equal to or smaller than the optical size. Some of the planetaries with optical rings 60 arcsec or more in diameter show double-peaked IRAS profiles. Many, such as NGC 6720 and NGC 6543 show all infrared sizes equal to the optical size, while others indicate increasing infrared size with wavelength. Deconvolved IRAS profiles are presented for the 57 planetaries at nearly all wavelengths where IRAS flux densities are 1-2 Jy or higher. 60 refs.

  12. Supernova remnants, planetary nebulae and the distance to NGC 4214

    NASA Astrophysics Data System (ADS)

    Dopita, Michael A.; Calzetti, Daniela; Maíz Apellániz, Jesús; Blair, William P.; Long, Knox S.; Mutchler, Max; Whitmore, Bradley C.; Bond, Howard E.; MacKenty, John; Balick, Bruce; Carollo, Marcella; Disney, Michael; Frogel, Jay A.; O'Connell, Robert; Hall, Donald; Holtzman, Jon A.; Kimble, Randy A.; McCarthy, Patrick; Paresce, Francesco; Saha, Abhijit; Walker, Alistair R.; Silk, Joe; Sirianni, Marco; Trauger, John; Windhorst, Rogier; Young, Erick

    2010-11-01

    We present narrow band, continuum subtracted H α, [S ii], H β, [O iii] and [O ii] data taken with the Wide Field Camera 3 on the Hubble Space Telescope in the nearby dwarf starburst galaxy NGC 4214. From these images, we identify seventeen new planetary nebula candidates, and seven supernova remnant candidates. We use the observed emission line luminosity function of the planetary nebulae to establish a new velocity-independent distance to NGC 4214. We conclude that the PNLF technique gives a reddening independent distance to NGC 4214 of 3.19±0.36 Mpc, and that our current best-estimate of the distance to this galaxy ids 2.98±0.13 Mpc.

  13. Probing Shocks of the Young Planetary Nebula NGC 7027

    NASA Astrophysics Data System (ADS)

    Montez, Rodolfo

    2013-09-01

    The rapid evolution of the planetary nebula NGC 7027 provides a rare glimpse at the evolution of the shocks. We propose a detailed spatial and spectroscopic study of the shock conditions in NGC 7027 that will enhance and bridge our understanding of the shocks seen in other planetary nebula. Comparison between the Cycle 1 observation and a new Cycle 15 observation will (i) confirm the presence of the two components in the extended X-ray emission, (ii) measure the changes (spatial and spectral) in the components, and, (iii) provide a valuable trove of tests and inputs for shock conditions and hydrodynamical simulations. We rely on the unprecedented spatial resolution and soft-sensitivity of Chandra.

  14. Forbidden O III electron temperature in planetary nebulae

    NASA Astrophysics Data System (ADS)

    Keenan, F. P.; Aggarwal, K. M.

    1989-06-01

    The electron-temperature-sensitive emission-line ratio I(2s2 2p2 1D - 2s2 2p2 1S)/I(2s2 2p2 3P1,2 - 2s2 2p2 1D) = I(4363 A)/I(4959 + 5007 A) has been determined based upon relative level populations for O III obtained using impact excitation rates calculated with the R-matrix code. Results are presented for a temperature range which is applicable to planetary nebulae. Electron temperatures derived from the observed R values of several planetary nebulae agree well with those determined from electron-temperature-sensitive line ratios is such other species as (semiforbidden C III)/C II, forbidden N II, and forbidden Ar II.

  15. Elemental abundances in high-excitation planetary nebulae

    NASA Technical Reports Server (NTRS)

    Marionni, P. A.; Harrington, J. P.

    1981-01-01

    The IUE satellite was used to obtain low dispersion spectra of the high excitation planetary nebulae IC 351, IC 2003, NGC 2022, IC 2165, NGC 2440, Hu 1-2, and IC 5217. Numerical modeling was undertaken to determine the chemical composition of these objects with particular emphasis on obtaining elemental carbon and nitrogen abundances. Large variations in the C/N ratio from object to object are suggested.

  16. Morphology of the Red Rectangle Proto-planetary Nebula

    NASA Astrophysics Data System (ADS)

    Koning, N.; Kwok, Sun; Steffen, W.

    2011-10-01

    The morphology of the Red Rectangle (RR) exhibits several singular attributes. Most prominent are a series of linear features perpendicular to the symmetry axis which appear as "ladder rungs" across the nebula. At the edge of each "rung" gas seemingly flows from bright knots in a parabolic shape toward the center of the nebula. We present a new model of the RR which explains these features as a projection effect of the more common concentric arcs seen in other proto-planetary nebulae (e.g., Egg Nebula). Using the three-dimensional morpho-kinematic modeling software SHAPE, we have created a model of the RR that consists of spherical shells evacuated by a bi-conical outflow. When the symmetry axis is oriented perpendicular to the line of sight, the spherical shells become linear, thereby reproducing the "rungs" seen in the RR. When oriented at different inclinations, the linear features become spherical as observed in the Egg Nebula. The model also accurately reproduces the bright knots and the parabolic outflows from these knots that have proven difficult to explain in the past. Using this model, we are able to place a lower limit on the speed of the outflow of ~158 km s-1.

  17. MORPHOLOGY OF THE RED RECTANGLE PROTO-PLANETARY NEBULA

    SciTech Connect

    Koning, N.; Kwok, Sun; Steffen, W. E-mail: sunkwok@hku.hk

    2011-10-10

    The morphology of the Red Rectangle (RR) exhibits several singular attributes. Most prominent are a series of linear features perpendicular to the symmetry axis which appear as 'ladder rungs' across the nebula. At the edge of each 'rung' gas seemingly flows from bright knots in a parabolic shape toward the center of the nebula. We present a new model of the RR which explains these features as a projection effect of the more common concentric arcs seen in other proto-planetary nebulae (e.g., Egg Nebula). Using the three-dimensional morpho-kinematic modeling software SHAPE, we have created a model of the RR that consists of spherical shells evacuated by a bi-conical outflow. When the symmetry axis is oriented perpendicular to the line of sight, the spherical shells become linear, thereby reproducing the 'rungs' seen in the RR. When oriented at different inclinations, the linear features become spherical as observed in the Egg Nebula. The model also accurately reproduces the bright knots and the parabolic outflows from these knots that have proven difficult to explain in the past. Using this model, we are able to place a lower limit on the speed of the outflow of {approx}158 km s{sup -1}.

  18. ChanPlaNS: The Chandra Planetary Nebula Survey

    NASA Astrophysics Data System (ADS)

    Kastner, Joel; Montez, Rodolfo; Freeman, Marcus; ChanPlaNS Team

    2015-01-01

    The physical mechanisms responsible for the morphological diversity among planetary nebulae (PNe) have been the subject of intense interest and hot debate among PN researchers over the past two decades. The PN shaping problem is multifaceted, with connections to (and implications for) a wide variety of astrophysical systems. Two areas of particular importance are (1) binary star astrophysics and (2) wind interactions and their implications for nebular shaping. X-ray observations play a pivotal role in the study of both of these fundamental aspects of PNe, by revealing (1) point-like X-ray sources at PN central stars that may be indicative of binary companions, and (2) diffuse X-ray emission generated by energetic, PN-shaping shocks. To assess the frequency of appearance and characteristics of these respective PN X-ray sources, we have undertaken the Chandra Planetary Nebula Survey (ChanPlaNS), the first comprehensive X-ray survey of planetary nebulae (PNe) in the solar neighborhood. ChanPlaNS began with a combined Cycle 12 Large Program and archival survey of 35 PNe, with emphasis on high-excitation nebulae, and continued via a Cycle 14 Large Program targeting an additional 24 known compact (R_neb <~ 0.4 pc) PNe. For the latter category of relatively young nebulae, we estimate that the ChanPlaNS survey is ~90% complete within ~1.5 kpc from the Sun. For the ~60 nebulae within this distance observed by Chandra, the point source detection rate is ~36%, and the diffuse X-ray source detection rate is ~27%. However, the point-like and diffuse X-ray detection rates, respectively, are significantly higher for PNe known to harbor binary central stars (~60%) and for the compact (young) PN subsample (~50%). These results demonstrate the potential for insight into PN shaping processes provided by ChanPlaNS. In companion presentations at this meeting (Montez et al.; Freeman et al.), we present highlights of the astrophysics gleaned to date from these Chandra detections (and

  19. Magellanic cloud planetary nebula with suspected strong forbidden iron lines

    PubMed Central

    Aller, L. H.; Czyzak, S. J.

    1983-01-01

    The relatively high-excitation nebula (Westerlund-Smith object 25) in the large Magellanic cloud shows prominent forbidden lines of [Ar IV], the close [Ne IV] pair λ4724, 4726, [Ca V] λ5309, [Fe V] λ4227, and probably [Fe VI] and [Fe VII], as well. A conventional interpretation of observations secured with a vidicon detector at the Cerro Tololo 4-m telescopes indicates an essentially “normal” helium abundance but depletions of N, O, Ne, and other elements with respect to our own galaxy. When a comparison is made with diffuse nebulae or H II regions in the large Magellanic cloud, we find helium to be more abundant, oxygen to be depleted, and nitrogen, neon, and argon to be comparable. The abundance of sulfur is uncertain. Iron in the gaseous phase is certainly more plentiful than in conventional planetaries. PMID:16593294

  20. Magellanic cloud planetary nebula with suspected strong forbidden iron lines.

    PubMed

    Aller, L H; Czyzak, S J

    1983-03-01

    The relatively high-excitation nebula (Westerlund-Smith object 25) in the large Magellanic cloud shows prominent forbidden lines of [Ar IV], the close [Ne IV] pair lambda4724, 4726, [Ca V] lambda5309, [Fe V] lambda4227, and probably [Fe VI] and [Fe VII], as well. A conventional interpretation of observations secured with a vidicon detector at the Cerro Tololo 4-m telescopes indicates an essentially "normal" helium abundance but depletions of N, O, Ne, and other elements with respect to our own galaxy. When a comparison is made with diffuse nebulae or H II regions in the large Magellanic cloud, we find helium to be more abundant, oxygen to be depleted, and nitrogen, neon, and argon to be comparable. The abundance of sulfur is uncertain. Iron in the gaseous phase is certainly more plentiful than in conventional planetaries. PMID:16593294

  1. Spectrophotometry of Bowen resonance fluorescence lines in three planetary nebulae

    NASA Technical Reports Server (NTRS)

    O'Dell, C. R.; Miller, Christopher O.

    1992-01-01

    The results are presented of a uniquely complete, carefully reduced set of observations of the O III Bowen fluorescence lines in the planetary nebulae NGC 6210, NGC 7027, and NGC 7662. A detailed comparison with the predictions of radiative excitation verify that some secondary lines are enhanced by selective population by the charge exchange mechanism involving O IV. Charge exchange is most important in NGC 6210, which is of significantly lower ionization than the other nebulae. In addition to the principal Bowen lines arising from Ly-alpha pumping of the O III O1 line, lines arising from pumping of the O3 line are also observed. Comparison of lines produced by O1 and O3 with the theoretical predictions of Neufeld indicate poor agreement; comparison with the theoretical predictions of Harrington show agreement with NGC 7027 and NGC 7662.

  2. Magellanic Cloud Planetary Nebula with Suspected Strong Forbidden Iron Lines

    NASA Astrophysics Data System (ADS)

    Aller, L. H.; Czyzak, S. J.

    1983-03-01

    The relatively high-excitation nebula (Westerlund-Smith object 25) in the large Magellanic cloud shows prominent forbidden lines of [Ar IV], the close [Ne IV] pair λ 4724, 4726, [Ca V] λ 5309, [Fe V] λ 4227, and probably [Fe VI] and [Fe VII], as well. A conventional interpretation of observations secured with a vidicon detector at the Cerro Tololo 4-m telescopes indicates an essentially ``normal'' helium abundance but depletions of N, O, Ne, and other elements with respect to our own galaxy. When a comparison is made with diffuse nebulae or H II regions in the large Magellanic cloud, we find helium to be more abundant, oxygen to be depleted, and nitrogen, neon, and argon to be comparable. The abundance of sulfur is uncertain. Iron in the gaseous phase is certainly more plentiful than in conventional planetaries.

  3. Planetary nebulae and their mimics: The MASH-MEN Project

    NASA Astrophysics Data System (ADS)

    Boissay, Rozenn; Parker, Quentin A.; Frew, David J.; Bojicic, Ivan

    2012-08-01

    The total number of true, likely and possible planetary nebulae (PN) now known in the Milky Way is about 3000, approximately twice the number known a decade ago. The new discoveries are a legacy of the recent availability of wide-field, narrowband imaging surveys, primarily in the light of Hα. The two most important are the AAO/UKST SuperCOSMOS Hα survey SHS and the Isaac Newton photometric Hα survey IPHAS, which are responsible for most of the new discoveries. A serious problem with previous PN catalogs is that several different kinds of astrophysical objects are able to mimic PN in some of their observed properties leading to significant contamination. These objects include H~II regions and Strömgren zones around young O/B stars, reflection nebulae, Wolf-Rayet ejecta, supernova remnants, Herbig-Haro objects, young stellar objects, B[e] stars, symbiotic stars and outflows, late-type stars, cataclysmic variables, low redshift emission-line galaxies, and even image/detector flaws. PN catalogs such as the Macquarie/AAO/Strasbourg Hα Planetary Nebula catalog (MASH) have been carefully vetted to remove these mimics using the wealth of new wide-field multi-wavelength data and our 100% follow-up spectroscopy to produce a compilation of new PN discoveries of high purity. During this process significant numbers of PN mimics have been identified. The aim of this project is to compile these MASH rejects into a catalog of Miscellaneous Emission Nebulae (MEN) and to highlight the most unusual and interesting examples. A new global analysis of these MEN objects is underway before publishing the MEN catalog online categorizing objects by type together with their spectra and multi-wavelength images.

  4. Hubble Space Telescope Image: Planetary Nebula IC 4406

    NASA Technical Reports Server (NTRS)

    2001-01-01

    This Hubble Space Telescope image reveals a rainbow of colors in this dying star, called IC 446. Like many other so-called planetary nebulae, IC 4406 exhibits a high degree of symmetry. The nebula's left and right halves are nearly mirror images of the other. If we could fly around IC 446 in a spaceship, we would see that the gas and dust form a vast donut of material streaming outward from the dying star. We do not see the donut shape in this photograph because we are viewing IC 4406 from the Earth-orbiting HST. From this vantage point, we are seeing the side of the donut. This side view allows us to see the intricate tendrils of material that have been compared to the eye's retina. In fact, IC 4406 is dubbed the 'Retina Nebula.' The donut of material confines the intense radiation coming from the remnant of the dying star. Gas on the inside of the donut is ionized by light from the central star and glows. Light from oxygen atoms is rendered blue in this image; hydrogen is shown as green, and nitrogen as red. The range of color in the final image shows the differences in concentration of these three gases in the nebula. This image is a composite of data taken by HST's Wide Field Planetary Camera 2 in June 2001 and in January 2002 by Bob O'Dell (Vanderbilt University) and collaborators, and in January by the Hubble Heritage Team (STScI). Filters used to create this color image show oxygen, hydrogen, and nitrogen gas glowing in this object.

  5. Chemical evolution models for NGC 6822 using planetary nebulae abundances

    NASA Astrophysics Data System (ADS)

    Hernández-Martínez, Liliana; Carigi, Leticia; Peña, Miriam; Peimbert, Manuel

    2012-08-01

    We present chemical evolution models for the dwarf irregular NGC 6822, using chemical abundances of Planetary Nebulae (PNe) and HII regions and also the mass of gas (M gas ) as observational constraints. Chemical evolution models have been calculated to reproduce the abundances as derived from both, collisionally excited lines (CELs) and recombination lines (RLs). In our models, the chemical contribution of low and intermediate mass stars (LIMS) is time delayed, while for the massive stars the chemical contribution is instantaneous, as in Franco & Carigi (2008). The chemical contribution of SNIa is included in our model, thus we are also able to reproduce the observational Fe/H abundance obtained from A stars.

  6. Planetary nebulae as probes of galactic evolution and populations

    NASA Astrophysics Data System (ADS)

    Stanghellini, Letizia

    2016-05-01

    Planetary Nebulae (PNe), the relics of the envelope ejected by low and intermediate-mass stars at the end of their evolution, carry a lot of information of the life of their progenitors and the environment where they originated. The field of PN and its population is more active than even, especially given the new generation of space- and ground-based datasets that have became available in the last few decades. In this paper we review a selection of topics centered in the importance of PNe as probes of galaxy evolution and populations.

  7. The forbidden S II electron density distribution over the planetary nebula NGC 7009

    NASA Astrophysics Data System (ADS)

    Meaburn, J.; Walsh, J. R.

    1981-08-01

    Electron densities have been measured from [S ii] 6716/6731 A line ratios for a grid of points over the surface of the planetary nebula NGC 7009 using a photon counting detector. The radial dependence of the electron density has been modelled, and the relationship provides possible evidence that the planetary nebula shell is driven by a strong stellar wind

  8. Planetary Nebulae: Reviews and Previews of a Rapidly Evolving Field

    NASA Astrophysics Data System (ADS)

    Balick, Bruce

    2015-01-01

    Observational results from the ground and space in the past decade and covering the entire spectrum have jolted and energized research into the nature, the formation, and the evolution of planetary nebulae (PNs). The 101-level bubble structure of PNs turned out to be a pleasant but misleading fantasy as observations by HST and ALMA revealed basic details of their infancy. Some combination of close geriatric binary stars (the precusrors of SN Ia's) and magnetic fields dredged into the dusty winds appear to play vital roles in the ejection and collimation of AGB atmospheres. As a result, PNe and their antecedents, AGB stars and prePNs, are providing an array of new opportunities to study asymmetric wind formation, complex gas dynamics, CNO production rates in various galactic environments, and galaxy structure and evolution. I shall review the highlights of recent results, summarize their interpretations, and show some of the observational opportunities to monitor in the next decade, many of which couple strongly to research to related fields.This talk is dedicated to the career of Olivier Chesneau (1972-2014) who pioneered new high-resolution imaging methods that peered into the deep inner cores of nascent planetary nebulae. We remember Olivier as everyone's enthusiastic friend and colleague whose career ended in full stride.

  9. Broad Halpha Wing Formation in the Planetary Nebula IC 4997.

    PubMed

    Lee; Hyung

    2000-02-10

    The young and compact planetary nebula IC 4997 is known to exhibit very broad wings with a width exceeding 5000 km s-1 around Halpha. We propose that the broad wings are formed through Rayleigh-Raman scattering that involves atomic hydrogen, by which Lybeta photons with a velocity width of a few 102 km s-1 are converted to optical photons and fill the Halpha broad wing region. The conversion efficiency reaches 0.6 near the line center, where the scattering optical depth is much larger than 1, and rapidly decreases in the far wings. Assuming that close to the central star there exists an unresolved inner compact core of high density, nH approximately 109-1010 cm-3, we use the photoionization code "CLOUDY" to show that sufficient Lybeta photons for scattering are produced. Using a top-hat-incident profile for the Lybeta flux and a scattering region with a H i column density NHi=2x1020 cm-2 and a substantial covering factor, we perform a profile-fitting analysis in order to obtain a satisfactory fit to the observed flux. We briefly discuss the astrophysical implications of the Rayleigh-Raman processes in planetary nebulae and other emission objects. PMID:10642203

  10. A Bipolar Planetary Nebula NGC 6537: Photoionization or Shock Heating?

    NASA Astrophysics Data System (ADS)

    Hyung, Siek

    1999-04-01

    NGC 6537 is an extremely high excitation bipolar planetary nebula. It exhibits a huge range of excitation from lines of [N I] to [Si VI] or [Fe VII], i.e. from neutral atoms to atoms requiring an ionization potential of 167eV. Its kinematical structures are of special interest. We are here primarily concerned with its high resolution spectrum as revealed by the Hamilton Echelle Spectrograph at Lick Observatory (resolution 0.2 A,) and supplemented by UV and near-UV data. Photoionization model reproduces the observed global spectrum of NGC 6537, the absolute H beta flux, and the observed visual or blue magnitude fairly well. The nebulosity of NGC 6537 is likely to be the result of photo-ionization by a very hot star of Teff 180,000 K, although the global nebular morphology and kinematics suggest an effect by strong stellar winds and resulting shock heating. NGC 6537 can be classified as a Peimbert Type I planetary nebula. It is extremely young and it may have originated from a star of about 5 M_sun.

  11. Magnetic fields around AGB stars and Planetary Nebulae

    NASA Astrophysics Data System (ADS)

    Vlemmings, W. H. T.

    2014-08-01

    Stars with a mass up to a few solar masses are one of the main contributors to the enrichment of the interstellar medium in dust and heavy elements. However, while significant progress has been made, the process of the mass-loss responsible for this enrichment is still not exactly known and forces beyond radiation pressure might be required. Often, the mass lost in the last phases of the stars life will become a spectacular planetary nebula. The shaping process of often strongly a-spherical PNe is equally elusive. Both binaries and magnetic fields have been suggested to be possible agents although a combination of both might also be a natural explanation. Here I review the current evidence for magnetic fields around AGB and post-AGB stars pre-Planetary Nebulae and PNe themselves. Magnetic fields appear to be ubiquitous in the envelopes of apparently single stars, challenging current ideas on its origin, although we have found that binary companions could easily be hidden from view. There are also strong indications of magnetically collimated outflows from post-AGB/pre-PNe objects supporting a significant role in shaping the circumstellar envelope.

  12. The ionization structure of planetary nebulae. VII. New observations of the Ring Nebula

    NASA Technical Reports Server (NTRS)

    Barker, Timothy

    1987-01-01

    New optical spectrophotometric observations of emission-line intensities have been made in eight positions in the Ring Nebula corresponding to those observed previously with the Ultraviolet Explorer satellite; the total coverage is therefore 1400 to 7200 A. The intensities are in generally good agreement with those found previously in corresponding positions. The Oand Balmer continuum electron temperatures agree well on the average and, like the Nelectron temperatures, decrease with increasing distance from the central star. As found previously for the Ring Nebula and for other planetaries in this series, the lambda 4267 C 2 line intensity near the central star implies a Cabundance that is higher than that determined from the lambda 1906, 1909 C 3 lines. The discrepancy again decreases with increasing distance from the central star and vanishes from the outermost positions, again suggesting that the excitation mechanism from the lambda 4267 line is not understood. Standard equations used to correct for the existence of elements in other than the optically observable ionization stages give results that are consistent and in appropriate agreement with abundances calculated using UV lines. The rather high abundances of O, N, and C, and, to some extent N, indicate that some mixing of CNO processed material into the nebular shell may have occurred in the Ring Nebula.

  13. A study of the far infrared counterparts of new candidates for planetary nebulae

    NASA Astrophysics Data System (ADS)

    Iyengar, K. V. K.

    1986-05-01

    The IRAS Point Source Catalog was searched for infrared counterparts of the fourteen new candidates for planetary nebulae of low surface brightness detected by Hartl and Tritton (1985). Five of these candidates were identified with sources in the Catalog. All five nebulae are found in regions of high cirrus flux at 100 microns, and all have both point sources and small size extended sources with numbers varying from field to field. The infrared emission from these nebulae is connected with dust temperatures of about 100 K, characteristic of planetary nebulae.

  14. UNUSUAL DUST EMISSION FROM PLANETARY NEBULAE IN THE MAGELLANIC CLOUDS

    SciTech Connect

    Bernard-Salas, J.; Sloan, G. C.; Gutenkunst, S.; Houck, J. R.; Peeters, E.; Matsuura, M.; Tielens, A. G. G. M.; Zijlstra, A. A.

    2009-07-10

    We present a Spitzer Space Telescope spectroscopic study of a sample of 25 planetary nebulae (PNe) in the Magellanic Clouds (MCs). The low-resolution modules are used to analyze the dust features present in the infrared spectra. This study complements a previous work by the same authors where the same sample was analyzed in terms of neon and sulfur abundances. Over half of the objects (14) show emission of polycyclic aromatic hydrocarbons, typical of carbon-rich dust environments. We compare the hydrocarbon emission in our objects to those of Galactic H II regions and PNe, and Large Magellanic Cloud/Small Magellanic Cloud H II regions. Amorphous silicates are seen in just two objects, enforcing the now well known fact that oxygen-rich dust is less common at low metallicities. Besides these common features, some PNe show very unusual dust. Nine objects show a strong silicon carbide feature at 11 {mu}m and 12 of them show magnesium sulfide emission starting at 25 {mu}m. The high percentage of spectra with silicon carbide in the MCs is not common. Two objects show a broadband which may be attributed to hydrogenated amorphous carbon and weak low-excitation atomic lines. It is likely that these nebulae are very young. The spectra of the remaining eight nebulae are dominated by the emission of fine-structure lines with a weak continuum due to thermal emission of dust, although in a few cases the signal-to-noise ratio in the spectra is low, and weak dust features may not have been detected.

  15. Ring Planetary Nebulae Ejected from Close Binary Stars

    NASA Astrophysics Data System (ADS)

    Bond, H. E.; Ciardullo, R.; Webbink, R.

    1996-12-01

    We report photometric observations of the central stars of three planetary nebulae (PNe) which appear to be thin circular rings. All three central stars have proven to be close binaries, from CCD observations made at the CTIO and KPNO 0.9-m telescopes. The southern-hemisphere PN Sp 1 is a nearly perfect circular ring. Its central star has a light curve which is a low-amplitude sinusoid with a period of 2.9 days, suggesting a reflection effect in a binary system seen nearly pole-on. We therefore suggested (Bond & Livio, ApJ 355, 568, 1990) that the nebula must be a true toroidal annulus, likewise seen nearly pole-on. SuWt 2 is another southern PN, which appears as a thin ellipse. If it were an Sp 1-like PN, seen almost edge-on, and also ejected from a close binary, we might hope to detect actual stellar eclipses. This has proven to be the case: the central star is an eclipsing binary with a period of 4.8 days. WeBo 1 is a northern PN recently discovered by Webbink and Bond. Morphologically the nebula is extremely similar to SuWt 2, in being an almost mathematically perfect ellipse. Recent observations at KPNO reveal that its central star is also a close binary, with a sinusoidal light curve and a period of approximately 5 days. It is thus becoming clear that some close binaries can undergo a common-envelope interaction that results in a much shorter orbital period accompanied by ejection of a thin nebular ring. Parallels with other objects, including SN 1987A, should be explored.

  16. FORMATION OF FULLERENES IN H-CONTAINING PLANETARY NEBULAE

    SciTech Connect

    GarcIa-Hernandez, D. A.; Manchado, A.; Stanghellini, L.; Shaw, R. A.; Villaver, E.; Szczerba, R.; Perea-Calderon, J. V. E-mail: amt@iac.e E-mail: shaw@noao.ed E-mail: eva.villaver@uam.e E-mail: Jose.Perea@sciops.esa.in

    2010-11-20

    Hydrogen depleted environments are considered an essential requirement for the formation of fullerenes. The recent detection of C{sub 60} and C{sub 70} fullerenes in what was interpreted as the hydrogen-poor inner region of a post-final helium shell flash planetary nebula (PN) seemed to confirm this picture. Here, we present strong evidence that challenges the current paradigm regarding fullerene formation, showing that it can take place in circumstellar environments containing hydrogen. We report the simultaneous detection of polycyclic aromatic hydrocarbons (PAHs) and fullerenes toward C-rich and H-containing PNe belonging to environments with very different chemical histories such as our own Galaxy and the Small Magellanic Cloud. We suggest that PAHs and fullerenes may be formed by the photochemical processing of hydrogenated amorphous carbon. These observations suggest that modifications may be needed to our current understanding of the chemistry of large organic molecules as well as the chemical processing in space.

  17. The ionization structure of planetary nebulae. Part 4: NGC 7662

    NASA Technical Reports Server (NTRS)

    Barker, T.

    1985-01-01

    Spectrophotometric observations of emission-line intensities over the spectral range 1400 to 7200 A were made in five positions in the planetary nebula NGC 7662. Standard equations used to correct for the existence of elements in other than the optically observable ionization stages show a consistent and approximate agreement with abundances calculated using ultraviolet lines. The abundances of C and N indicate that some mixing of CNO-processed material into the nebular shell may have occurred in NGC 7662; the low He abundance, however, indicates that little or no He enrichment occurred. The Ar, Ne, and O and S abundances appear to be low. It is suggested that the progenitor to NGC 7662 may have formed out of somewhat metal-poor material.

  18. Near-infrared spectroscopy of proto-planetary nebulae

    NASA Technical Reports Server (NTRS)

    Hrivnak, Bruce J.; Kwok, Sun; Geballe, T. R.

    1994-01-01

    Sixteen proto-planetary nebulae were observed with low-resolution infrared spectroscopy in the H and K bands, and four were observed in the L band. In the H band, most of the objects show hydrogen Brackett lines (from n = 10 goes to 4 to n = 20 goes to 4) in absorption. In the K band, absorption bands (delta (nu) = 2) of CO were observed to as high as nu = 6 goes to 4, and in three cases the CO bands are in emission. The CO spectrum of 22272 + 5435 was found to change from emission to absorption over a 3 month interval. The CO emission most likely arises from collisional excitation resulting from recent episodes of mass loss. One new object which possibly shows weak 3.3 micron emission was found.

  19. Wolf-Rayet central stars of planetary nebulae

    NASA Astrophysics Data System (ADS)

    Todt, H.; Hamann, W.-R.

    A significant number of the central stars of planetary nebulae (CSPNe) are hydrogen-deficient, showing a chemical composition of helium, carbon, and oxygen. Most of them exhibit Wolf-Rayet-like emission line spectra, similar to those of the massive WC Pop I stars, and are therefore classified as of spectral type [WC]. In the last years, CSPNe of other Wolf-Rayet spectral subtypes have been identified, namely PB 8, which is of spectral type [WN/C], and IC 4663 and Abell 48, which are of spectral type [WN]. We review spectral analyses of Wolf-Rayet type central stars of different evolutionary stages and discuss the results in the context of stellar evolution. Especially we consider the question of a common evolutionary channel for [WC] stars. The constraints on the formation of [WN] or [WC/N] subtype stars will also be addressed.

  20. Discovery of new planetary nebulae in the Small Magellanic Cloud

    NASA Astrophysics Data System (ADS)

    Drašković, D.; Parker, Q. A.; Reid, W. A.; Stupar, M.

    2016-07-01

    We present six new planetary nebulae (PNe) discovered in the Small Magellanic Cloud (SMC) from deep UK Schmidt telescope (UKST) narrow band Ha and broad-band short- red “SR” continuum images and confirmed spectroscopically. These 6 preliminary discoveries provide a 6% increase to the previously known SMC PN population of ∼⃒100. Once spectroscopic follow-up of all our newly identified candidates is complete, we expect to increase the total number of known SMC PNe by up to 50%. This will permit a significant improvement to determination of the SMC PN luminosity function (PNLF) and enable further insights into the chemical evolution and kinematics of the SMC PN population.

  1. Radio-continuum Emission from Magellanic Clouds Planetary Nebulae

    NASA Astrophysics Data System (ADS)

    Filipovic, Miroslav

    2015-08-01

    Comparison of recent Australia Telescope Compact Array (ATCA) / Parkes mosaic surveys of the Magellanic Clouds (MCs) with positions of known planetary nebulae (PNe) have revealed a total of about 50 radio counterparts. Six (15) Small Magellanic Cloud (SMC) candidates were found in 5~GHz surveys, while ~35 were found in the Large Magellanic Cloud (LMC). Followup high resolution ATCA observations at 6 and 3 cm (4" and 2" beams, respectively) reveal that these sources are located within 1" of their optical counterparts. They are extended with higher than expected flux densities. Complimentary optical PNe spectra have typical electron temperatures and densities. Estimates of nebular ionized mass, based on these elevated radio flux densities, suggest they may be the result of significant circumstellar envelopes. These envelopes may have been formed from winds ejected from high mass (up to 8 solar) progenitor stars.

  2. What is shaping the planetary nebula K3-35?

    NASA Astrophysics Data System (ADS)

    Gómez, Y.; Tafoya, D.; Anglada, G.; Miranda, L. F.; Uscanga, L.; Torrelles, J. M.; Velázquez, P. F.

    2011-02-01

    K 3-35 is a very young planetary nebula (PN) with a characteristic S-shaped radio emission morphology. It is the first PN where water vapor maser was detected: the emission is located in a torus-like structure with a radius of 100 AU and also at the surprisingly large distance of 5000 AU from the star, in the tips of the bipolar lobes. Several mechanism have been proposed to explain the bipolar morphology of PNe, and in the case of K 3-35 we believe we may be observing several of them at the same time: i) a disk-like structure traced by the H2O masers, ii) a precessing bipolar jet probably due to the presence of a binary companion and iii) circular polarization in the OH 1665 MHz masers, which suggests the presence of a magnetic field. Additional observations and modeling are needed to establish what mechanisms are shaping K 3-35.

  3. An ISO and IUE Study of Planetary Nebula NGC 2440

    NASA Technical Reports Server (NTRS)

    Salas, J. Bernard; Pottasch, S. R.; Feibelman, W. A.; Wesselius, P. R.; Oegerle, William R. (Technical Monitor)

    2002-01-01

    The infrared and ultraviolet spectra of planetary nebula NGC 2440 is presented. The observations were made respectively by the Infrared Space Observatory (ISO) and International Ultraviolet Explorer (IUE) These data, in conjunction with published optical observations have been used to derive electron temperature and density. A trend of electron temperature with ionization potential is found. In particular the electron temperature increases from 11000 to 18000 K with increasing IBM. The electron density has a constant value of 4500/cu cm in agreement with previous determination. The chemical abundance has been derived for the following elements; helium, carbon, nitrogen, oxygen, neon, sulfur and argon. The ionization correction factor turns out to be very small (almost unnecessary) for all species except sulfur.

  4. EXPANSION PARALLAX OF THE PLANETARY NEBULA IC 418

    SciTech Connect

    Guzman, Lizette; Loinard, Laurent; Gomez, Yolanda; Morisset, Christophe

    2009-07-15

    In this paper, we present radio continuum observations of the planetary nebula IC 418 obtained at two epochs separated by more than 20 years. These data allow us to show that the angular expansion rate of the ionization front in IC 418 is 5.8 {+-} 1.5 mas yr{sup -1}. If the expansion velocity of the ionization front is equal to the expansion velocity of the gas along the line of sight as measured by optical spectroscopy, then the distance to IC 418 must be 1.1 {+-} 0.3 kpc. Recent theoretical predictions appropriate for the case of IC 418, however, suggest that the ionization front may be expanding about 20% faster than the material. Under this assumption, the distance to IC 418 would increase to 1.3 {+-} 0.4 kpc.

  5. A search for pulsations in planetary nebulae nuclei

    SciTech Connect

    Hine, B.P.A. III.

    1988-01-01

    The author presents the results of a survey of the central stars of planetary nebulae design to detect g-mode pulsations driven by hydrogen and/or helium shell burning. Using newly developed high-speed photometric instrumentation to overcome the inherent difficulties in observing these central stars in the presence of their nebulae, he has obtained time-series photometric data for 51 central stars in an effort to detect the g-mode pulsations predicted by Kawaler and his colleagues. He detects no periodic variations, for periods between 40 and 500 seconds, in the data down to a limit of approximately 0.5 (average) millimagnitudes. Since the theoretical calculations require these pulsations in the presence of shell burning, he must conclude that either the shell burning sources are extinguished prior to this evolutionary stage, or some mechanism is inhibiting the growth of these pulsations. If the shell burning source is indeed extinguished prior to the central star becoming a white dwarf, then this implies that white dwarfs are formed with hydrogen layer masses less than 10{sup {minus}6}M mass of sum.

  6. Abundances of planetary nebulae in the Galactic bulge

    NASA Astrophysics Data System (ADS)

    Pottasch, S. R.; Bernard-Salas, J.

    2015-11-01

    Context. Planetary nebulae (PNe) abundances are poorly known for those nebulae in the Galactic bulge. This is because of the high and uneven extinction in the bulge which makes visual spectral measurements difficult. In addition, the extinction corrections may be unreliable. Elements considered are O, N, Ne, S, Ar, and Cl. Aims: We determine the abundances in 19 PNe, 18 of which are located in the bulge. This doubles the number of PNe abundance determinations in the bulge. The Galactic abundance gradient is discussed for five elements. Methods: The mid-infrared spectra measured by the Spitzer Space Telescope are used to determine the abundances. This part of the spectrum is little affected by extinction for which an uncertain correction is no longer necessary. In addition the connection with the visible and ultraviolet spectrum becomes simpler because hydrogen lines are observed both in the infrared and in the visible spectra. In this way we more than double the number of PNe with reliable abundances. Results: Reliable abundances are obtained for O, N, Ne, S, and Ar for Galactic bulge PNe. Conclusions: The Galactic abundance gradient is less steep than previously thought. This is especially true for oxygen. The sulfur abundance is reliable because all stages of ionization expected have been measured. It is not systematically low compared to oxygen as has been found for some Galactic PNe. Based on observations with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology.

  7. The Conical Outflow of NGC 7026, a Multipolar Planetary Nebula

    NASA Astrophysics Data System (ADS)

    Clark, David M.; López, J.; Steffen, W.; Richer, M. G.

    2013-01-01

    We use the 3-dimensional visualization and kinematic program, Shape, together with high-resolution spectra and detailed HST images to study the complex planetary nebula (PN) NGC 7026. The spectra were acquired using the Manchester Echelle Spectrometer at San Pedro Martir Observatory in Baja California, Mexico. This PN displays remarkable symmetry consisting of three pairs of lobes and four sets of knots, all symmetrical about the nucleus and exhibiting a conical outflow. We also investigate the relationship between the 3-D structure and extended X-ray emission using recently acquired XMM-Newton observations from the literature. The X-ray emission is predominantly confined to the closed, northern lobes of this PN and also shows an abrupt termination in the middle of the SE lobe, which our long slit data shows to be open. Here is where the shocked, fast wind appears to be escaping the interior of the nebula and the X-ray emission cools rapidly in this region.

  8. The spectrum of the planetary nebula IC 418

    NASA Technical Reports Server (NTRS)

    Hyung, Siek; Aller, Lawrence H.; Feibelman, Walter A.

    1994-01-01

    A detailed high-spectral-resolution study of the spectrum of IC 418 is made for the region 3650 to 10050 A, using the Hamilton echelle spectrograph of Lick Observatory, and of the UV spectral region with archival International Ultraviolet Explorer (IUE) data. From high-resolution images in both the near- and mid-infrared, Hora et al. (1993) showed that IC 418 probably has a compact shell interior to the detached, well-known, main shell emission. If one assumes a black body or Hubeny (or standard LTE) model atmosphere energy distribution, it does not appear possible to construct a fully satisfactory nebula model that will simultaneously represent the H-beta flux, the (O III) 5007/H-beta ratio, and the scale of this planetary nebula (PN). Fortunately, IUE and IR data supply information on ions in addition to those optically observed so that the chemical composition can be reasonably well established by summing over concentrations of observed ions. In spite of the fact that IC 418 is carbon rich in sense of having a C/O ratio exceeding the solar value, it is a 'metal-poor' object. Possibly it resembles IC 4997 but in a more advanced evolutionary phase. The central star is variable and has a strong wind.

  9. Deuterium Astration in the Planetary Nebula Sh 2-216?

    NASA Astrophysics Data System (ADS)

    Oliveira, Cristina M.; Chayer, P.; Moos, H. Warren; Kruk, J. W.; Rauch, T.

    2006-12-01

    Sh 2-216 is a large and old low surface brightness planetary nebula at a distance of 130 pc. Its central star, WD0439+466, has been observed by FUSE and STIS allowing us to derive abundances of several elements along the sightline: D/H = (0.76 + 0.12 -0.11)E-5, O/H = (0.89 + 0.13 0.11)E-4, and N/H = (3.24 + 0.61 0.53)E-5. This fairly short sightline contains a large amount of hydrogen, most of which is in molecular form (J=0 through J=9), leading to an average volume density of 0.54 cm^(-3), higher than that of similar sightlines. In addition, we detect also absorption by HD J=0,1 and CO. We argue that most of the gas along this sightline is associated with the planetary nebula and that the low D/H ratio is likely the result of this gas being recently astrated. This would be the first time that the D/H ratio has been directly measured in astrated gas. The O/H and N/H ratios derived here are lower than typical values measured in other PN; however there is a large scatter in PN abundances. For these two species, ionization corrections not taken into account here might be important. Financial support to U. S. participants has been provided in part by NASA contract NAS5-32985 to Johns Hopkins University.

  10. Improved spectral descriptions of planetary nebulae central stars

    NASA Astrophysics Data System (ADS)

    Weidmann, W. A.; Méndez, R. H.; Gamen, R.

    2015-07-01

    Context. At least 492 central stars of Galactic planetary nebulae (CSPNs) have been assigned spectral types. Since many CSPNs are faint, these classification efforts are frequently made at low spectral resolution. However, the stellar Balmer absorption lines are contaminated with nebular emission; therefore in many cases a low-resolution spectrum does not enable the determination of the H abundance in the CSPN photosphere. Whether or not the photosphere is H deficient is arguably the most important fact we should expect to extract from the CSPN spectrum, and should be the basis for an adequate spectral classification system. Aims: Our purpose is to provide accurate spectral classifications and contribute to the knowledge of central stars of planetary nebulae and stellar evolution. Methods: We have obtained and studied higher quality spectra of CSPNs described in the literature as weak emission-line star (WELS). We provide descriptions of 19 CSPN spectra. These stars had been previously classified at low spectral resolution. We used medium-resolution spectra taken with the Gemini Multi-Object Spectrograph (GMOS). We provide spectral types in the Morgan-Keenan (MK) system whenever possible. Results: Twelve stars in our sample appear to have normal H rich photospheric abundances, and five stars remain unclassified. The rest (two) are most probably H deficient. Of all central stars described by other authors as WELS, we find that at least 26% of them are, in fact, H rich O stars, and at least 3% are H deficient. This supports the suggestion that the denomination WELS should not be taken as a spectral type, because, as a WELS is based on low-resolution spectra, it cannot provide enough information about the photospheric H abundance.

  11. Recombination Line vs. Forbidden Line Abundances in Planetary Nebulae

    NASA Astrophysics Data System (ADS)

    Robertson-Tessi, M.; Garnett, D. R.

    2004-05-01

    Recombination lines (RLs) of C II, N II, and O II in planetary nebulae (PNe) have been found to give abundances that are much larger in some cases than abundances from collisionally-excited forbidden lines (CELs). The origins of this abundance discrepancy are highly debated. We present new spectroscopic observations of O II and C II recombination lines for six planetary nebulae. With these data we compare the abundances derived from the optical recombination lines with those determined from collisionally-excited lines. Combining our new data with published results on RLs in other PNe, we examine the discrepancy in abundances derived from RLs and CELs. We find that there is a wide range in the measured abundance discrepancy Δ (O+2) = log O+2(RL) - log O+2(CEL), ranging from approximately 0.1 dex (within the 1σ measurement errors) up to 1.3 dex. This tends to rule out errors in the recombination coefficients as a source of the discrepancy. Most RLs yield similar abundances, with the notable exception of O II multiplet V15, known to arise primarily from dielectronic recombination, which gives abundances averaging 0.6 dex higher than other O II RLs. We compare Δ (O+2) against a variety of physical properties of the PNe to look for clues as to the mechanism responsible for the abundance discrepancy. The strongest correlation is found with Balmer surface brightness; high surface brightness, compact PNe show small values of Δ (O+2), while large low surface brightness PNe show the largest discrepancies. Rougher correlations of Δ (O+2) are found with He+2/He+ and with the expansion velocity. No correlations are seen with electron temperature, electron density, central star effective temperature and luminosity, stellar mass loss rate, or nebular morphology. Similar results are found for carbon, comparing C II RL abundances with ultraviolet measurements of C III]. This work is supported by NSF grant AST-0203905.

  12. Planetary systems and real planetary nebulae from planet destruction near white dwarfs

    NASA Astrophysics Data System (ADS)

    Bear, Ealeal; Soker, Noam

    2015-07-01

    We suggest that tidal destruction of Earth-like and icy planets near a white dwarf (WD) might lead to the formation of one or more low-mass - Earth-like and lighter - planets in tight orbits around the WD. The formation of the new WD planetary system starts with a tidal breakup of the parent planet to planetesimals near the tidal radius of about 1 R⊙. Internal stress forces keep the planetesimal from further tidal breakup when their radius is less than about 100 km. We speculate that the planetesimals then bind together to form new sub-Earth daughter-planets at a few solar radii around the WD. More massive planets that contain hydrogen supply the WD with fresh nuclear fuel to reincarnate its stellar-giant phase. Some of the hydrogen will be inflated in a large envelope. The envelope blows a wind to form a nebula that is later (after the entire envelope is lost) ionized by the hot WD. We term this glowing ionized nebula that originated from a planet a real planetary nebula (RPN). This preliminary study of daughter-planets from a planet and the RPN scenarios are of speculative nature. More detailed studies must follow to establish whether the suggested scenarios can indeed take place.

  13. Multiwavelength Imaging of Planetary Nebulae: Resolving & Disentangling Structure

    NASA Astrophysics Data System (ADS)

    Freeman, Marcus J.

    2015-10-01

    Planetary nebulae (PNe) represent the late stages of low-mass stellar evolution. The formation of the myriad of PNe morphologies involves processes that are present in many other astrophysical systems such as the wind-blown bubbles of massive stars. In this dissertation we present the results of an X-ray study of PNe, and two modeling projects that incorporate the resulting data with the goal of furthering our understanding of their X-ray properties and morphologies, and the 3D multiwavelength structure of PNe. This work expands the Chandra Planetary Nebula Survey (ChanPlaNS), which was designed to investigate X-ray emission from PNe, from 35 to 59 objects. The results from Cycle 14 Chandra observations of 24 PNe brought the overall ChanPlaNS diffuse X-ray detection rate to ~27% and the point source detection rate to ∼36%. The detection of diffuse X-ray emission is unmistakably associated with young (≲ 5 × 10^3 yr), compact (R_neb ≲ 0.15 pc) PNe that exhibit closed elliptical structures and high electron densities (n_e ≳ 10^3 cm^-3). Utilizing the ChanPlaNS data for 14 PNe that exhibit diffuse X-ray emission, we constructed simple, spherically symmetric two-phase models using the astrophysical modeling tool, SHAPE. Our models consisted of a hot bubble and swept-up shell with the intent of investigating the X- ray morphology of these objects and the extinction caused by the swept-up shell. We compared simulated and observed radial profiles and we conclude that while most (∼79%) PNe are best described by a limb-darkened X-ray morphology, this is due to nebular extinction of an intrinsically limb-brightened hot bubble structure. Expanding upon our two-phase model, we used SHAPE to generate a 3D model of the brightest diffuse X-ray PN, BD+30 3639, with the model constrained by previously published multiwavelength data extending from the radio to the X-ray regimes. Our aim was to investigate the multiwavelength 3D morphology of this well-studied nebula and

  14. Recombination Line versus Forbidden Line Abundances in Planetary Nebulae

    NASA Astrophysics Data System (ADS)

    Robertson-Tessi, Mark; Garnett, Donald R.

    2005-04-01

    Recombination lines (RLs) of C II, N II, and O II in planetary nebulae (PNs) have been found to give abundances that are much larger in some cases than abundances from collisionally excited forbidden lines (CELs). The origins of this abundance discrepancy are highly debated. We present new spectroscopic observations of O II and C II recombination lines for six planetary nebulae. With these data we compare the abundances derived from the optical recombination lines with those determined from collisionally excited lines. Combining our new data with published results on RLs in other PNs, we examine the discrepancy in abundances derived from RLs and CELs. We find that there is a wide range in the measured abundance discrepancy Δ(O+2)=logO+2(RL)-logO+2(CEL), ranging from approximately 0.1 dex (within the 1 σ measurement errors) up to 1.4 dex. This tends to rule out errors in the recombination coefficients as a source of the discrepancy. Most RLs yield similar abundances, with the notable exception of O II multiplet V15, known to arise primarily from dielectronic recombination, which gives abundances averaging 0.6 dex higher than other O II RLs. We compare Δ(O+2) against a variety of physical properties of the PNs to look for clues as to the mechanism responsible for the abundance discrepancy. The strongest correlations are found with the nebula diameter and the Balmer surface brightness; high surface brightness, compact PNs show small values of Δ(O+2), while large low surface brightness PNs show the largest discrepancies. An inverse correlation of Δ(O+2) with nebular density is also seen. A marginal correlation of Δ(O+2) is found with expansion velocity. No correlations are seen with electron temperature, He+2/He+, central star effective temperature and luminosity, stellar mass-loss rate, or nebular morphology. Similar results are found for carbon in comparing C II RL abundances with ultraviolet measurements of C III].

  15. OBSERVATIONAL STUDY OF THE MULTISTRUCTURED PLANETARY NEBULA NGC 7354

    SciTech Connect

    Contreras, M. E.; Vazquez, R.; Miranda, L. F.; Zavala, S.; Ayala, S. E-mail: vazquez@astrosen.unam.mx E-mail: lorenzo@astro.uson.mx E-mail: sayala@ideabc.org

    2010-04-15

    We present an observational study of the planetary nebula (PN) NGC 7354 consisting of narrowband H{alpha} and [N II]{lambda}6584 imaging as well as low- and high-dispersion long-slit spectroscopy, and VLA-D radio continuum. According to our imaging and spectroscopic data, NGC 7354 has four main structures: a quite round outer shell and an elliptical inner shell, a collection of low-excitation bright knots roughly concentrated on the equatorial region of the nebula, and two asymmetrical jet-like features, not aligned either with the shells' axes, or with each other. We have obtained physical parameters like electron temperature and electron density as well as ionic and elemental abundances for these different structures. Electron temperature and electron density slightly vary throughout the nebula going from {approx_equal}11, 000 to {approx_equal}14, 000 K, and from {approx_equal}1000 to {approx_equal} 3000 cm{sup -3}, respectively. The local extinction coefficient c {sub H{beta}} shows an increasing gradient from south to north and a decreasing gradient from east to west consistent with the number of equatorial bright knots present in each direction. Abundance values show slight internal variations but most of them are within the estimated uncertainties. In general, abundance values are in good agreement with the ones expected for PNe. Radio continuum data are consistent with optically thin thermal emission. Mean physical parameters derived from the radio emission are electron density n{sub e} = 710 cm{sup -3} and M(H II) = 0.22 M {sub sun}. We have used the interactive three-dimensional modeling tool SHAPE to reproduce the observed morphokinematic structures in NGC 7354 with different geometrical components. Our observations and model show evidence that the outer shell is moving faster ({approx_equal}35 km s{sup -1}) than the inner one ({approx_equal} 30 km s{sup -1}). Our SHAPE model includes several small spheres placed on the outer shell wall to reproduce

  16. The star fish twins: Two young planetary nebulae with extreme multipolar morphology

    NASA Technical Reports Server (NTRS)

    Sahai, R.

    2000-01-01

    We present alpha images of two objects, He 2-47 and M1-37, obtained during a Hubble Space Telescope imaging survey of young planetary nebulae (PNs) selected on the basis of their low-excitation characteristics.

  17. An atlas of emission line fluxes of planetary nebulae in the 1150-3200 A region

    NASA Technical Reports Server (NTRS)

    Feibelman, W. A.; Mccracken, C. W.

    1981-01-01

    Emission line fluxes for 28 planetary nebulae are presented. The nebulae were chosen to cover a wide range of excitation classes, apparent diameters, location in the sky, and types of central stars. All objects were observed in the low dispersion mode of the IUE spectrographs, using the large entrance aperture.

  18. WISE properties of planetary nebulae from the DSH catalogue

    NASA Astrophysics Data System (ADS)

    Kronberger, M.; Jacoby, G. H.; Harmer, D.; Patchick, D.

    2014-04-01

    A decade has passed since the discovery of Patchick 1, the first planetary nebula (PN) found by an amateur astronomer since the early days of PN research. Since then, the members of the Deep Sky Hunters (DSH) collaboration have identified ˜200 PN candidates in fields mostly outside of the boundaries covered by the IPHAS and SHS surveys . Further investigations based on narrowband imaging, primarily to reveal H-alpha and [OIII] line emission, and/or spectroscopic observations on 157 of these enabled classifying 64 candidates as true PNe on those morphologies and spectral properties. Additional 42 objects with unavailable spectra are considered as probable or possible PNe based on their morphologies alone. The remaining 51 objects were found to be PN mimics of various nature, such as supernova remnants, interlopers, reflection nebulae, or plate faults. The majority of the PN candidates from the DSH sample were found by the visual inspection of multicolour imagery from the Digitized Sky Survey (DSS), the Sloan Digitized Sky Survey (SDSS), and widefield narrowband images of the Milky Way. However, in recent years, the candidate selection process has been facilitated by the availability of deep satellite-based wide-field surveys providing images at wavelengths outside the optical regime, such as the Wide-field Infrared Survey Explorer (WISE) and the Galaxy Evolution Explorer (GALEX). In this contribution, we provide an overview on the current status of the DSH project and discuss the mid-infrared properties of a subsample of the true and probable DSH PNe located at Galactic latitudes |b| > 5¬∞. It is shown that spherical PNe are significantly less likely to appear on WISE band images than PNe of other morphological classes.

  19. H2 Imaging of Three Proto-Planetary and Young Planetary Nebulae

    NASA Astrophysics Data System (ADS)

    Volk, Kevin; Hrivnak, Bruce J.; Kwok, Sun

    2004-12-01

    High-resolution (0.15") 2.12 μm H2 and narrowband K images have been obtained of one cool proto-planetary nebula, IRAS 20028+3910, and two hot proto-planetary/young planetary nebulae, IRAS 19306+1407 and IRAS 22023+5249. The observations were made with an adaptive optics system and near-infrared imager on the Gemini North 8 m telescope. All three nebulae are seen to be extended, and in two and possibly all three of them H2 is found to be emitting from bipolar lobes. In IRAS 19306+1407, H2 emission is seen arising from a ring close to the star and from the edges of emerging bipolar lobes. In IRAS 20028+3910, one bright lobe and a very faint second lobe are seen in the H2 and K-band images, similar to the published visible images, but in the H2 and K-band images a faint filament appears to connect the two lobes. The central star is not seen in IRAS 20028+3910, indicating that the nebula is optically thick even at 2 μm, which is unusual. The images suggest that extended H2 emission is often the manifestation of fast-slow wind interactions in the bipolar lobes. The paper is based on observations obtained at the Gemini Observatory with the Adaptive Optics System Hokupa'a/QUIRC, developed and operated by the University of Hawaii Adaptive Optics Group, with support from the National Science Foundation. The Gemini Observatory is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the Particle Physics and Astronomy Research Council (United Kingdom), the National Research Council (Canada), Comisión Nacional de Investigación Científica y Tecnológica (CONICYT; Chile), the Australian Research Council (Australia), Laboratório Nacional de Astrofísica (CNPq; Brazil), and Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET; Argentina).

  20. Planetary nebulae: understanding the physical and chemical evolution of dying stars.

    PubMed

    Weinberger, R; Kerber, F

    1997-05-30

    Planetary nebulae are one of the few classes of celestial objects that are active in every part of the electromagnetic spectrum. These fluorescing and often dusty expanding gaseous envelopes were recently found to be quite complex in their dynamics and morphology, but refined theoretical models can account for these discoveries. Great progress was also made in understanding the mechanisms that shape the nebulae and the spectra of their central stars. In addition, applications for planetary nebulae have been worked out; for example, they have been used as standard candles for long-range distances and as tracers of the enigmatic dark matter. PMID:9161999

  1. Central stars of planetary nebulae: New spectral classifications and catalogue

    NASA Astrophysics Data System (ADS)

    Weidmann, W. A.; Gamen, R.

    2011-02-01

    Context. There are more than 3000 confirmed and probable known Galactic planetary nebulae (PNe), but central star spectroscopic information is available for only 13% of them. Aims: We undertook a spectroscopic survey of central stars of PNe at low resolution and compiled a large list of central stars for which information was dispersed in the literature. Methods: We observed 45 PNs using the 2.15 m telescope at Casleo, Argentina. Results: We present a catalogue of 492 confirmed and probable CSPN and provide a preliminary spectral classification for 45 central star of PNe. This revises previous values of the proportion of CSPN with atmospheres poor in hydrogen in at least 30% of cases and provide statistical information that allows us to infer the origin of H-poor stars. Based on data collected at the Complejo Astronómico El Leoncito (CASLEO), which is operated under agreement between the Consejo Nacional de Investigaciones Científicas y Técnicas de la República Argentina y Universidades Nacionales de La Plata, Córdoba y San Juan, Argentina.

  2. Three New Candidate Planetary Nebulae near the Galactic Center

    NASA Astrophysics Data System (ADS)

    Simpson, Janet P.; Sellgren, Kristen; Ramirez, Solange; Cotera, Angela; An, Deokkeun

    2015-08-01

    We report the discovery of three candidate planetary nebulae (PNe) detected in lines of sight close to our Galactic Center: G0.098-0.051, G0.399+0.208, and G359.963-0.120. These objects are identified by being compact continuum sources with exceptionally high excitation as seen in spectra of forbidden lines taken with Spitzer Space Telescope's Infrared Spectrograph and downloaded from the Spitzer Heritage Archive. In particular, the high excitation lines include [Na III] 7.32 micron, [O IV] 25.9 micron, and [Ne V] 14.3 and 24.3 micron. Such lines are not seen in Galactic H II regions but only are found in PNe and supernova remnants; we exclude the last by the existance of the co-located continuum sources of size a few arcsec. We note that none of these sources has any significant associated emission from polycyclic aromatic hydrocarbons, which is otherwise common in the Galactic Center and in PNe. We will present spectra, abundance analyses, additional data from radio and near-infrared telescopes, and photoionization and shock models computed with Cloudy (Ferland et al. 2013) and MAPPINGS III (Allen et al. 2008).

  3. A two-mode planetary nebula luminosity function

    NASA Astrophysics Data System (ADS)

    Rodríguez-González, A.; Hernández-Martínez, L.; Esquivel, A.; Raga, A. C.; Stasińska, G.; Peña, M.; Mayya, Y. D.

    2015-03-01

    Context. We propose a new planetary nebula luminosity function (PNLF) that includes two populations in the distribution. Our PNLF is a direct extension of the canonical function proposed by Jacoby et al. (1987), in order to avoid problems related with the histogram construction, it is cast in terms of cumulative functions. Aims: We are interested in recovering the shape of the faint part of the PNLF in a consistent manner, for galaxies with and without a dip in their PNLFs. Methods: The parameters for the two-mode PNLF are obtained with a genetic algorithm, which obtains a best fit to the PNLF varying all of the parameters simultaneously in a broad parameter space. Results: We explore a sample of nine galaxies with various Hubble types and construct their PNLF. All of the irregular galaxies, except one, are found to be consistent with a two-mode population, while the situation is less clear for ellipticals and spirals.For the case of NGC 6822, we show that the two-mode PNLF is consistent with previous studies of the star formation history within that galaxy. Our results support two episodes of star formation, in which the second episode is significantly stronger.

  4. An Observational Study of Pulsations in Proto-Planetary Nebulae

    NASA Astrophysics Data System (ADS)

    Hrivnak, Bruce J.; Lu, Wenxian; Henson, Gary D.; Hillwig, Todd C.

    2016-01-01

    We have been carrying out a long-term monitoring program to study the light variability in proto-planetary nebulae (PPNe). PPNe are post-Asymptotic Giant Branch objects in transition between the AGB and PN phases in the evolution of low and intermediate-mass stars. As such, it is not surprising that they display pulsational variability. We have been carrying out photometric monitoring of 30 of these at the Valparaiso University campus observatory over the last 20 years, with the assistance of undergraduate students. The sample size has been enlarged over the past six years by observations made using telescopes in the SARA consortium at KPNO and CTIO. Periods have been determined for those of F-G spectral types. We have also enlarged the sample with PPNe from outside the Milky Way by determining periods of eight PPNe in the lower metalicity environment of the Magellanic Clouds. Periods for the entire sample range from 35 to 160 days. Some clear patterns have emerged, with those of higher temperature possessing shorter periods and smaller amplitudes, indicating a reduction in period and pulsation amplitude as the objects evolve. Radial velocity monitoring of several of the brightest of these has allowed us to document their changes in brightness, color, and size during a pulsation cycle. The results of this study will be presented. This research is supported by grants from the National Science Foundation (most recently AST 1413660), with additional student support from the Indiana Space Grant Consortium.

  5. Radio planetary nebulae in the Small Magellanic Cloud

    NASA Astrophysics Data System (ADS)

    Leverenz, Howard; Filipović, Miroslav D.; Bojičić, I. S.; Crawford, E. J.; Collier, J. D.; Grieve, K.; Drašković, D.; Reid, W. A.

    2016-03-01

    We present ten new radio continuum (RC) detections at catalogued planetary nebula (PN) positions in the Small Magellanic Cloud (SMC): SMP S6, LIN 41, LIN 142, SMP S13, SMP S14, SMP S16, J 18, SMP S18, SMP S19 and SMP S22. Additionally, six SMC radio PNe previously detected, LIN 45, SMP S11, SMP S17, LIN 321, LIN 339 and SMP S24 are also investigated (re-observed) here making up a population of 16 radio detections of catalogued PNe in the SMC. These 16 radio detections represent ˜15 % of the total catalogued PN population in the SMC. We show that six of these objects have characteristics that suggest that they are PN mimics: LIN 41, LIN 45, SMP S11, LIN 142, LIN 321 and LIN 339. We also present our results for the surface brightness—PN radius relation (Σ-D) of the SMC radio PN population. These are consistent with previous SMC and LMC PN measurements of the (Σ-D) relation.

  6. A SURVEY FOR PLANETARY NEBULAE IN M31 GLOBULAR CLUSTERS

    SciTech Connect

    Jacoby, George H.; De Marco, Orsola; Lee, Myung Gyoon; Herrmann, Kimberly A.; Hwang, Ho Seong; Davies, James E.; Kaplan, Evan E-mail: rbc@astro.psu.edu E-mail: mglee@astrog.snu.ac.kr E-mail: hhwang@cfa.harvard.edu E-mail: evanskaplan@gmail.com

    2013-05-20

    We report the results of an [O III] {lambda}5007 spectroscopic survey for planetary nebulae (PNe) located within the star clusters of M31. By examining R {approx} 5000 spectra taken with the WIYN+Hydra spectrograph, we identify 3 PN candidates in a sample of 274 likely globular clusters, 2 candidates in objects which may be globular clusters, and 5 candidates in a set of 85 younger systems. The possible PNe are all faint, between {approx}2.5 and {approx}6.8 mag down the PN luminosity function, and, partly as a consequence of our selection criteria, have high excitation, with [O III] {lambda}5007 to H{beta} ratios ranging from 2 to {approx}> 12. We discuss the individual candidates, their likelihood of cluster membership, and the possibility that they were formed via binary interactions within the clusters. Our data are consistent with the suggestion that PN formation within globular clusters correlates with binary encounter frequency, though, due to the small numbers and large uncertainties in the candidate list, this study does not provide sufficient evidence to confirm the hypothesis.

  7. THE CURIOUS CONUNDRUM REGARDING SULFUR ABUNDANCES IN PLANETARY NEBULAE

    SciTech Connect

    Henry, R. B. C.; Maguire, Mason; Speck, Angela; Karakas, Amanda I.; Ferland, Gary J. E-mail: mr.magu@ou.edu E-mail: akarakas@mso.anu.edu.au

    2012-04-10

    Sulfur abundances derived from optical emission line measurements and ionization correction factors (ICFs) in planetary nebulae are systematically lower than expected for the objects' metallicities. We have carefully considered a large range of explanations for this 'sulfur anomaly', including: (1) correlations between the size of the sulfur deficit and numerous nebular and central star properties, (2) ICFs which undercorrect for unobserved ions, (3) effects of dielectronic recombination on the sulfur ionization balance, (4) sequestering of S into dust and/or molecules, and (5) excessive destruction of S or production of O by asymptotic giant branch stars. It appears that all but the second scenario can be ruled out. However, we find evidence that the sulfur deficit is generally reduced but not eliminated when S{sup +3} abundances determined directly from IR measurements are used in place of the customary sulfur ICF. We tentatively conclude that the sulfur anomaly is caused by the inability of commonly used ICFs to properly correct for populations of ionization stages higher than S{sup +2}.

  8. THE DECELERATION OF NEBULAR SHELLS IN EVOLVED PLANETARY NEBULAE

    SciTech Connect

    Pereyra, Margarita; Richer, Michael G.; Lopez, Jose Alberto E-mail: richer@astrosen.unam.mx

    2013-07-10

    We have selected a group of 100 evolved planetary nebulae (PNe) and study their kinematics based upon spatially-resolved, long-slit, echelle spectroscopy. The data have been drawn from the San Pedro Martir Kinematic Catalogue of PNe. The aim is to characterize in detail the global kinematics of PNe at advanced stages of evolution with the largest sample of homogenous data used to date for this purpose. The results reveal two groups that share kinematics, morphology, and photo-ionization characteristics of the nebular shell and central star luminosities at the different late stages under study. The typical flow velocities we measure are usually larger than seen in earlier evolutionary stages, with the largest velocities occurring in objects with very weak or absent [N II] {lambda}6584 line emission, by all indications the least evolved objects in our sample. The most evolved objects expand more slowly. This apparent deceleration during the final stage of PNe evolution is predicted by hydrodynamical models, but other explanations are also possible. These results provide a template for comparison with the predictions of theoretical models.

  9. Single rotating stars and the formation of bipolar planetary nebula

    SciTech Connect

    García-Segura, G.; Villaver, E.; Langer, N.; Yoon, S.-C.; Manchado, A.

    2014-03-10

    We have computed new stellar evolution models that include the effects of rotation and magnetic torques under different hypotheses. The goal is to test whether a single star can sustain the rotational velocities needed in the envelope for magnetohydrodynamical(MHD) simulations to shape bipolar planetary nebulae (PNe) when high mass-loss rates take place. Stellar evolution models with main sequence masses of 2.5 and 5 M {sub ☉} and initial rotational velocities of 250 km s{sup –1} have been followed through the PNe formation phase. We find that stellar cores have to be spun down using magnetic torques in order to reproduce the rotation rates observed for white dwarfs. During the asymptotic giant branch phase and beyond, the magnetic braking of the core has a practically null effect on increasing the rotational velocity of the envelope since the stellar angular momentum is efficiently removed by the wind. We have also tested the best possible case scenarios in rather non-physical contexts to give enough angular momentum to the envelope. We find that we cannot get the envelope of a single star to rotate at the speeds needed for MHD simulations to form bipolar PNe. We conclude that single stellar rotators are unlikely to be the progenitors of bipolar PNe under the current MHD model paradigm.

  10. Hydrogen-deficient Central Stars of Planetary Nebulae

    NASA Astrophysics Data System (ADS)

    Todt, H.; Kniazev, A. Y.; Gvaramadze, V. V.; Hamann, W.-R.; Pena, M.; Graefener, G.; Buckley, D.; Crause, L.; Crawford, S. M.; Gulbis, A. A. S.; Hettlage, C.; Hooper, E.; Husser, T.-O.; Kotze, P.; Loaring, N.; Nordsieck, K. H.; O'Donoghue, D.; Pickering, T.; Potter, S.; Romero-Colmenero, E.; Vaisanen, P.; Williams, T.; Wolf, M.

    2015-06-01

    A significant number of the central stars of planetary nebulae (CSPNe) are hydrogen-deficient and are considered as the progenitors of H-deficient white dwarfs. Almost all of these H-deficient CSPNe show a chemical composition of helium, carbon, and oxygen. Most of them exhibit Wolf-Rayet-like emission line spectra and are therefore classified as of spectral type [WC]. In the last years, CSPNe of other Wolf-Rayet spectral subtypes have been identified, namely PB 8 (spectral type [WN/WC]), IC 4663 and Abell 48 (spectral type [WN]). We performed spectral analyses for a number of Wolf-Rayet type central stars of different evolutionary stages with the help of our Potsdam Wolf-Rayet (PoWR) model code for expanding atmospheres to determine relevant stellar parameters. The results of our recent analyses will be presented in the context of stellar evolution and white dwarf formation. Especially the problems of a uniform evolutionary channel for [WC] stars as well as constraints to the formation of [WN] or [WN/WC] subtype stars will be addressed.

  11. Polarization properties of OH emission in planetary nebulae

    NASA Astrophysics Data System (ADS)

    Gómez, José F.; Uscanga, Lucero; Green, James A.; Miranda, Luis F.; Suárez, Olga; Bendjoya, Philippe

    2016-09-01

    We present the interferometric, full-polarization observations of the four ground-state transitions of OH, towards five confirmed and one candidate OH-emitting planetary nebulae (OHPNe). OHPNe are believed to be very young PNe, and information on their magnetic fields (provided by their polarization) could be key to understand the early evolution of PNe. We detect significant circular and linear polarization in four and two objects, respectively. Possible Zeeman pairs are seen in JaSt 23 and IRAS 17393-2727, resulting in estimates of magnetic field strengths between 0.8 and 24 mG. We also report the new detection of OH emission at 1720 MHz towards Vy 2-2, making it the third known PN with this type of emission. We suggest that younger PNe have spectra dominated by narrow maser features and higher degrees of polarization. Shock-excited emission at 1720 MHz seems to be more common in PNe than in early evolutionary phases, and could be related to equatorial ejections during the early PN phase.

  12. Dust and molecules in extra-galactic planetary nebulae

    NASA Astrophysics Data System (ADS)

    Garcia-Hernandez, Domingo Aníbal

    2015-08-01

    Extra-galactic planetary nebulae (PNe) permit the study of dust and molecules in metallicity environments other than the Galaxy. Their known distances lower the number of free parameters in the observations vs. models comparison, providing strong constraints on the gas-phase and solid-state astrochemistry models. Observations of PNe in the Galaxy and other Local Group galaxies such as the Magellanic Clouds (MC) provide evidence that metallicity affects the production of dust as well as the formation of complex organic molecules and inorganic solid-state compounds in their circumstellar envelopes. In particular, the lower metallicity MC environments seem to be less favorable to dust production and the frequency of carbonaceous dust features and complex fullerene molecules is generally higher with decreasing metallicity. Here, I present an observational review of the dust and molecular content in extra-galactic PNe as compared to their higher metallicity Galactic counterparts. A special attention is given to the level of dust processing and the formation of complex organic molecules (e.g., polycyclic aromatic hydrocarbons, fullerenes, and graphene precursors) depending on metallicity.

  13. Spectroscopy of planetary nebulae in the region of Canis Major

    NASA Astrophysics Data System (ADS)

    Kniazev, A. Yu.

    2012-11-01

    We present the results of a pilot project of spectroscopic observations for planetary nebulae (PNe) and PN candidates in Canis Major, a sky region where the remnant of a disrupted dwarf galaxy cannibalized by the Milky Way may be located. The spectra of seven objects were taken while testing the SALT spectrograph (South African Astronomical Observatory). All elemental abundances have been obtained by the T e method, where the electron temperature is calculated directly using the measured weak auroral [OIII] λ 4363 Å and/or [NII] λ 5755 Å lines. We have measured the intensities of all the detected emission lines and determined the abundances of oxygen and several other elements (N, Ne, S, Cl, C, and He) in all PNe. The radial velocity for one PN has been measured for the first time and the velocities for all of the remaining PNe have been measured with a considerably better accuracy than that of the previously published ones. The elemental abundances for three PNe have been calculated for the first time and the accuracies of determining the abundances for three others have been improved. The measured heavy-element abundance ratios (S/O, Ne/O, Cl/O) are in good agreement with their typical values for HII regions. Among the PNe studied, ESO 428-05 is the first and so far the most likely candidate for belonging to the remnants of a possible dwarf galaxy disrupted by the tidal interaction with the Milky Way.

  14. Searching for Intracluster Planetary Nebulae in the Dorado group

    NASA Astrophysics Data System (ADS)

    Feldmeier, John; Ciardullo, Robin; Jacoby, George; Durrell, Pat

    2002-08-01

    A key problem in extragalactic astronomy is how galaxy clusters and groups dynamically evolve. Although the properties of these systems depend sensitively on the rates of galactic cannibalism, outside accretion, and tidal-stripping, the relative importance of these mechanisms is unknown. The one property we can observe, the fraction of light removed from galaxies via tidal-stripping, is difficult to detect, and until recently, had only been observed in a few very rich galaxy clusters. Over the past few years, we have successfully detected intracluster planetary nebulae (IPN) in large numbers in both the Virgo and Fornax clusters. However, the amount of intracluster starlight in poorer clusters and groups is still mostly unknown. This is unfortunate because theoretical scenarios of intracluster star production make strong predictions on the amount of intracluster starlight as a function of cluster richness. If the intracluster stars are primarily produced by collisions with other galaxies, the fraction of intracluster starlight should correlate strongly with cluster richness. We propose to use the CTIO 4-meter, and the MOSAIC II imager to search the Dorado galaxy group for intracluster PN. Dorado is intermediate in richness to the clusters already studied, and has evidence for tidal interaction. We also plan to study the PN population around two early-type galaxies in the cluster core that are strongly interacting, using the PN as dynamical test particles.

  15. Chemical Abundances of Compact Planetary Nebulae in the Galactic Disk

    NASA Astrophysics Data System (ADS)

    Lee, Ting-Hui; Shaw, R. A.; Stanghellini, L.

    2014-01-01

    We present preliminary results from an optical spectroscopic survey of compact planetary nebulae (PNe) in the Galactic disk. This is an ongoing optical+infrared spectral survey of 150 compact PNe to build a complete sample of PN chemical abundances in the Galactic disk. The optical spectra will be combined with Spitzer spectra of IR collisional lines to improve abundance constraints. Our targets are mostly young PNe, which are well suited for studying the impact of metallicity and dust on PN morphology. Our main objectives are: (1) to constrain stellar evolution models, particularly the metallicity-dependent onset of hot-bottom burning; (2) to quantify the contribution of low- to intermediate-mass stars to chemical enrichment; and (3) to improve the ionization correction factors for Ne, O, S, and Ar that we have observed in the IR. We will also compare these findings to our optical+IR Magellanic Cloud PN abundances to better understand the influence of environment metallicity on stellar chemical yields.

  16. Spitzer mid-infrared spectroscopic observations of planetary nebulae

    NASA Astrophysics Data System (ADS)

    Mata, H.; Ramos-Larios, G.; Guerrero, M. A.; Nigoche-Netro, A.; Toalá, J. A.; Fang, X.; Rubio, G.; Kemp, S. N.; Navarro, S. G.; Corral, L. J.

    2016-06-01

    We present Spitzer Space Telescope archival mid-infrared (mid-IR) spectroscopy of a sample of 11 planetary nebulae (PNe). The observations, acquired with the Spitzer Infrared Spectrograph (IRS), cover the spectral range 5.2-14.5 μm that includes the H2 0-0 S(2) to S(7) rotational emission lines. This wavelength coverage has allowed us to derive the Boltzmann distribution and calculate the H2 rotational excitation temperature (Tex). The derived excitation temperatures have consistent values ≃900 ± 70 K for different sources despite their different structural components. We also report the detection of mid-IR ionic lines of [Ar III], [S IV], and [Ne II] in most objects, and polycyclic aromatic hydrocarbon features in a few cases. The decline of the [Ar III]/[Ne II] line ratio with the stellar effective temperature can be explained either by a true neon enrichment or by high density circumstellar regions of PNe that presumably descend from higher mass progenitor stars.

  17. Carbon and Nitrogen Enrichment Patterns in Planetary Nebulae

    NASA Astrophysics Data System (ADS)

    Dufour, Reginald

    2011-10-01

    The goal of this project is to assess the role played in carbon production by low and intermediate mass stars {LIMS}, i.e. the progenitors of planetary nebulae {PNe}. One of the most pressing problems in galactic chemical evolution today is understanding the relative roles of LIMS {1-8 M_sun} versus massive stars {8-120 M_sun} in affecting the cosmic level of the element C. We are launching a fresh, ambitious project whose purpose is to employ STIS to obtain UV spectra of unprecedented-quality of 10 carefully chosen, bright solar metallicity PNe spanning a broad range in progenitor mass. Line strength measurements of important emission lines of C, N, and O such as OIII] 1660-6, NIII] 1747-54, CIII] 1907-9, and {when He++ is strong} CIV] 1550 and OIV] 1400 in each object will be used along with our own in-house abundance software to determine ion and element abundances for these three species. In turn, these results will be used to assess stellar yields {productivity rates} available in the literature. Favored yield sets will be used to calculate our own chemical evolution models in order to assess directly the importance of intermediate-mass stars in the cosmic evolution of C.

  18. The density profile of the elliptical planetary nebula NGC 3242

    NASA Technical Reports Server (NTRS)

    Soker, Noam; Zucker, Daniel B.; Balick, Bruce

    1992-01-01

    We present the three-dimensional density structure of the elliptical planetary nebula NGC 3242, deconvolved from its H-alpha image. Using the simplistic assumptions that each mass element preserves its original velocity, which is radial and depends only on latitude, we deduce from this density profile the variation of mass-loss rate from the progenitor of NGC 3242 with latitude and time. The resulting somewhat qualitative mass-loss geometry and history are used to constrain models for the formation of the elliptical structure of NGC 3242. We argue that a triple system, with a very close brown dwarf companion and a more massive distant tertiary star, is compatible with the morphology of NGC 3242. In this model the brown dwarf, of about 0.01 solar mass, shared a common envelope with the progenitor star, and spun up the envelope through deposition of angular momentum. The oblate rotating envelope blew an axisymmetrical wind. We suggest that the presence of a third star, with a mass of about 1 solar mass and an orbital period of about 4000 years, could have caused the large scale deviation from axial symmetry seen in the density structure.

  19. Magnetic fields in Planetary Nebulae: paradigms and related MHD frontiers

    NASA Astrophysics Data System (ADS)

    Blackman, Eric G.

    2009-04-01

    Many, if not all, post AGB stellar systems swiftly transition from a spherical to a powerful aspherical pre-planetary nebula (pPNE) outflow phase before waning into a PNe. The pPNe outflows require engine rotational energy and a mechanism to extract this energy into collimated outflows. Just radiation and rotation are insufficient but a symbiosis between rotation, differential rotation and large scale magnetic fields remains promising. Present observational evidence for magnetic fields in evolved stars is suggestive of dynamically important magnetic fields, but both theory and observation are rife with research opportunity. I discuss how magnetohydrodynamic outflows might arise in pPNe and PNe and distinguish different between approaches that address shaping vs. those that address both launch and shaping. Scenarios involving dynamos in single stars, binary driven dynamos, or accretion engines cannot be ruled out. One appealing paradigm involves accretion onto the primary post-AGB white dwarf core from a low mass companion whose decaying accretion supply rate owers first the pPNe and then the lower luminosity PNe. Determining observational signatures of different MHD engines is a work in progress. Accretion disk theory and large scale dynamos pose many of their own fundamental challenges, some of which I discuss in a broader context.

  20. Kinematical Structure of the Planetary Nebula NGC 7009

    NASA Astrophysics Data System (ADS)

    Lee, Seong-Jae; Hyung, S.

    2012-01-01

    We investigated the line profiles of the planetary nebula NGC 7009 using the (10-m) Keck HIRES and (1.8-m) BOES spectral data, obtained in 1998, August 14-16 and 2009, October 2. The HIRES long-slit data were secured along the major and minor axes, while the BOES fiber data were obtained from the central region of the nebula. The Keck 2D kinematical data, i.e., sky-field vs. velocity frame, suggest some interesting features. We confirmed the high density inner boundary of the main shell consisting of numerous high density structures, a receding hot-bubble like structure & approaching 2-3" high density blobs in W-SW cap region; and sub-arc second scale blobs in the hollow zone along the major axis. We also identified the density range of the main & outer shells near S-SE bright rim and 2" diameter hot bubble-like structure near the N-NW bright rim along the minor axis. For the 5 strategically important positions, E-NE & W-SW caps; S-SE & N-NW rims; and CSPN, we decomposed the one-dimensional spectral line profiles of the important lines in the wavelength range of 3250-8725A. The analyzed lines are HeI5875, 6678, 7065; HeII7592, 4686; [OII]7319; [OIII]4363, 4959, 5007; [NII]6548, 6583; NIII4097; [SII]6716, 6730; [SIII]6312, 9068; [ArIII]7136, 7751; [ArIV]4711, 4740; and [ClIV]7529, 8045. Most of the low-to-medium excitation lines and some of high excitation lines showed double + 3rd wing components. The 3rd wing component in the low-to-medium excitation lines are due to the outer ring or high density blobs, but in some cases, the fast blue or red wing component found in the low-to-medium lines profile is likely to be an independent geometrical feature, similar to the jet-like outflows. Inside the main shell, there appears to be an inner zone that is responsible for some unusual feature in the high excitation HeI and HeII line profiles.

  1. Evolution of planetary nebulae. III. Position-velocity images of butterfly-type nebulae

    SciTech Connect

    Icke, V.; Preston, H.L.; Balick, B.

    1989-02-01

    Observations of the motions of the shells of the planetary nebulae NGC 2346, NGC 2371-2, NGC 2440, NGC 6058, NGC 6210, IC 1747, IC 5217, J-320, and M2-9 are presented. These are all 'butterfly' type PNs, and show evidence for bipolar shocks. The observations are interpreted in terms of a fast spherical wind, driven by the central star into a quasi-toroidal envelope deposited earlier by the star, during its slow-wind phase on the asymptotic giant branch. It is shown that this model, which is a straightforward extension of a mechanism previously invoked to account for elliptical PNs, reproduces the essential kinematic features of butterfly PNs. It is inferred that the envelopes of butterflies must have a considerable equator-to-pole density gradient, and it is suggested that the origin of this asphericity must be sought in an as yet unknown mechanism during the AGB, Mira, or OH/IR phases of late stellar evolution. 28 references.

  2. Evolution of planetary nebulae. I. An improved synthetic model

    NASA Astrophysics Data System (ADS)

    Marigo, P.; Girardi, L.; Groenewegen, M. A. T.; Weiss, A.

    2001-11-01

    We present a new synthetic model to follow the evolution of a planetary nebula (PN) and its central star, starting from the onset of AGB phase up to the white dwarf cooling sequence. The model suitably combines various analytical prescriptions to account for different (but inter-related) aspects of planetary nebulae, such as: the dynamical evolution of the primary shell and surrounding ejecta, the photoionisation of H and He by the central star, the nebular emission of a few relevant optical lines (e.g. Hβ ; He II lambda 4686; [O III] lambda 5007). Particular effort has been put into the analytical description of dynamical effects such as the three-winds interaction and the shell thickening due to ionisation (i.e. the thin-shell approximation is relaxed), that are nowadays considered important aspects of the PN evolution. Predictions of the synthetic model are tested by comparison with both findings of hydrodynamical calculations, and observations of Galactic PNe. The sensitiveness of the results to the model parameters (e.g. transition time, mass of the central star, H-/He-burning tracks, etc.) is also discussed. We briefly illustrate the systematic differences that are expected in the luminosities and lifetimes of PNe with either H- or He-burning central stars, which result in different ``detection probabilities'' across the H-R diagram, in both Hβ and [OIII] lambda5007 lines. Adopting reasonable values of the model parameters, we are able to reproduce, in a satisfactory way, many general properties of PNe, like the ionised mass-nebular radius relationship, the trends of a few main nebular line ratios, and the observed ranges of nebular shell thicknesses, electron densities, and expansion velocities. The models naturally predict also the possible transitions from optically-thick to optically-thin configurations (and vice versa). In this context, our analysis indicates that the condition of optical thinness to the H continuum plays an important role in producing

  3. Chandra Discovers Elusive "Hot Bubble" in Planetary Nebula

    NASA Astrophysics Data System (ADS)

    2000-06-01

    NASA's Chandra X-ray Observatory has imaged for the first time a "hot bubble" of gas surrounding a dying, Sun-like star. This large region of very hot gas in the planetary nebula BD+30 3639 has a peculiar shape and contains elements produced in the core of the dying star. "The new Chandra image offers conclusive proof for the existence of the "hot bubble" that theorists have long predicted," said Professor Joel Kastner, of the Chester F. Carlson Center of Imaging Science at the Rochester Institute of Technology. Kastner leads a team of scientists who reported on this observation at the 196th national meeting of the American Astronomical Society in Rochester, New York. The Chandra image shows a region of 3 million degree Celsius gas that appears to fit inside the shell of ionized gas seen by the Hubble Space Telescope. The optical and X-ray emitting regions of BD+30 3639, which lies between 5000 and 8000 light years away, are roughly one million times the volume of our solar system. A planetary nebula (so called because it looks like a planet when viewed with a small telescope) is formed when a dying red giant star puffs off its outer layer, leaving behind a hot core that will eventually collapse to form a dense star called a white dwarf. According to theory, a "hot bubble" is formed when a new, two million mile per hour wind emanating from the hot core rams into the ejected atmosphere, producing energetic shocks and heating the interaction region to temperatures of millions of degrees. Previous X-ray observations hinted that X rays might be coming from a region larger than the central star but it remained for Chandra to provide definite proof. The shape of the X-ray emission was a surprise to the researchers. "This suggests that the red giant atmosphere was not ejected symmetrically,"said Kastner. "It might be pointing to an unseen companion star," The spectrum shows a large abundance of neon in the X-ray-emitting gas. This indicates that gas contained in the hot

  4. Central Stars of Planetary Nebulae in the LMC

    NASA Technical Reports Server (NTRS)

    Bianchi, Luciana

    2004-01-01

    In FUSE cycle 2's program B001 we studied Central Stars of Planetary Nebulae (CSPN) in the Large Magellanic Could. All FUSE observations have been successfully completed and have been reduced, analyzed and published. The analysis and the results are summarized below. The FUSE data were reduced using the latest available version of the FUSE calibration pipeline (CALFUSE v2.2.2). The flux of these LMC post-AGB objects is at the threshold of FUSE's sensitivity, and thus special care in the background subtraction was needed during the reduction. Because of their faintness, the targets required many orbit-long exposures, each of which typically had low (target) count-rates. Each calibrated extracted sequence was checked for unacceptable count-rate variations (a sign of detector drift), misplaced extraction windows, and other anomalies. All the good calibrated exposures were combined using FUSE pipeline routines. The default FUSE pipeline attempts to model the background measured off-target and subtracts it from the target spectrum. We found that, for these faint objects, the background appeared to be over-estimated by this method, particularly at shorter wavelengths (i.e., < 1000 A). We therefore tried two other reductions. In the first method, subtraction of the measured background is turned off and and the background is taken to be the model scattered-light scaled by the exposure time. In the second one, the first few steps of the pipeline were run on the individual exposures (correcting for effects unique to each exposure such as Doppler shift, grating motions, etc). Then the photon lists from the individual exposures were combined, and the remaining steps of the pipeline run on the combined file. Thus, more total counts for both the target and background allowed for a better extraction.

  5. THE FIRST ''WATER FOUNTAIN'' COLLIMATED OUTFLOW IN A PLANETARY NEBULA

    SciTech Connect

    Gómez, José F.; Miranda, Luis F.; Guerrero, Martín A.; Rizzo, J. Ricardo; García-García, Enrique; Green, James A.; Uscanga, Lucero; Ramos-Larios, Gerardo

    2015-02-01

    ''Water fountains'' (WFs) are evolved objects showing high-velocity, collimated jets traced by water maser emission. Most of them are in the post-asymptotic giant branch (post-AGB) and they may represent one of the first manifestations of collimated mass loss in evolved stars. We present water maser, carbon monoxide, and mid-infrared spectroscopic data (obtained with the Australia Telescope Compact Array, Herschel Space Observatory, and the Very Large Telescope, respectively) toward IRAS 15103–5754, a possible planetary nebula (PN) with WF characteristics. Carbon monoxide observations show that IRAS 15103–5754 is an evolved object, while the mid-IR spectrum displays unambiguous [Ne II] emission, indicating that photoionization has started and thus, its nature as a PN is confirmed. Water maser spectra show several components spreading over a large velocity range (≅ 75 km s{sup –1}) and tracing a collimated jet. This indicates that the object is a WF, the first WF known that has already entered the PN phase. However, the spatial and kinematical distribution of the maser emission in this object are significantly different from those in other WFs. Moreover, the velocity distribution of the maser emission shows a ''Hubble-like'' flow (higher velocities at larger distances from the central star), consistent with a short-lived, explosive mass-loss event. This velocity pattern is not seen in other WFs (which are presumably in earlier evolutionary stages). We therefore suggest that we are witnessing a fundamental change of mass-loss processes in WFs, with water masers being pumped by steady jets in post-AGB stars, but tracing explosive/ballistic events as the object enters the PN phase.

  6. Dusty disks around central stars of planetary nebulae

    SciTech Connect

    Clayton, Geoffrey C.; De Marco, Orsola; Nordhaus, Jason; Green, Joel; Rauch, Thomas; Werner, Klaus; Chu, You-Hua E-mail: orsola@science.mq.edu.au E-mail: joel@astro.as.utexas.edu E-mail: werner@astro.uni-tuebingen.de

    2014-06-01

    Only a few percent of cool, old white dwarfs (WDs) have infrared excesses interpreted as originating in small hot disks due to the infall and destruction of single asteroids that come within the star's Roche limit. Infrared excesses at 24 μm were also found to derive from the immediate vicinity of younger, hot WDs, most of which are still central stars of planetary nebulae (CSPNe). The incidence of CSPNe with this excess is 18%. The Helix CSPN, with a 24 μm excess, has been suggested to have a disk formed from collisions of Kuiper belt-like objects (KBOs). In this paper, we have analyzed an additional sample of CSPNe to look for similar infrared excesses. These CSPNe are all members of the PG 1159 class and were chosen because their immediate progenitors are known to often have dusty environments consistent with large dusty disks. We find that, overall, PG 1159 stars do not present such disks more often than other CSPNe, although the statistics (five objects) are poor. We then consider the entire sample of CSPNe with infrared excesses and compare it to the infrared properties of old WDs, as well as cooler post-asymptotic giant branch (AGB) stars. We conclude with the suggestion that the infrared properties of CSPNe more plausibly derive from AGB-formed disks rather than disks formed via the collision of KBOs, although the latter scenario cannot be ruled out. Finally, there seems to be an association between CSPNe with a 24 μm excess and confirmed or possible binarity of the central star.

  7. The First "Water Fountain" Collimated Outflow in a Planetary Nebula

    NASA Astrophysics Data System (ADS)

    Gómez, José F.; Suárez, Olga; Bendjoya, Philippe; Rizzo, J. Ricardo; Miranda, Luis F.; Green, James A.; Uscanga, Lucero; García-García, Enrique; Lagadec, Eric; Guerrero, Martín A.; Ramos-Larios, Gerardo

    2015-02-01

    "Water fountains" (WFs) are evolved objects showing high-velocity, collimated jets traced by water maser emission. Most of them are in the post-asymptotic giant branch (post-AGB) and they may represent one of the first manifestations of collimated mass loss in evolved stars. We present water maser, carbon monoxide, and mid-infrared spectroscopic data (obtained with the Australia Telescope Compact Array, Herschel Space Observatory, and the Very Large Telescope, respectively) toward IRAS 15103-5754, a possible planetary nebula (PN) with WF characteristics. Carbon monoxide observations show that IRAS 15103-5754 is an evolved object, while the mid-IR spectrum displays unambiguous [Ne II] emission, indicating that photoionization has started and thus, its nature as a PN is confirmed. Water maser spectra show several components spreading over a large velocity range (sime 75 km s-1) and tracing a collimated jet. This indicates that the object is a WF, the first WF known that has already entered the PN phase. However, the spatial and kinematical distribution of the maser emission in this object are significantly different from those in other WFs. Moreover, the velocity distribution of the maser emission shows a "Hubble-like" flow (higher velocities at larger distances from the central star), consistent with a short-lived, explosive mass-loss event. This velocity pattern is not seen in other WFs (which are presumably in earlier evolutionary stages). We therefore suggest that we are witnessing a fundamental change of mass-loss processes in WFs, with water masers being pumped by steady jets in post-AGB stars, but tracing explosive/ballistic events as the object enters the PN phase.

  8. Observing Planetary Nebulae with JWST and Extremely Large Telescopes

    NASA Astrophysics Data System (ADS)

    Sahai, Raghvendra

    2015-01-01

    Most stars in the Universe that leave the main sequence in a Hubble time will end their lives evolving through the Planetary Nebula (PN) evolutionary phase. The heavy mass loss which occurs during the preceding AGB phase is important across astrophysics, dramatically changing the course of stellar evolution, dominantly contributing to the dust content of the interstellar medium, and influencing its chemical composition. The evolution from the AGB phase to the PN phases remains poorly understood, especially the dramatic transformation that occurs in the morphology of the mass-ejecta as AGB stars and their round circumstellar envelopes evolve into mostly PNe, the majority of which deviate strongly from spherical symmetry. In addition, although the PN [OIII] luminosity function (PNLF) has been used as a standard candle (on par with distance indicators such as Cepheids), we do not understand why it works. It has been argued that the resolution of these issues may be linked to binarity and associated processes such as mass transfer and common envelope evolution.Thus, understanding the formation and evolution of PNe is of wide astrophysical importance. PNe have long been known to emit across a very large span of wavelengths, from the radio to X-rays. Extensive use of space-based observatories at X-ray (Chandra/ XMM-Newton), optical (HST) and far-infrared (Spitzer, Herschel) wavelengths in recent years has produced significant new advances in our knowledge of these objects. Given the expected advent of the James Webb Space Telescope in the near future, and ground-based Extremely Large Telescope(s) somewhat later, this talk will focus on future high-angular-resolution, high-sensitivity observations at near and mid-IR wavelengths with these facilities that can help in addressing the major unsolved problems in the study of PNe.

  9. Abell 58 - a Planetary Nebula with an ONe-rich knot: a signature of binary interaction? .

    NASA Astrophysics Data System (ADS)

    Lau, H. H. B.; De Marco, O.; Liu, X.-W.

    We have investigated the possibility that binary evolution is involved in the formation of the planetary nebula Abell 58. In particular, we assume a neon nova is responsible for the observed high oxygen and neon abundances of the central hydrogen-deficient knot of the H-deficient planetary nebula Abell 58 and the ejecta from the explosion are mixed with the planetary nebula. We have investigated different scenarios involving mergers and wind accretion and found that the most promising formation scenario involves a primary SAGB star that ends its evolution as an ONe white dwarf with an AGB companion at a moderately close separation. Mass is deposited on the white dwarf through wind accretion. So neon novae could occur just after the secondary AGB companion undergoes its final flash. However, the initial separation has to be fine-tuned. To estimate the frequency of such systems we evolve a population of binary systems and find that that Abell 58-like objects should indeed be rare and the fraction of Abell-58 planetary nebula is on the order of 10-4, or lower, among all planetary nebulae.

  10. Water-maser emission from a planetary nebula with a magnetized torus.

    PubMed

    Miranda, L F; Gómez, Y; Anglada, G; Torrelles, J M

    2001-11-15

    A star like the Sun becomes a planetary nebula towards the end of its life, when the envelope ejected during the earlier giant phase becomes photoionized as the surface of the remnant star reaches a temperature of approximately 30,000 K. The spherical symmetry of the giant phase is lost in the transition to a planetary nebula, when non-spherical shells and powerful jets develop. Molecules that were present in the giant envelope are progressively destroyed by the radiation. The water-vapour masers that are typical of the giant envelopes therefore are not expected to persist in planetary nebulae. Here we report the detection of water-maser emission from the planetary nebula K3-35. The masers are in a magnetized torus with a radius of about 85 astronomical units and are also found at the surprisingly large distance of about 5,000 astronomical units from the star, in the tips of bipolar lobes of gas. The precessing jets from K3-35 are probably involved in the excitation of the distant masers, although their existence is nevertheless puzzling. We infer that K3-35 is being observed at the very moment of its transformation from a giant star to a planetary nebula. PMID:11713522

  11. International Ultraviolet Explorer satellite observations of seven high-excitation planetary nebulae.

    PubMed

    Aller, L H; Keyes, C D

    1980-03-01

    Observations of seven high-excitation planetary nebulae secured with the International Ultraviolet Explorer (IUE) satellite were combined with extensive ground-based data to obtain electron densities, gas kinetic temperatures, and ionic concentrations. We then employed a network of theoretical model nebulae to estimate the factors by which observed ionic concentrations must be multiplied to obtain elemental abundances. Comparison with a large sample of nebulae for which extensive ground-based observations have been obtained shows nitrogen to be markedly enhanced in some of these objects. Possibly most, if not all, high-excitation nebulae evolve from stars that have higher masses than progenitors of nebulae of low-to-moderate excitation. PMID:16592781

  12. Extinction-independent determination of temperatures for central stars of planetary nebulae

    NASA Astrophysics Data System (ADS)

    Grewing, M.; Neri, R.

    1990-09-01

    A method to determine temperatures for central stars of planetary nebulae from ultraviolet color indices which are essentially extinction-independent is described and applied. Using a standard extinction law (Seaton, 1979) and assuming that the continuum emission from the nuclei of planetary nebulae can be approximated by black-body distributions, It is shown that the color indices m(1225-1475) -m(1910-2140), m(1225-1475) -m(2195-2395), and m(1475-1725) -m(1738-1951) satisfy the condition of extinction independence for EB-V between the values of 0 and 1.0 for all temperatures T between 20,000 and 100,000 K within an accuracy of a few percent. Using data retrieved from the Unified Low Dispersion Archive of the IUE database for 40 planetary nebulae, their UV color indices were determined, and, from these, their color temperatures were found.

  13. POSSIBLE SUBGROUPS OF GLOBULAR CLUSTERS AND PLANETARY NEBULAE IN NGC 5128

    SciTech Connect

    Woodley, Kristin A.; Harris, William E. E-mail: harris@physics.mcmaster.ca

    2011-01-15

    We use recently compiled position and velocity data for the globular cluster and planetary nebula subsystems in NGC 5128, the nearby giant elliptical, to search for evidence of past dwarf-satellite accretion events. Beyond a 10' ({approx}11 kpc) radius in galactocentric distance, we find tentative evidence for four subgroups of globular clusters and four subgroups of planetary nebulae. These each have more than four members within a search radius of 2' and internal velocity dispersion of {approx}<40 km s{sup -1}, typical parameters for a dwarf galaxy. In addition, two of the globular cluster groupings overlap with two of the planetary nebulae groupings, and two subgroupings also appear to overlap with previously known arc and shell features in the halo light. Simulation tests of our procedure indicate that the probability of finding false groups due to chance is <1%.

  14. Observations of the planetary nebula RWT 152 with OSIRIS/GTC

    NASA Astrophysics Data System (ADS)

    Aller, A.; Miranda, L. F.; Olguín, L.; Solano, E.; Ulla, A.

    2016-08-01

    RWT 152 is one of the few known planetary nebulae with an sdO central star. We present subarcsecond red tunable filter Hα imaging and intermediate-resolution, long-slit spectroscopy of RWT 152 obtained with OSIRIS/GTC with the goal of analyzing its properties. The Hα image reveals a bipolar nebula with a bright equatorial region and multiple bubbles in the main lobes. A faint circular halo surrounds the main nebula. The nebular spectra reveal a very low-excitation nebula with weak emission lines from H+, He+, and double-ionized metals, and absence of emission lines from neutral and single-ionized metals, except for an extremely faint [N II] λ6584 emission line. These spectra may be explained if RWT 152 is a density-bounded planetary nebula. Low nebular chemical abundances of S, O, Ar, N, and Ne are obtained in RWT 152, which, together with the derived high peculiar velocity (˜ 92-131 km s-1), indicate that this object is a halo planetary nebula. The available data are consistent with RWT 152 evolving from a low-mass progenitor (˜ 1 M⊙) formed in a metal-poor environment.

  15. A Detailed Study of the Structure of the Nested Planetary Nebula, Hb 12, the Matryoshka Nebula

    NASA Astrophysics Data System (ADS)

    Clark, D. M.; López, J. A.; Edwards, M. L.; Winge, C.

    2014-11-01

    We present near-IR, integral field spectroscopic observations of the planetary nebula (PN) Hb 12 using Near-infrared Integral Field Spectrograph (NIFS) on Gemini-North. Combining NIFS with the adaptive optics system Altair, we provide a detailed study of the core and inner structure of this PN. We focus the analysis in the prominent emission lines [Fe II] (1.6436 μm), He I (2.0585 μm), H2 (2.1214 μm), and Brγ (2.16553 μm). We find that the [Fe II] emission traces a tilted system of bipolar lobes, with the northern lobe being redshifted and the southern lobe blueshifted. The [Fe II] emission is very faint at the core and only present close to the systemic velocity. There is no H2 emission in the core, whereas the core is prominent in the He I and Brγ recombination lines. The H2 emission is concentrated in equatorial arcs of emission surrounding the core and expanding at ~30 km s-1. These arcs are compared with Hubble Space Telescope images and shown to represent nested loops belonging to the inner sections of a much larger bipolar structure that replicates the inner one. The He I and Brγ emission from the core clearly show a cylindrical central cavity that seems to represent the inner walls of an equatorial density enhancement or torus. The torus is 0.''2 wide (≡200 AU radius at a distance of 2000 pc) and expanding at <=30 km s-1. The eastern wall of the inner torus is consistently more intense than the western wall, which could indicate the presence of an off-center star, such as is observed in the similar hourglass PN, MyCn 18. A bipolar outflow is also detected in Brγ emerging within 0.''1 from the core at ~ ± 40 km s-1.

  16. A Study of Planetary Nebulae using the Faint Object Infrared Camera for the SOFIA Telescope

    NASA Technical Reports Server (NTRS)

    Davis, Jessica

    2012-01-01

    A planetary nebula is formed following an intermediate-mass (1-8 solar M) star's evolution off of the main sequence; it undergoes a phase of mass loss whereby the stellar envelope is ejected and the core is converted into a white dwarf. Planetary nebulae often display complex morphologies such as waists or torii, rings, collimated jet-like outflows, and bipolar symmetry, but exactly how these features form is unclear. To study how the distribution of dust in the interstellar medium affects their morphology, we utilize the Faint Object InfraRed CAmera for the SOFIA Telescope (FORCAST) to obtain well-resolved images of four planetary nebulae--NGC 7027, NGC 6543, M2-9, and the Frosty Leo Nebula--at wavelengths where they radiate most of their energy. We retrieve mid infrared images at wavelengths ranging from 6.3 to 37.1 micron for each of our targets. IDL (Interactive Data Language) is used to perform basic analysis. We select M2-9 to investigate further; analyzing cross sections of the southern lobe reveals a slight limb brightening effect. Modeling the dust distribution within the lobes reveals that the thickness of the lobe walls is higher than anticipated, or rather than surrounding a vacuum surrounds a low density region of tenuous dust. Further analysis of this and other planetary nebulae is needed before drawing more specific conclusions.

  17. Morphological study of three Abell's planetary nebulae - A33, A36, and A79

    NASA Astrophysics Data System (ADS)

    Hua, C. T.; Nguyen-Trong, T.

    1983-01-01

    The Abell list discovered in the Palomar Sky Survey includes the three objects A33, A36 and A79, which have been classified as old planetary nebulae. The monochromatic images of these three objects in H-alpha, H-beta, and the forbidden lines N II 6584 A and S II 6717 A, are presented and discussed. The forbidden line N II/H-alpha intensity ratio is found to be useful because of its implications in the evolutionary behavior of planetary nebulae.

  18. Near-infrared and ultraviolet spectrophotometry of the young planetary nebula Hubble 12

    NASA Technical Reports Server (NTRS)

    Rudy, Richard J.; Rossano, George S.; Erwin, Peter; Puetter, R. C.; Feibelman, Walter A.

    1993-01-01

    The young planetary nebula Hubble 12 is observed using near-IR and UV spectrophotometry. The brightness of the O I lines, which is greater than in any other planetary nebula yet measured, indicates that fluorescent excitation by stellar continuum is the principal mechanism generating these lines. Extinction, electron density, and electron temperature are determined using infrared measurements combined with UV data and published optical observations. The range in extinction, density, and temperature implies that, within the ionized region, pockets of emission with distinctly different conditions exist. Logarithmic abundances for helium, oxygen, and sulfur are presented.

  19. Spectrophotometry of Planetary Nebulae in the Bulge of M31

    NASA Astrophysics Data System (ADS)

    Roth, Martin M.; Becker, Thomas; Kelz, Andreas; Schmoll, Jürgen

    2004-03-01

    We introduce crowded-field integral field (3D) spectrophotometry as a useful technique for the study of resolved stellar populations in nearby galaxies. The spectroscopy of individual extragalactic stars, which is now feasible with efficient instruments and large telescopes, is confronted with the observational challenge of accurately subtracting the bright, spatially and wavelength-dependent nonuniform background of the underlying galaxy. As a methodological test, we present a pilot study with selected extragalactic planetary nebulae (XPNe) in the bulge of M31, demonstrating how 3D spectroscopy is able to improve the limited accuracy of background subtraction that one would normally obtain with classical slit spectroscopy. It is shown that because of the absence of slit effects, 3D spectroscopy is a most suitable technique for spectrophometry. We present spectra and line intensities for five XPNe in M31, obtained with the MPFS instrument at the Russian 6 m Bolshoi Teleskop Azimutal'nij, INTEGRAL at the William Herschel Telescope , and PMAS at the Calar Alto 3.5 m telescope. The results for two of our targets, for which data are available in the literature, are compared with previously published emission-line intensities. The three remaining PNe have been observed spectroscopically for the first time. One object is shown to be a previously misidentified supernova remnant. Our monochromatic Hα maps are compared with direct Fabry-Pérot and narrowband filter images of the bulge of M31, verifying the presence of filamentary emission of the interstellar medium in the vicinity of our objects. We present an example of a flux-calibrated and continuum-subtracted filament spectrum and demonstrate how the interstellar medium component introduces systematic errors in the measurement of faint diagnostic PN emission lines when conventional observing techniques are employed. It is shown how these errors can be eliminated with 3D spectroscopy, using the full two

  20. Far-Infrared Spectroscopy of Planetary Nebulae with the KAO

    NASA Technical Reports Server (NTRS)

    Rubin, Robert H.; Colgan, S.; Haas, M. R.; Lord, S. D.; Simpson, Janet P.

    1996-01-01

    We present new far-infrared line observations of the planetary nebulae (PNs) NGC 7027, NGC 7009, and NGC 6210 obtained with the Kuiper Airborne Observatory (KAO). The bulk of our data are for NGC 7027 and NGC 7009, including [Ne(V)] 24 micrometers, [O(IV)] 26 micrometers, [O(III)] (52, 88) micrometers, and [N(III)] 57 micrometers. Our data for [O(III)] (52, 88) and [N(III)] 57 in NGC 7027 represent the first measurements of these lines in this source. The large [O(III)] 52/88-micrometer flux ratio implies an electron density (cubic cm) of log N(sub e)[O(III)] = 4.19, the largest Ne ever inferred from these lines. We derive N(++)/O(++) = 0.394 +/- 0.062 for NGC 7027 and 0.179 +/- 0.043 for NGC 6210. We are able to infer the O(+3)/O(++) ionic ratio from our data. As gauged by this ionic ratio, NGC 7027 is substantially higher ionization than is NGC 7009 - consistent with our observation that the former produces copious [Ne(V)] emission while the latter does not. These data help characterize the stellar ionizing radiation field. From our [O(IV)] and [O(III)] fluxes, we are able to show that O(++) is by far the dominant oxygen ion in NGC 7009. As a result, the O/H abundance inferred using these data tends to corroborate the value found from UV/optical, collisionally excited lines. We determined accurate rest wavelengths for the [Ne(V)] 2s(2)2p(2)P(sub 1) to 2s(2)2p(2)3P(sub 0) (lambda(sub rest) = 24.316 +/- 0.008 micrometers) and [O(IV)] 2s(2)2p(2)P(sup 0, sub 3/2) to 2s(2)2p(2)P(sup 0, sub 1/2) (lambda(sub rest) = 25.887 +/- 0.007 micrometers) transitions from observations of one or both of the bright PNs NGC 7027 and NGC 7009. Our [O(IV)] value, to the best of our knowledge, is the most accurate direct determination of this lambda(sub rest). These new KAO data will be beneficial for comparison with ISO observations of these PNs.

  1. Central Stars of Planetary Nebulae in the SMC

    NASA Technical Reports Server (NTRS)

    Bianchi, Luciana

    2004-01-01

    In FUSE cycle 3's program C056 we studied four Central Stars of Planetary Nebulae (CSPN) in the Small Magellanic Could. All FUSE observations have been successfully completed and have been reduced and analyzed. The observation of one object (SMP SMC 5) appeared to be off-target and no useful stellar flux was gathered. For another observation (SMP SMC 1) the voltage problems resulted in the loss of data from one of the SiC detectors, but we were still able to analyze the remaining data. The analysis and the results are summarized below. The FUSE data were reduced using the latest available version of the FUSE calibration pipeline (CALFUSE v2.4). The flux of these SMC post-AGB objects is at the threshold of FUSE S sensitivity, and the targets required many orbit-long exposures, each of which typically had low (target) count-rates. The background subtraction required special care during the reduction, and was done in a similar manner to our FUSE cycle 2 BOO1 objects. The resulting calibrated data from the different channels were compared in the overlapping regions for consistency. The final combined, extracted spectra of each target was then modeled to determine the stellar and nebular parameters. The FUSE spectra, combined with archival HST spectra, have been analyzed using stellar atmospheres codes such as TLUSTY and CMFGEN to derive photospheric and wind parameters of the central stars, and with ISM models to determine the amount and temperature of the surrounding atomic and molecular hydrogen. We have combined these results with those of our cycle 4 (D034) program (CSPN of the LMC) in Herald & Bianchi 2004a (paper in preparation, will be submitted to ApJ in June 2004). Two of the three SMC objects analyzed were found to have significantly lower stellar temperatures than had been predicted using nebular photoionization models, indicating either a hotter ionizing companion or the existence of strong shocks in the nebular environment. The analysis also revealed that

  2. Evolution of Planetary Nebulae with WR-type Central Stars

    NASA Astrophysics Data System (ADS)

    Danehkar, Ashkbiz

    2014-04-01

    This thesis presents a study of the kinematics, physical conditions and chemical abundances for a sample of Galactic planetary nebulae (PNe) with Wolf-Rayet (WR) and weak emission-line stars (wels), based on optical integral field unit (IFU) spectroscopy obtained with the Wide Field Spectrograph (WiFeS) on the Australian National University 2.3 telescope at Siding Spring Observatory, and complemented by spectra from the literature. PNe surrounding WR-type stars constitute a particular study class for this study. A considerable fraction of currently well-identified central stars of PNe exhibit 'hydrogen-deficient' fast expanding atmospheres characterized by a large mass-loss rate. Most of them were classified as the carbon-sequence and a few of them as the nitrogen-sequence of the WR-type stars. What are less clear are the physical mechanisms and evolutionary paths that remove the hydrogen-rich outer layer from these degenerate cores, and transform it into a fast stellar wind. The aim of this thesis is to determine kinematic structure, density distribution, thermal structure and elemental abundances for a sample of PNe with different hydrogen-deficient central stars, which might provide clues about the origin and formation of their hydrogen-deficient stellar atmospheres. Hα and [N II] emission features have been used to determine kinematic structures. Based on spatially resolved observations of these emission lines, combined with archival Hubble Space Telescope imaging for compact PNe, morphological structures of these PNe have been determined. Comparing the velocity maps from the IFU spectrograph with those provided by morpho-kinematic models allowed disentangling of the different morphological components of most PNe, apart from the compact objects. The results indicate that these PNe have axisymmetric morphologies, either bipolar or elliptical. In many cases, the associated kinematic maps for PNe around hot WR-type stars also show the presence of so-called fast

  3. An imaging and spectroscopic study of the planetary nebulae in NGC 5128 (Centaurus A). Planetary nebulae catalogues

    NASA Astrophysics Data System (ADS)

    Walsh, J. R.; Rejkuba, M.; Walton, N. A.

    2015-02-01

    Context. Planetary nebulae (PNe) are excellent tracers of the common low mass stars through their strong and narrow emission lines. The velocities of large numbers of PNe are excellent tracers of galaxy kinematics. NGC 5128, the nearest large early-type galaxy, offers the possibility to gather a large sample. Aims: Imaging and spectroscopic observations of PNe in NGC 5128 were obtained to find and measure their velocities. Combined with literature data, a large sample of high quality kinematic probes is assembled for dynamical studies. Methods: NTT imaging was obtained in 15 fields in NGC 5128 across 1° with EMMI and [O III] and off-band filters. Newly detected sources, combined with literature PN, were used as input for FLAMES multi-fibre spectroscopy in MEDUSA mode. Spectra of the 4600-5100 Å region were analysed and velocities measured based on [O III]4959, 5007 Å and often Hβ. Results: The chief results are catalogues of 1118 PN candidates and 1267 spectroscopically confirmed PNe in NGC 5128. The catalogue of PN candidates contains 1060 PNe discovered with NTT EMMI imaging and 58 from literature surveys. The spectroscopic PN catalogue has FLAMES radial velocity and emission line measurements for 1135 PNe, of which 486 are new. Another 132 PN radial velocities are available from the literature. For 629 PNe observed with FLAMES, Hβ was measured in addition to [O III]. Nine targets show double-lined or more complex profiles, and their possible origin is discussed. FLAMES spectra of 48 globular clusters were also targetted: 11 had emission lines detected (two with multiple components), but only 3 are PNe likely to belong to the host globular. Conclusions: The total of 1267 confirmed PNe in NGC 5128 with radial velocity measurements (1135 with small velocity errors) is the largest collection of individual kinematic probes in an early-type galaxy. This PN dataset, as well as the catalogue of PN candidates, are valuable resources for detailed investigation of NGC

  4. The "Príncipes de Asturias" nebula: a new quadrupolar planetary nebula from the IPHAS survey

    NASA Astrophysics Data System (ADS)

    Mampaso, A.; Corradi, R. L. M.; Viironen, K.; Leisy, P.; Greimel, R.; Drew, J. E.; Barlow, M. J.; Frew, D. J.; Irwin, J.; Morris, R. A. H.; Parker, Q. A.; Phillipps, S.; Rodríguez-Flores, E. R.; Zijlstra, A. A.

    2006-10-01

    Context: .The Isaac Newton Telescope Photometric Hα Survey (IPHAS) is currently mapping the Northern Galactic plane reaching to r'=20 mag with typically 1primeprime resolution. Hundreds of Planetary Nebulae (PNe), both point-like and resolved, are expected to be discovered. We report on the discovery of the first new PN from this survey: it is an unusual object located at a large galactocentric distance and has a very low oxygen abundance. Aims: .Detecting and studying new PNe will lead to improved estimates of the population size, binary fraction and lifetimes, and yield new insights into the chemistry of the interstellar medium at large galactocentric distances. Methods: .Compact nebulae are searched for in the IPHAS photometric catalogue, selecting those candidates with a strong Hα excess in the r'-Hα vs. r'-i' colour-colour diagram. Searches for extended nebulae are by visual inspection of the mosaics of continuum-subtracted Hα images at a spatial sampling of 5×5 arcsec^2. Follow-up spectroscopy enables confirmation of the PNe, and their physico-chemical study. Results: .The first planetary nebula discovered via IPHAS imagery shows an intricate morphology: there is an inner ring surrounding the central star, bright inner lobes with an enhanced waist, and very faint lobular extensions reaching up to more than 100''. We classify it as a quadrupolar PN, a rather unusual class of planetary showing two pairs of misaligned lobes. From long-slit spectroscopy we derive T_e[ Nii] =12 800±1000 K, Ne = 390±40 cm-3, and chemical abundances typical of Peimbert's type I nebulae (He/H =0.13, N/O =1.8) with an oxygen abundance of 12+log(O/H)=8.17±0.15. A kinematic distance of 7.0+4.5-3.0 kpc is derived, implying an unusually large size of >4 pc for the nebula. The photometry of the central star indicates the presence of a relatively cool companion. This, and the evidence for a dense circumstellar disk and quadrupolar morphology, all of which are rare among PNe, support

  5. Compact reflection nebulae, a transit phase of evolution from post-AGB to planetary nebulae

    NASA Technical Reports Server (NTRS)

    Hu, J. Y.; Slijkhuis, S.

    1989-01-01

    In a search of the optical counter-part of candidates of protoplanetary nebulae on the plates of UK Schmidt, ESO Schmidt, and POSS, five compact reflection nebulae associated with post-AGB stars were found. A simplified model (dust shell is spherical symmetric, expansion velocity of dust shell is constant, Q(sub sca)(lambda) is isotropic, and the dust grain properties are uniform) is used to estimate the visible condition of the dust shell due to the scattering of the core star's light. Under certain conditions the compact reflection nebulae can be seen of the POSS or ESO/SRC survey plates.

  6. Polarization due to dust scattering in the planetary nebula Cn1-1

    NASA Technical Reports Server (NTRS)

    Bhatt, Harish C.

    1989-01-01

    The peculiar emission-line object Cn1-1 (=HDE330036=PK330+4 degrees 1), classified both as a symbiotic star and as a planetary nebula, was detected by the Infrared Astronomical Satellite (IRAS) as a strong source of far-infrared dust in the system. Bhatt and Mallik (1986) discussed the nature of the dust in Cn1-1 and argued that the object is a Type I protoplanetary nebula in a binary system. The argument presented here is that the polarization is intrinsic to Cn1-1 and is due to scattering by large (compared to interstellar) dust grains in the protoplanetary nebula that are asymmetrically distributed around the central star. The large degree of polarization (approximately 3 percent for the Cn1-1 distance of approximately 450 pc) with a large lambda(sub max) is naturally explained if it is caused by scattering by large dust grains in the Cn1-1 nebula. Since the H(sub alpha) line is also polarized at the same level and position angle as the continuum, the dust must be asymmetrically distributed around the central star. The morphology of the protoplanetary nebula in Cn1-1 may be bipolar. Thus, the polarization observations support the suggestion that Cn1-1 is a bipolar Type I planetary nebula.

  7. A detailed study of the structure of the nested planetary nebula, Hb 12, the Matryoshka nebula

    SciTech Connect

    Clark, D. M.; López, J. A.; Edwards, M. L.; Winge, C. E-mail: jal@astrosen.unam.mx E-mail: cwinge@gemini.edu

    2014-11-01

    We present near-IR, integral field spectroscopic observations of the planetary nebula (PN) Hb 12 using Near-infrared Integral Field Spectrograph (NIFS) on Gemini-North. Combining NIFS with the adaptive optics system Altair, we provide a detailed study of the core and inner structure of this PN. We focus the analysis in the prominent emission lines [Fe II] (1.6436 μm), He I (2.0585 μm), H{sub 2} (2.1214 μm), and Br{sub γ} (2.16553 μm). We find that the [Fe II] emission traces a tilted system of bipolar lobes, with the northern lobe being redshifted and the southern lobe blueshifted. The [Fe II] emission is very faint at the core and only present close to the systemic velocity. There is no H{sub 2} emission in the core, whereas the core is prominent in the He I and Br{sub γ} recombination lines. The H{sub 2} emission is concentrated in equatorial arcs of emission surrounding the core and expanding at ∼30 km s{sup –1}. These arcs are compared with Hubble Space Telescope images and shown to represent nested loops belonging to the inner sections of a much larger bipolar structure that replicates the inner one. The He I and Br{sub γ} emission from the core clearly show a cylindrical central cavity that seems to represent the inner walls of an equatorial density enhancement or torus. The torus is 0.''2 wide (≡200 AU radius at a distance of 2000 pc) and expanding at ≤30 km s{sup –1}. The eastern wall of the inner torus is consistently more intense than the western wall, which could indicate the presence of an off-center star, such as is observed in the similar hourglass PN, MyCn 18. A bipolar outflow is also detected in Br{sub γ} emerging within 0.''1 from the core at ∼ ± 40 km s{sup –1}.

  8. Spectrum and chemical analysis of the double-ring planetary nebula IC 1297

    NASA Technical Reports Server (NTRS)

    Aller, Lawrence H.; Keyes, Charles D.; Feibelman, Walter A.

    1986-01-01

    The double-ring planetary nebula IC 1297 resembles NGC 7662 in appearance, although it is of much lower surface brightness. What is remarkable is the great strength of the dielectronic recombination O V line. Although this line is seen as a P Cygni feature in a number of planetary nebulae, it is in those instances accompanied by a strong continuum and other easily recognized features of stellar origin. No star is visible on CCD images of IC 1297. Optical region measurements are supplemented by IUE observations. The following logarithmic abundance values are found: log N(He) = 11.065; log N(forbidden C) = 8.6; log N(N) = 8.1; log N(O) = 8.74; log N(Ne) = 8.16; log N(S) = 7.0; log N(Cl) = 5.4; log N(Ar) = 6.2. The nebula shows no dramatic pattern of nucleogenesis events.

  9. The morphology and interaction with the interstellar medium of the planetary nebula IC 4593

    NASA Technical Reports Server (NTRS)

    Zucker, Daniel B.; Soker, Noam

    1993-01-01

    We present a morphological study of the planetary nebula IC 4593, based on our observations in H-alpha, forbidden O III, and forbidden S II. From the H-alpha intensity map, we calculate densities and masses for constituent structures and for the nebula as a whole. We argue that the morphology of IC 4593 suggests that it is moving supersonically through the ISM, and that the ISM shock may be thermally unstable, oscillating between adiabatic and radiative (isothermal) shock conditions. Spectroscopic observations are necessary to further explore the nature of the interaction between IC 4593 and the ISM. An improved understanding of such interactions will greatly expand the potential use of planetary nebulae to probe the ISM.

  10. Physical parameters for 12 planetary nebulae and their central stars in the Magellanic Clouds

    NASA Technical Reports Server (NTRS)

    Aller, Lawrence H.; Keyes, Charles D.; Maran, Stephen P.; Gull, Theodore R.; Michalitsianos, Andrew G.; Stecher, Theodore P.

    1987-01-01

    Nebular and central star parameters and elemental abundances of C, N, O, Ne, S, and Ar are presented for the planetary nebulae N2, N5, N43, N54, and N67 in the SMC and P2, P7, P9, P25, P33, and P40 in the LMC. The nebular chemical compositions are affected by nuclear processes in the precursor stars, which may not have been sufficiently massive to synthesize Ne, S, or Ar, which appear to be deficient with respect to their solar abundances by factors of roughly four and five for the LMC and SMC, respectively. Even after excluding nebulae formed by stars in which O apparently was destroyed by nuclear processes, O depletion in the LMC and SMC nebulae is significantly greater than in galactic planetaries. The estimated masses of the 12 remnant central stars range from 0.58 to 0.71 solar mass.

  11. Dynamos in asymptotic-giant-branch stars as the origin of magnetic fields shaping planetary nebulae.

    PubMed

    Blackman, E G; Frank, A; Markiel, J A; Thomas, J H; Van Horn, H M

    2001-01-25

    Planetary nebulae are thought to be formed when a slow wind from the progenitor giant star is overtaken by a subsequent fast wind generated as the star enters its white dwarf stage. A shock forms near the boundary between the winds, creating the relatively dense shell characteristic of a planetary nebula. A spherically symmetric wind will produce a spherically symmetric shell, yet over half of known planetary nebulae are not spherical; rather, they are elliptical or bipolar in shape. A magnetic field could launch and collimate a bipolar outflow, but the origin of such a field has hitherto been unclear, and some previous work has even suggested that a field could not be generated. Here we show that an asymptotic-giant-branch (AGB) star can indeed generate a strong magnetic field, having as its origin a dynamo at the interface between the rapidly rotating core and the more slowly rotating envelope of the star. The fields are strong enough to shape the bipolar outflows that produce the observed bipolar planetary nebulae. Magnetic braking of the stellar core during this process may also explain the puzzlingly slow rotation of most white dwarf stars. PMID:11206538

  12. THE EVOLUTION OF THE KINEMATICS OF NEBULAR SHELLS IN PLANETARY NEBULAE IN THE MILKY WAY BULGE

    SciTech Connect

    Richer, Michael G.; Lopez, Jose Alberto; Garcia-Diaz, Maria Teresa; Clark, David M.; Pereyra, Margarita; Diaz-Mendez, Enrique E-mail: jal@astrosen.unam.m E-mail: dmclark@astrosen.unam.m E-mail: e.d.mendez@tcu.ed

    2010-06-10

    We study the line widths in the [O III]{lambda}5007 and H{alpha} lines for two groups of planetary nebulae in the Milky Way bulge based upon spectroscopy obtained at the Observatorio Astronomico Nacional in the Sierra San Pedro Martir (OAN-SPM) using the Manchester Echelle Spectrograph. The first sample includes objects early in their evolution, having high H{beta} luminosities, but [O III]{lambda}5007/H{beta} < 3. The second sample comprises objects late in their evolution, with He II {lambda}4686/H{beta}>0.5. These planetary nebulae represent evolutionary phases preceding and following those of the objects studied by Richer et al. in 2008. Our sample of planetary nebulae with weak [O III]{lambda}5007 has a line width distribution similar to that of the expansion velocities of the envelopes of asymptotic giant branch stars and shifted to systematically lower values as compared to the less evolved objects studied by Richer et al. The sample with strong He II {lambda}4686 has a line width distribution indistinguishable from that of the more evolved objects from Richer et al., but a distribution in angular size that is systematically larger and so they are clearly more evolved. These data and those of Richer et al. form a homogeneous sample from a single Galactic population of planetary nebulae, from the earliest evolutionary stages until the cessation of nuclear burning in the central star. They confirm the long-standing predictions of hydrodynamical models of planetary nebulae, where the kinematics of the nebular shell are driven by the evolution of the central star.

  13. THE CHANDRA PLANETARY NEBULA SURVEY (ChanPlaNS). III. X-RAY EMISSION FROM THE CENTRAL STARS OF PLANETARY NEBULAE

    SciTech Connect

    Montez, R. Jr.; Kastner, J. H.; Freeman, M.; and others

    2015-02-10

    We present X-ray spectral analysis of 20 point-like X-ray sources detected in Chandra Planetary Nebula Survey observations of 59 planetary nebulae (PNe) in the solar neighborhood. Most of these 20 detections are associated with luminous central stars within relatively young, compact nebulae. The vast majority of these point-like X-ray-emitting sources at PN cores display relatively ''hard'' (≥0.5 keV) X-ray emission components that are unlikely to be due to photospheric emission from the hot central stars (CSPN). Instead, we demonstrate that these sources are well modeled by optically thin thermal plasmas. From the plasma properties, we identify two classes of CSPN X-ray emission: (1) high-temperature plasmas with X-ray luminosities, L {sub X}, that appear uncorrelated with the CSPN bolometric luminosity, L {sub bol} and (2) lower-temperature plasmas with L {sub X}/L {sub bol} ∼ 10{sup –7}. We suggest these two classes correspond to the physical processes of magnetically active binary companions and self-shocking stellar winds, respectively. In many cases this conclusion is supported by corroborative multiwavelength evidence for the wind and binary properties of the PN central stars. By thus honing in on the origins of X-ray emission from PN central stars, we enhance the ability of CSPN X-ray sources to constrain models of PN shaping that invoke wind interactions and binarity.

  14. The Chandra Planetary Nebula Survey (ChanPlaNS). III. X-Ray Emission from the Central Stars of Planetary Nebulae

    NASA Astrophysics Data System (ADS)

    Montez, R., Jr.; Kastner, J. H.; Balick, B.; Behar, E.; Blackman, E.; Bujarrabal, V.; Chu, Y.-H.; Corradi, R. L. M.; De Marco, O.; Frank, A.; Freeman, M.; Frew, D. J.; Guerrero, M. A.; Jones, D.; Lopez, J. A.; Miszalski, B.; Nordhaus, J.; Parker, Q. A.; Sahai, R.; Sandin, C.; Schonberner, D.; Soker, N.; Sokoloski, J. L.; Steffen, M.; Toalá, J. A.; Ueta, T.; Villaver, E.; Zijlstra, A.

    2015-02-01

    We present X-ray spectral analysis of 20 point-like X-ray sources detected in Chandra Planetary Nebula Survey observations of 59 planetary nebulae (PNe) in the solar neighborhood. Most of these 20 detections are associated with luminous central stars within relatively young, compact nebulae. The vast majority of these point-like X-ray-emitting sources at PN cores display relatively "hard" (>=0.5 keV) X-ray emission components that are unlikely to be due to photospheric emission from the hot central stars (CSPN). Instead, we demonstrate that these sources are well modeled by optically thin thermal plasmas. From the plasma properties, we identify two classes of CSPN X-ray emission: (1) high-temperature plasmas with X-ray luminosities, L X, that appear uncorrelated with the CSPN bolometric luminosity, L bol and (2) lower-temperature plasmas with L X/L bol ~ 10-7. We suggest these two classes correspond to the physical processes of magnetically active binary companions and self-shocking stellar winds, respectively. In many cases this conclusion is supported by corroborative multiwavelength evidence for the wind and binary properties of the PN central stars. By thus honing in on the origins of X-ray emission from PN central stars, we enhance the ability of CSPN X-ray sources to constrain models of PN shaping that invoke wind interactions and binarity.

  15. Hubble Space Telescope Snapshot Search for Planetary Nebulae in Globular Clusters of the Local Group

    NASA Astrophysics Data System (ADS)

    Bond, Howard E.

    2015-04-01

    Single stars in ancient globular clusters (GCs) are believed incapable of producing planetary nebulae (PNs), because their post-asymptotic-giant-branch evolutionary timescales are slower than the dissipation timescales for PNs. Nevertheless, four PNs are known in Galactic GCs. Their existence likely requires more exotic evolutionary channels, including stellar mergers and common-envelope binary interactions. I carried out a snapshot imaging search with the Hubble Space Telescope (HST) for PNs in bright Local Group GCs outside the Milky Way. I used a filter covering the 5007 Å nebular emission line of [O iii], and another one in the nearby continuum, to image 66 GCs. Inclusion of archival HST frames brought the total number of extragalactic GCs imaged at 5007 Å to 75, whose total luminosity slightly exceeds that of the entire Galactic GC system. I found no convincing PNs in these clusters, aside from one PN in a young M31 cluster misclassified as a GC, and two PNs at such large angular separations from an M31 GC that membership is doubtful. In a ground-based spectroscopic survey of 274 old GCs in M31, Jacoby et al. found three candidate PNs. My HST images of one of them suggest that the [O iii] emission actually arises from ambient interstellar medium rather than a PN; for the other two candidates, there are broadband archival UV HST images that show bright, blue point sources that are probably the PNs. In a literature search, I also identified five further PN candidates lying near old GCs in M31, for which follow-up observations are necessary to confirm their membership. The rates of incidence of PNs are similar, and small but nonzero, throughout the GCs of the Local Group. Based on observations with the NASA/ESA Hubble Space Telescope obtained at the Space Telescope Science Institute, and from the data archive at STScI, which are operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555.

  16. Deciphering the bipolar planetary nebula Abell 14 with 3D ionization and morphological studies

    NASA Astrophysics Data System (ADS)

    Akras, S.; Clyne, N.; Boumis, P.; Monteiro, H.; Gonçalves, D. R.; Redman, M. P.; Williams, S.

    2016-04-01

    Abell 14 is a poorly studied object despite being considered a born-again planetary nebula. We performed a detailed study of its 3D morphology and ionization structure using the SHAPE and MOCASSIN codes. We found that Abell 14 is a highly evolved, bipolar nebula with a kinematical age of ˜19 400 yr for a distance of 4 kpc. The high He abundance, and N/O ratio indicate a progenitor of 5 M⊙ that has experienced the third dredge-up and hot bottom burning phases. The stellar parameters of the central source reveal a star at a highly evolved stage near to the white dwarf cooling track, being inconsistent with the born-again scenario. The nebula shows unexpectedly strong [N I] λ5200 and [O I] λ6300 emission lines indicating possible shock interactions. Abell 14 appears to be a member of a small group of highly evolved, extreme type-I planetary nebulae (PNe). The members of this group lie at the lower-left corner of the PNe regime on the [N II]/Hα versus [S II]/Hα diagnostic diagram, where shock-excited regions/objects are also placed. The low luminosity of their central stars, in conjunction with the large physical size of the nebulae, result in a very low photoionization rate, which can make any contribution of shock interaction easily perceptible, even for small velocities.

  17. Ionized magnesium in the planetary nebula NGC 7027

    NASA Technical Reports Server (NTRS)

    Evans, N. J., II; Natta, A.; Russell, R. W.; Wyant, J.; Beckwith, S.

    1984-01-01

    Observations of NGC 7027 are presented for six ionic lines: Mg(+3) (4.48 microns), Mg(+4) (5.61 microns), H(0) (4.05 and 7.46 microns), Ne(+5) (7.64 microns), and Ar(+5) (4.53 microns). The magnesium lines are consistent with the measurements of Russell, Soifer, and Willner (1977), and the hydrogen lines are consistent with the line strengths predicted from the radio flux. Upper limits were obtained for the neon and argon lines. The abundance of magnesium in the central part of the nebula is highly uncertain because the fine-structure collision strengths are poorly known. The strong gradient of magnesium abundance from the inner to the outer portions of the nebula derived by Pequignot and Stasinska (1980) could be an artifact of this uncertainty. A brief analysis of the effective stellar temperature derived from the magnesium line ratios is given.

  18. Mysteries and Discoveries from the Chandra Planetary Nebulae Suvery (ChanPlaNS)

    NASA Astrophysics Data System (ADS)

    Montez, Rodolfo; Kastner, J. H.; ChanPlaNS Team

    2013-04-01

    Chandra observations of planetary nebulae (PNe) have ushered in a new wave of discoveries and mysteries in this class of evolved stars. The X-ray emission from PNe comes in two flavors: compact sources in the vicinity of the central star and extended sources that fill the nebular cavities generated during the PN formation process. The latter variety, called hot bubbles, are chemically-enriched with helium shell burning products (C, O, and Ne) and their temperatures seem to be regulated by heat conduction across the bubble-nebula interface or by charge-exchange with "pickup ions" within the bubble. Perhaps more exotic are the compact sources at PN central stars. The (relatively hard) X-ray spectral energy distributions of all but one of these point sources cannot be explained by blackbody-like emission from the hot central stars but, instead, suggest the presence of even hotter thermal plasmas. The origin of this plasma emission may be coronae of binary companions, NLTE photospheric emission from the central (proto) white dwarfs, low-level accretion, or shocks in the chemically-enriched stellar wind. We are uncovering and investigating all of these phenomena via the Chandra Planetary Nebulae Survey (ChanPlaNS), a volume-limited archival and multi-cycle survey of planetary nebulae in the solar neighborhood. I present the highlights from our analysis and results and the promising prospects afforded by ChanPlaNS.

  19. X-ray Emission from the Pre-planetary Nebula Henize 3-1475

    NASA Technical Reports Server (NTRS)

    Sahai, Raghvendra; Kastner, Joel H.; Frank, Adam; Morris, Mark; Blackman, Eric G.

    2003-01-01

    We report the first detection of X-ray emission in a pre-planetary nebula, He 3-1475. Pre-planetary nebulae are rare objects in the short transition stage between the asymptotic giant branch (AGB) and planetary nebula evolutionary phases, and He 3-1475, characterized by a remarkable S-shaped chain of optical knots, is one of the most noteworthy members of this class. Observations with the Advanced CCD Imaging Spectrometer on board the Chandra X-Ray Observatory show the presence of compact emission coincident with the brightest optical knot in this bipolar object, which is displaced from the central star by 2'.7 along the polar axis. Model fits to the X-ray spectrum indicate an X-ray temperature and luminosity, respectively, of (4.3-5.7) x 10(exp 6) K and (4 +/- 1.4) x 10(exp 31) (D/5 kpc)(exp 2) ergs s(exp -1) respectively. Our 3 sigma upper limit on the luminosity of compact X-ray emission from the central star in He 3-1475 is approximately equal to 5 x 10(exp 31) (D/5 kpc)(exp 2) ergs s(exp -1). The detection of X-rays in He 3-1475 is consistent with models in which fast collimated post-AGB outflows are crucial to the shaping of nebulae; we discuss such models in the context of our observations.

  20. Light Variations of the Anomalous Central Star of Planetary Nebula Sh 2-71

    NASA Astrophysics Data System (ADS)

    Mikulášek, Z.; Skopal, A.; Zejda, M.; Pejcha, O.; Kohoutek, L.; Motl, D.; Vittone, A. A.; Errico, L.

    2007-03-01

    We present an analysis of light variations in UBV (RI)_{C} of the anomalous object in the center of planetary nebula Sh 2-71. We refined the linear ephemeris of the light maxima to JD_{max}=2449862.0+68.101(E-96), but also identified long-term, obviously non-periodic variations. The latter manifest themselves in large O-C shifts, a variable profile of light curves (hereafter LC) and changes in the mean brightness of the object. Our spectroscopic observations suggested the presence of a superdense nebula in the center of Sh 2-71.

  1. Evolution of Planetary Nebulae with WR-type Central Stars

    NASA Astrophysics Data System (ADS)

    Danehkar, Ashkbiz

    2014-04-01

    This thesis presents a study of the kinematics, physical conditions and chemical abundances for a sample of Galactic planetary nebulae (PNe) with Wolf-Rayet (WR) and weak emission-line stars (wels), based on optical integral field unit (IFU) spectroscopy obtained with the Wide Field Spectrograph (WiFeS) on the Australian National University 2.3 telescope at Siding Spring Observatory, and complemented by spectra from the literature. PNe surrounding WR-type stars constitute a particular study class for this study. A considerable fraction of currently well-identified central stars of PNe exhibit 'hydrogen-deficient' fast expanding atmospheres characterized by a large mass-loss rate. Most of them were classified as the carbon-sequence and a few of them as the nitrogen-sequence of the WR-type stars. What are less clear are the physical mechanisms and evolutionary paths that remove the hydrogen-rich outer layer from these degenerate cores, and transform it into a fast stellar wind. The aim of this thesis is to determine kinematic structure, density distribution, thermal structure and elemental abundances for a sample of PNe with different hydrogen-deficient central stars, which might provide clues about the origin and formation of their hydrogen-deficient stellar atmospheres. Hα and [N II] emission features have been used to determine kinematic structures. Based on spatially resolved observations of these emission lines, combined with archival Hubble Space Telescope imaging for compact PNe, morphological structures of these PNe have been determined. Comparing the velocity maps from the IFU spectrograph with those provided by morpho-kinematic models allowed disentangling of the different morphological components of most PNe, apart from the compact objects. The results indicate that these PNe have axisymmetric morphologies, either bipolar or elliptical. In many cases, the associated kinematic maps for PNe around hot WR-type stars also show the presence of so-called fast

  2. Symmetric and asymmetric planetary nebulae and the time variation of the radial abundance gradients

    NASA Astrophysics Data System (ADS)

    Maciel, W.; Costa, R. D. D.

    2014-04-01

    Planetary nebulae (PN) are excellent laboratories to study the chemical evolution of their host galaxies, especially concerning the radial abundance gradients and their time and spatial variations. Current chemical evolution models predict either some steepening or flattening of the abundance gradients with time, and PN can be useful in order to provide observational constraints on this issue. It is generally believed that asymmetrical nebulae, especially bipolars, are formed by younger, more massive progenitor stars, while symmetrical nebulae, such as the round and elliptical objects, are formed by older, less massive stars. As a consequence, if the abundance gradients change with time, some differences are expected between the gradients measured in symmetrical and asymmetrical nebulae. We have considered a large sample of well-studied galactic PN for which accurate abundances of O, S, Ne, and Ar are known, and for which a reliable morphological classification can be made. Average abundances and radial gradients of the ratios O/H, S/H, Ne/H and Ar/H were then determined for the main morphological classes, comprising B, E, R, and P nebulae. It is found that the average abundances of the younger objects are larger than those of the older nebulae, as expected on chemical evolution grounds, but the derived gradients are essentially the same within the uncertainties. It can then be concluded that the radial abundance gradients have not changed appreciably since the older progenitor stars were born, approximately 4 to 5 Gyr ago.

  3. Unidentified infrared features in proto-planetary nebulae

    NASA Technical Reports Server (NTRS)

    Kwok, S.; Hrivnak, B. J.

    1989-01-01

    The discovery of an unidentified emission feature at 21 microns in the spectra of three protoplanetary nebulae is reported. These objects show large far infrared excess due to a circumstellar dust envelope surrounding a carbon rich central star. Optical, infrared and radio observations of three cool Infrared Astronomy Satellite sources suggest that they are carbon rich objects. Their low resolution spectra show a broad unidentified emission feature at 21 microns which could originate from the bending mode of a hydrocarbon molecule. The similarity of all three objects suggests that this feature is unlikely to be the result of instrumental effects.

  4. AN OPTICAL-INFRARED STUDY OF THE YOUNG MULTIPOLAR PLANETARY NEBULA NGC 6644

    SciTech Connect

    Hsia, Chih Hao; Kwok Sun; Zhang Yong; Koning, Nico; Volk, Kevin E-mail: sunkwok@hku.h E-mail: nkoning@iras.ucalgary.c

    2010-12-10

    High-resolution Hubble Space Telescope imaging of the compact planetary nebula NGC 6644 has revealed two pairs of bipolar lobes and a central ring lying close to the plane of the sky. From mid-infrared imaging obtained with the Gemini Telescope, we have found a dust torus which is oriented nearly perpendicular to one pair of the lobes. We suggest that NGC 6644 is a multipolar nebula and construct a three-dimensional model that allows the visualization of the object from different lines of sight. These results suggest that NGC 6644 may have similar intrinsic structures as other multipolar nebulae and the phenomenon of multipolar nebulosity may be more common than previously believed.

  5. Far-infrared line observations of planetary nebulae. 1: The O 3 spectrum

    NASA Technical Reports Server (NTRS)

    Dinerstein, H. L.; Lester, D. F.; Werner, M. W.

    1985-01-01

    Observations of the far-infrared fine structure lines of O III have been obtained for six planetary nebulae. The infrared measurements are combined with optical O III line fluxes to probe physical conditions in the gas. From the observed line intensity ratios, a simultaneous solution was obtained for electron temperature and density, as well as means of evaluating the importance of inhomogeneities. Densities determined from the far-infrared O III lines agree well density diagnostics from other ions, indicating a fairly homogeneous density in the emitting gas. Temperatures are determined separately from the O III 4363/5007 A and 5007 A/52 micron intensity ratios and compared. Systematically higher values are derived from the former ratio, which is expected from a nebula which is not isothermal. Allowance for the presence of temperature variations within these nebulae raises their derived oxygen abundances, determinations to be reconciled with the solar value.

  6. Far-infrared line observations of planetary nebulae. I - The forbidden O III spectrum

    NASA Astrophysics Data System (ADS)

    Dinerstein, H. L.; Lester, D. F.; Werner, M. W.

    1985-04-01

    Observations of the far-infrared fine structure lines of O III have been obtained for six planetary nebulae. The infrared measurements are combined with optical O III line fluxes to probe physical conditions in the gas. From the observed line intensity ratios, a simultaneous solution was obtained for electron temperature and density, as well as means of evaluating the importance of inhomogeneities. Densities determined from the far-infrared O III lines agree well with density diagnostics from other ions, indicating a fairly homogeneous density in the emitting gas. Temperatures are determined separately from the O III 4363/5007 A and 5007 A/52 micron intensity ratios and compared. Systematically higher values are derived from the former ratio, which is expected from a nebula which is not isothermal. Allowance for the presence of temperature variations within these nebulae raises their derived oxygen abundances, determinations to be reconciled with the solar value.

  7. Measurement of S II forbidden lines in three southern planetary nebulae

    NASA Astrophysics Data System (ADS)

    Macron, A.; Louise, R.

    1990-06-01

    Three southern planetary nebulae (NGC 2818, He 2-130, and NGC 3132) have been observed with the IDS (Image Dessector Scanner) combined with the Boller and Chivens spectrograph mounted at the Cassegrain focus of the 1.52 m telescope of the ESO in Chile. The spectrograph dispersion was 60 A/mm in the spectral range 6170-7298 A. Spectra were obtained from an array of positions across each nebula along the E-W direction and/or N-S direction. In order to derive electron density, only the S II forbidden lines (6617 A-6731 A) are given here. The results are in agreement with a shell structure for the observed nebulae.

  8. Observations and morphological study of ring planetary nebulae in forbidden O III

    NASA Astrophysics Data System (ADS)

    Louise, R.

    1982-03-01

    A photometric study is presented of the morphology of forbidden O III emission from 10 ring planetary nebulae. Observations were made in a narrowband interference filter centered at 5007 A for the objects NGC 40, 1514, 2392, 6543, 6781, 6826, 7354, 7048, 7009 and 7662, and used to obtain values for the major axis, the distance separating two successive maxima of the photometric profile, the ring/center intensity ratio and eccentricity. These parameters are found to be consistent with a shell model for most of the nebulae, although it is noted that the model only applies to the O III distribution. Fine structure is also found in certain nebulae, indicating the presence of more complex structures to which the shell model is only a first approximation.

  9. Hubble Space Telescope Imaging of the Binary Nucleus of the Planetary Nebula EGB 6

    NASA Astrophysics Data System (ADS)

    Liebert, James; Bond, Howard E.; Dufour, P.; Ciardullo, Robin; Meakes, Michael G.; Renzini, Alvio; Gianninas, A.

    2013-05-01

    EGB 6 is an ancient, low-surface-brightness planetary nebula. The central star, also cataloged as PG 0950+139, is a very hot DAOZ white dwarf (WD) with an apparent M dwarf companion, unresolved from the ground but detected initially through excesses in the JHK bands. Its kinematics indicates membership in the Galactic disk population. Inside of EGB 6 is an extremely dense emission knot—completely unexpected since significant mass loss from the WD should have ceased ~105 yr ago. The electron density of the compact nebula is very high (2.2 × 106 cm-3), as indicated by collisional de-excitation of forbidden emission lines. Hubble Space Telescope imaging and grism spectroscopy are reported here. These resolve the WD and apparent dM companion—at a separation of 0.''166, or a projected 96_{-45}^{+204} AU at the estimated distance of 576_{-271}^{+1224} pc (using the V magnitude). Much to our surprise, we found that the compact emission nebula is superposed on the dM companion, far from the photoionizing radiation of the WD. Moreover, a striking mid-infrared excess has recently been reported in the Spitzer/IRAC and MIPS bands, best fit with two dust shells. The derived ratio L IR/L WD = 2.7 × 10-4 is the largest yet found for any WD or planetary nucleus. The compact nebula has maintained its high density for over three decades. We discuss two possible explanations for the origin and confinement of the compact nebula, neither of which is completely satisfactory. This leaves the genesis and confinement of the compact nebula an astrophysical puzzle, yet similar examples appear in the literature. Based on observations made with the NASA/ESA Hubble Space Telescope (HST), obtained by the Space Telescope Science Institute. STScI is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555.

  10. HUBBLE SPACE TELESCOPE IMAGING OF THE BINARY NUCLEUS OF THE PLANETARY NEBULA EGB 6

    SciTech Connect

    Liebert, James; Bond, Howard E.; Ciardullo, Robin; Dufour, P.; Meakes, Michael G.; Renzini, Alvio; Gianninas, A. E-mail: bond@stsci.edu E-mail: mgmeakes@gmail.com E-mail: alvio.renzini@oapd.inaf.it

    2013-05-20

    EGB 6 is an ancient, low-surface-brightness planetary nebula. The central star, also cataloged as PG 0950+139, is a very hot DAOZ white dwarf (WD) with an apparent M dwarf companion, unresolved from the ground but detected initially through excesses in the JHK bands. Its kinematics indicates membership in the Galactic disk population. Inside of EGB 6 is an extremely dense emission knot-completely unexpected since significant mass loss from the WD should have ceased {approx}10{sup 5} yr ago. The electron density of the compact nebula is very high (2.2 Multiplication-Sign 10{sup 6} cm{sup -3}), as indicated by collisional de-excitation of forbidden emission lines. Hubble Space Telescope imaging and grism spectroscopy are reported here. These resolve the WD and apparent dM companion-at a separation of 0.''166, or a projected 96{sub -45}{sup +204} AU at the estimated distance of 576{sub -271}{sup +1224} pc (using the V magnitude). Much to our surprise, we found that the compact emission nebula is superposed on the dM companion, far from the photoionizing radiation of the WD. Moreover, a striking mid-infrared excess has recently been reported in the Spitzer/IRAC and MIPS bands, best fit with two dust shells. The derived ratio L{sub IR}/L{sub WD} = 2.7 Multiplication-Sign 10{sup -4} is the largest yet found for any WD or planetary nucleus. The compact nebula has maintained its high density for over three decades. We discuss two possible explanations for the origin and confinement of the compact nebula, neither of which is completely satisfactory. This leaves the genesis and confinement of the compact nebula an astrophysical puzzle, yet similar examples appear in the literature.

  11. ABUNDANCES OF PLANETARY NEBULAE IN THE OUTER DISK OF M31

    SciTech Connect

    Kwitter, Karen B.; Lehman, Emma M. M.; Balick, Bruce; Henry, R. B. C. E-mail: emmalehman@gmail.com E-mail: rhenry@ou.edu

    2012-07-01

    We present spectroscopic observations and chemical abundances of 16 planetary nebulae (PNe) in the outer disk of M31. The [O III] {lambda}4363 line is detected in all objects, allowing a direct measurement of the nebular temperature essential for accurate abundance determinations. Our results show that the abundances in these M31 PNe display the same correlations and general behaviors as Type II PNe in the Milky Way. We also calculate photoionization models to derive estimates of central star properties. From these we infer that our sample PNe, all near the bright-end cutoff of the planetary nebula luminosity function, originated from stars near 2 M{sub Sun }. Finally, under the assumption that these PNe are located in M31's disk, we plot the oxygen abundance gradient, which appears shallower than the gradient in the Milky Way.

  12. Detection of C60 and C70 in a young planetary nebula.

    PubMed

    Cami, Jan; Bernard-Salas, Jeronimo; Peeters, Els; Malek, Sarah Elizabeth

    2010-09-01

    In recent decades, a number of molecules and diverse dust features have been identified by astronomical observations in various environments. Most of the dust that determines the physical and chemical characteristics of the interstellar medium is formed in the outflows of asymptotic giant branch stars and is further processed when these objects become planetary nebulae. We studied the environment of Tc 1, a peculiar planetary nebula whose infrared spectrum shows emission from cold and neutral C60 and C70. The two molecules amount to a few percent of the available cosmic carbon in this region. This finding indicates that if the conditions are right, fullerenes can and do form efficiently in space. PMID:20651118

  13. New DSH planetary nebulae and candidates from optical and infrared surveys

    NASA Astrophysics Data System (ADS)

    Kronberger, Matthias; Parker, Quentin A.; Jacoby, George H.; Acker, Agnes; Alves, Filipe; Bojicic, Ivan; Eigenthaler, Paul; Frew, David J.; Harmer, Dianne; Patchick, Dana; Reid, Warren; Schedler, Johannes

    2016-07-01

    To date, the planetary nebula (PN) survey of the Deep Sky Hunters collaboration has led to the detection of more than 250 previously unknown candidate planetary nebulae (PNe). About 60% of them were found during the past two years and are expected to be true, likely or possible PNe because careful vetting has already thrown out more doubtful objects. The majority of the new PN candidates are located within the boundaries of the SHS and IPHAS Ha surveys and were discovered by combining MIR data from the WideField Infrared Survey Explorer (WISE) with optical data from the IPHAS, SHS and DSS surveys, and UV data from the Galaxy Evolution Explorer(GALEX).

  14. A far-infrared emission feature in carbon-rich stars and planetary nebulae

    NASA Technical Reports Server (NTRS)

    Forrest, W. J.; Houck, J. R.; Mccarthy, J. F.

    1981-01-01

    The 16-30 micron spectra of several carbon stars and the planetary nebulae IC 418 and NGC 6572 have been obtained using the NASA C-141 Kuiper Airborne Observatory. A newly observed emission feature appears in the spectrum of IRC +10216 and several other carbon stars at wavelengths greater than 24 microns. The feature is interpreted as resulting from a solid-state resonance in the dust grains which have condensed around these stars. A similar feature appears in the spectra of IC 418 and NGC 6572, implying that the same type of dust is present. Since the dust probably condensed from a carbon-rich gas, this indicates an evolutionary link between carbon stars and these planetary nebulae. No identification for the grain material has been found, but some clues are apparent which could aid in the identification.

  15. The dusty side of planetary nebulae: a HerPlaNS view

    NASA Astrophysics Data System (ADS)

    Ueta, Toshiya; Ladjal, Djazia; pre=", HerPlaNS team

    2016-07-01

    HerPlaNS (Herschel Planetary Nebula Survey) is a far-IR imaging/spectroscopic survey of planetary nebulae (PNe) using the Herschel Space Observatory. In this presentation, we review our investigation into the physical properties of the cold dust component of the target PNe. We find that the far-IR surface brightness emission from PNe is generally dominated by thermal dust emission, which exhibits particular characteristics in terms of the dust emissivity and dust temperature compared with dust grains found elsewhere. The PN dust displays little variation in the emissivity while a large spread in the temperature, suggesting the presence of rather homogeneous dust chemistry and size distribution in the circumstellar environs.

  16. 3D-Spectroscopy of Extragalactic Planetary Nebulae as Diagnostic Probes for Galaxy Evolution

    NASA Astrophysics Data System (ADS)

    Kelz, A.; Monreal-Ibero, A.; Roth, M. M.; Sandin, C.; Schönberner, D.; Steffen, M.

    In addition to study extragalactic stellar populations in their integrated light, the detailed analysis of individual resolved objects has become feasible, mainly for luminous giant stars and for extragalactic planetary nebulae (XPNe) in nearby galaxies. A recently started project at the Astrophysical Institute Potsdam (AIP), called ``XPN--Physics'', aims to verify if XPNe are useful probes to measure the chemical abundances of their parent stellar population. The project involves theoretical and observational work packages.

  17. The spectrum of HM Sagittae: A planetary nebula excited by a Wolf-Rayet star

    NASA Technical Reports Server (NTRS)

    Brown, L. W.; Feibelman, W. A.; Hobbs, R. W.; Mccracken, C. W.

    1977-01-01

    A total of image tube spectrograms of HM Sagittae were obtained. More than 70 emission lines, including several broad emission features, were identified. An analysis of the spectra indicates that HM Sagittae is a planetary nebula excited by a Wolf-Rayet star. The most conspicuous Wolf-Rayet feature is that attributed to a blend of C III at 4650 A and He II at 4686 A.

  18. Interleaved FITS DS9 segmentation with shell script metaprogramming for planetary nebulae detection

    NASA Astrophysics Data System (ADS)

    Stenborg, T. N.

    2014-04-01

    A technique for efficient inspection of large volumes of imaging data for planetary nebulae (PNe) is demonstrated. Image segmentation to subscreen size is automated. Inspection of consecutive small images mitigates inadvertently missing sections of large images with manual image traversal. Automated interleaving of on-band and off-band images with corresponding difference imaging is carried out. Bi-directional single-click navigation of a segmented, interleaved data set allows blinking of complementary images and efficient identification of PNe candidates.

  19. Search with Copernicus for ultraviolet emission lines in the planetary nebula NGC 3242

    NASA Technical Reports Server (NTRS)

    Schwartz, R. D.; Snow, T. P., Jr.; Upson, W. L., II

    1978-01-01

    The high-excitation planetary nebula NGC 3242 has been observed with the ultraviolet telescope-spectrometer aboard Copernicus. Wavelength intervals corresponding to the emission lines of O VI at 1032 A, He II at 1085 A, Si III at 1206 A, and N V at 1239 A have been scanned. Upper limits to the observed fluxes are reported and compared with predicted emission-line fluxes from this object.

  20. Two different periods present in the binary nucleus of the planetary nebula LoTr5

    NASA Astrophysics Data System (ADS)

    Kuczawska, Ewa; Mikolajewski, M.

    1993-10-01

    We present new photoelectric UBV observations of IN Com -- the binary nucleus of the planetary nebula LoTr5, carried out in April 1993 with the double beam photometer at Mt. Suhora Observatory. Low-amplitude variations were detected with a period of about 5.d92, in agreement with the results of Noskova (1989) and Bond and Livio (1990), but also higher frequency variability was discovered. A preliminary ephemeris is given. We speculate on the origin of the observed variabilities.

  1. The Complex Environment of the High Excitation Planetary Nebula NGC 3242

    NASA Technical Reports Server (NTRS)

    Noriega-Crespo, A.; Meaburn, J.; Lopez, J.

    1999-01-01

    Spatially resolved profiles of the H (alpha), [N II] 6584 A and [O III] 5007 A nebular emission lines, obtained with the Manchester echelle spectrometer combined with the 2.1 m San Pedro Martir telescope have revealed the velocity structure of the nebular core and of one of the three (A,B and C) inner haloes of the high excitation planetary nebula NGC 3242.

  2. Nebular and auroral forbidden transitions of AR IV in some planetary nebulae

    NASA Astrophysics Data System (ADS)

    Czyzak, S. J.; Sonneborn, G.; Aller, L. H.; Shectman, S. A.

    1980-10-01

    Measurements of auroral and nebular type transitions in several planetary nebulae of high surface brightness show that currently available collisional cross sections and transition probabilities for 3p(3) configurations in Ar(3+) may be in error. The observed auroral/nebular line ratio is always larger than the predicted value, and the disagreement is further aggravated if auroral lines are weakened by telluric line absorption.

  3. IUE survey of planetary nebulae in the large and small magellanic clouds

    NASA Technical Reports Server (NTRS)

    Gull, T. R.; Michalitsianos, A. G.; Maran, S. P.; Stecher, T. P.; Aller, L. H.; Keyes, C. D.

    1986-01-01

    Twelve planetary nebulae of the 15 surveyed by IUE in the Megellanic Clouds were analyzed. Chemical abundances and other nebular parameters were determined, along with masses for the central stars. The latter are clustered in the range 0.58 to 0.71 solar masses, contrary to preliminary finding for 3 of the stars. This difference is attributed to the adoption of stellar atmosphere models that better represent the emergent flux distributions below the Lyman limit.

  4. Evidence for Deuterium Astration in the Planetary Nebula Sh 2-216?

    NASA Astrophysics Data System (ADS)

    Oliveira, Cristina M.; Chayer, Pierre; Moos, H. Warren; Kruk, Jeffrey W.; Rauch, Thomas

    2007-05-01

    We present FUSE observations of the line of sight to WD 0439+466 (LS V +46 21), the central star of the old planetary nebula Sh 2-216. The FUSE data show absorption by many interstellar and stellar lines, in particular D I, H2 (J=0-9), HD J=0-1, and CO. Many other stellar and ISM lines are detected in the STIS E140M HST spectra of this sight line, which we use to determine N(H I). We derive, for the neutral gas, D/H=0.76+0.12-0.11×10-5, O/H=0.89+0.15-0.11×10-4, and N/H=3.24+0.61-0.55×10-5. We argue that most of the gas along this sight line is associated with the planetary nebula. The low D/H ratio is likely the result of this gas being processed through the star (astrated) but not mixed with the ISM. This would be the first time that the D/H ratio has been measured in predominantly astrated gas. The O/H and N/H ratios derived here are lower than typical values measured in other planetary nebulae likely due to unaccounted for ionization corrections. Based on observations made with the NASA-CNES-CSA Far Ultraviolet Spectroscopic Explorer. FUSE is operated for NASA by The Johns Hopkins University under NASA contract NAS5-32985.

  5. An Analysis and Classification of Dying AGB Stars Transitioning to Pre-Planetary Nebulae

    NASA Technical Reports Server (NTRS)

    Blake, Adam C.

    2011-01-01

    The principal objective of the project is to understand part of the life and death process of a star. During the end of a star's life, it expels its mass at a very rapid rate. We want to understand how these Asymptotic Giant Branch (AGB) stars begin forming asymmetric structures as they start evolving towards the planetary nebula phase and why planetary nebulae show a very large variety of non-round geometrical shapes. To do this, we analyzed images of just-forming pre-planetary nebula from Hubble surveys. These images were run through various image correction processes like saturation correction and cosmic ray removal using in-house software to bring out the circumstellar structure. We classified the visible structure based on qualitative data such as lobe, waist, halo, and other structures. Radial and azimuthal intensity cuts were extracted from the images to quantitatively examine the circumstellar structure and measure departures from the smooth spherical outflow expected during most of the AGB mass-loss phase. By understanding the asymmetrical structure, we hope to understand the mechanisms that drive this stellar evolution.

  6. Imaging the Elusive H-poor Gas in the High adf Planetary Nebula NGC 6778

    NASA Astrophysics Data System (ADS)

    García-Rojas, Jorge; Corradi, Romano L. M.; Monteiro, Hektor; Jones, David; Rodríguez-Gil, Pablo; Cabrera-Lavers, Antonio

    2016-06-01

    We present the first direct image of the high-metallicity gas component in a planetary nebula (NGC 6778), taken with the OSIRIS Blue Tunable Filter centered on the O ii λ4649+50 Å optical recombination lines (ORLs) at the 10.4 m Gran Telescopio Canarias. We show that the emission of these faint O ii ORLs is concentrated in the central parts of the planetary nebula and is not spatially coincident either with emission coming from the bright [O iii] λ5007 Å collisionally excited line (CEL) or the bright Hα recombination line. From monochromatic emission line maps taken with VIMOS at the 8.2 m Very Large Telescope, we find that the spatial distribution of the emission from the auroral [O iii] λ4363 line resembles that of the O ii ORLs but differs from nebular [O iii] λ5007 CEL distribution, implying a temperature gradient inside the planetary nebula. The centrally peaked distribution of the O ii emission and the differences with the [O iii] and H i emission profiles are consistent with the presence of an H-poor gas whose origin may be linked to the binarity of the central star. However, determination of the spatial distribution of the ORLs and CELs in other PNe and a comparison of their dynamics are needed to further constrain the geometry and ejection mechanism of the metal-rich (H-poor) component and hence, understand the origin of the abundance discrepancy problem in PNe.

  7. A Morpho-kinematic and Spectroscopic study of Bipolar Planetary Nebulae

    NASA Astrophysics Data System (ADS)

    Clyne, Niall

    2015-09-01

    In this thesis, studies of the kinematic properties for a sample of Galactic bipolar planetary nebulae, based on optical and infrared observations, were performed using a morpho-kinematic code, optical and NIR diagnostic diagrams, and techniques using data analyses. The mechanisms that form complex bipolar planetary nebulae remain unclear, and their shapes can be generated either as a planetary or symbiotic nebula. The origin of the material ionised by the white dwarf is very different in these two scenarios, and it complicates the understanding of the morphologies of planetary nebulae. The physical properties, structure, and dynamics of the bipolar nebulae, MyCn 18, M 2-9, Mz 3, Hen 2-104, and Abell 14, are each investigated in detail with the aim of understanding their nature, shaping mechanisms, and evolutionary history. For MyCn 18, VLT infrared images, VLT ISAAC infrared spectra, and long-slit optical echelle spectra are used to investigate the inner and outer regions of the nebula. The morpho-kinematic modelling tool shape was used to firmly constrain the structure and kinematics of the source. A timescale analysis was used to help determine the kinematical age of the nebula and its main components. A spectroscopic study of MyCn 18's central region reveals the detailed make-up of its nebular composition. Molecular hydrogen, atomic helium, and Brackett gamma emission are detected in the central regions. ISAAC spectra from a slit position along the narrow waist of the nebula demonstrate that the ionised gas resides closer to the centre of the nebula than the molecular emission. A final reconstructed 3-D model of MyCn 18 was generated, providing kinematical information on the expansion velocity of its nebular components by means of position-velocity arrays (or observed long-slit spectra). A kinematical age of the nebula and its components were obtained using the position-velocity arrays and timescale analysis. For M 2-9, Mz 3, and Hen 2-104, long-slit optical

  8. Photometry of the Stingray Nebula (V839 Ara) from 1889 TO 2015 across the Ionization of Its Planetary Nebula

    NASA Astrophysics Data System (ADS)

    Schaefer, Bradley E.; Edwards, Zachary I.

    2015-10-01

    Up until around 1980, the Stingray was an ordinary B1 post-AGB star, but then it suddenly sprouted bright emission lines like in a planetary nebula (PN), and soon after this the Hubble Space Telescope (HST) discovered a small PN around the star, so apparently we have caught a star in the act of ionizing a PN. We report here on a well-sampled light curve from 1889 to 2015, with unique coverage of the prior century plus the entire duration of the PN formation plus three decades of its aftermath. Surprisingly, the star anticipated the 1980s ionization event by declining from B = 10.30 in 1889 to B = 10.76 in 1980. Starting in 1980, the central star faded fast, at a rate of 0.20 mag year-1, reaching B = 14.64 in 1996. This fast fading is apparently caused by the central star shrinking in size. From 1994 to 2015, the V-band light curve is almost entirely from the flux of two bright [O iii] emission lines from the unresolved nebula, and it shows a consistent decline at a rate of 0.090 mag year-1. This steady fading (also seen in the radio and infrared) has a timescale equal to that expected for ordinary recombination within the nebula, immediately after a short-duration ionizing event in the 1980s. We are providing the first direct measure of the rapidly changing luminosity of the central star on both sides of a presumed thermal pulse in 1980, with this providing a strong and critical set of constraints, and these are found to sharply disagree with theoretical models of PN evolution.

  9. Photometry of the Stingray Nebula (V839 Ara) from 1889 TO 2015 across the Ionization of Its Planetary Nebula

    NASA Astrophysics Data System (ADS)

    Schaefer, Bradley E.; Edwards, Zachary I.

    2015-10-01

    Up until around 1980, the Stingray was an ordinary B1 post-AGB star, but then it suddenly sprouted bright emission lines like in a planetary nebula (PN), and soon after this the Hubble Space Telescope (HST) discovered a small PN around the star, so apparently we have caught a star in the act of ionizing a PN. We report here on a well-sampled light curve from 1889 to 2015, with unique coverage of the prior century plus the entire duration of the PN formation plus three decades of its aftermath. Surprisingly, the star anticipated the 1980s ionization event by declining from B = 10.30 in 1889 to B = 10.76 in 1980. Starting in 1980, the central star faded fast, at a rate of 0.20 mag year‑1, reaching B = 14.64 in 1996. This fast fading is apparently caused by the central star shrinking in size. From 1994 to 2015, the V-band light curve is almost entirely from the flux of two bright [O iii] emission lines from the unresolved nebula, and it shows a consistent decline at a rate of 0.090 mag year‑1. This steady fading (also seen in the radio and infrared) has a timescale equal to that expected for ordinary recombination within the nebula, immediately after a short-duration ionizing event in the 1980s. We are providing the first direct measure of the rapidly changing luminosity of the central star on both sides of a presumed thermal pulse in 1980, with this providing a strong and critical set of constraints, and these are found to sharply disagree with theoretical models of PN evolution.

  10. The rocket ultraviolet spectrum of the planetary nebula NGC 7027

    NASA Technical Reports Server (NTRS)

    Bohlin, R. C.; Marionni, P. A.; Stecher, T. P.

    1975-01-01

    An ultraviolet spectrum of NGC 7027 was obtained with a rocket-borne telescope. The observed fluxes are given on an absolute basis and upper limits are given for the strongest predicted lines which were not observed. The extinction correction was made on the basis of the observed and calculated line ratios for the hydrogenic recombination line of He 2 at 1640A to H beta. The extinction is in agreement with ground based determinations. When corrected for extinction the C 4 resonance line at 1549A is in good agreement with the intensity calculated from models, but the C 3 intercombination line at 1909A is a factor of ten too bright. The addition of dielectronic recombination to the models sufficiently changes the C 3 concentration to reduce the discrepancy to a factor of four. The abundance of carbon is assumed to be 2 x 0.0001 that of hydrogen. Using carbon abundances for the sun, this discrepancy disappears and there must be attenuation in the C 4 line. Since the optical depth is approximately 10,000 at the line center, no appreciable number of absorbing grains can exist in the C 4 producing region of the nebula.

  11. A spectroscopic and photometric study of the planetary nebulae Kn 61 and Pa 5

    SciTech Connect

    García-Díaz, Ma. T.; González-Buitrago, D.; López, J. A.; Zharikov, S.; Tovmassian, G.; Borisov, N.; Valyavin, G. E-mail: dgonzalez@astro.unam.mx E-mail: zhar@astro.unam.mx E-mail: borisov@sao.ru

    2014-09-01

    We present the first morpho-kinematical analysis of the planetary nebulae Kn 61 and Pa 5 and explore the nature of their central stars. Our analysis is based on high-resolution and medium-resolution spectroscopic observations, deep narrow-band imaging, and integral photometry. This material allows us to identify the morphological components and study their kinematics. The direct images and spectra indicate an absence of the characteristic [N II] and [S II] emission lines in both nebulae. The nebular spectrum of Kn 61 suggests a hydrogen deficient planetary nebula and the stellar spectrum of the central star reveals a hydrogen-deficient PG 1159-type star. The [O III] position velocity diagram reveals that Kn 61 is a closed, empty, spherical shell with a thin border and a filamentary surface expanding at 67.6 km s{sup –1} and the shell is currently not expanding isotropically. We derived a kinematic age of ∼1.6 × 10{sup 4} yr for an assumed distance of 4 kpc. A photometric period of ∼5.7(±0.4) days has been detected for Kn 61, indicating the presence of a possible binary system at its core. A possible link between filamentary spherical shells and PG 1159-type stars is noted. The morphology of Pa 5 is dominated by an equatorial toroid and faint polar extensions. The equatorial region of this planetary nebula is expanding at 45.2 km s{sup –1}. The stellar spectrum corresponds to a very hot star and is dominated by a steep blue rising continuum and He II, Balmer, and Ca II photospheric lines.

  12. The central star of the planetary nebula Abell 78

    NASA Technical Reports Server (NTRS)

    Kaler, J. B.; Feibelman, W. A.

    1984-01-01

    The ultraviolet spectrum of the nucleus of Abell 78, one of the two planetaries known to contain zones of nearly pure helium, is studied. The line spectrum and wind velocities are examined, the determination of interstellar extinction for assessing circumstellar dust is improved, and the temperature, luminosity, and core mass are derived. The results for A78 are compared with results for A30, and it is concluded that the dust distributions around the two central stars are quite different. The temperature of the A78 core is not as high as previously believed, and almost certainly lies between 67,000 K and 130,000 K. The most likely temperature range is 77,000-84,000 K. The core mass lies between 0.56 and 0.70 solar mass, with the most likely values between 0.56 and 0.58 solar mass.

  13. Hubble Space Telescope observations of planetary nebulae in the magellanic clouds. 2: SMP 85, a young planetary

    NASA Technical Reports Server (NTRS)

    Dopita, Michael A.; Vassiliadis, Emanuel; Meatheringham, Stephen J.; Ford, Holland C.; Bohlin, Ralph; Wood, Peter R.; Stecher, Theodore P.; Maran, Stephen P.; Harrington, J. Patrick

    1994-01-01

    We have obtained Hubble Space Telescope Planetary Camera images in the (O III) lambda 5007 A emission line, and Faint Object Spectrograph (FOS) UV spectrophotometry of the low-excitation planetary nebula SMP 85 in the Large Magellanic Cloud. By combining these results with existing optical spectrophotometry, absolute flux measurements, and dynamical and density information, we have been able to construct a fully self-consistent nebular model. This proves that SMP 85 is a dense, young, carbon-rich object which started to be ionized about 500-1000 years ago, and which contains a substantial inner reservoir of atomic or molecular gas, probably in the form of many small cloudlets. These cloudlets have been ejected at a velocity not exceeding 6 km/s, a result which, together with the morphology is an important clue to mass loss during late asymptotic giant branch (AGB) evolution. We have directly detected the central star through its UV continuum emission, and from both Zanstra techniques and nebular modeling derive a stellar temperature of 46000 +/- 2000 K, a stellar luminosity of 7300 +/- 700 solar luminosity, and a core mass of 0.63-0.67 solar mass. The nebular analysis also demonstrates that there is severe depletion of the nebular gases onto dust grains, most likely of the calcium magnesium silicate variety; a surprising result in view of the carbon-rich nature of the ionized nebula.

  14. The True Nature of the Alleged Planetary Nebula W16-185

    NASA Astrophysics Data System (ADS)

    Roman-Lopes, A.; Abraham, Z.

    2006-04-01

    We report the discovery of a small cluster of massive stars embedded in a NIR nebula in the direction of the IRAS 15411-5352 point source, which is related to the alleged planetary nebula W16-185. The majority of the stars present large NIR excess characteristic of young stellar objects and have bright counterparts in the Spitzer IRAC images; the most luminous star (IRS 1) is the NIR counterpart of the IRAS source. We found very strong unresolved Brγ emission at the IRS 1 position and more diluted and extended emission across the continuum nebula. From the sizes and electron volume densities we concluded that they represent ultracompact and compact H II regions, respectively. Comparing the Brγ emission with the 7 mm free-free emission, we estimated that the visual extinction ranges between 14 and 20 mag. We found that only one star (IRS 1) can provide the number of UV photons necessary to ionize the nebula. Based on observations made at Laboratório Nacional de Astrofísica, Ministério da Ciência e Tecnologia, Brazil.

  15. A compact planetary nebula around the hot white dwarf EGB 6/PG 0950 + 139

    NASA Technical Reports Server (NTRS)

    Liebert, James; Green, Richard; Bond, Howard E.; Holberg, J. B.; Wesemael, F.

    1989-01-01

    The remarkable central star (0950 + 139), a very hot DA/DAO white dwarf, of the planetary nebula EGB 6 is described. Follow-up observations relevant to the analyses of both the nebula and the stellar photosphere are presented. Three kinds of scenarios are discussed to account for the existence of this peculiar nebula, but none appears very promising. The first consideration is that the nebula was ejected from the white dwarf as a discret event. This hypothesis is heavily constrained by the nebular size, density, and expansion rate; by the low luminosity and radius of the star; and by the absence of evidence for variation in density-sensitive forbidden lines from 1978 to 1987. No plausible mechanism can cause the observed amount of mass to be lost directly from a white dwarf in a steady or sporadic wind, at outflow velocities orders of magnitude below the escape velocity. Final consideration is given to the possibility that the gas is lost from a close companion star, but there is no evidence that this is a close binary system.

  16. The disappearance of eclipses in the central star of the planetary nebula NGC 2346

    NASA Astrophysics Data System (ADS)

    Hao, Xiang-Liang

    1991-12-01

    Results are presented from photographic observations carried out between 1981 and 1987 of the central star in the NGC 2346 planetary nebula, the AGK -0 deg 695 star. It was found that, starting at the end of 1981, there occurred several large-amplitude eclipses which continued for several years, after which the amplitude began to decrease rapidly, from about 4 mag in 1984 to about 1.1 mag in 1986, and was finally reduced to about 0.4-mag fluctuations in 1987. It is suggested that the cause of the unexpected eclipses in NGC 2346 was an ejection of matter from hot regions of the surface of the sdO star. As the ejected matter encountered the cold cloud around the nebula, it was cooled to dust particles, forming an optically thick cloudlets spread over the binary orbit.

  17. C/O and N/O ratios in planetary nebulae with [WC] central stars

    NASA Astrophysics Data System (ADS)

    García-Rojas, J.; Peña, M.; Delgado-Inglada, G.; García-Hernández, D. A.; Morisset, C.

    2014-04-01

    Planetary nebulae (PNe) around [WR] central stars (WRPNe) constitute a particular photoionized nebula class, representing about 10-15% of the PNe with known progenitor. We have studied 14 of them, detecting a large number of optical recombination lines (ORLs) from different ions of O and C (O+, O++, C++, C+3). This allows us to determine the C/O ratio, which is of paramount importance to constraint stellar evolution models. We have compared the obtained N/O and C/O ratios obtained with those derived from stellar evolution models, and we estimate that about half of our PNe have progenitors with initial masses similar to or larger than 4 Msun . These results are consistent with the results obtained from an independent analysis by Górny & García-Hernández (2014).

  18. Modelling the 3D morphology and proper motions of the planetary nebula NGC 6302

    NASA Astrophysics Data System (ADS)

    Uscanga, L.; Velázquez, P. F.; Esquivel, A.; Raga, A. C.; Boumis, P.; Cantó, J.

    2014-08-01

    We present 3D hydrodynamical simulations of an isotropic fast wind interacting with a previously ejected toroidally shaped slow wind in order to model both the observed morphology and the kinematics of the planetary nebula (PN) NGC 6302. This source, also known as the Butterfly nebula, presents one of the most complex morphologies ever observed in PNe. From our numerical simulations, we have obtained an intensity map for the Hα emission to make a comparison with the Hubble Space Telescope (HST) observations of this object. We have also carried out a proper motion (PM) study from our numerical results, in order to compare with previous observational studies. We have found that the two interacting stellar wind model reproduce well the morphology of NGC 6302, and while the PMs in the models are similar to the observations, our results suggest that an acceleration mechanism is needed to explain the Hubble-type expansion found in HST observations.

  19. Nebular and auroral emission lines of [Cl iii] in the optical spectra of planetary nebulae

    PubMed Central

    Keenan, Francis P.; Aller, Lawrence H.; Ramsbottom, Catherine A.; Bell, Kenneth L.; Crawford, Fergal L.; Hyung, Siek

    2000-01-01

    Electron impact excitation rates in Cl III, recently determined with the R-matrix code, are used to calculate electron temperature (Te) and density (Ne) emission line ratios involving both the nebular (5517.7, 5537.9 Å) and auroral (8433.9, 8480.9, 8500.0 Å) transitions. A comparison of these results with observational data for a sample of planetary nebulae, obtained with the Hamilton Echelle Spectrograph on the 3-m Shane Telescope, reveals that the R1 = I(5518 Å)/I(5538 Å) intensity ratio provides estimates of Ne in excellent agreement with the values derived from other line ratios in the echelle spectra. This agreement indicates that R1 is a reliable density diagnostic for planetary nebulae, and it also provides observational support for the accuracy of the atomic data adopted in the line ratio calculations. However the [Cl iii] 8433.9 Å line is found to be frequently blended with a weak telluric emission feature, although in those instances when the [Cl iii] intensity may be reliably measured, it provides accurate determinations of Te when ratioed against the sum of the 5518 and 5538 Å line fluxes. Similarly, the 8500.0 Å line, previously believed to be free of contamination by the Earth's atmosphere, is also shown to be generally blended with a weak telluric emission feature. The [Cl iii] transition at 8480.9 Å is found to be blended with the He i 8480.7 Å line, except in planetary nebulae that show a relatively weak He i spectrum, where it also provides reliable estimates of Te when ratioed against the nebular lines. Finally, the diagnostic potential of the near-UV [Cl iii] lines at 3344 and 3354 Å is briefly discussed. PMID:10759562

  20. Ionized gas and planetary nebulae in the bulge of the blue S0 galaxy NGC 5102

    NASA Technical Reports Server (NTRS)

    Mcmillan, Russet; Ciardullo, Robin; Jacoby, George H.

    1994-01-01

    We present the results of an investigation into the morphology and dynamics of ionized gas in the bulge of the gas-rich S0 galaxy NGC 5102. We show that the bulge of NGC 5102 contains a ring of ionized gas, approximately 1.3 kpc in diameter, which is centered well away from the nucleus. Through spectroscopy and (O III) lambda-5007 imaging, we show that the gas is excited by a low-velocity shock, which varies from approximately 50 to approximately 70 km/s along the ring. Fabry-Perot images in H-alpha confirm that the gas is moving slowly, and suggest that the structure is a supershell, approximately 10(exp 7) yr old. This age is significantly younger than the galaxy's nuclear starburst, which is approximately 2 x 10(exp 8) yr old. We also use our (O III) lambda-5007 images to identify planetary nebulae (PNs) in the bulge and inner disk of NGC 5102. Using the planetary nebula luminosity function, we derive a distance modulus to the galaxy of (m - M)(sub 0) = 27.47(sup +0.18)(sub -0.27), or 3.1(sup +0.3)(sub -0.4) Mpc, confirming its membership in the NGC 5128 group. Our derived value of 47.2(sup +12.2)(sub -9.2) x 10(exp -9) for the bolometric luminosity-specific PN density, alpha(sub 2.5), is higher than that observed for the bulge of M31 or the giant ellipticals of the Virgo Cluster, but not significantly different from that found for the small, normal ellipticals NGC 3377 or M32. The high value for alpha(sub 2.5) suggests that virtually all of NGC 5102's stars will someday evolve through the planetary nebula stage.

  1. Ionized gas and planetary nebulae in the bulge of the blue S0 galaxy NGC 5102

    NASA Astrophysics Data System (ADS)

    McMillan, R.; Ciardullo, R.; Jacoby, G. H.

    1994-11-01

    We present the results of an investigation into the morphology and dynamics of ionized gas in the bulge of the gas-rich S0 galaxy NGC 5102. We show that the bulge of NGC 5102 contains a ring of ionized gas, approximately 1.3 kpc in diameter, which is centered well away from the nucleus. Through spectroscopy and (O III) lambda-5007 imaging, we show that the gas is excited by a low-velocity shock, which varies from approximately 50 to approximately 70 km/s along the ring. Fabry-Perot images in H-alpha confirm that the gas is moving slowly, and suggest that the structure is a supershell, approximately 107 yr old. This age is significantly younger than the galaxy's nuclear starburst, which is approximately 2 x 108 yr old. We also use our (O III) lambda-5007 images to identify planetary nebulae (PNs) in the bulge and inner disk of NGC 5102. Using the planetary nebula luminosity function, we derive a distance modulus to the galaxy of (m - M)0 = 27.47+0.18-0.27, or 3.1+0.3-0.4 Mpc, confirming its membership in the NGC 5128 group. Our derived value of 47.2+12.2-9.2 x 10-9 for the bolometric luminosity-specific PN density, alpha2.5, is higher than that observed for the bulge of M31 or the giant ellipticals of the Virgo Cluster, but not significantly different from that found for the small, normal ellipticals NGC 3377 or M32. The high value for alpha2.5 suggests that virtually all of NGC 5102's stars will someday evolve through the planetary nebula stage.

  2. Nebular and auroral emission lines of [Cl III] in the optical spectra of planetary nebulae.

    PubMed

    Keenan, F P; Aller, L H; Ramsbottom, C A; Bell, K L; Crawford, F L; Hyung, S

    2000-04-25

    Electron impact excitation rates in Cl III, recently determined with the R-matrix code, are used to calculate electron temperature (T(e)) and density (N(e)) emission line ratios involving both the nebular (5517.7, 5537.9 A) and auroral (8433.9, 8480.9, 8500.0 A) transitions. A comparison of these results with observational data for a sample of planetary nebulae, obtained with the Hamilton Echelle Spectrograph on the 3-m Shane Telescope, reveals that the R(1) = I(5518 A)/I(5538 A) intensity ratio provides estimates of N(e) in excellent agreement with the values derived from other line ratios in the echelle spectra. This agreement indicates that R(1) is a reliable density diagnostic for planetary nebulae, and it also provides observational support for the accuracy of the atomic data adopted in the line ratio calculations. However the [Cl iii] 8433.9 A line is found to be frequently blended with a weak telluric emission feature, although in those instances when the [Cl iii] intensity may be reliably measured, it provides accurate determinations of T(e) when ratioed against the sum of the 5518 and 5538 A line fluxes. Similarly, the 8500.0 A line, previously believed to be free of contamination by the Earth's atmosphere, is also shown to be generally blended with a weak telluric emission feature. The [Cl iii] transition at 8480.9 A is found to be blended with the He i 8480.7 A line, except in planetary nebulae that show a relatively weak He i spectrum, where it also provides reliable estimates of T(e) when ratioed against the nebular lines. Finally, the diagnostic potential of the near-UV [Cl iii] lines at 3344 and 3354 A is briefly discussed. PMID:10759562

  3. The Transformation of an AGB Star to a Planetary Nebula: How the Journey Begins

    NASA Astrophysics Data System (ADS)

    Sahai, Raghvendra; Blumenfeld, C.; Morris, M.; S'anchez Contreras, C.; Claussen, M.

    2010-01-01

    We report the results from an HST imaging survey of a sample of late AGB stars with a detected history of extensive past mass-loss, i.e., those in which this process has now come to an end. The goal of this survey is to identify and characterise the earliest stages of the process that transforms these objects, first into bipolar or multipolar pre-planetary nebulae (PPNe), and then into similarly-shaped planetary nebulae. Since the cessation of mass-loss leads to the lack of hot dust close to the star, their thermal emission at short ( 25 micron) wavelengths, is expected to be lower than that for typical AGB stars. We have therefore used the IRAS 25 to 12 micron flux ratio, F25/F12 > 0.33 (but < 0.67 in order to exclude PPNe), to select a list of 60 such ``nascent pre-planetary nebulae" (or nPPNe); 48 were imaged in our SNAPshot imaging program. We found compact, but non-stellar, morphologies in about a quarter of our observed sample. The remaining objects are either unresolved, or only marginally resolved. Aspherical structure is seen in the resolved objects. The aspherical structure in nPPNe is different from that observed in PPNe, which generally show limb-brightened, roughly equal-sized lobes on both sides of the center. In contrast, only one-sided structures are seen in our survey nPPNe. In some objects, a diffuse, round, halo is also seen, representing the undisturbed AGB mass-loss envelope. A few sources show discrete circular (partial) arc-like features. The discovery of the one-side collimated features, together with detailed earlier studies of a few nPPNe (e.g. V Hya, IRC+10216), supports the hypothesis that the mechanism for creating the large-scale density inhomogeneties are high velocity outflows carving the AGB mass-loss envelope from the inside out.

  4. A Search for Gas-Phase Zirconium in s-process Enriched Planetary Nebulae

    NASA Astrophysics Data System (ADS)

    Dinerstein, Harriet L.; Lacy, J. H.; Sellgren, K.; Sterling, N. C.

    2006-12-01

    We report results from a search for the ground-state fine-structure line of triply ionized zirconium (Zr) near 8 microns, for several planetary nebulae known to have enhanced abundances of other light neutron-capture elements. The observations were made with the high spectral resolution mid-IR spectrometer TEXES (Lacy et al. 2002, PASP, 114, 153) on the IRTF. Zr, atomic number Z = 40, is part of the “light s-process” peak of nuclei which are synthesized in the region between the H and He-burning shells within AGB stars and mixed into the stellar envelope by dredge-up processes before expulsion of a planetary nebula. The targets included objects for which we have demonstrated that Ge (Z = 32) is enhanced by up to a factor of 5 (Sterling et al. 2005, ApJ, 625, 368), and Kr (Z = 36) is enhanced by factors of up to 10 (Sterling et al. 2006, submitted; Sterling & Dinerstein, in preparation). According to both evolutionary models and observations of Galactic S-type stars, Zr can be even more highly enriched than Ge or Kr, with enrichment factors of up to 20 30 (Busso et al. 2001, ApJ, 557, 802; Vanture & Wallerstein 2002, ApJ, 564, 397). If Zr is present primarily in gaseous form in these planetary nebulae, our failure to detect the mid-IR Zr line sets constraints on a combination of the initial mass of the progenitor stars and the details of the s-process and convective mixing. An alternate interpretation is that much of the Zr, a highly refractory element, is locked up in dust grains that formed in the AGB star’s atmosphere before or during envelope ejection. This research was supported by NSF grants AST 97-31156 and 04-06809.

  5. Detection of the Carbon Monoxide Ion (CO+) in the Interstellar Medium and a Planetary Nebula

    NASA Technical Reports Server (NTRS)

    Latter, William B.; Walker, Christopher K.; Maloney, Philip R.

    1993-01-01

    We report detection of the carbon monoxide ion (CO+) in the interstellar medium (Ml7SW) and a planetary nebula (NGC 7027). These detections are based on observations of three millimeter and submillimeter transitions in M17SW and one in NGC 7027. Chemical models suggest that CO+ should be most abundant where complex molecules are least likely to be present. In our search for CO+ we therefore minimized the chance of confusion while maximizing the probability of detection by observing regions whose chemistry is dominated by the effects of ultraviolet radiation.

  6. A Survey for hot Central Stars of Planetary Nebulae I. Methods and First Results

    NASA Astrophysics Data System (ADS)

    Kanarek, Graham C.; Shara, Michael M.; Faherty, Jacqueline K.; Zurek, David; Moffat, Anthony F. J.

    2016-03-01

    We present the results of initial spectrographic followup with the Very Large Telescope (UT3, Melipal) for Ks ≥ 14 Galactic plane C IV emission-line candidates in the near-infrared (NIR). These 7 faint stars all display prominent He I and/or C IV emission lines characteristic of a carbon-rich Wolf-Rayet star. They have NIR colours which are much too blue to be those of distant, classical WR stars. The magnitudes and colours are compatible with those expected for central stars of planetary nebulae, and are likely to come from massive progenitor populations. Our survey has identified thousands of such candidates.

  7. Planetary nebulae in the NGC 3379 group - Testing a new standard candle

    NASA Astrophysics Data System (ADS)

    Ciardullo, Robin; Jacoby, George H.; Ford, Holland C.

    The forbidden O III 5007 A planetary nebula luminosity function (PNLF) of three early type galaxies in the Leo Cloud are compared and used to estimate distances. The shape of the PNLF, in particular the sharp bright end cutoff, is found to be the same in each galaxy and identical to that observed in M31, implying that this shape is universal and an excellent standard candle. From maximum likelihood analyses, the most probable distances to NGC 3377, NGC 3379, and NGC 3384 are 9.7, 9.1, and 9.4 Mpc, respectively, with 1 sigma errors of about 12 percent.

  8. The stellar seismology of hot white dwarfs and planetary nebula nuclei

    NASA Technical Reports Server (NTRS)

    Kawaler, Steven D.

    1987-01-01

    The pulsation properties of hot white dwarfs make it possible to determine their mass, surface composition, rotation, and rate of evolution, and provide constraints on their internal structure. Period spacings are sensitive measures of stellar mass and indicate surface layer structure. Measurement of the rate of period change for these stars provide a way to determine their cooling rates. Attention is also given to how well (or poorly) models of excitation of the pulsations fit within current models of planetary nebula nuclei and hot white dwarfs.

  9. The hydrodynamics of aspherical planetary nebulae. II - Numerical modelling of the early evolution

    NASA Astrophysics Data System (ADS)

    Icke, Vincent; Balick, Bruce; Frank, Adam

    1992-01-01

    Initial results are presented from numerical hydrodynamic calculations of the early evolution of aspherical planetary nebulae. It is found that the interacting winds produce the customary triple discontinuity, and that the outer shock's morphology conforms with remarkable fidelity to the analytic expectations. The inner shock develops in transient fashion, due to a reflection off the equatorial belt in which the shock deflects and focuses the fast wind. The shapes of the contact discontinuity and the flow behind the leading shock indicate two qualitatively distinct patterns.

  10. Forbidden O II studies of galactic planetary nebulae and extragalactic H II complexes

    NASA Astrophysics Data System (ADS)

    Odell, C. R.; Castaneda, H. O.

    1984-08-01

    The 3727-A doublet ratio of forbidden O II was observed in five planetary nebulae and nine extragalactic groupings of H II regions (H II Complexes). The theoretical relation between this doublet ratio and nebular density was rederived using the most up-to-date atomic parameters, permitting columnar densities to be determined for all objects. The structure of extragalactic H II Complexes is discussed, and a preferred model advanced. A new method of distance determination for extragalactic systems is proposed and evaluated in the context of the presently available data.

  11. Nebular kinematics of planetary nebulae as tests of possible differences of distribution of permitted and forbidden emission lines

    NASA Astrophysics Data System (ADS)

    Torres-Peimbert, S.; Arrieta, A.; Georgiev, L.; Richer, M.

    2009-05-01

    In gaseous nebulae the abundances of heavy elements derived from recombination lines are systematically higher than those derived from collisionally excited lines. The possible explanations to obtain compatible solutions are: either to attribute the difference to the presence of temperature inhomogeneities or to the presence of dense clumps of colder enriched material. We have obtained long slit echelle spectrograms in several planetary nebulae to try to shed light on this topic. We present preliminary results for NGC 6543.

  12. STARING INTO THE WINDS OF DESTRUCTION: HST/NICMOS IMAGES OF THE PLANETARY NEBULA NGC 7027

    NASA Technical Reports Server (NTRS)

    2002-01-01

    The Hubble Space Telescope's Near Infrared Camera and Multi-Object Spectrometer (NICMOS) has captured a glimpse of a brief stage in the burnout of NGC 7027, a medium-mass star like our sun. The infrared image (on the left) shows a young planetary nebula in a state of rapid transition. This image alone reveals important new information. When astronomers combine this photo with an earlier image taken in visible light, they have a more complete picture of the final stages of star life. NGC 7027 is going through spectacular death throes as it evolves into what astronomers call a 'planetary nebula.' The term planetary nebula came about not because of any real association with planets, but because in early telescopes these objects resembled the disks of planets. A star can become a planetary nebula after it depletes its nuclear fuel - hydrogen and helium - and begins puffing away layers of material. The material settles into a wind of gas and dust blowing away from the dying star. This NICMOS image captures the young planetary nebula in the middle of a very short evolutionary phase, lasting perhaps less than 1,000 years. During this phase, intense ultraviolet radiation from the central star lights up a region of gas surrounding it. (This gas is glowing brightly because it has been made very hot by the star's intense ultraviolet radiation.) Encircling this hot gas is a cloud of dust and cool molecular hydrogen gas that can only be seen by an infrared camera. The molecular gas is being destroyed by ultraviolet light from the central star. THE INFRARED VIEW -- The composite color image of NGC 7027 (on the left) is among the first data of a planetary nebula taken with NICMOS. This picture is actually composed of three separate images taken at different wavelengths. The red color represents cool molecular hydrogen gas, the most abundant gas in the universe. The image reveals the central star, which is difficult to see in images taken with visible light. Surrounding it is an

  13. On the terminal velocities of winds in central stars of planetary nebulae

    NASA Technical Reports Server (NTRS)

    Heap, Sara R.

    1986-01-01

    The theory of radiatively driven stellar winds is applied to the central stars of planetary nebulae, and the predicted relation between escape velocity and terminal velocity of the wind is assessed. Ultraviolet spectra obtained with IUE indicate that the terminal velocities of winds from planetary nuclei, which range from 600 to 3600 km/sec, are strongly correlated with stellar temperature. The theory of radiative winds predicts that the terminal velocity of the wind = T(1.2), the constant of proportionality being a function of stellar mass and line-force parameter, alpha. Given a mass of 0.60 solar mass for central stars with winds, the line-force parameter alpha = 0.70, a value higher than Abbott's predictions, alpha = 0.61 (1982).

  14. Large planetary nebulae and their significance to the late stages of stellar evolution

    NASA Technical Reports Server (NTRS)

    Kaler, James B.; Shaw, Richard A.; Kwitter, Karen B.

    1990-01-01

    Spectrophotometry of 75 large PNe with Shklovsky radii greater than 0.15 pc is presented and used to calculate nebular parameters and compositions, stellar Zanstra temperatures and luminosities, and core masses. Nine new Peimbert type I nebulae are identified. About 40 percent of the stars that are on cooling tracks are above 0.7 solar mass, and over 15 percent are above 0.8 solar mass. The large planetaries demonstrate a clear positive correlation between nitrogen enrichment and core mass. N/O is anticorrelated with O/H. The radii of the nebulae whose stars lie along specific cooling tracks increase monotonically with decreasing central star temperature. For a given central temperature, the nebular radii also increase with increasing core mass, showing that in this part of the log L-log T plane the higher mass cores evolve more slowly in agreement with theoretical prediction. However, theoretical evolutionary rates for the large nebulae stars appear to be much too slow.

  15. Abundances in planetary nebulae: NGC 1535, NGC 6629, He2-108, and Tc1

    NASA Astrophysics Data System (ADS)

    Pottasch, S. R.; Surendiranath, R.; Bernard-Salas, J.

    2011-07-01

    Context. Models have been made of stars of a given mass that produce planetary nebulae that usually begin on the AGB (although they may begin earlier) and run to the white dwarf stage. While these models cover the so-called dredge-up phases when nuclear reactions occur and the newly formed products are brought to the surface, it is important to compare the abundances predicted by the models with the abundances actually observed in PNe. Aims: The aim of the paper is to determine the abundances in a group of PNe with uniform morphological and kinematic properties. The PNe we discuss are circular with rather low-temperature central stars and are rather far from the galactic plane. We discuss the effect these abundances have on determining the evolution of the central stars of these PNe. Methods: The mid-infrared spectra of the planetary nebulae NGC 1535, NGC 6629, He2-108, and Tc1 (IC 1266) taken with the Spitzer Space Telescope are presented. These spectra were combined with the ultraviolet IUE spectra and with the spectra in the visual wavelength region to obtain complete, extinction-corrected spectra. The chemical composition of these nebulae is then found by directly calculating and adding individual ion abundances. For two of these PNe, we attempted to reproduce the observed spectrum by making a model nebula. This proved impossible for one of the nebulae and the reason for this is discussed. The resulting abundances are more accurate than earlier studies for several reasons, the most important is that inclusion of the far infrared spectra increases the number of observed ions and makes it possible to include the nebular temperature gradient in the abundance calculations. Results: The abundances of the above four PNe have been determined and compared to the abundances found in five other PNe with similar properties studied earlier. These abundances are further compared with values predicted by the models of Karakas (2003). From this comparison we conclude that the

  16. A model of the planetary nebula NGC 2392 determined from velocity observations

    NASA Technical Reports Server (NTRS)

    Odell, C. R.; Ball, M. E.

    1985-01-01

    High-resolution slit spectra are combined with published photometric and velocity data to develop a model of the double-ring planetary nebula NGC 2392. The inner ring is due to an incomplete, prolate spheroid shell with most of the material concentrated near the minor axis circumference. The spheroid is seen almost pole-on, open at the sharp ends, and the formal velocity of expansion (93 km/s) at the ends is a record high for planetary nebulae. The outer ring is a nearly round spheroid of approximately 16 km/s expansion velocity and a different tilt angle than the inner shell. It is surrounded by rapidly expanding material with velocities of at least 75 km/s. A high-velocity stream of material is formed at the open ends of the inner shell and is accelerated by the central star's stellar wind to velocities of at least + or - 190 km/s, providing the first direct evidence for the kinematic role of a strong stellar wind. The inner shell age is approximately 800 yr, arguing that the shell material was preferentially ejected from the equator of the parent star, in contradiction with the usual predictions of theory.

  17. Chemical Abundances of the Planetary Nebula IC 4634 and Its Central Star

    NASA Technical Reports Server (NTRS)

    Hyung, S.; Aller, L. H.; Feibelman, W. A.

    1999-01-01

    We have measured the spectral line intensities of the metal poor planetary nebula IC 4634. Using a photo-ionization model calculation, we try to fit the the optical and UV region spectra, i.e., Hamilton Echelle and IUE observations. From direct images, one expects complicated density variations, but the model predicts a range in densities that may be smaller than actually exist. We find N(sub epsilon) approximates 5000 /cubic meter. In spite of the geometrical complexity of the S shaped double-lobed structure, the simple photoionization model with a spherical symmetry can fit most emission lines, fairly well. The derived chemical composition has been compared with previous estimates and also with the Sun - The metallicity in IC 4634 appears to be lower than in the Sun or the average planetary nebula. The most likely temperature of the central ionizing source of IC 4634 appears to be about 55,000 K. We find a central star mass of about 0.55 Solar Mass from comparison with theoretical evolutionary tracks.

  18. Abundances of Planetary Nebulae in the Outer Disk of M31

    NASA Astrophysics Data System (ADS)

    Kwitter, Karen B.; Lehman, Emma M. M.; Balick, Bruce; Henry, R. B. C.

    2012-07-01

    We present spectroscopic observations and chemical abundances of 16 planetary nebulae (PNe) in the outer disk of M31. The [O III] λ4363 line is detected in all objects, allowing a direct measurement of the nebular temperature essential for accurate abundance determinations. Our results show that the abundances in these M31 PNe display the same correlations and general behaviors as Type II PNe in the Milky Way. We also calculate photoionization models to derive estimates of central star properties. From these we infer that our sample PNe, all near the bright-end cutoff of the planetary nebula luminosity function, originated from stars near 2 M ⊙. Finally, under the assumption that these PNe are located in M31's disk, we plot the oxygen abundance gradient, which appears shallower than the gradient in the Milky Way. Partially based on observations obtained with the Apache Point Observatory 3.5 m telescope, which is owned and operated by the Astrophysical Research Consortium; and on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the Science and Technology Facilities Council (United Kingdom), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), Ministerio da Ciencia e Tecnologia (Brazil), and Ministerio de Ciencia, Tecnología e Innovación Productiva (Argentina).

  19. A Detailed Investigation into the Use of Planetary Nebulae as Standard Candles

    NASA Technical Reports Server (NTRS)

    Ciardullo, Robin

    2000-01-01

    The program's goal was to understand the physics underlying the [O III] (lambda)5007 planetary nebula luminosity function (PNLF) and evaluate its accuracy as an extragalactic distance indicator. Work under the grant concentrated in two areas. The first major goal was to extensively test the PNLF method to find its limits. We did this performing yet another internal test of the method in the core galaxies of the Fornax Cluster, performing external comparisons of PNLF distances with distances derived from Cepheids and the Surface Brightness Fluctuation method (SBF), and, in general, examining the PNLF in as many different galactic environments as possible, including the disks of late-type spirals. Because of the difficulty distinguishing planetary nebulae (PNe) from H II regions, and because spiral galaxies have uneven internal extinction, the process of identifying "statistical" samples of PNe in these objects is extremely complicated. Nevertheless, by using the ratio of [O III] (lambda)5007 to H(alpha) as a diagnostic, we were able to effectively discriminate PNe from most H II regions, and apply the method to systems such as NGC 300, M101, M51, and M96. The second goal of this research was to determine theoretically, why the PNLF is such an excellent standard candle.

  20. The discovery and characterisation of binary central stars in planetary nebulae

    NASA Astrophysics Data System (ADS)

    Jones, David

    2016-07-01

    Close binary central stars of planetary nebulae are key in constraining the poorly- understood common-envelope phase of evolution, which in turn is critical in understanding the formation of a wide-range of astrophysical phenomena (including cataclysmic variables, low-mass X-ray binaries and supernovae type Ia). Here, I present the results of our on-going, targeted search for close-binaries in planetary nebulae which has led to the discovery of more than ten new central binaries in just the last few years (almost the same as the total discovered during the 1980s and 1990s together). This success has been rooted in the targeted selection of objects for study, based on morphological features deemed typical of binarity, as well as novel observing strategies (including the employment of narrow-band filters for photometry to minimise nebular contamination), both of which are discussed. These new discoveries coupled with the painstaking characterisation of both newly discovered systems and those from the literature mean that we are now in a position to begin to probe the poorly understood common-envelope phase.

  1. YOUNG PLANETARY NEBULAE: HUBBLE SPACE TELESCOPE IMAGING AND A NEW MORPHOLOGICAL CLASSIFICATION SYSTEM

    SciTech Connect

    Sahai, Raghvendra; Villar, Gregory G.; Morris, Mark R.

    2011-04-15

    Using Hubble Space Telescope images of 119 young planetary nebulae (PNs), most of which have not previously been published, we have devised a comprehensive morphological classification system for these objects. This system generalizes a recently devised system for pre-planetary nebulae, which are the immediate progenitors of PNs. Unlike previous classification studies, we have focused primarily on young PNs rather than all PNs, because the former best show the influences or symmetries imposed on them by the dominant physical processes operating at the first and primary stage of the shaping process. Older PNs develop instabilities, interact with the ambient interstellar medium, and are subject to the passage of photoionization fronts, all of which obscure the underlying symmetries and geometries imposed early on. Our classification system is designed to suffer minimal prejudice regarding the underlying physical causes of the different shapes and structures seen in our PN sample, however, in many cases, physical causes are readily suggested by the geometry, along with the kinematics that have been measured in some systems. Secondary characteristics in our system, such as ansae, indicate the impact of a jet upon a slower-moving, prior wind; a waist is the signature of a strong equatorial concentration of matter, whether it be outflowing or in a bound Keplerian disk, and point symmetry indicates a secular trend, presumably precession, in the orientation of the central driver of a rapid, collimated outflow.

  2. Pulsational variability in proto-planetary nebulae and other post-AGB objects

    NASA Astrophysics Data System (ADS)

    Hrivnak, Bruce J.

    2016-07-01

    Light and velocity curves of several classes of pulsating stars have been successfully modeled to determine physical properties of the stars. In this observational study, we review briefly the pulsational variability of the main classes of post-AGB stars. Our attention is focused in particular on proto-planetary nebulae (PPNe), those in the short-lived phase from AGB stars to the planetary nebulae. New light curves and period analyses have been used to determine the following general properties of the PPNe variability: (a) periods range from 35 to 160 days for those of F—G spectral types, with much shorter periods (< 1 day) found for those of early-B spectral type; (b) there is a correlation between the pulsation period, maximum amplitude, and temperature of the star, with cooler stars pulsating with longer periods and larger amplitudes; (c) similar correlations are found for carbon-rich, oxygen-rich, and lower-metalicity PPNe; and (d) multiple periods are found for all of them, with P2/P1 = 1.0±0.1. New models are needed to exploit these results.

  3. Two-temperature X-ray emission from the planetary nebula NGC 7293

    NASA Technical Reports Server (NTRS)

    Leahy, D. A.; Zhang, C. Y.; Kwok, Sun

    1994-01-01

    ROSAT Position Sensitive Proportional Counter (PSPC) observations of the planetary nebula NGC are reported here. This planetary nebula is here the first discovered to show clearly two components in its X-ray spectrum. A two-component model consisting of a blackbody and a Raymond-Smith thermal plasma is fitted to the observed ROSAT PSPC spectrum. This results in a temperature of T(sub 1) = 1.4 x 10(exp 5) K for the blackbody component and a temperature T(sub 2) = 8.7 x 10(exp 6) K for the hot plasma component, at a hydrogen column density N(sub H) = 1.4 x 10(exp 20)/sq cm. The temperature of the blackbody component is consistent with the helium Zanstra temperature of the central star, indicating that it may be attributed to the photosphere of the central star. The high-temperature component is possibly from a corona around the central star, which may be related to a strong convection in the star. An alternative explanation is that the hot plasma resides in a hot bubble predicted by the interacting wind model. A lower limit of the electron density in the hot plasma is found to be approximately 10/cu cm.

  4. Constraining Engine Paradigms of Pre-Planetary Nebulae Using Kinematic Properties of their Outflows

    NASA Astrophysics Data System (ADS)

    Blackman, E.

    2014-04-01

    Binary interactions and accretion plausibly conspire to produce the ubiquitous collimated outflows from planetary nebulae (PN) and their presumed pre-planetary nebulae (PPN) progenitors. But which accretion engines are viable? The difficulty in observationally resolving the engines warrants indirect constraints. I discuss how momentum outflow data for PPN can be used to determine the minimum required accretion rate for presumed main sequence (MS) or white dwarf (WD) accretors by comparing to several example accretion rates inferred from published models. While the main goal is to show the method in anticipation of more data and better theoretical constraints, taking the present results at face value already rule out modes of accretion: Bondi-Hoyle Lyttleton (BHL) wind accretion and wind Roche lobe overflow (M-WRLOF, based on Mira parameters) are too feeble for all 19/19 objects for a MS accretor. For a WD accretor, BHL is ruled out for 18/19 objects and M-WRLOF for 15/19 objects. Roche lobe overflow from the primary can accommodate 7/19 objects but only common envelope evolution accretion modes seem to be able to accommodate all 19 objects. Sub-Eddington rates for a MS accretor are acceptable but 8/19 would require super-Eddington rates for a WD. I also briefly discuss a possible anti-correlation between age and maximum observed outflow speed, and the role of magnetic fields.

  5. The double-degenerate, super-Chandrasekhar nucleus of the planetary nebula Henize 2-428.

    PubMed

    Santander-García, M; Rodríguez-Gil, P; Corradi, R L M; Jones, D; Miszalski, B; Boffin, H M J; Rubio-Díez, M M; Kotze, M M

    2015-03-01

    The planetary nebula stage is the ultimate fate of stars with masses one to eight times that of the Sun (M(⊙)). The origin of their complex morphologies is poorly understood, although several mechanisms involving binary interaction have been proposed. In close binary systems, the orbital separation is short enough for the primary star to overfill its Roche lobe as the star expands during the asymptotic giant branch phase. The excess gas eventually forms a common envelope surrounding both stars. Drag forces then result in the envelope being ejected into a bipolar planetary nebula whose equator is coincident with the orbital plane of the system. Systems in which both stars have ejected their envelopes and are evolving towards the white dwarf stage are said to be double degenerate. Here we report that Henize 2-428 has a double-degenerate core with a combined mass of ∼1.76M(⊙), which is above the Chandrasekhar limit (the maximum mass of a stable white dwarf) of 1.4M(⊙). This, together with its short orbital period (4.2 hours), suggests that the system should merge in 700 million years, triggering a type Ia supernova event. This supports the hypothesis of the double-degenerate, super-Chandrasekhar evolutionary pathway for the formation of type Ia supernovae. PMID:25686608

  6. A kinematic study of planetary nebulae in the dwarf irregular galaxy IC10

    NASA Astrophysics Data System (ADS)

    Gonçalves, Denise R.; Teodorescu, Ana M.; Alves-Brito, Alan; Méndez, Roberto H.; Magrini, Laura

    2012-10-01

    We present positions, kinematics and the planetary nebula luminosity function (PNLF) for 35 planetary nebulae (PNe) in the nearest starburst galaxy IC10 extending out to 3 kpc from the galaxy's centre. We take advantage of the deep imaging and spectroscopic capabilities provided by the Faint Object Camera and Spectrograph on the 8.2 m Subaru Telescope. The PN velocities were measured through the slitless-spectroscopy technique, which allows us to explore the kinematics of IC10 with high precision. Using these velocities, we conclude that there is a kinematic connection between the H I envelope located around IC10 and the galaxy's PN population. By assuming that the PNe in the central regions and in the outskirts have similar ages, our results put strong observational constraints on the past tidal interactions in the Local Group. This is so because by dating the PN central stars, we, therefore, infer the epoch of a major episode of star formation likely linked to the first encounter of the H I extended envelope with the galaxy. Our deep [O III] images also allow us to use the PNLF to estimate a distance modulus of 24.1 ± 0.25, which is in agreement with recent results in the literature based on other techniques. Based on data collected at the Subaru Telescope, which is operated by the National Astronomical Observatory of Japan.

  7. Detection of the NE III 36 micron forbidden line in the planetary nebula NGC 6543

    NASA Astrophysics Data System (ADS)

    Shure, M. A.; Houck, J. R.; Gull, G. E.; Herter, T.

    1984-06-01

    The first observation of the Ne III 36.02 micron forbidden line in a planetary nebula, NGC 6543, is presented. Since the dominant form of neon in medium-excitation to high-excitation planetary nebulae is Ne III, the abundance of this ion is important in determining the total neon abundance. Use of the 36 micron line for an abundance determination has the advantage of insensitivity to temperature uncertainties. However, current atomic parameters lead to a Ne III abundance in NGC 6543 which is 4.5 times the cosmic neon abundance and 2.6 times the abundance from optical line studies. Although such a high abundance cannot be ruled out immediately, inaccuracies in the infrared level collision strengths are suspected because resonances were neglected in their calculation. The 36 micron line is also useful as a temperature probe when combined with the Ne III 3868-A forbidden line. When compared to Ne III 15.56 micron forbidden line fluxes, a temperature-insensitive density estimate may be obtained. The utility of these line ratios depends upon the actual infrared level collision strengths, which will affect the density range over which they are sensitive.

  8. Discovery of a [WO] central star in the planetary nebula Th 2-A

    NASA Astrophysics Data System (ADS)

    Weidmann, W. A.; Gamen, R.; Díaz, R. J.; Niemela, V. S.

    2008-09-01

    Context: About 2500 planetary nebulae are known in our Galaxy but only 224 have central stars with reported spectral types in the Strasbourg-ESO Catalogue of Galactic Planetary Nebulae (Acker et al. 1992; Acker et al. 1996). Aims: We have started an observational program aiming to increase the number of PN central stars with spectral classification. Methods: By means of spectroscopy and high resolution imaging, we identify the position and true nature of the central star. We carried out low resolution spectroscopic observations at CASLEO telescope, complemented with medium resolution spectroscopy performed at Gemini South and Magellan telescopes. Results: As a first outcome of this survey, we present for the first time the spectra of the central star of the PN Th 2-A. These spectra show emission lines of ionized C and O, typical in Wolf-Rayet stars. Conclusions: We identify the position of that central star, which is not the brightest one of the visual central pair. We classify it as of type [WO 3]pec, which is consistent with the high excitation and dynamical age of the nebula. Based on data collected at (i) the Complejo Astronómico El Leoncito (CASLEO), which is operated under agreement between the Consejo Nacional de Investigaciones Científicas y Técnicas de la República Argentina y Universidades Nacionales de La Plata, Córdoba y San Juan, Argentina; (ii) the 6.5 m Magellan Telescopes at Las Campanas Observatory, Chile; (iii) the 8 m Gemini South Telescope, Chile.

  9. A disc inside the bipolar planetary nebula M2-9

    NASA Astrophysics Data System (ADS)

    Lykou, F.; Chesneau, O.; Zijlstra, A. A.; Castro-Carrizo, A.; Lagadec, E.; Balick, B.; Smith, N.

    2011-03-01

    Aims: Bipolarity in proto-planetary and planetary nebulae is associated with events occurring in or around their cores. Past infrared observations have revealed the presence of dusty structures around the cores, many in the form of discs. Characterising those dusty discs provides invaluable constraints on the physical processes that govern the final mass expulsion of intermediate mass stars. We focus this study on the famous M2-9 bipolar nebula, where the moving lighthouse beam pattern indicates the presence of a wide binary. The compact and dense dusty core in the centre of the nebula can be studied by means of optical interferometry. Methods: M2-9 was observed with VLTI/MIDI at 39-47 m baselines with the UT2-UT3 and UT3-UT4 baseline configurations. These observations are interpreted using a dust radiative transfer Monte Carlo code. Results: A disc-like structure is detected perpendicular to the lobes, and a good fit is found with a stratified disc model composed of amorphous silicates. The disc is compact, 25 × 35 mas at 8 μm and 37 × 46 mas at 13 μm. For the adopted distance of 1.2 kpc, the inner rim of the disc is ~15 AU. The mass represents a few percent of the mass found in the lobes. The compactness of the disc puts strong constraints on the binary content of the system, given an estimated orbital period 90-120 yr. We derive masses of the binary components between 0.6-1.0 M⊙ for a white dwarf and 0.6-1.4 M⊙ for an evolved star. We present different scenarios on the geometric structure of the disc accounting for the interactions of the binary system, which includes an accretion disc as well. Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere, Chile, ESO N: 079.D-146.

  10. The evolution of planetary nebulae. V. The diffuse X-ray emission

    NASA Astrophysics Data System (ADS)

    Steffen, M.; Schönberner, D.; Warmuth, A.

    2008-10-01

    Context: Observations with space-borne X-ray telescopes revealed the existence of soft, diffuse X-ray emission from the inner regions of planetary nebulae. Although the existing images support the idea that this emission arises from the hot shocked central-star wind which fills the inner cavity of a planetary nebula, existing models have difficulties to explain the observations consistently. Aims: We investigate how the inclusion of thermal conduction changes the physical parameters of the hot shocked wind gas and the amount of X-ray emission predicted by time-dependent hydrodynamical models of planetary nebulae with central stars of normal, hydrogen-rich surface composition. Methods: We upgraded our 1D hydrodynamics code NEBEL by to account for energy transfer due to heat conduction, which is of importance at the interface separating the hot shocked wind gas (“hot bubble”) from the much cooler nebular material. With this new version of NEBEL we recomputed a selection of our already existing hydrodynamical sequences and obtained synthetic X-ray spectra for representative models along the evolutionary tracks by means of the freely available CHIANTI package. Results: Heat conduction leads to lower temperatures and higher densities within a bubble and brings the physical properties of the X-ray emitting domain into close agreement with the values derived from observations. The amount of X-rays emitted during the course of evolution depends on the energy dumped into the bubble by the fast stellar wind, on the efficiency of “evaporating” cool nebular gas via heat conduction, and on the bubble's expansion rate. We find from our models that the X-ray luminosity of a planetary nebula increases during its evolution across the HR diagram until stellar luminosity and wind power decline. Depending on the central-star mass and the evolutionary phase, our models predict X-ray [ 0.45-2.5 keV] luminosities between 10-8 and 10-4 of the stellar bolometric luminosities, in

  11. Bubbles and Knots in the Kinematical Structure of the Bipolar Planetary Nebula NGC 2818

    NASA Astrophysics Data System (ADS)

    Vázquez, Roberto

    2012-06-01

    High-resolution Hubble Space Telescope archive imaging and high-dispersion spectroscopy are used to study the complex morphological and kinematical structure of the planetary nebula, NGC 2818. We analyze narrowband Hα, [O III], [N II], [S II], and He II images, addressing important morphological features. Ground-based long-slit echelle spectra were obtained crossing NGC 2818 at five different positions to precisely determine kinematical features in the structure of the nebula. A distance of 2.5 kpc was used to determine physical scales. Constructing models to fit the data with modern computational tools, we find NGC 2818 is composed of (1) a non-uniform bipolar structure with a semimajor axis of 0.92 pc (75''), possibly deformed by the stellar wind, (2) a 0.17 pc (14'') diameter central region, which is potentially the remnant of an equatorial enhancement, and (3) a great number of cometary knots. These knots are preferentially located inside a radius of 0.24 pc (20'') around the central star. The major axis of the main structure is oriented at i ~= 60° with respect to the line of sight and at P.A. = +89° on the plane of the sky. Expansion velocities of this nebula are V pol = 105 km s-1 and V eq = 20 km s-1, which lead to our estimate of the kinematical age of τk ~= 8400 ± 3400 yr (assuming homologous expansion). Our observations do not support the idea that high-velocity collimated ejections are responsible for the formation of microstructures inside the nebula. We determine the systemic velocity of NGC 2818 to be V HEL = +26 ± 2 km s-1.

  12. BUBBLES AND KNOTS IN THE KINEMATICAL STRUCTURE OF THE BIPOLAR PLANETARY NEBULA NGC 2818

    SciTech Connect

    Vazquez, Roberto

    2012-06-01

    High-resolution Hubble Space Telescope archive imaging and high-dispersion spectroscopy are used to study the complex morphological and kinematical structure of the planetary nebula, NGC 2818. We analyze narrowband H{alpha}, [O III], [N II], [S II], and He II images, addressing important morphological features. Ground-based long-slit echelle spectra were obtained crossing NGC 2818 at five different positions to precisely determine kinematical features in the structure of the nebula. A distance of 2.5 kpc was used to determine physical scales. Constructing models to fit the data with modern computational tools, we find NGC 2818 is composed of (1) a non-uniform bipolar structure with a semimajor axis of 0.92 pc (75''), possibly deformed by the stellar wind, (2) a 0.17 pc (14'') diameter central region, which is potentially the remnant of an equatorial enhancement, and (3) a great number of cometary knots. These knots are preferentially located inside a radius of 0.24 pc (20'') around the central star. The major axis of the main structure is oriented at i {approx_equal} 60 Degree-Sign with respect to the line of sight and at P.A. = +89 Degree-Sign on the plane of the sky. Expansion velocities of this nebula are V{sub pol} = 105 km s{sup -1} and V{sub eq} = 20 km s{sup -1}, which lead to our estimate of the kinematical age of {tau}{sub k} {approx_equal} 8400 {+-} 3400 yr (assuming homologous expansion). Our observations do not support the idea that high-velocity collimated ejections are responsible for the formation of microstructures inside the nebula. We determine the systemic velocity of NGC 2818 to be V{sub HEL} = +26 {+-} 2 km s{sup -1}.

  13. When Asymmetric Cosmic Bubbles Betray a Difficult Marriage: the Study of Binary Central Stars of Planetary Nebulae

    NASA Astrophysics Data System (ADS)

    Boffin, H. M. J.; Miszalski, B.

    2011-09-01

    Planetary Nebulae represent a powerful window into the evolution of low-intermediate mass stars that have undergone extensive mass-loss. The nebula manifests itself in an extremely wide variety of shapes, but exactly how the mass lost is shaped into such a diverse range of morphologies is still highly uncertain despite over thirty years of vigorous debate. Binaries have long been thought to offer a solution to this vexing problem. Now, thanks to recent surveys and improved observing strategies, it appears clearly that a binary channel, in particular common-envelope (CE) evolution, is responsible for a large fraction of planetary nebulae. Moreover, as planetary nebulae are just “fresh out of the oven” compared to other post-CE systems, they provide invaluable contributions to the study of common-envelope evolution and to the formation of jets in binary systems. Our studies have also started to identify strong links between binarity and morphology, including a high proportion of bipolar nebulae and rings of low ionisation filaments resembling SN 1987A. Equally important are the newly found binary CSPN with intermediate periods, which appear linked to chemically peculiar stars whose composition was modified by binary evolution. Their study may also reveal much information on mass and angular momentum transfer processes in binary stars. Here we show examples of four PNe for which we have discovered their binary nature, including the discovery of a rare case of a barium-rich cool central star.

  14. Post Asymptotic Giant Branch and Central Stars of Planetary Nebulae in the Galactic Halo

    NASA Astrophysics Data System (ADS)

    Weston, Simon

    2012-01-01

    Post asymptotic giant branch (post-AGB) stars, central stars of planetary nebulae (CSPNe) and planetary nebulae (PNe) are important phases of stellar evolution as the material they feedback is the seed of subsequent star formation in a galaxy. The majority of low and intermediate mass stars are expected to evolve through these channels, however, it is uncertain how many actually do, and at what rate. The Galactic halo, with its older population, provides a direct test of evolutionary models for low mass stars. Birthrate estimates of PNe are uncertain and worse still, are in contradiction with accepted white dwarf (WD) birthrate estimates. Much of the uncertainty stems from the lack of complete samples and poorly determined distance estimates. New surveys such as the Sloan Digital Sky Survey (SDSS), Galaxy Evolutionary Explorer (GALEX) and the INT Photometric Ha Survey (IPHAS) have discovered many new PNe and have observed the far edges of the Galaxy. Improved methods of determining distances to CSPNe are presented here, using model atmospheres, evolutionary tracks and high resolution reddening maps utilising these revolutionary surveys. Locating the CSPN is non-trivial particularly for evolved PNe, as they are extended with their central star often displaced from the centre of the nebula. Therefore, photometric criteria are required to locate the CSPN in the nebula's field. Synthetic photometry of the CSPNe is derived from spectral energy distributions (SEDs) computed from a grid of model atmospheres covering the parameter range of CSPNe. The SEDs are convolved with filter transmission curves to compute synthetic magnitudes for a given photometric system which are then calibrated with standard stars and WDs. A further project borne out of a search for luminous central stars of faint PNe, resulted in a systematic search for post-AGB stars in the Galactic halo. In this work, new candidate halo post-AGB stars are discovered from a search through the SDSS spectroscopic

  15. Narrowband Near-Infrared Imaging of Young Planetary Nebulae and Transition Objects: Probing Core and Halo Structures

    NASA Technical Reports Server (NTRS)

    Hora, Joseph L.; Latter, William B.

    1997-01-01

    The new images presented here have high spatial resolution and are very sensitive to low levels of emission. We compare our new data to existing imaging and spectroscopic data to give clues as to the structure and formation of planetary nebulae, the role of shocks, and the evolution of photon-dominated regions.

  16. Planetary Accretion in the Inner Solar System: Dependence on Nebula Surface Density Profile and Giant Planet Eccentricities

    NASA Technical Reports Server (NTRS)

    Chambers, J. E.; Cassen, P.

    2002-01-01

    We present 32 N-body simulations of planetary accretion in the inner Solar System, examining the effect of nebula surface density profile and initial eccentricities of Jupiter and Saturn on the compositions and orbits of the inner planets. Additional information is contained in the original extended abstract.

  17. X-RAY EMISSION FROM THE BINARY CENTRAL STARS OF THE PLANETARY NEBULAE HFG 1, DS 1, AND LOTR 5

    SciTech Connect

    Montez, Rodolfo; Kastner, Joel H.; De Marco, Orsola; Chu, You-Hua

    2010-10-01

    Close binary systems undergoing mass transfer or common envelope interactions can account for the morphological properties of some planetary nebulae. The search for close binary companions in planetary nebulae is hindered by the difficulty of detecting cool, late-type, main-sequence companions in binary systems with hot pre-white-dwarf primaries. However, models of binary planetary nebula progenitor systems predict that mass accretion or tidal interactions can induce rapid rotation in the companion, leading to X-ray-emitting coronae. To test such models, we have searched for, and detected, X-ray emission from three binary central stars within planetary nebulae: the post-common envelope close binaries in HFG 1 and DS 1 consisting of O-type subdwarfs with late-type, main-sequence companions and the binary system in LoTr 5 consisting of O-type subdwarf and rapidly rotating, late-type giant companion. The X-ray emission in each case is best characterized by spectral models consisting of two optically thin thermal plasma components with characteristic temperatures of {approx}10 MK and 15-40 MK and total X-ray luminosities {approx}10{sup 30} erg s{sup -1}. We consider the possible origin of the X-ray emission from these binary systems and conclude that the most likely origin is, in each case, a corona around the late-type companion, as predicted by models of interacting binaries.

  18. Forbidden lines of (O I) in the high-resolution optical spectra of planetary nebulae

    NASA Astrophysics Data System (ADS)

    Keenan, F. P.; Aller, L. H.; Hyung, S.; Brown, P. J. F.

    1995-02-01

    Electron impact excitation rates for transitions in O I, calculated with the R-matrix code, are used to derive the electron-temperature sensitive emission-line ratio R = I(2s22p4 (1D) -2s22p4 1S/2s22p4 (3P)1,2-2s22p4 1D = I(5577 A)/I(6300+6365 A), for a range of electron temperatures Te = 5000-20 000 K) and densities (ne = 104 - 106/cu cm) applicable to planetary nebulae. Experimental values of R for a number of planetaries have been measured from high-resolution (approximately 0.6 A FWHM) spectra obtained with the Hamilton Echelle spectrograph on the 3-m telescope at the Lick Observatory. These measurements should be particularly reliable, as the sample of planetaries was restricted to those with large enough radial velocities for the nebular (O I) 5577 A emission to be red- or blue-shifted from the atmospheric airglow feature by a sufficient amount for the former to be reliably determined. Electron temperatures deduced from the observed values of R are generally in good agreement with those derived from Te-sensitive line ratios in other species, providing observational support for the accuracy of the atomic data adopted in the calculations.

  19. DETECTION OF THE CENTRAL STAR OF THE PLANETARY NEBULA NGC 6302

    SciTech Connect

    Szyszka, C.; Walsh, J. R.; Zijlstra, Albert A.; Tsamis, Y. G.

    2009-12-10

    NGC 6302 is one of the highest ionization planetary nebulae (PNe) known and shows emission from species with ionization potential > 300 eV. The temperature of the central star must be > 200,000 K to photoionize the nebula, and has been suggested to be up to approx400,000 K. On account of the dense dust and molecular disk, the central star has not convincingly been directly imaged until now. NGC 6302 was imaged in six narrowband filters by Wide Field Camera 3 on the Hubble Space Telescope as part of the Servicing Mission 4 Early Release Observations. The central star is directly detected for the first time, and is situated at the nebula center on the foreground side of the tilted equatorial disk. The magnitudes of the central star have been reliably measured in two filters (F469N and F673N). Assuming a hot blackbody, the reddening has been measured from the (4688-6766 A) color and a value of c = 3.1, A{sub v} = 6.6 mag determined. A G-K main-sequence binary companion can be excluded. The position of the star on the H-R diagram suggests a fairly massive PN central star of about 0.64 M {sub sun} close to the white dwarf cooling track. A fit to the evolutionary tracks for (T, L, t) = (200,000 K, 2000 L {sub sun}, 2200 yr), where t is the nebular age, is obtained; however, the luminosity and temperature remain uncertain. The model tracks predict that the star is rapidly evolving, and fading at a rate of almost 1% per year. Future observations could test this prediction.

  20. Hu 1-2: a metal-poor bipolar planetary nebula with fast collimated outflows

    NASA Astrophysics Data System (ADS)

    Fang, X.; Guerrero, M. A.; Miranda, L. F.; Riera, A.; Velázquez, P. F.; Raga, A. C.

    2015-09-01

    We present narrow-band optical and near-IR imaging and optical long-slit spectroscopic observations of Hu 1-2, a Galactic planetary nebula (PN) with a pair of [N II]-bright, fast-moving (>340 km s-1) bipolar knots. Intermediate-dispersion spectra are used to derive physical conditions and abundances across the nebula, and high-dispersion spectra to study the spatio-kinematical structure. Generally, Hu 1-2 has high He/H (≈0.14) and N/O ratios (≈0.9), typical of Type I PNe. On the other hand, its abundances of O, Ne, S, and Ar are low as compared with the average abundances of Galactic bulge and disc PNe. The position-velocity maps can be generally described as an hour-glass shaped nebula with bipolar expansion, although the morphology and kinematics of the innermost regions cannot be satisfactorily explained with a simple, tilted equatorial torus. The spatio-kinematical study confines the inclination angle of its major axis to be within 10° of the plane of sky. As in the irradiated bow-shocks of IC 4634 and NGC 7009, there is a clear stratification in the emission peaks of [O III], Hα, and [N II] in the north-west (NW) knot of Hu 1-2. Fast collimated outflows in PNe exhibit higher excitation than other low-ionization structures. This is particularly the case for the bipolar knots of Hu 1-2, with He II emission levels above those of collimated outflows in other Galactic PNe. The excitation of the knots in Hu 1-2 is consistent with the combined effects of shocks and UV radiation from the central star. The mechanical energy and luminosity of the knots are similar to those observed in the PNe known to harbour a post-common envelope (post-CE) close binary central star.

  1. Ultraviolet Fe VII absorption and Fe II emission lines of central stars of planetary nebulae

    NASA Technical Reports Server (NTRS)

    Cheng, Kwang-Ping; Feibelman, Walter A.; Bruhweiler, Frederick C.

    1991-01-01

    The SWP camera of the IUE satellite was used in the high-dispersion mode to search for Fe VII absorption and Fe II high-excitation emission lines in five additional very hot central stars of planetary nebulae. Some of the Fe VII lines were detected at 1208, 1239, and 1332 A in all the objects of this program, LT 5, NGC 6058, NGC 7094, A43, and Lo 1 (= K1-26), as well as some of the Fe II emission lines at A 1360, 1776, 1869, 1881, 1884, and 1975 A. Two additional objects, NGC 2867 and He 2-131, were obtained from the IUE archive and were evaluated. The present study probably exhausts the list of candidates that are sufficiently bright and hot to be reached with the high-dispersion mode of the IUE.

  2. A molecular line survey of a sample of AGB stars and planetary nebulae

    NASA Astrophysics Data System (ADS)

    Smith, C. L.; Zijlstra, A. A.; Fuller, G. A.

    2015-11-01

    A millimeter molecular line survey of three carbon-rich asymptotic giant branch stars and two oxygen-rich planetary nebulae has been carried out over the frequency range 80.5-115.5 GHz. 68 different transitions were detected in the data from 27 different molecular species. The hyperfine structure of C2H and C13CH has been fitted to constrain the optical depth of their transitions. All other transitions have been constrained on the basis of their line profile shapes. Rotation temperatures and column densities have been calculated for all possible species, with adaptations to the methods applied in order to account for the hyperfine structure of various transitions. From the column densities, carbon, silicon and sulphur isotopic ratios have been determined. The results corroborate IRAS 15194-5115 as a J-type star, whilst excluding IRAS 15082-4808 and IRAS 07454-7112 as such.

  3. Infrared dust features of late-type stars and planetary nebulae

    NASA Technical Reports Server (NTRS)

    Glaccum, W.

    1995-01-01

    The author presents 16-65 micron spectra of late-type stars and proto-planetary nebulae (PPN) obtained with the Goddard 24-channel spectrophotometer from the Kuiper Airborne Observatory (KAO). The spectra of these objects contain most of the 9-13 known dust features, all discovered from the KAO, at wavelengths greater than 22 microns. The 8-100 micron spectra of a few representative objects are modeled with simple grains selected from a wide range of candidate solids. Hot sapphire is the most likely source of the 13 micron feature found in some M and MS star. Likely candidates for other features include ice, sulfides, and crystalline silicates. Also presented is a review of grain candidate materials for which optical properties in the far infrared have been measured, and a list of those for which measurements are needed.

  4. AKARI/IRC Near-infrared Spectral Atlas of Galactic Planetary Nebulae

    NASA Astrophysics Data System (ADS)

    Ohsawa, Ryou; Onaka, Takashi; Sakon, Itsuki; Matsuura, Mikako; Kaneda, Hidehiro

    2016-04-01

    Near-infrared (2.5-5.0 μm) low-resolution (λ/Δλ ˜ 100) spectra of 72 Galactic planetary nebulae (PNe) were obtained with the Infrared Camera (IRC) in the post-helium phase. The IRC, equipped with a 1‧ × 1‧ window for spectroscopy of a point source, was capable of obtaining near-infrared spectra in a slit-less mode without any flux loss due to a slit. The spectra show emission features including hydrogen recombination lines and the 3.3-3.5 μm hydrocarbon features. The intensity and equivalent width of the emission features were measured by spectral fitting. We made a catalog providing unique information on the investigation of the near-infrared emission of PNe. In this paper, details of the observations and characteristics of the catalog are described.

  5. GT2_ncox_1: Faint Extended Dust Envelopes of Young Planetary Nebulae

    NASA Astrophysics Data System (ADS)

    Cox, N.

    2011-05-01

    We propose to trace the distribution of cold dust in the extended envelopes of a selected sample of young Planetary Nebulae (PNe). Information on the mass-loss and overall envelope ejection process of Asymptotic Giant Branch (AGB) stars is imprinted in the morphology of the extended dust shells formed throughout the AGB phase. In particular the origin of asymmetrical PN shapes and their relation to spherical mass-loss presumed to occur on the AGB phase can be illuminated upon. We propose to use PACS to follow-up on AKARI/FIS observations of young PNe to study their mass-loss history. Only Herschel's unprecedented spatial resolution and sensitivity in the far-IR can detect the faint extended cold dust emission in these objects.

  6. Upper limits to the magnetic field in central stars of planetary nebulae

    SciTech Connect

    Asensio Ramos, A.; Martínez González, M. J.; Manso Sainz, R.; Corradi, R. L. M.; Leone, F.

    2014-06-01

    More than about 20 central stars of planetary nebulae (CSPNs) have been observed spectropolarimetrically, yet no clear, unambiguous signal of the presence of a magnetic field in these objects has been found. We perform a statistical (Bayesian) analysis of all the available spectropolarimetric observations of CSPN to constrain the magnetic fields in these objects. Assuming that the stellar field is dipolar and that the dipole axis of the objects is oriented randomly (isotropically), we find that the dipole magnetic field strength is smaller than 400 G with 95% probability using all available observations. The analysis introduced allows integration of future observations to further constrain the parameters of the distribution, and it is general, so that it can be easily applied to other classes of magnetic objects. We propose several ways to improve the upper limits found here.

  7. Hubble space telescope observations and geometric models of compact multipolar planetary nebulae

    SciTech Connect

    Hsia, Chih-Hao; Chau, Wayne; Zhang, Yong; Kwok, Sun E-mail: wwlljj1314@gmail.com E-mail: sunkwok@hku.hk

    2014-05-20

    We report high angular resolution Hubble Space Telescope observations of 10 compact planetary nebulae (PNs). Many interesting internal structures, including multipolar lobes, arcs, two-dimensional rings, tori, and halos, are revealed for the first time. These results suggest that multipolar structures are common among PNs, and these structures develop early in their evolution. From three-dimensional geometric models, we have determined the intrinsic dimensions of the lobes. Assuming the lobes are the result of interactions between later-developed fast winds and previously ejected asymptotic giant branch winds, the geometric structures of these PNs suggest that there are multiple phases of fast winds separated by temporal variations and/or directional changes. A scenario of evolution from lobe-dominated to cavity-dominated stages is presented. The results reported here will provide serious constraints on any dynamical models of PNs.

  8. International ultraviolet explorer spectral atlas of planetary nebulae, central stars, and related objects

    NASA Technical Reports Server (NTRS)

    Feibelman, Walter A.; Oliversen, Nancy A.; Nicholsbohlin, Joy; Garhart, Matthew P.

    1988-01-01

    The International Ultraviolet Explorer (IUE) archives contain a wealth of information on high quality ultraviolet spectra of approximately 180 planetary nebulae, their central stars, and related objects. Selected are representative low-dispersion IUE spectra in the range 1200 to 3200 A for 177 objects arranged by Right Ascension (RA) for this atlas. For most entries, the combined short wavelength (SWP) (1200to 1900) and long wavelength (LWR) (or LWP, 1900 to 3200 A) regions are shown on 30 cm by 10 cm Calcomp plots on a uniform scale to facilitate intercomparison of the spectra. Each calibrated spectrum is also shown on an expanded vertical scale to bring out some of the weaker features.

  9. Determination of hyperfine-induced transition rates from observations of a planetary nebula.

    PubMed

    Brage, Tomas; Judge, Philip G; Proffitt, Charles R

    2002-12-31

    Observations of the planetary nebula NGC3918 made with the STIS instrument on the Hubble Space Telescope reveal the first unambiguous detection of a hyperfine-induced transition 2s2p 3P(o)(0)-->2s2 1S0 in the berylliumlike emission line spectrum of N IV at 1487.89 A. A nebular model allows us to confirm a transition rate of 4x10(-4) sec(-1)+/-33% for this line. The measurement represents the first independent confirmation of the transition rate of hyperfine-induced lines in low ionization stages, and it provides support for the techniques used to compute these transitions for the determination of very low densities and isotope ratios. PMID:12513129

  10. Planetary Nebulae from the AKARI Far-IR All-Sky Maps

    NASA Astrophysics Data System (ADS)

    Ueta, T.; Fullard, A.; Tomasino, R. L.

    2015-12-01

    The far-IR all-sky mapping data obtained by the AKARI Astronomical Satellite were released to the public in January 2015. These maps are expected to provide us with further insights into our understanding of the far-IR universe for the first time since IRAS, especially for extended objects. While the AKARI far-IR all-sky maps are calibrated against the diffuse background emission and a flux correction scheme for point sources is provided, it is not necessarily obvious how one flux-corrects extended sources. Here, we briefly summarize a new flux-correction method for extended objects detected in the AKARI far-IR all-sky maps and its application to planetary nebulae.

  11. HASH: the Hong Kong/AAO/Strasbourg Hα planetary nebula database

    NASA Astrophysics Data System (ADS)

    Parker, Quentin A.; Bojičić, Ivan S.; Frew, David J.

    2016-07-01

    By incorporating our major recent discoveries with re-measured and verified contents of existing catalogues we provide, for the first time, an accessible, reliable, on-line SQL database for essential, up-to date information for all known Galactic planetary nebulae (PNe). We have attempted to: i) reliably remove PN mimics/false ID's that have biased previous studies and ii) provide accurate positions, sizes, morphologies, multi-wavelength imagery and spectroscopy. We also provide a link to CDS/Vizier for the archival history of each object and other valuable links to external data. With the HASH interface, users can sift, select, browse, collate, investigate, download and visualise the entire currently known Galactic PNe diversity. HASH provides the community with the most complete and reliable data with which to undertake new science.

  12. Any Density Changes Near the Inner Shell of the Planetary Nebula NGC 6803?

    NASA Astrophysics Data System (ADS)

    Lee, Seong-Jae; Hyung, S.

    2013-06-01

    Most recent high dispersion spectral data, secured at Lick Observatory in 1995 and 2001, suggested a large density increase near the inner shell boundary of the elliptical ring planetary nebula NGC 6803, e.g., Ne = 8900 (10^3.95) --> 14,400 (10^4.16)/cm^3 in [Ar IV] (Lee and Hyung 2013). We further analyzed high dispersion spectroscopic data observed in 2012 February with the Bohyunsan fiber-fed echelle spectrograph (BOES) attached to the Bohyunsan Observatory 1.8m telescope. The BOES diagnostic line ratios indicate a large change between 2001 & 2012 observations; -0.23, +0.39, +0.13, -0.28 dex for [S II], [O II], [N II], and [Cl III], respectively. For example, the 2012 BOES [Ar IV] line ratio implies a decreasing density of N=11,700 (10^4.07)/cm^3. We discuss the changes of physical conditions and kinematics of NGC 6803.

  13. Probing the dynamics of elliptical galaxies by planetary nebulae in the framework of MOdified Newtonian Dynamics

    NASA Astrophysics Data System (ADS)

    Tian, Yong; Ko, Chung-Ming

    2015-08-01

    Planetary nebulae (PNe) at large distances from the centre of a galaxy provide us a tool to study its dynamics there. Romanowsky et al. (2003) reported the dynamics of three luminous elliptical galaxies up to 6 effective radii, and all of them can be explained by Newtonian dynamics without dark matter. Milgrom & Sanders (2003) deem that the result can be understood in the framework of MOND (MOdified Newtonian dynamics). We revisit this problem as more measurements are available in the past decade. In this contribution, we present our result on 7 elliptical galaxies with PNe data up to 6-8 effective radii and also stellar data from SAURON. We conclude that MOND can well explain the dynamics of all these galaxies.

  14. The spectrum of the central star of the planetary nebula in M22

    NASA Technical Reports Server (NTRS)

    Harrington, J. P.; Paltoglou, George

    1993-01-01

    New optical observations of the central star of the planetary nebula IRAS 18333-2357 in the globular cluster M22 show lines of H I, He II, C IV, N IV, and N V. The spectrum closely resembles the sdO star KS 292, which has surface abundances enhanced by products of hydrogen shell burning and helium burning, and an effective temperature of 75,000 K. The lines of C in IRAS 18333-2357 seem somewhat stronger than in KS 292, and the lines of N are considerably stronger. The presence of substantial hydrogen is surprising in view of the hydrogen-poor nature of the nebular ejecta. If IRAS 18333-2357 is as hot as its analog, its luminosity is about 14,000 lunar luminosity. This value is higher than that theoretically expected for single-star evolution of M22 cluster stars.

  15. Formation and Evolution of Binary Planetary Nebula Nuclei and Related Objects

    NASA Astrophysics Data System (ADS)

    Iben, Icko, Jr.; Tutukov, Alexander V.

    1993-11-01

    A study is made of the evolution of close binaries in which the primary first fills its Roche lobe after the exhaustion of helium at its center and before the onset of thermal pulses. Initial masses are in the range 3-6 M0. Also examined is the evolution of a 1 Msun model which fills its Roche lobe on the first giant branch when the mass of its helium degenerate core reaches 0.4 M0. In all cases, a common envelope scenario is assumed, and mass is removed from the model primary on a timescale shorter than the initial thermal timescale of the envelope of the primary until the model contracts within a final Roche lobe of predetermined size. After the removal of the common envelope, systems are very close binaries in which the evolved remnant has either a carbon-oxygen (CO) core and a helium-burning shell (progenitor of mass 2.3-8 Msun) or a helium core and a hydrogen-burning shell (progenitor of mass 1-2.3 Msun). The more massive remnants fill their Roche lobes for an extended period, transferring first hydrogen-rich material at a rate ˜10-8±1 Msun yr-1 for up to 106 yr, and then helium at a rate ˜10-6±1 Msun yr-1 for (1-4) × 105 yr. As much as ˜0.4 Msun of nearly pure helium can be transferred to an accretor. A possible real analog of the hydrogen-transferring models is U Sco, although, in many instances, a hydrogen-transferring episode may be bypassed or considerably shortened if the hot remnant blows a strong enough wind. Possible observational analogs of helium transferring models are bright ultrasoft X-ray sources like CAL 83 and CAL 87 in the Large Magellanic Cloud and some classes of supernova precursors. Our models help to explain the number and properties of hot helium OB subdwarfs. A method for estimating initial orbital periods of binary planetary nebula nuclei is introduced and used to infer the initial characteristics of binary systems which have produced close binary central stars, precataclysmic variables, and related systems. Using existing

  16. Fully relativistic study of forbidden transitions of OII : Electron density diagnosis for planetary nebulas

    NASA Astrophysics Data System (ADS)

    Chen, Shaohao; Qing, Bo; Li, Jiaming

    2007-10-01

    Using the multiconfiguration Dirac-Fock method, including the quantum electrodynamics corrections, especially with the Breit interactions, we calculate the electric quadrupole (E2) and magnetic dipole (M1) transition rates for the two transitions D5/2,3/2o2→S3/2o4 of OII . We show systematically that the correlation effects owing to core electron excitations and the Breit interactions are vitally important for the transition rates. We present a benchmark for the intensity ratio between the two transitions in the limit of high electron density in planetary nebulas, i.e., r(∞)=0.345-0.014+0.028 , which is in good agreement with modern astronomical observations.

  17. Fully relativistic study of forbidden transitions of O II: Electron density diagnosis for planetary nebulas

    SciTech Connect

    Chen Shaohao; Qing Bo; Li Jiaming

    2007-10-15

    Using the multiconfiguration Dirac-Fock method, including the quantum electrodynamics corrections, especially with the Breit interactions, we calculate the electric quadrupole (E2) and magnetic dipole (M1) transition rates for the two transitions {sup 2}D{sub 5/2,3/2}{sup o}{yields}{sup 4}S{sub 3/2}{sup o} of O II. We show systematically that the correlation effects owing to core electron excitations and the Breit interactions are vitally important for the transition rates. We present a benchmark for the intensity ratio between the two transitions in the limit of high electron density in planetary nebulas, i.e., r({infinity})=0.345{sub -0.014}{sup +0.028}, which is in good agreement with modern astronomical observations.

  18. Alternative methods for determination of the temperature of central stars of planetary nebulae

    NASA Astrophysics Data System (ADS)

    Elizalde, Flavio

    1992-03-01

    This work presents the formulation and application of three methods for determining the temperature of central stars in planetary nebulae. The methods are based on global spectroscopic indices for comparing objects with models. The spectroscopic data are taken from the literature, while models were calculated with the CLOUDY code. The three methods are: the Ir method compares the ratio of helium to hydrogen lines; the S-N1/2 method generalizes the energy balance method for different metalicity classes and different gas densities; the TIN method makes a direct comparison between the spectroscopic indices of the model and the object, minimizing their differences. In this method the chemical abundances of the main elements are calculated. The Ir method was applied to 78 objects; the S-N1/2 method was applied to 85 objects while the TIN method was used upon 8 nebulae. The results are discussed and compared to other determinations in the literature. One of the main conclusions is that only about half of the objects are optically thick. Finally, future developments and applications are suggested.

  19. Large Magellanic Cloud Planetary Nebula Morphology: Probing Stellar Populations and Evolution.

    PubMed

    Stanghellini; Shaw; Balick; Blades

    2000-05-10

    Planetary nebulae (PNe) in the Large Magellanic Cloud (LMC) offer the unique opportunity to study both the population and evolution of low- and intermediate-mass stars, by means of the morphological type of the nebula. Using observations from our LMC PN morphological survey, and including images available in the Hubble Space Telescope Data Archive and published chemical abundances, we find that asymmetry in PNe is strongly correlated with a younger stellar population, as indicated by the abundance of elements that are unaltered by stellar evolution (Ne, Ar, and S). While similar results have been obtained for Galactic PNe, this is the first demonstration of the relationship for extragalactic PNe. We also examine the relation between morphology and abundance of the products of stellar evolution. We found that asymmetric PNe have higher nitrogen and lower carbon abundances than symmetric PNe. Our two main results are broadly consistent with the predictions of stellar evolution if the progenitors of asymmetric PNe have on average larger masses than the progenitors of symmetric PNe. The results bear on the question of formation mechanisms for asymmetric PNe-specifically, that the genesis of PNe structure should relate strongly to the population type, and by inference the mass, of the progenitor star and less strongly on whether the central star is a member of a close binary system. PMID:10813674

  20. RESOLVING THE ELECTRON TEMPERATURE DISCREPANCIES IN H II REGIONS AND PLANETARY NEBULAE: {kappa}-DISTRIBUTED ELECTRONS

    SciTech Connect

    Nicholls, David C.; Dopita, Michael A.; Sutherland, Ralph S.

    2012-06-20

    The measurement of electron temperatures and metallicities in H II regions and planetary nebulae (PNe) has-for several decades-presented a problem: results obtained using different techniques disagree. What is worse, they disagree consistently. There have been numerous attempts to explain these discrepancies, but none has provided a satisfactory solution to the problem. In this paper, we explore the possibility that electrons in H II regions and PNe depart from a Maxwell-Boltzmann equilibrium energy distribution. We adopt a '{kappa}-distribution' for the electron energies. Such distributions are widely found in solar system plasmas, where they can be directly measured. This simple assumption is able to explain the temperature and metallicity discrepancies in H II regions and PNe arising from the different measurement techniques. We find that the energy distribution does not need to depart dramatically from an equilibrium distribution. From an examination of data from H II regions and PNe, it appears that {kappa} {approx}> 10 is sufficient to encompass nearly all objects. We argue that the kappa-distribution offers an important new insight into the physics of gaseous nebulae, both in the Milky Way and elsewhere, and one that promises significantly more accurate estimates of temperature and metallicity in these regions.

  1. COMPARING SHOCKS IN PLANETARY NEBULAE WITH THE SOLAR WIND TERMINATION SHOCK

    SciTech Connect

    Soker, Noam; Rahin, Roi; Behar, Ehud; Kastner, Joel H.

    2010-12-20

    We show that suprathermal particles, termed pick-up ions (PUIs), might reduce the postshock temperature of the fast wind and jets in some planetary nebulae (PNs) and in symbiotic systems. The goal is to explain the finding that the temperature of the 'hot bubble' formed by the postshock gas in some PNs and symbiotic nebulae is lower, sometimes by more than an order of magnitude, than the value expected from simple hydrodynamical calculations. Although various explanations have been proposed, there is as yet no preferred solution for this 'low temperature problem'. PUIs have been invoked to explain the low temperature behind the termination shock of the solar wind. While in the case of the solar wind the neutral atoms that turn into PUIs penetrate the preshock solar wind region from the interstellar medium, in PNs the PUI source is more likely slowly moving clumps embedded in the fast wind or jets. These clumps are formed by instabilities or from backflowing cold gas. Our estimates indicate that in young PNs these PUIs will thermalize before leaving the system. Only in older PNs whose sizes exceed {approx}5000 AU and for which the fast wind mass loss rate is M-dot{sub w{approx}}<10{sup -7} M-sun yr{sup -1} do we expect the PUIs to be an efficient carrier of energy out of the postshock region (the hot bubble).

  2. PLANETARY NEBULAE DETECTED IN THE SPITZER SPACE TELESCOPE GLIMPSE II LEGACY SURVEY

    SciTech Connect

    Zhang Yong; Sun Kwok E-mail: sunkwok@hku.h

    2009-11-20

    We report the result of a search for the infrared counterparts of 37 planetary nebulae (PNs) and PN candidates in the Spitzer Galactic Legacy Infrared Mid-Plane Survey Extraordinaire II (GLIMPSE II) survey. The photometry and images of these PNs at 3.6, 4.5, 5.8, 8.0, and 24 mum, taken through the Infrared Array Camera (IRAC) and the Multiband Imaging Photometer for Spitzer (MIPS), are presented. Most of these nebulae are very red and compact in the IRAC bands, and are found to be bright and extended in the 24 mum band. The infrared morphology of these objects are compared with Halpha images of the Macquarie-AAO-Strasbourg (MASH) and MASH II PNs. The implications for morphological difference in different wavelengths are discussed. The IRAC data allow us to differentiate between PNs and H II regions and be able to reject non-PNs from the optical catalog (e.g., PNG 352.1 - 00.0). Spectral energy distributions are constructed by combing the IRAC and MIPS data with existing near-, mid-, and far-IR photometry measurements. The anomalous colors of some objects allow us to infer the presence of aromatic emission bands. These multi-wavelength data provide useful insights into the nature of different nebular components contributing to the infrared emission of PNs.

  3. Interpretation of two compact planetary nebulae, IC 4997 and NGC 6572, with aid of theoretical models.

    PubMed

    Hyung, S; Aller, L H

    1993-01-15

    Observations of two dense compact planetary nebulae secured with the Hamilton Echelle spectrograph at Lick Observatory combined with previously published UV spectra secured with the International Ultraviolet Explorer enable us to probe the electron densities and temperatures (plasma diagnostics) and ionic concentrations in these objects. The diagnostic diagrams show that no homogenous model will work for these nebulae. NGC 6572 may consist of an inner torordal ring of density 25,000 atoms/cm3 and an outer conical shell of density 10,000 atoms/cm3. The simplest model of IC 4997 suggests a thick inner shell with a density of about 107 atoms/cm3 and an outer envelope of density 10,000 atoms/cm3. The abundances of all elements heavier than He appear to be less than the solar values in NGC 6572, whereas He, C, N, and O may be more abundant in IC 4997 than in the sun. IC 4997 presents puzzling problems. PMID:11607347

  4. FUSE Observations of Neutron-Capture Elements in Wolf-Rayet Planetary Nebulae

    NASA Astrophysics Data System (ADS)

    Dinerstein, H.

    We propose to obtain FUSE observations of planetary nebula central stars of the WC Wolf-Rayet ([WC]) class, in order to search for the products of neutron-capture processes in these stars and provide constraints on their evolutionary status. Although the origin of the [WC]'s is controversial, their H-deficient, C-rich surface compositions indicate that they have experienced a high degree of mixing and/or mass loss. Thus one might expect the nebulae they produce to show enhanced concentrations of He-burning and other nuclear products, such as nuclei produced by slow neutron capture during the AGB phase. We have already detected an absorption line from one such element, Germanium (Sterling, Dinerstein, & Bowers 2002), while conducting a search for H2 absorption from nebular molecular material FUSE GI programs A085 and B069). Since the strongest Ge enhancements were found in PNe with [WC] central stars, we propose to enlarge the sample of such objects observed by FUSE. THIS TEMPORARY AND PARTIAL SCRIPT COVERS ONE TARGET, HE 2-99, AND REQUESTS AN EXPOSURE TIME OF 15 KSEC. PHASE 2 INFORMATION FOR THE REMAINDER OF THE PROGRAM'S TOTAL TIME ALLOCATION OF 60 KSEC WILL BE SUBMITTED AT A LATER TIME.

  5. A catalog of planetary nebula candidates and HII regions in NGC 3109

    NASA Astrophysics Data System (ADS)

    Peña, M.; Richer, M. G.; Stasińska, G.

    2007-04-01

    Aims:Images obtained with the ESO VLT and FORS1 in [O iii] 5007 on- and off-band, as well as rGunn filters, are analyzed to search for planetary nebula (PN) candidates. Methods: In the continuum-subtracted [O iii] 5007 on-band images, a large number of emission-line regions were detected. We describe the criteria employed for distinguishing PN candidates from compact HII regions. Results: The most unambiguous discriminators for the two classes of nebulae are the sizes and properties of the ionizing stars. Based upon these criteria, we have found 20 PN candidates for which we present coordinates, nebular [O iii] fluxes, and stellar magnitudes. The cumulative luminosity function for these PNe is discussed. A catalog of HII regions listing coordinates, nebular [O iii] fluxes, stellar magnitudes, and other characteristics is also presented. We find that HII regions are rather concentrated towards the disk of the galaxy, while PNe are distributed also above and below this structure, consistent with their belonging to an older stellar population. Based on observations collected at the European Southern Observatory, VLT, Paranal, Chile, program ID 076.B-0166.

  6. Shaping the Red Rectangle Proto-planetary Nebula by a Precessing Jet

    NASA Astrophysics Data System (ADS)

    Velázquez, Pablo F.; Steffen, Wolfgang; Raga, Alejandro C.; Haro-Corzo, Sinhué; Esquivel, Alejandro; Cantó, Jorge; Riera, Angels

    2011-06-01

    We carried out three-dimensional hydrodynamical simulations (employing the YGUAZÚ-A code) of a precessing jet launched by a star in a binary system. Synthetic scattered light intensity maps were generated in order to compare them with images of the Red Rectangle proto-planetary nebula (PPN), which contains the binary system HD 44179. Our results show that the angular size, the global biconical or hourglass morphology, and the existence of its "ladder rungs" features can be explained in terms of a jet precessing with a period 20 times the orbital period of the HD 44179 system, a semi-angle of 30° (of the precession cone), and a velocity of 300 km s-1. In addition, we calculated the flux predicted from the models, which is of the same order of magnitude as the observed flux in the outer regions of the nebula. Finally, the orbital motion was found to have a negligible influence on the large-scale morphology of the PPN.

  7. Fast, Low-ionization Emission Regions of the Planetary Nebula M2-42

    NASA Astrophysics Data System (ADS)

    Danehkar, A.; Parker, Q. A.; Steffen, W.

    2016-02-01

    Spatially resolved observations of the planetary nebula M2-42 (PN G008.2-04.8) obtained with the Wide Field Spectrograph on the Australian National University 2.3 m telescope have revealed the remarkable features of bipolar collimated jets emerging from its main structure. Velocity-resolved channel maps derived from the [N ii] λ6584 emission line disentangle different morphological components of the nebula. This information is used to develop a three-dimensional morpho-kinematic model, which consists of an equatorial dense torus and a pair of asymmetric bipolar outflows. The expansion velocity of about 20 km s-1 is measured from the spectrum integrated over the main shell. However, the deprojected velocities of the jets are found to be in the range of 80-160 km s-1 with respect to the nebular center. It is found that the mean density of the collimated outflows, 595 ± 125 cm-3, is five times lower than that of the main shell, 3150 cm-3, whereas their singly ionized nitrogen and sulfur abundances are about three times higher than those determined from the dense shell. The results indicate that the features of the collimated jets are typical of fast, low-ionization emission regions.

  8. Molecular hydrogen maps of extended planetary nebulae - the Dumbbell, the Ring, and NGC 2346

    SciTech Connect

    Zuckerman, B.; Gatley, I.

    1988-01-01

    The 3.8-m United Kingdom Infrared Telecsope at Mauna Kea was used to obtain complete H2 maps of three extended planetary nebulae (PNs) that are representative of two of the most common PN morphologies, bow tie and bipolar ring: the Dumbbell (NGC 6853), the Ring (NGC 6720), and the NG 2346, are discussed. The results of map analysis indicates that the S(1) emission from H2 closely follows the optical morphology of the three nebulae. The H2 emission is more extended than the main emitting mass of ionized gas and, in NGCC 2346, there is evidence for a dense torus of hot H2 surrounding the central star. The H2 emissionl appears to be shock-excited. Examinations of existing H2 measurements indicate that strong H2 emission is preferentially present in PNs that lie at small galactic latitude, implying that massive main-sequence stars produce ionization-bounded PNs, whereas low-mass stars produce density-bounded PNs. Thus, maps of H2 emission may not only be used to determine whether a given PN is ionization-bounded or density-bounded, but also to estimate the mass of the progenitor star. 83 references.

  9. Chemical Abundances of Planetary Nebulae in the Bulge and Disk of M31

    NASA Technical Reports Server (NTRS)

    Jacoby, George H.; Ciardullo, Robin

    1998-01-01

    We derive abundances and central star parameters for 15 planetary nebulae (PNe) in M31: 12 in the bulge and 3 in a disk field 14 kpc from the nucleus. No single abundance value characterizes the bulge stars: although the median abundances of the sample are similar to those seen for PNe in the LMC, the distribution of abundances is several times broader, spanning over 1 decade. None of the PNe in our sample approach the super metal-rich ([Fe/H] approximately 0.25) expectations for the bulge of M31, although a few PNe in the sample of Stasinska, Richer, & Mc Call (1998) come close. This [O/H] vs [Fe/H] discrepancy is likely due to a combination of factors, including an inability of metal-rich stars to produce bright PNe, a luminosity selection effect, and an abundance gradient in the bulge of M31. We show that PNe that are near the bright limit of the [O III] lambda.5007 planetary nebula luminosity function (PNLF) span nearly a decade in oxygen abundance, and thus, support the use of the PNLF for deriving distances to galaxies (Jacoby 1996) with differing metallicities. We also identify a correlation between central star mass and PN dust formation that partially alleviates any dependence of the PNLF maximum magnitude on population age. Additionally, we identify a spatially compact group of 5 PNe having unusually high O/H; this subgroup may arise from a recent merger, but velocity information is needed to assess the true nature of the objects.

  10. PLANETARY NEBULAE IN THE ELLIPTICAL GALAXY NGC 821: KINEMATICS AND DISTANCE DETERMINATION

    SciTech Connect

    Teodorescu, A. M.; Mendez, R. H.; Kudritzki, R. P.; Bernardi, F.; Riffeser, A. E-mail: mendez@ifa.hawaii.ed

    2010-09-20

    Using a slitless spectroscopy method with the 8.2 m Subaru telescope and its FOCAS Cassegrain spectrograph, we have increased the number of planetary nebula (PN) detections and PN velocity measurements in the flattened elliptical galaxy NGC 821. A comparison with the detections reported previously by the Planetary Nebulae Spectrograph group indicates that we have confirmed most of their detections. The velocities measured by the two groups, using different telescopes, spectrographs, and slitless techniques, are in good agreement. We have built a combined sample of 167 PNs and have confirmed the Keplerian decline of the line-of-sight velocity dispersion reported previously. We also confirm misaligned rotation from the combined sample. A dark matter halo may exist around this galaxy, but it is not needed to keep the PN velocities below the local escape velocity as calculated from the visible mass. We have measured the m(5007) magnitudes of 145 PNs and produced a statistically complete sample of 40 PNs in NGC 821. The resulting PN luminosity function (PNLF) was used to estimate a distance modulus of 31.4 mag, equivalent to 19 Mpc. We also estimated the PN formation rate. NGC 821 becomes the most distant galaxy with a PNLF distance determination. The PNLF distance modulus is smaller than the surface brightness fluctuation (SBF) distance modulus by 0.4 mag. Our kinematic information permits to rule out the idea that a shorter PNLF distance could be produced by the contamination of the PNLF by background galaxies with emission lines redshifted into the on-band filter transmission curve.

  11. 3.4 Micron Emission from Aliphatic Hydrocarbons in Proto-Planetary Nebulae

    NASA Astrophysics Data System (ADS)

    Hrivnak, B. J.; Kwok, S.; Geballe, T. R.

    2002-12-01

    A family of infrared emission features at 3.3, 6.2, 7.7, 8.6, 11.3 μ m are seen in a variety of objects with strong uv radiation fields. These features are attributed to stretching and bending modes of aromatic compounds. An aliphatic feature has been detected at 3.4 μ m in some of these same objects. Proto-planetary nebulae (PPNs) are in a short-lived stage of evolution between the asymptotic giant branch and planetary nebula (PN) phases. It is observed that in this transitional stage, the strengths of some of these infrared emission features differ from those seen in PNs. In particular, the 3.4 μ m feature, which is usually much weaker than the 3.3 μ m feature, is of comparable strength in some PPNs. To better understand the properties of these features, we carried out medium-resolution (R ~2000) spectroscopy of a sample of PPNs in the 3 μ m region using the NIRSPEC spectrograph on the Keck II telescope. Eight PPNs were observed. These resulted in the first detection of the 3.4 μ m feature in two objects and possible detections in two others and the first detection of the 3.3 μ m feature in two other objects. We will discuss what has been learned from the observations of the 3.4 μ m feature and review the evidence for a correlation of the ratio of the 3.4 to 3.3 μ m features with spectral type. These observations were carried out in the service observing mode as part of a program of limited access to Keck provided to the Gemini Observatory community. This work was funded in part by grants to BJH from the NSF and to SK by NSERC.

  12. Expanding the Search for Spectroscopic Binaries in Proto-Planetary Nebulae

    NASA Astrophysics Data System (ADS)

    Hrivnak, B.; Bohlender, D.; Kerber, F.; Lu, W.; Seifahrt, A.; Van de Steene, G.; Van Winckel, H.

    2014-04-01

    Binaries are often invoked as a shaping mechanism for the asymmetrical shapes of planetary nebulae and proto-planetary nebulae (PPNe) - particularly those that are elliptical, bipolar, or point symmetric. To test this hypothesis, we have been carrying out radial velocity monitoring of a sample of PPNe. The results of an initial study of seven bright PPNe have been published, based primarily on our observations from 1991-1995 and 2007-2010 at the Dominion Astrophysical Observatory (Victoria, Canada). Six of the seven showed no long-term variations between the two time intervals while one, IRAS 22272+5435, gave evidence of a variation consistent with a P > 22 yr (Hrivnak et al. 2011, ApJ, 734, 25). All seven of these objects do show shorter-term pulsational variations, on the order of 35-130 day over a range of about 14 km/s (peak-to-peak). We have expanded this search in two ways. Firstly, we have increased the temporal baseline by continuing to monitor the bright seven objects in radial velocity and increased the sampling with the addition of observations from the Hermes spectrograph on the Mercator telescope (Canary Islands). This has resulted in a second object with possible long-term variability that may indicate a binary companion. Secondly, we have started to monitor three edge-on PPNe with near-infrared spectroscopy; the stars are hidden in visible light but seen in the near infrared. These should show the full orbital velocity if it exists. Observations were begun in 2010, primarily from the ESO-VLT. While the spectra are more complicated than expected, we have found tantalizing evidence for systematic velocity variations in one of these three. Preliminary results for both of these expanded studies were presented. The research is supported in part by a grant from the NSF to BJH (AST-1009974).

  13. The Near-Infrared Spectrum of the Planetary Nebula IC 5117

    NASA Astrophysics Data System (ADS)

    Rudy, Richard J.; Lynch, David K.; Mazuk, S.; Puetter, R. C.; Dearborn, David S. P.

    2001-01-01

    Infrared spectroscopy from 0.8 to 2.5 μm is presented for the planetary nebula IC 5117. The emission lines of IC 5117 span a wide range of ionization that includes He II, [S III], [S II], [N I], and H2. The reddening measured from the hydrogen lines is E(B-V)=0.79, most of which is probably interstellar in origin. The He/H abundance ratio is 0.113+/-0.015, with approximately 10% of the helium being doubly ionized. Using our measurements of [S II] and [S III] lines and published observations of [S IV], we find a sulfur abundance, relative to hydrogen, of N(S)/N(H)=7.8×10-6, or approximately half the solar value. Fluxes and flux limits for several lines of molecular hydrogen are presented. Measurements of 1-0 transitions, together with the limits on 2-1 transitions, indicate Tvib~Trot=1900 K, suggesting a purely collisional excitation mechanism. The ortho-to-para ratio is ~3, a value that is also indicative of collisional excitation. The presence of [C I] λ9850 is consistent with previous studies of IC 5117 that indicated carbon is more abundant than oxygen. IC 5117 follows the trend of planetary nebulae that display bipolar outflows and H2 emission to be carbon-rich. We confirm the results of Zhang & Kwok, who reported infrared continuum emission substantially in excess of that produced by the ionized gas. This emission is most likely due to hot dust (T~1300 K) and accounts for roughly half of the continuum between 1.5 and 2 μm.

  14. THE DOUBLE-DEGENERATE NUCLEUS OF THE PLANETARY NEBULA TS 01: A CLOSE BINARY EVOLUTION SHOWCASE

    SciTech Connect

    Tovmassian, Gagik; Richer, Michael G.; Yungelson, Lev; Rauch, Thomas; Suleimanov, Valery; Napiwotzki, Ralf; Stasinska, Grazyna; Tomsick, John; Wilms, Joern; Morisset, Christophe; Pena, Miriam

    2010-05-01

    We present a detailed investigation of SBS 1150+599A, a close binary star hosted by the planetary nebula PN G135.9+55.9 (TS 01). The nebula, located in the Galactic halo, is the most oxygen-poor known to date and is the only one known to harbor a double degenerate core. We present XMM-Newton observations of this object, which allowed the detection of the previously invisible component of the binary core, whose existence was inferred so far only from radial velocity (RV) and photometric variations. The parameters of the binary system were deduced from a wealth of information via three independent routes using the spectral energy distribution (from the infrared to X-rays), the light and RV curves, and a detailed model atmosphere fitting of the stellar absorption features of the optical/UV component. We find that the cool component must have a mass of 0.54 {+-} 0.2 M{sub sun}, an average effective temperature, T{sub eff}, of 58,000 {+-} 3000 K, a mean radius of 0.43 {+-} 0.3 R{sub sun}, a gravity, log g = 5.0 {+-} 0.3, and that it nearly fills its Roche lobe. Its surface elemental abundances are found to be: 12 + log He/H = 10.95 {+-} 0.04 dex, 12 + log C/H = 7.20 {+-} 0.3 dex, 12 + log N/H < 6.92, and 12 + log O/H < 6.80, in overall agreement with the chemical composition of the planetary nebula. The hot component has T{sub eff} = 160-180 kK, a luminosity of about {approx}10{sup 4} L{sub sun} and a radius slightly larger than that of a white dwarf. It is probably bloated and heated as a result of intense accretion and nuclear burning on its surface in the past. The total mass of the binary system is very close to the Chandrasekhar limit. This makes TS 01 one of the best Type Ia supernova progenitor candidates. We propose two possible scenarios for the evolution of the system up to its present stage.

  15. Planetary Nebulae in the LMC: a study on stellar evolution and Populations.

    NASA Astrophysics Data System (ADS)

    Stanghellini, Letizia

    2001-07-01

    The final phase of the evolution of low- and intermediate-mass stars, the Planetary Nebula {PN} ejection, is thought to provide the main source of carbon and nitrogen enrichment in galaxies. Stellar generations forming from a carbon- and nitrogen-enriched medium are a necessary condition for planetary and life evolution. It is essential to understand how stars go through the process of shedding their chemically- enriched shells, and to test the predictions of stellar evolution theory on the relationship between stellar mass and elemental enrichment. LMC PNe are ideal probes for this study. Their abundances can be directly related to the mass of the central stars and to that of the stellar progenitor, without the great {distance and reddening} uncertainties that affect Galactic PNe. The UV lines are essential for calculating the abundances of the element related to stellar evolution {C, N, O} and progenitor populations {e.g., Ne}. We propose to acquire STIS UV spectroscopy for LMC PNe whose morphology has been previously determined with HST. We will derive the {C, N, O} abundance-to-mass relation, and determine the extent to which the mass of the progenitors of asymmetric PNe exceed that of symmetric PNe.

  16. 3D pyCloudy modelling of bipolar planetary nebulae: Evidence for fast fading of the lobes

    NASA Astrophysics Data System (ADS)

    Gesicki, K.; Zijlstra, A. A.; Morisset, C.

    2016-01-01

    Aims: The origin and evolution of the shapes of bipolar planetary nebulae are poorly understood. We postulate that their history can be traced through their internal velocity fields in a procedure similar to the one well established for spherical objects. Such an analysis requires 3D photoionization and kinematical modelling that is computationally very time consuming. We apply an axially symmetric pseudo-3D photoionization model, pyCloudy, to derive the structures of six bipolar nebulae and two suggested post-bipolars in an attempt to constrain the bipolar planetary nebulae evolution. Methods: HST images and VLT/UVES spectroscopy are used for the modelling. The targets are located in the direction of the Galactic bulge. A 3D model structure is used as input to the photoionization code in order to fit the HST images. Line profiles of different ions constrain the velocity field. The model and associated velocity fields allow us to derive masses, velocities, and ages. Results: The 3D models find much lower ionized masses than required in 1D models: ionized masses are reduced by factors of 2-7. The selected bi-lobed planetary nebulae show a narrow range of ages: the averaged radii and velocities result in values between 1300 and 2000 yr. The lobes are fitted well with velocities that increase linearly with radius. These Hubble-type flows have been found before, and suggest that the lobes form at a defined point in time. The lobes appear to be slightly younger, by ~500 yr, than the main (host) nebulae; they seem to form at an early phase of PN evolution and fade after 1-2 kyr. We find that 30-35% of bulge PNe pass through a bipolar phase. Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere, Chile (proposal 075.D-0104) and HST (program 9356).

  17. The post-common envelope central stars of the planetary nebulae Henize 2-155 and Henize 2-161

    NASA Astrophysics Data System (ADS)

    Jones, D.; Boffin, H. M. J.; Rodríguez-Gil, P.; Wesson, R.; Corradi, R. L. M.; Miszalski, B.; Mohamed, S.

    2015-08-01

    We present a study of Hen 2-155 and Hen 2-161, two planetary nebulae which bear striking morphological similarities to other planetary nebulae known to host close-binary central stars. Both central stars are revealed to be photometric variables while spectroscopic observations confirm that Hen 2-155 is host to a double-eclipsing, post-common-envelope system with an orbital period of 3h33m making it one of the shortest period binary central stars known. The observations of Hen 2-161 are found to be consistent with a post-common-envelope binary of period ~1 day. A detailed model of the central star of Hen 2-155 is produced, showing the nebular progenitor to be a hot, post-AGB remnant of approximately 0.62 M⊙, consistent with the age of the nebula, and the secondary star to be an M dwarf whose radius is almost twice the expected zero age main sequence radius for its mass. In spite of the small numbers, all main-sequence companions, of planetary nebulae central stars, to have had their masses and radii constrained by both photometric and spectroscopic observations have also been found to display this "inflation". The cause of the "inflation" is uncertain but is probably related to rapid accretion, immediately before the recent common-envelope phase, to which the star has not yet thermally adjusted. The chemical composition of both nebulae is also analysed, showing both to display elevated abundance discrepancy factors. This strengthens the link between elevated abundance discrepancy factors and close binarity in the nebular progenitor. Full Tables 2-5, and 7 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/580/A19

  18. Cathodoluminescence Study of Meteoritic Pre-Solar Nanodiamonds: An Implication for Origin of Diamond Particles in NGC 7027 Planetary Nebula

    NASA Astrophysics Data System (ADS)

    Arnold, Gucsik; Simonia, I.; Ninagawa, K.; Nishido, H.; Nakazato, M.

    2009-12-01

    Primitive meteorites contain abundant (up to 1500 ppm) amounts of nanodiamonds. At least some subpopulation must be of pre-solar (stardust?) origin, as indicated by the isotopic composition of trace elements the diamonds carry, in particular noble gases and tellurium. On the other hand, the isotopic composition of the major element, carbon, is unremarkable, i.e. within the range reasonably expected for Solar System materials. As a consequence many workers believe that the majority of the diamonds is of local, i.e. Solar System origin and that the fraction that is pre-solar is relatively small. Two main theories exist for the formation process of the meteoritic nanodiamonds: (1) Chemical vapour deposition (CVD), and (2) shock origin. In this study, we present results of the study of meteoritic nanodiamonds from different primitive chondritic meteorites the by means of the Scanning Electron Microscope-Cathodoluminescence (SEM-CL) measurements in an attempt to obtain further constraints with regard to the formation process and their application to astrophysics. Planetary nebula NGC 7027 is C-rich object indicating that the presence of of nanodiamond dust particles in the dust matter of this nebula is highly possible. K2 (Ultradispersed Detonation Diamonds-UDD) and meteoritic (i.e., Boronisko, Efremovka, etc.) nanodiamond samples were selected to the cathodoluminescence microscopical and spectroscopical studies. They show characteristic CL spectral features at around 388 (3.1 eV; A-center), 452 (2.69 eV; N-center) and 483 nm, which are in a good agreement with spectral properties (at 463.8 nm) of planetary nebula NGC7027. In a conclusion, according to this preliminary laboratory experiment, diamond particles in nebula NGC7027 may be originated due to ejection of the outer parts of the Red Giants during planetary nebula formation.

  19. The emerging planetary nebula CRL 618 and its unsettled central star(s)

    SciTech Connect

    Balick, B.; Riera, A.; Raga, A.; Velázquez, P. F.; Kwitter, K. B. E-mail: angels.riera@upc.edu E-mail: pablo@nucleares.unam.mx

    2014-11-01

    We report deep long-slit emission-line spectra, the line flux ratios, and Doppler profile shapes of various bright optical lines. The low-ionization lines (primarily [N I], [O I], [S II], and [N II]) originate in shocked knots, as reported by many previous observers. Dust-scattered lines of higher ionization are seen throughout the lobes but do not peak in the knots. Our analysis of these line profiles and the readily discernible stellar continuum shows that (1) the central star is an active symbiotic (whose spectrum resembles the central stars of highly bipolar and young planetary nebulae such as M2-9 and Hen2-437) whose compact companion shows a WC8-type spectrum, (2) extended nebular lines of [O III] and He I originate in the heavily obscured nuclear H II region, and (3) the Balmer lines observed throughout the lobes are dominated by reflected Hα emission from the symbiotic star. Comparing our line ratios with those observed historically shows that (1) the [O III]/Hβ and He I/Hβ ratios have been steadily rising by large amounts throughout the nebula, (2) the Hα/Hβ ratio is steadily decreasing while Hγ/Hβ remains nearly constant, and (3) the low-ionization line ratios formed in the shocked knots have been in decline in different ways at various locations. We show that the first two of these results might be expected if the symbiotic central star has been active and if its bright Hα line has faded significantly in the past 20 years.

  20. Planetary Nebulae As A Laboratory For Molecular Hydrogen in the Early Universe

    NASA Astrophysics Data System (ADS)

    Sellgren, Kris; Bromm, Volker; Dinerstein, Harriet

    2008-03-01

    We propose to obtain Spitzer IRS observations of the mid-infrared rotational lines of H2 in planetary nebulae (PNe) with very hot central stars, T > 100,000 K. Our primary motivation is to investigate the excitation and cooling of H2 exposed to UV radiation near very hot stars, which can serve as a proxy for conditions in the early universe. Cosmological simulations show that the first stellar generation (Pop. III) had high masses, > 100 Msun, and hot photospheres. The UV radiation they produced and its effect on the thermal state of the ambient H2 is relevant to subsequent star formation because stellar masses are determined by accretion processes which depend on temperature, and the metal-free primordial gas cooled primarily through excited H2. Yet the effects of this radiative feedback are uncertain: for example, whether it triggers or suppresses further star formation, and the resultant characteristic masses of second generation stars, which are key to cosmic reionization. PNe with hot central stars may be the only place where we can study the relevant microphysics. We therefore propose to obtain Spitzer spectra of such nebulae, sampling regions with a range of gas densities and radiation field dilution factors. We will use the results to derive an improved H2 cooling function to be incorporated into state of the art cosmological models. Our targets have been previously observed in the near-infrared H2 lines, so we have confidence that the lower excitation rotational lines are detectable. Evidence already exists that in some PNe the excited rotational states are overpopulated relative to standard fluorescence models, and that this may be related to the presence of Lyman-continuum photons. The observations proposed here will enable us to verify and quantify this phenomenon, and improve our understanding of H2 excitation. Spitzer is the only facility at present - and for at least the next decade - which can accomplish these goals.

  1. Imaging and high-resolution spectroscopy of the Planetary Nebula NGC 3242

    NASA Astrophysics Data System (ADS)

    Gómez-Muñoz, Marco Antonio; Wendolyn Blanco Cárdenas, Mónica; Vázquez, Roberto; Zavala, Saúl A.; Guillén, Pedro F.; Ayala, Sandra A.

    2015-08-01

    We present a high-resolution imaging and high-dispersion spectroscopy study of the complex morphological and kinematical structure of the planetary nebula NGC 3242. We analyze narrowband Hα, [O III] and [N II] images, addressing important morphological features: in the [O III] image we found one knot oriented to PA=-4°, in the [N II] image, three knots oriented at PA1=155°, PA2=+157°, and PA3=-45.5°, and in the Hα image, two bubbles in the internal region, one of them oriented toward SE and the other toward NW. Additionally we used the unsharp-masking technique and found faint structures in the halo that have not been studied before. These structures are presented in two pairs of arcs, one pair oriented toward PA=-35° and the other toward PA=140°. NGC 3242 is a morphologically rich PN with bubbles, asymmetrical outflows, and some knots in a double-shell nebular structure. Ground-based long-slit echelle spectra were obtained crossing NGC 3242 at twelve different positions to precisely determine kinematical features in the structure of the nebula. We obtain a systemic velocity of VLSR=-6.6 km/s. We have used the software SHAPE (Steffen et al. 2011, IEEE Trans. Vis. Comput. Graphics, 17, 454), to reconstruct a 3D model of NGC 3242 which fits all our observational data. Preliminary results (deprojected velocities and kinematical ages) of all these structures will be presented.This project has been supported by grant PAPIIT-DGAPA-UNAM IN107914. MWB is in grateful receipt of a DGAPA-UNAM postdoctoral scholarship. MAG acknowledges CONACYT for his graduate scholarship.

  2. The Emerging Planetary Nebula CRL 618 and its Unsettled Central Star(s)

    NASA Astrophysics Data System (ADS)

    Balick, B.; Riera, A.; Raga, A.; Kwitter, K. B.; Velázquez, P. F.

    2014-11-01

    We report deep long-slit emission-line spectra, the line flux ratios, and Doppler profile shapes of various bright optical lines. The low-ionization lines (primarily [N I], [O I], [S II], and [N II]) originate in shocked knots, as reported by many previous observers. Dust-scattered lines of higher ionization are seen throughout the lobes but do not peak in the knots. Our analysis of these line profiles and the readily discernible stellar continuum shows that (1) the central star is an active symbiotic (whose spectrum resembles the central stars of highly bipolar and young planetary nebulae such as M2-9 and Hen2-437) whose compact companion shows a WC8-type spectrum, (2) extended nebular lines of [O III] and He I originate in the heavily obscured nuclear H II region, and (3) the Balmer lines observed throughout the lobes are dominated by reflected Hα emission from the symbiotic star. Comparing our line ratios with those observed historically shows that (1) the [O III]/Hβ and He I/Hβ ratios have been steadily rising by large amounts throughout the nebula, (2) the Hα/Hβ ratio is steadily decreasing while Hγ/Hβ remains nearly constant, and (3) the low-ionization line ratios formed in the shocked knots have been in decline in different ways at various locations. We show that the first two of these results might be expected if the symbiotic central star has been active and if its bright Hα line has faded significantly in the past 20 years.

  3. Spectrophotometry near the atmospheric cutoff of the strongest Bowen resonance fluorescence lines of O III in two planetary nebulae

    NASA Technical Reports Server (NTRS)

    O'Dell, C. R.; Opal, Chet B.

    1989-01-01

    Spectrophotometric results are presented for the stronger, well-resolved Bowen O III resonance fluorescence emission lines in the planetary nebulae 7027 and NGC 7662 down to and including the intrinsically strong line at 3133 A. These data are combined with results from the IUE atlas of spectra and similar results for the longer wavelength lines by Likkel and Aller (1986) to give the first full coverage of the Bowen lines. Good agreement is found with fluorescence theory for the primary cascade lines, except for the Likkel and Aller results. The efficiency of conversion of the exciting He II Ly-alpha into O III lines is determined, and values comparable to other planetary nebulae are found.

  4. A SPITZER/INFRARED SPECTROGRAPH SPECTRAL STUDY OF A SAMPLE OF GALACTIC CARBON-RICH PROTO-PLANETARY NEBULAE

    SciTech Connect

    Zhang Yong; Kwok Sun; Hrivnak, Bruce J. E-mail: sunkwok@hku.h

    2010-12-10

    Recent infrared spectroscopic observations have shown that proto-planetary nebulae (PPNs) are sites of active synthesis of organic compounds in the late stages of stellar evolution. This paper presents a study of Spitzer/Infrared Spectrograph spectra for a sample of carbon-rich PPNs, all except one of which show the unidentified 21 {mu}m emission feature. The strengths of the aromatic infrared band, 21 {mu}m, and 30 {mu}m features are obtained by decomposition of the spectra. The observed variations in the strengths and peak wavelengths of the features support the model that the newly synthesized organic compounds gradually change from aliphatic to aromatic characteristics as stars evolve from PPNs to planetary nebulae.

  5. The Interstellar Extinction Towards the Milky Way Bulge with Planetary Nebulae, Red Clump, and RR Lyrae Stars

    NASA Astrophysics Data System (ADS)

    Nataf, David M.

    2016-06-01

    I review the literature covering the issue of interstellar extinction towards the Milky Way bulge, with emphasis placed on findings from planetary nebulae, RR Lyrae, and red clump stars. I also report on observations from HI gas and globular clusters. I show that there has been substantial progress in this field in recent decades, most particularly from red clump stars. The spatial coverage of extinction maps has increased by a factor ~ 100 × in the past 20 yr, and the total-to-selective extinction ratios reported have shifted by ~ 20-25%, indicative of the improved accuracy and separately, of a steeper-than-standard extinction curve. Problems remain in modelling differential extinction, explaining anomalies involving the planetary nebulae, and understanding the difference between bulge extinction coefficients and `standard' literature values.

  6. Sulfur- and Silicon-bearing Molecules in Planetary Nebulae: The Case of m2-48

    NASA Astrophysics Data System (ADS)

    Edwards, J. L.; Ziurys, L. M.

    2014-10-01

    Molecular-line observations of the bipolar planetary nebula (PN) M2-48 have been conducted using the Sub-Millimeter Telescope and the 12 m antenna of the Arizona Radio Observatory at 1, 2, and 3 mm. M2-48 is estimated to be ~4800 yr old, midway through the PN evolutionary track. SiO and SO2 were detected in this source—the first identification of either molecule in a PN. CN, HCN, HNC, CS, SO, HCO+, N2H+, and several 13C isotopologues such as 13CN, H13CN, and H13CO+ were also observed toward this object. A radiative transfer analysis of multiple SiO transitions indicates a gas kinetic temperature of T K ~ 55 K and a density of n(H2) ~ 9 × 105 cm-3 in M2-48, in agreement with previous CS and CO modeling. After CO, CN, and SO were found to be the most prevalent molecules in this nebula, with fractional abundances, relative to H2, of f ~ 3.8 × 10-7 and 2.4 × 10-7, respectively. SO2 and HCN are also abundant, with f ~ 1.2 × 10-7, indicating an [SO]/[SO2] ratio of ~2. Relatively high ion abundances were measured in M2-48 as well, with f ~ 10-7 for both HCO+ and N2H+. An [HCN]/[HNC] ratio of ~2 was determined, as typically observed in other PNe, independent of age. The high abundances of SO and SO2, along with the presence of SiO with f ~ 2.9 × 10-8, suggest O/C > 1 in this source; furthermore, the prevalence of CN and N2H+ indicates nitrogen enrichment. The 12C/13C ratio of ~3 in the nebula was also established. These factors indicate hot-bottom burning occurred in the progenitor star of M2-48, suggesting an initial mass > 4 M ⊙.

  7. SULFUR- AND SILICON-BEARING MOLECULES IN PLANETARY NEBULAE: THE CASE OF M2-48

    SciTech Connect

    Edwards, J. L.; Ziurys, L. M.

    2014-10-20

    Molecular-line observations of the bipolar planetary nebula (PN) M2-48 have been conducted using the Sub-Millimeter Telescope and the 12 m antenna of the Arizona Radio Observatory at 1, 2, and 3 mm. M2-48 is estimated to be ∼4800 yr old, midway through the PN evolutionary track. SiO and SO{sub 2} were detected in this source—the first identification of either molecule in a PN. CN, HCN, HNC, CS, SO, HCO{sup +}, N{sub 2}H{sup +}, and several {sup 13}C isotopologues such as {sup 13}CN, H{sup 13}CN, and H{sup 13}CO{sup +} were also observed toward this object. A radiative transfer analysis of multiple SiO transitions indicates a gas kinetic temperature of T {sub K} ∼ 55 K and a density of n(H{sub 2}) ∼ 9 × 10{sup 5} cm{sup –3} in M2-48, in agreement with previous CS and CO modeling. After CO, CN, and SO were found to be the most prevalent molecules in this nebula, with fractional abundances, relative to H{sub 2}, of f ∼ 3.8 × 10{sup –7} and 2.4 × 10{sup –7}, respectively. SO{sub 2} and HCN are also abundant, with f ∼ 1.2 × 10{sup –7}, indicating an [SO]/[SO{sub 2}] ratio of ∼2. Relatively high ion abundances were measured in M2-48 as well, with f ∼ 10{sup –7} for both HCO{sup +} and N{sub 2}H{sup +}. An [HCN]/[HNC] ratio of ∼2 was determined, as typically observed in other PNe, independent of age. The high abundances of SO and SO{sub 2}, along with the presence of SiO with f ∼ 2.9 × 10{sup –8}, suggest O/C > 1 in this source; furthermore, the prevalence of CN and N{sub 2}H{sup +} indicates nitrogen enrichment. The {sup 12}C/{sup 13}C ratio of ∼3 in the nebula was also established. These factors indicate hot-bottom burning occurred in the progenitor star of M2-48, suggesting an initial mass > 4 M {sub ☉}.

  8. Ultraviolet spectra of planetary nebulae. VII - The abundance of carbon in the very low excitation nebula He 2-131

    NASA Astrophysics Data System (ADS)

    Adams, S.; Seaton, M. J.

    1982-07-01

    Features observed in infrared spectra suggest that certain very low excitation (VLE) nebulae have low C/O abundance ratios (Cohen & Barlow 1980; Aitken & Roche 1982). Fluxes in the multiplets [O II] sun2470 and [O II] λ2326 have been measured for the VLE nebula He 2-131 = HD 138403 using lUE high-dispersion spectra. An analysis similar to that of Harrington et al. (1980) for IC 418 gives C/O = 0.3 for He 2-131, compared with C/O = 1.3 for IC 418 and 0.6 for the Sun.

  9. SAO 244567 - A post-AGB star which has turned into a planetary nebula within the last 40 years

    NASA Astrophysics Data System (ADS)

    Parthasarathy, M.; Garcia-Lario, P.; Pottasch, S. R.; Manchado, A.; Clavel, J.; de Martino, D.; van de Steene, G. C. M.; Sahu, K. C.

    1993-01-01

    SAO 244567 (Hen 1357 = CPD -59 deg 6926 = IRAS 17119-5926) is an IRAS source with far infrared colors and flux distribution similar to those of planetary nebulae. The IUE ultraviolet spectra obtained in July 1988 and April 1992 show nebular emission lines, and also the changes in the spectra suggest the formation of the planetary nebula and the rapid evolution of the central star. The optical spectrum of this star obtained by Henize around 1950 shows only the H-alpha line in emission, while the most recent one, obtained in 1990 shows strong forbidden emission lines corresponding to a low excitation and young planetary nebula. The IUE ultraviolet spectra show evidence for the presence of stellar wind and mass loss. The stellar lines show P-Cygni type profiles and the terminal velocity of the stellar wind is about - 3000 km/s. The spectral type of the central star is O8 V. The presence of a detached cold dust shell (125 K), high galactic latitude and abundances suggest that SAO 244567 has recently evolved from a low or intermediate mass progenitor star which has ejected its outer envelope during the AGB stage of evolution and is rapidly evolving towards hotter spectral types.

  10. Episodic mass loss from the hydrogen-deficient central star of the planetary nebula Longmore 4

    SciTech Connect

    Bond, Howard E.

    2014-09-01

    A spectacular transient mass-loss episode from the extremely hot, hydrogen-deficient central star of the planetary nebula (PN) Longmore 4 (Lo 4) was discovered in 1992 by Werner et al. During that event, the star temporarily changed from its normal PG 1159 spectrum to that of an emission-line low-luminosity early-type Wolf-Rayet [WCE] star. After a few days, Lo 4 reverted to its normal, predominantly absorption-line PG 1159 type. To determine whether such events recur, and if so how often, I monitored the optical spectrum of Lo 4 from early 2003 to early 2012. Out of 81 spectra taken at random dates, 4 of them revealed mass-loss outbursts similar to that seen in 1992. This indicates that the episodes recur approximately every 100 days (if the recurrence rate has been approximately constant and the duration of a typical episode is ∼5 days), and that the star is in a high-mass-loss state about 5% of the time. Since the enhanced stellar wind is hydrogen-deficient, it arises from the photosphere and is unlikely to be related to phenomena such as a binary or planetary companion or infalling dust. I speculate on plausible mechanisms for these unique outbursts, including the possibility that they are related to the non-radial GW Vir-type pulsations exhibited by Lo 4. The central star of the PN NGC 246 has stellar parameters similar to those of Lo 4, and it is also a GW Vir-type pulsator with similar pulsation periods. I obtained 167 spectra of NGC 246 between 2003 and 2011, but no mass ejections were found.

  11. Episodic Mass Loss from the Hydrogen-deficient Central Star of the Planetary Nebula Longmore 4

    NASA Astrophysics Data System (ADS)

    Bond, Howard E.

    2014-09-01

    A spectacular transient mass-loss episode from the extremely hot, hydrogen-deficient central star of the planetary nebula (PN) Longmore 4 (Lo 4) was discovered in 1992 by Werner et al. During that event, the star temporarily changed from its normal PG 1159 spectrum to that of an emission-line low-luminosity early-type Wolf-Rayet [WCE] star. After a few days, Lo 4 reverted to its normal, predominantly absorption-line PG 1159 type. To determine whether such events recur, and if so how often, I monitored the optical spectrum of Lo 4 from early 2003 to early 2012. Out of 81 spectra taken at random dates, 4 of them revealed mass-loss outbursts similar to that seen in 1992. This indicates that the episodes recur approximately every 100 days (if the recurrence rate has been approximately constant and the duration of a typical episode is ~5 days), and that the star is in a high-mass-loss state about 5% of the time. Since the enhanced stellar wind is hydrogen-deficient, it arises from the photosphere and is unlikely to be related to phenomena such as a binary or planetary companion or infalling dust. I speculate on plausible mechanisms for these unique outbursts, including the possibility that they are related to the non-radial GW Vir-type pulsations exhibited by Lo 4. The central star of the PN NGC 246 has stellar parameters similar to those of Lo 4, and it is also a GW Vir-type pulsator with similar pulsation periods. I obtained 167 spectra of NGC 246 between 2003 and 2011, but no mass ejections were found. Based on observations with the 1.5 m telescope operated by the SMARTS Consortium at Cerro Tololo Interamerican Observatory.

  12. Water Fountains in the Sky: Streaming Water Jets from Aging Star Provide Clues to Planetary-Nebula Formation

    NASA Astrophysics Data System (ADS)

    2002-06-01

    Astronomers using the National Science Foundation's Very Long Baseline Array (VLBA) radio telescope have found that an aging star is spewing narrow, rotating streams of water molecules into space, like a jerking garden hose that has escaped its owner's grasp. The discovery may help resolve a longstanding mystery about how the stunningly beautiful objects called planetary nebulae are formed. Artist's Conception of W43A. Artist's conception of W43A, with the aging star surrounded by a disk of material and a precessing, twisted jet of molecules streaming away from it in two directions. Credit: Kirk Woellert/National Science Foundation. The astronomers used the VLBA, operated by the National Radio Astronomy Observatory, to study a star called W43A. W43A is about 8,500 light-years from Earth in the direction of the constellation Aquila, the eagle. This star has come to the end of its normal lifetime and, astronomers believe, is about to start forming a planetary nebula, a shell of brightly glowing gas lit by the hot ember into which the star will collapse. "A prime mystery about planetary nebulae is that many are not spherical even though the star from which they are ejected is a sphere," said Phillip Diamond, director of the MERLIN radio observatory at Jodrell Bank in England, and one of the researchers using the VLBA. "The spinning jets of water molecules we found coming from this star may be one mechanism for producing the structures seen in many planetary nebulae," he added. The research team, led by Hiroshi Imai of Japan's National Astronomical Observatory (now at the Joint Institute for VLBI in Europe, based in the Netherlands), also includes Kumiko Obara of the Mizusawa Astrogeodynamics Observatory and Kagoshima University; Toshihiro Omodaka, also of Kagoshima University; and Tetsuo Sasao of the Japanese National Astronomical Observatory. The scientists reported their findings in the June 20 issue of the scientific journal Nature. As stars similar to our Sun

  13. A Treasure Trove of Molecules: Uncovering the Molecular Content of Planetary Nebulae

    NASA Astrophysics Data System (ADS)

    Schmidt, Deborah Rose; Ziurys, Lucy M.

    2016-06-01

    We have undertaken a systematic study of the molecular content of planetary nebulae (PNe) using the facilities of the Arizona Radio Observatory (ARO). A search for HCN and HCO+ in seventeen PNe in which CO had previously been detected has been carried out. The J=1→0 and J=3→2 transitions of both molecules were searched for using the ARO 12-M Telescope and ARO Sub-Millimeter Telescope respectively. At least one transition of either molecule was detected in thirteen sources. Assuming a kinetic temperature of 20 K, the abundances of these two molecule, relative to H2, were determined to be f(HCN) ~ 0.1 – 9.1 × 10-7 and f(HCO+) ~ 0.04 – 7.4 × 10-7. The abundances of both species were found to remain relatively constant with nebular age, in contrast to predictions of chemical models. A subset of eleven of these PNe were subsequently searched for the J=1→0 and J=3→2 transitions of CCH and HNC. HNC was detected in ten sources, resulting in HCN/HNC ratios of ~2-6, while CCH has been detected in eight. The most current results for the abundances of both molecules will be reported. The correlation of CCH and C60 will also be presented. Establishing molecular abundances in PNe is vital to our understanding of their environments as well as the nature of their ejecta, which populate the interstellar medium (ISM).

  14. The Shaping of the Multipolar Pre-planetary Nebula CRL 618 by Multidirectional Bullets

    NASA Astrophysics Data System (ADS)

    Huang, Po-Sheng; Lee, Chin-Fei; Moraghan, Anthony; Smith, Michael

    2016-04-01

    In order to understand the formation of the multipolar structures of the pre-planetary nebula CRL 618, we perform 3D simulations using a multidirectional bullet model. The optical lobes of CRL 618 and fast molecular outflows at the tips of the lobes have been found to have similar expansion ages of ˜100 yr. Additional fast molecular outflows were found near the source along the outflow axes with ages of ˜45 yr, suggesting a second episode of bullet ejections. Thus, in our simulations, two episodes of bullet ejections are assumed. The shaping process is simulated using the ZEUS-3D hydrodynamics code that includes molecular and atomic cooling. In addition, molecular chemistry is also included to calculate the CO intensity maps. Our results show the following: (1) Multiepoch bullets interacting with the toroidal dense core can produce the collimated multiple lobes as seen in CRL 618. The total mass of the bullets is ˜0.034 M⊙, consistent with the observed high-velocity (HV) CO emission in fast molecular outflows. (2) The simulated CO J = 3-2 intensity maps show that the low-velocity cavity wall and the HV outflows along the lobes are reasonably consistent with the observations. The position-velocity diagram of the outflows along the outflow axes shows a linear increase of velocity with distance, similar to the observations. The ejections of these bullets could be due to magnetorotational explosions or nova-like explosions around a binary companion.

  15. Central stars of planetary nebulae. II. New OB-type and emission-line stars

    NASA Astrophysics Data System (ADS)

    Weidmann, W. A.; Gamen, R.

    2011-07-01

    Context. There are more than 3000 confirmed and probably known Galactic planetary nebulae (PNe), but central star spectroscopic information is available for only 13% of them. Aims: We have undertaken a spectroscopic survey of the central stars in PNe to identify their spectral types. Methods: We performed spectroscopic observations at low resolution with the 2-m telescope at CASLEO, Argentina. Results: We present the spectra of 46 central stars of PNe, most of them are OB-type and emission-line stars. Based on data collected at the Complejo Astronómico El Leoncito (CASLEO), which is operated under agreement between the Consejo Nacional de Investigaciones Científicas y Técnicas de la República Argentina y Universidades Nacionales de La Plata, Córdoba y San Juan, Argentina.The reduced spectra (FITS files) are available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/531/A172

  16. Studies of hydrodynamic events in stellar evolution. 3: Ejection of planetary nebulae

    NASA Technical Reports Server (NTRS)

    Sparks, W. M.; Kutter, G. S.

    1973-01-01

    The dynamic behavior of the H-rich envelope (0.101 solar mass) of an evolved star (1.1 solar mass) as the luminosity rises to 19000 solar luminosity during the second ascent of the red giant branch. For luminosities in the range 3100 L 19000 solar luminosity the H-rich envelope pulsates like a long-period variable (LPV) with periods of the order of a year. As L reaches 19000 solar luminosity, the entire H-rich envelope is ejected as a shell with speeds of a few 10 km/s. The ejection occurs on a timescale of a few LPV pulsation periods. This ejection is associated with the formation of a planetary nebula. The computations are based on an implicit hydrodynamic computer code. T- and RHO-dependent opacities and excitation and ionization energies are included. As the H-rich envelope is accelerated off the stellar core, the gap between envelope and core is approximated by a vacuum, filled with radiation. Across the vacuum, the luminosity is conserved and the anisotropy of the radiation is considered as well as the solid angle subtended by the remnant star at the inner surface of the H-rich envelope. Spherical symmetry and the diffusion approximation are assumed.

  17. Studies of hydrodynamic events in stellar evolution. III Ejection of planetary nebulae

    NASA Technical Reports Server (NTRS)

    Kutter, G. S.; Sparks, W. M.

    1974-01-01

    Investigation of the dynamic behavior of the hydrogen-rich envelope (0.101 solar mass) of an evolved star (1.1 solar mass) as the luminosity rises to 19,000 solar luminosities during the second ascent of the red-giant branch. For luminosities in the range 3100 less than L less than 19,000 solar luminosities the H-rich envelope pulsates like a long-period variable (LPV) with periods of the order of a year. As L reaches 19,000 solar luminosities, the entire H-rich envelope is ejected as a shell with speeds of a few times 10 km sec. The ejection occurs on a time scale of a few LPV pulsation periods. This ejection is shown to be related to the formation of a planetary nebula. The computations are based on an implicit hydrodynamic computer code. Tand rho-dependent opacities and excitation and ionization energies are included. As the H-rich envelope is accelerated off the stellar core, the gap between envelope and core is approximated by a vacuum filled with radiation.

  18. X-ray Emission from the Born-Again Planetary Nebula Abell 30

    NASA Astrophysics Data System (ADS)

    Guerrero, M. A.

    2013-05-01

    The planetary nebula (PN) Abell 30 underwent a very late thermal pulse that resulted in the ejection of knots of hydrogen-poor material. ROSAT detected soft X-ray emission from these knots. We present deep Chandra and XMM-Newton observations that show this X-ray emission to consist of two components: a point-source at the central star and diffuse emission associated with the hydrogen-poor knots and the cloverleaf structure inside the nebular shell. The spatial distribution and spectral properties of the diffuse X-ray emission suggest that it is generated by the shock-heated plasma produced by the interaction of the present stellar wind with the hydrogen-poor ejecta of the born-again event. Charge-exchange reactions between the ions of the stellar winds and the born-again ejecta may also contribute to this emission. The origin of the X-ray emission from the central star of A 30 is puzzling: shocks in the present fast stellar wind and photospheric emission can be ruled out, while the development of a new, compact hot bubble confining the fast stellar wind seems implausible.

  19. Planetary and meteoritic Mg/Si and δ30 Si variations inherited from solar nebula chemistry

    NASA Astrophysics Data System (ADS)

    Dauphas, Nicolas; Poitrasson, Franck; Burkhardt, Christoph; Kobayashi, Hiroshi; Kurosawa, Kosuke

    2015-10-01

    The bulk chemical compositions of planets are uncertain, even for major elements such as Mg and Si. This is due to the fact that the samples available for study all originate from relatively shallow depths. Comparison of the stable isotope compositions of planets and meteorites can help overcome this limitation. Specifically, the non-chondritic Si isotope composition of the Earth's mantle was interpreted to reflect the presence of Si in the core, which can also explain its low density relative to pure Fe-Ni alloy. However, we have found that angrite meteorites display a heavy Si isotope composition similar to the lunar and terrestrial mantles. Because core formation in the angrite parent-body (APB) occurred under oxidizing conditions at relatively low pressure and temperature, significant incorporation of Si in the core is ruled out as an explanation for this heavy Si isotope signature. Instead, we show that equilibrium isotopic fractionation between gaseous SiO and solid forsterite at ∼1370 K in the solar nebula could have produced the observed Si isotope variations. Nebular fractionation of forsterite should be accompanied by correlated variations between the Si isotopic composition and Mg/Si ratio following a slope of ∼1, which is observed in meteorites. Consideration of this nebular process leads to a revised Si concentration in the Earth's core of 3.6 (+ 6.0 / - 3.6) wt% and provides estimates of Mg/Si ratios of bulk planetary bodies.

  20. Unusual Shock-excited OH Maser Emission in a Young Planetary Nebula

    NASA Astrophysics Data System (ADS)

    Qiao, Hai-Hua; Walsh, Andrew J.; Gómez, José F.; Imai, Hiroshi; Green, James A.; Dawson, Joanne R.; Shen, Zhi-Qiang; Ellingsen, Simon P.; Breen, Shari L.; Jones, Paul A.; Gibson, Steven J.; Cunningham, Maria R.

    2016-01-01

    We report on OH maser emission toward G336.644-0.695 (IRAS 16333-4807), which is a H2O maser-emitting Planetary Nebula (PN). We have detected 1612, 1667, and 1720 MHz OH masers at two epochs using the Australia Telescope Compact Array, hereby confirming it as the seventh known case of an OH-maser-emitting PN. This is only the second known PN showing 1720 MHz OH masers after K 3-35 and the only evolved stellar object with 1720 MHz OH masers as the strongest transition. This PN is one of a group of very young PNe. The 1612 MHz and 1667 MHz masers are at a similar velocity to the 22 GHz H2O masers, whereas the 1720 MHz masers show a variable spectrum, with several components spread over a higher velocity range (up to 36 km s-1). We also detect Zeeman splitting in the 1720 MHz transition at two epochs (with field strengths of ˜2 to ˜10 mG), which suggests the OH emission at 1720 MHz is formed in a magnetized environment. These 1720 MHz OH masers may trace short-lived equatorial ejections during the formation of the PN.

  1. Constraints on common envelope magnetic fields from observations of jets in planetary nebulae

    NASA Astrophysics Data System (ADS)

    Tocknell, James; De Marco, Orsola; Wardle, Mark

    2014-04-01

    The common envelope (CE) interaction describes the swallowing of a nearby companion by a growing, evolving star. CEs that take place during the asymptotic giant branch phase of the primary may lead to the formation of a planetary nebula (PN) with a post-CE close binary in the middle. We have used published observations of masses and kinematics of jets in four post-CE PN to infer physical characteristics of the CE interaction. In three of the four systems studied, Abell 63, ETHOS 1 and the Necklace PN, the kinematics indicate that the jets were launched a few thousand years before the CE and we favour a scenario where this happened before Roche lobe overflow, although better models of wind accretion and wind Roche lobe overflow are needed. The magnetic fields inferred to launch pre-CE jets are of the order of a few gauss. In the fourth case, NGC 6778, the kinematics indicate that the jets were launched about 3000 yr after the CE interaction. Magnetic fields of the order of a few hundreds to a few thousands gauss are inferred in this case, approximately in line with predictions of post-CE magnetic fields. However, we remark that in the case of this system, we have not been able to find a reasonable scenario for the formation of the two jet pairs observed: the small orbital separation may preclude the formation of even one accretion disc able to supply the necessary accretion rate to cause the observed jets.

  2. Automatic Derivation of Statistical Data Analysis Algorithms: Planetary Nebulae and Beyond

    NASA Astrophysics Data System (ADS)

    Fischer, Bernd; Hajian, Arsen; Knuth, Kevin; Schumann, Johann

    2004-04-01

    AUTOBAYES is a fully automatic program synthesis system for the data analysis domain. Its input is a declarative problem description in form of a statistical model; its output is documented and optimized C/C++ code. The synthesis process relies on the combination of three key techniques. Bayesian networks are used as a compact internal representation mechanism which enables problem decompositions and guides the algorithm derivation. Program schemas are used as independently composable building blocks for the algorithm construction; they can encapsulate advanced algorithms and data structures. A symbolic-algebraic system is used to find closed-form solutions for problems and emerging subproblems. In this paper, we describe the application of AUTOBAYES to the analysis of planetary nebulae images taken by the Hubble Space Telescope. We explain the system architecture, and present in detail the automatic derivation of the scientists' original analysis as well as a refined analysis using clustering models. This study demonstrates that AUTOBAYES is now mature enough so that it can be applied to realistic scientific data analysis tasks.

  3. MULTIPLE FAST MOLECULAR OUTFLOWS IN THE PRE-PLANETARY NEBULA CRL 618

    SciTech Connect

    Lee, Chin-Fei; Huang, Po-Sheng; Sahai, Raghvendra; Sánchez Contreras, Carmen; Tay, Jeremy Jian Hao

    2013-11-01

    CRL 618 is a well-studied pre-planetary nebula. It has multiple highly collimated optical lobes, fast molecular outflows along the optical lobes, and an extended molecular envelope that consists of a dense torus in the equator and a tenuous round halo. Here we present our observations of this source in CO J = 3-2 and HCN J = 4-3 obtained with the Submillimeter Array at up to ∼0.''3 resolutions. We spatially resolve the fast molecular outflow region previously detected in CO near the central star and find it to be composed of multiple outflows that have similar dynamical ages and are oriented along the different optical lobes. We also detect fast molecular outflows further away from the central star near the tips of the extended optical lobes and a pair of equatorial outflows inside the dense torus. We find that two episodes of bullet ejections in different directions are needed, one producing the fast molecular outflows near the central star and one producing the fast molecular outflows near the tips of the extended optical lobes. One possibility to launch these bullets is a magneto-rotational explosion of the stellar envelope.

  4. Planetary Nebulae in the MW, LMC, SMC: Results from FUSE and HST data

    NASA Technical Reports Server (NTRS)

    Herald, J. E.; Bianchi, L.

    2003-01-01

    We use FUSE and HST data to study Planetary Nebulae (PN) systems in the Milky Way, LMC and SMC. Theoretically, metallicity affects several aspects of the post-AGB evolution, including mass-loss and the yield of processed material, which are important factors in the chemical evolution of galaxies. Therefore, it is very important to study PNe in different environments. In Bianchi's FUSE programs, we observed CSPN in the Milky Way (Cycle 1), LMC (Cycle 2) and SMC (Cyde 3), representing a range of metallicities from solar to 1/10th solar. The far-UV range reveals the spectrum of the central star (CSPN), uniquely enabling a direct estimate of the ionizing source parameters. Combined with archive HST data, these spectra provide a measurement of T(sub eff), log g, L(sub bol), abundances, wind velocity and mass-loss rate for these post-AGB stars. Additionally, these spectra provide a measurement of the circumstellar H2 and HI, which added to the mass of the central star and of the ionized shell allows us to test theoretical initial-final mass relations, and to put together a complete picture of the star's evolution.

  5. A search for diffuse bands in fullerene planetary nebulae: evidence of diffuse circumstellar bands

    NASA Astrophysics Data System (ADS)

    Díaz-Luis, J. J.; García-Hernández, D. A.; Kameswara Rao, N.; Manchado, A.; Cataldo, F.

    2015-01-01

    Large fullerenes and fullerene-based molecules have been proposed as carriers of diffuse interstellar bands (DIBs). The recent detection of the most common fullerenes (C60 and C70) around some planetary nebulae (PNe) now enable us to study the DIBs towards fullerene-rich space environments. We search DIBs in the optical spectra towards three fullerene-containing PNe (Tc 1, M 1-20, and IC 418). Special attention is given to DIBs which are found to be unusually intense towards these fullerene sources. In particular, an unusually strong 4428 Å absorption feature is a common charateristic of fullerene PNe. Similar to Tc 1, the strongest optical bands of neutral C60 are not detected towards IC 418. Our high-quality (S/N > 300) spectra for PN Tc 1, together with its large radial velocity, permit us to search for the presence of diffuse bands of circumstellar origin, which we refer to as diffuse circumstellar bands (DCBs). We report the first tentative detection of two DCBs at 4428 and 5780 Å in the fullerene-rich circumstellar environment around the PN Tc 1. Laboratory and theoretical studies of fullerenes in their multifarious manifestations (carbon onions, fullerene clusters, or even complex species formed by fullerenes and other molecules like PAHs or metals) may help solve the mystery of some of the diffuse band carriers. Appendix A is available in electronic form at http://www.aanda.org

  6. PHYSICAL STRUCTURE OF THE PLANETARY NEBULA NGC 3242 FROM THE HOT BUBBLE TO THE NEBULAR ENVELOPE

    SciTech Connect

    Ruiz, Nieves; Guerrero, MartIn A.; Chu, You-Hua; Gruendl, Robert A. E-mail: mar@iaa.es E-mail: gruendl@astro.illinois.edu

    2011-09-15

    One key feature of the interacting stellar winds model of the formation of planetary nebulae (PNe) is the presence of shock-heated stellar wind confined in the central cavities of PNe. This so-called hot bubble should be detectable in X-rays. Here we present XMM-Newton observations of NGC 3242, a multiple-shell PN whose shell morphology is consistent with the interacting stellar winds model. Diffuse X-ray emission is detected within its inner shell with a plasma temperature of {approx}2.35 x 10{sup 6} K and an intrinsic X-ray luminosity of {approx}2 x 10{sup 30} erg s{sup -1} at the adopted distance of 0.55 kpc. The observed X-ray temperature and luminosity are in agreement with 'ad hoc' predictions of models including heat conduction. However, the chemical abundances of the X-ray-emitting plasma seem to imply little evaporation of cold material into the hot bubble, whereas the thermal pressure of the hot gas is unlikely to drive the nebular expansion as it is lower than that of the inner shell rim. These inconsistencies are compounded by the apparent large filling factor of the hot gas within the central cavity of NGC 3242.

  7. Searching for planetary nebulae at the Galactic halo via J-PAS

    NASA Astrophysics Data System (ADS)

    Gonçalves, Denise R.; Aparício-Villegas, T.; Akras, S.; Cortesi, A.; Borges-Fernandes, M.; Daflon, S.; Pereira, C. B.; Lorenz-Martins, S.; Marcolino, W.; Kanaan, A.; Viironen, K.; de Oliveira, C. Mendes; Molino, A.; Ederoclite, A.

    2016-08-01

    The Javalambre-Physics of the Accelerating Universe Astrophysical Survey (J-PAS) is a narrow-band imaging, very wide field cosmological survey. It will last 5 years and will observe 8500 sq. deg. of the sky. There will be 54 contiguous narrow-band filters of 145Å FWHM, from 3,500 to 10,000Å. Two broad-band filters will be added at the extremes, UV and IR, plus the 3-g, r, and i- SDSS filters. Thus, J-PAS can be an important tool to search for new planetary nebulae (PNe) at the halo, increasing their numbers, because only 14 of them have been convincingly identified in the literature. Halo PNe are able to reveal precious information for the study of stellar evolution and the early chemical conditions of the Galaxy. The characteristic low continuum and intense emission lines of PNe make them good objects to be searched by J-PAS. Though covering a significantly smaller sky area, data from the ALHAMBRA survey were used to test our J-PAS strategy to search for PNe. Our first results are shown in this contribution.

  8. PLANETARY NEBULAE DETECTED IN THE SPITZER SPACE TELESCOPE GLIMPSE 3D LEGACY SURVEY

    SciTech Connect

    Zhang Yong; Hsia, Chih-Hao; Kwok, Sun E-mail: xiazh@hku.hk

    2012-01-20

    We used the data from the Spitzer Legacy Infrared Mid-Plane Survey Extraordinaire (GLIMPSE) to investigate the mid-infrared (MIR) properties of planetary nebulae (PNs) and PN candidates. In previous studies of GLIMPSE I and II data, we have shown that these MIR data are very useful in distinguishing PNs from other emission-line objects. In the present paper, we focus on the PNs in the field of the GLIMPSE 3D survey, which has a more extensive latitude coverage. We found a total of 90 Macquarie-AAO-Strasbourg (MASH) and MASH II PNs and 101 known PNs to have visible MIR counterparts in the GLIMPSE 3D survey area. The images and photometry of these PNs are presented. Combining the derived IRAC photometry at 3.6, 4.5, 5.8, and 8.0 {mu}m with the existing photometric measurements from other infrared catalogs, we are able to construct spectral energy distributions (SEDs) of these PNs. Among the most notable objects in this survey is the PN M1-41, whose GLIMPSE 3D image reveals a large bipolar structure of more than 3 arcmin in extent.

  9. FORMATION OF BIPOLAR PLANETARY NEBULAE BY INTERMEDIATE-LUMINOSITY OPTICAL TRANSIENTS

    SciTech Connect

    Soker, Noam; Kashi, Amit E-mail: kashia@physics.technion.ac.il

    2012-02-10

    We present surprising similarities between some bipolar planetary nebulae (PNe) and eruptive objects with peak luminosity between novae and supernovae. The latter group is termed ILOT for intermediate-luminosity optical transients (other terms are intermediate-luminosity red transients and red novae). In particular, we compare the PN, NGC 6302 and the pre-PNe OH231.8+4.2, M1-92, and IRAS 22036+5306 with the ILOT NGC 300 OT2008-1. These similarities lead us to propose that the lobes of some (but not all) PNe and pre-PNe were formed in an ILOT event (or several close sub-events). We suggest that in both types of objects the several months long outbursts are powered by mass accretion onto a main-sequence (MS) companion from an asymptotic giant branch (AGB, or extreme-AGB) star. Jets launched by an accretion disk around the MS companion shape the bipolar lobes. Some of the predictions that result from our comparison is that the ejecta of some ILOTs will have morphologies similar to those of bipolar PNe, and that the central stars of the PNe that were shaped by ILOTs should have an MS binary companion with an eccentric orbit of several years long period.

  10. THREE-DIMENSIONAL PHOTOIONIZATION STRUCTURE AND DISTANCES OF PLANETARY NEBULAE. IV. NGC 40

    SciTech Connect

    Monteiro, Hektor; Falceta-Goncalves, Diego E-mail: dfalceta@usp.br

    2011-09-10

    Continuing our series of papers on the three-dimensional (3D) structure and accurate distances of planetary nebulae (PNe), we present here the results obtained for PN NGC 40. Using data from different sources and wavelengths, we construct 3D photoionization models and derive the physical quantities of the ionizing source and nebular gas. The procedure, discussed in detail in the previous papers, consists of the use of 3D photoionization codes constrained by observational data to derive the 3D nebular structure, physical and chemical characteristics, and ionizing star parameters of the objects by simultaneously fitting the integrated line intensities, the density map, the temperature map, and the observed morphologies in different emission lines. For this particular case we combined hydrodynamical simulations with the photoionization scheme in order to obtain self-consistent distributions of density and velocity of the nebular material. Combining the velocity field with the emission-line cubes we also obtained the synthetic position-velocity plots that are compared to the observations. Finally, using theoretical evolutionary tracks of intermediate- and low-mass stars, we derive the mass and age of the central star of NGC 40 as (0.567 {+-} 0.06) M{sub sun} and (5810 {+-} 600) yr, respectively. The distance obtained from the fitting procedure was (1150 {+-} 120) pc.

  11. SPECTROSCOPIC OBSERVATIONS OF PLANETARY NEBULAE IN THE NORTHERN SPUR OF M31

    SciTech Connect

    Fang, X.; Liu, X.-W.; Zhang, Y.; Garcia-Benito, R.

    2013-09-10

    We present spectroscopy of three planetary nebulae (PNe) in the Northern Spur of the Andromeda galaxy (M31) obtained with the Double Spectrograph on the 5.1 m Hale Telescope at the Palomar Observatory. The samples were selected from the observations of Merrett et al. Our purpose is to investigate the formation of the substructures of M31 using PNe as a tracer of chemical abundances. The [O III] {lambda}4363 line is detected in the spectra of two objects, enabling temperature determinations. Ionic abundances are derived from the observed collisionally excited lines, and elemental abundances of nitrogen, oxygen, neon, sulfur, and argon are estimated. We study the correlations between oxygen and the {alpha}-element abundance ratios using our sample and the M31 disk and bulge PNe from the literature. In one of the three PNe, we observed a relatively higher oxygen abundance compared to the disk sample of M31 at similar galactocentric distances. The results of at least one of the three Northern Spur PNe might be in line with the proposed possible origin of the Northern Spur substructure of M31, i.e., the Northern Spur is connected to the Southern Stream and both substructures comprise the tidal debris of the satellite galaxies of M31.

  12. Panchromatic Hubble Andromeda Treasury. IX. A photometric survey of planetary nebulae in M31

    SciTech Connect

    Veyette, Mark J.; Williams, Benjamin F.; Dalcanton, Julianne J.; Balick, Bruce; Fouesneau, Morgan; Caldwell, Nelson; Girardi, Léo; Gordon, Karl D.; Kalirai, Jason; Rosenfield, Philip; Seth, Anil C.

    2014-09-10

    We search the Hubble Space Telescope (HST) Advanced Camera for Surveys and Wide Field Camera 3 broadband imaging data from the Panchromatic Hubble Andromeda Treasury (PHAT) survey to identify detections of cataloged planetary nebulae (PNs). Of the 711 PNs currently in the literature within the PHAT footprint, we find 467 detected in the broadband. For these 467, we are able to refine their astrometric accuracy from ∼0.''3 to 0.''05. Using the resolution of the HST, we are able to show that 152 objects currently in the catalogs are definitively not PNs, and we show that 32 objects thought to be extended in ground-based images are actually point-like and therefore good PN candidates. We also find one PN candidate that is marginally resolved. If this is a PN, it is up to 0.7 pc in diameter. With our new photometric data, we develop a method of measuring the level of excitation in individual PNs by comparing broadband and narrowband imaging and describe the effects of excitation on a PN's photometric signature. Using the photometric properties of the known PNs in the PHAT catalogs, we search for more PNs, but do not find any new candidates, suggesting that ground-based emission-line surveys are complete in the PHAT footprint to F475W ≅ 24.

  13. First detection of 3He+ in the planetary nebula IC 418

    NASA Astrophysics Data System (ADS)

    Guzman-Ramirez, L.; Rizzo, J. R.; Zijlstra, A. A.; García-Miró, C.; Morisset, C.; Gray, M. D.

    2016-07-01

    The 3He isotope is important to many fields of astrophysics, including stellar evolution, chemical evolution, and cosmology. The isotope is produced in low-mass stars which evolve through the planetary nebula (PN) phase. 3He abundances in PNe can help test models of the chemical evolution of the Galaxy. We present the detection of the 3He+ emission line using the single dish Deep Space Station 63, towards the PN IC 418. We derived a 3He/H abundance in the range 1.74 ± 0.8 × 10-3 to 5.8 ± 1.7 × 10-3, depending on whether part of the line arises in an outer ionized halo. The lower value for 3He/H ratio approaches values predicted by stellar models which include thermohaline mixing, but requires that large amounts of 3He are produced inside low-mass stars which enrich the interstellar medium (ISM). However, this overpredicts the 3He abundance in H II regions, the ISM, and protosolar grains, which is known to be of the order of 10-5. This discrepancy questions our understanding of the evolution of the 3He, from circumstellar environments to the ISM.

  14. ORBITS OF NEARBY PLANETARY NEBULAE AND THEIR INTERACTION WITH THE INTERSTELLAR MEDIUM

    SciTech Connect

    Wu Zhenyu; Ma Jun; Zhou Xu; Du Cuihua

    2011-03-15

    We present and analyze the orbits of eight nearby planetary nebulae (PNs) using two different Galactic models. The errors of the derived orbital parameters are determined with a Monte Carlo method. Based on the derived orbital parameters, we find that Sh 2-216, DeHt 5, NGC 7293, A21, and Ton 320 belong to the thin-disk population, and PG 1034 + 001 and A31 belong to the thick-disk population. PuWe 1 probably belongs to the thick-disk population, but its population classification is very uncertain due to the large errors of its derived orbital parameters. The PN-interstellar medium (ISM) interactions are observed for the eight PNs in our sample. The position angles of the proper motions of the PNs are consistent with the directions of the PN-ISM interaction regions. The kinematic ages of PNs are much smaller than the time for them to cross the Galactic plane. Using the models of Borkowski et al. and Soker et al., the PN-ISM interaction can be used to derive the local density of ISM in the vicinity of evolved PNs. According to the three-dimensional hydrodynamic simulations of Wareing et al. (WZO), Sh 2-216, A21, and Ton 320 are in the WZO 3 stage, PG 1034 + 001 and NGC 7293 are in the WZO 1 stage, and PuWe 1 is in the WZO 2 stage.

  15. Far-Ultraviolet Temperature Diagnostics for Hot Central Stars of Planetary Nebulae

    NASA Technical Reports Server (NTRS)

    Sonneborn, G.; Ipin, R. C.; Herald, J.

    2007-01-01

    The effective temperature of hot central stars of planetary nebulae is usually determined from the ratios of optical He II lines. However, far-ultraviolet spectra from the FUSE satellite of several hot (T(sub eff) > 70,000 K) hydrogen-rich central stars have stellar features that imply a significantly hotter effective temperature than that determined from He II. There are many stellar features in the long wavelength portion of the FUSE spectrum. These include O VI 1146-47, F VI 1039.5, FeVII 1118.6, 1141.4, FeVI 1120.9, 1131.5, and NiVI 1124.2, 1148.2. The strong FVI 1139.5 line is of interest because of the large overabundance (over 100X solar) of F in some PG1159 stars reported recently by Werner et al. (2005). Modeling these spectral features may provide an method for measuring the effective temperature of these stars independent of the He II lines. An example of HD 200516, the central star of NGC 7009 (T(sub eff)= 82000 K from He II vs 95000 K from Far-W metal lines) is presented.

  16. The First Water Fountain in a Planetary Nebula with Synchrotron Emission

    NASA Astrophysics Data System (ADS)

    Suárez, O.; Gómez, J. F.; Bendjoya, Ph.; Miranda, L. F.; Guerrero, M. A.; Uscanga, L.; Green, J. A.; Rizzo, J. R.; Ramos-Larios, G.

    2015-12-01

    Planetary nebulae (PNe) show a great variety of morphologies at optical wavelengths that might be due to the effects of jets (Sahai & Trauger [8]) and where magnetic fields might also play an important role. The special class of "water fountain" stars, showing high-velocity, collimated jets traced by water maser emission are key objects to understand the transition to the PN phase and the effect of the jets. IRAS 15103-5754 has been revealed as the youngest PN known, caught just at its birth. It is the first PN that shows water fountain characteristics (Gómez et al. [5]), and it shows, for the first time, direct evidence of the presence of synchrotron emission in a PN, tracing energetic, magnetized shocks (Suárez et al. [9]). Moreover, we observed a sudden change in the spectral distribution of its radio continuum emission, which marks the fast, recent passage of the ionization front over the radio-emitting region (Suárez et al. [9]).

  17. A search for hydrogenated fullerenes in fullerene-containing planetary nebulae

    NASA Astrophysics Data System (ADS)

    Díaz-Luis, J. J.; García-Hernández, D. A.; Manchado, A.; Cataldo, F.

    2016-05-01

    Detections of C60 and C70 fullerenes in planetary nebulae (PNe) of the Magellanic Clouds and of our own Galaxy have raised the idea that other forms of carbon, such as hydrogenated fullerenes (fulleranes like C60H36 and C60H18), buckyonions, and carbon nanotubes, may be widespread in the Universe. Here we present VLT/ISAAC spectra (R ~ 600) in the 2.9-4.1 μm spectral region for the Galactic PNe Tc 1 and M 1-20, which have been used to search for fullerene-based molecules in their fullerene-rich circumstellar environments. We report the non-detection of the most intense infrared bands of several fulleranes around ~3.4-3.6 μm in both PNe. We conclude that if fulleranes are present in the fullerene-containing circumstellar environments of these PNe, then they seem to be much less abundant than C60 and C70. Our non-detections, together with the (tentative) fulleranes detection in the proto-PN IRAS 01005+7910, suggest that fulleranes may be formed in the short transition phase between AGB stars and PNe, but they are quickly destroyed by the UV radiation field from the central star.

  18. First release of the IPHAS catalogue of new extended planetary nebulae

    NASA Astrophysics Data System (ADS)

    Sabin, L.; Parker, Q. A.; Corradi, R. L. M.; Guzman-Ramirez, L.; Morris, R. A. H.; Zijlstra, A. A.; Bojičić, I. S.; Frew, D. J.; Guerrero, M.; Stupar, M.; Barlow, M. J.; Mora, F. Cortés; Drew, J. E.; Greimel, R.; Groot, P.; Irwin, J. M.; Irwin, M. J.; Mampaso, A.; Miszalski, B.; Olguín, L.; Phillipps, S.; García, M. Santander; Viironen, K.; Wright, N. J.

    2014-10-01

    We present the first results of our search for new, extended planetary nebulae (PNe) based on careful, systematic, visual scrutiny of the imaging data from the Isaac Newton Telescope Photometric Hα Survey of the Northern Galactic plane (IPHAS). The newly uncovered PNe will help to improve the census of this important population of Galactic objects that serve as key windows into the late-stage evolution of low- to intermediate-mass stars. They will also facilitate study of the faint end of the ensemble Galactic PN luminosity function. The sensitivity and coverage of IPHAS allows PNe to be found in regions of greater extinction in the Galactic plane and/or those PNe in a more advanced evolutionary state and at larger distances compared to the general Galactic PN population. Using a set of newly revised optical diagnostic diagrams in combination with access to a powerful, new, multiwavelength imaging data base, we have identified 159 true, likely and possible PNe for this first catalogue release. The ability of IPHAS to unveil PNe at low Galactic latitudes and towards the Galactic Anticentre, compared to previous surveys, makes this survey an ideal tool to contribute to the improvement of our knowledge of the whole Galactic PN population.

  19. First Detection of 3He+ in the Planetary Nebula IC 418

    NASA Astrophysics Data System (ADS)

    Guzman-Ramirez, L.; Rizzo, J. R.; Zijlstra, A. A.; García-Miró, C.; Morisset, C.; Gray, M. D.

    2016-04-01

    The 3He isotope is important to many fields of astrophysics, including stellar evolution, chemical evolution, and cosmology. The isotope is produced in low-mass stars which evolve through the planetary nebula (PN) phase. 3He abundances in PNe can help test models of the chemical evolution of the Galaxy. We present the detection of the 3He+ emission line using the single dish Deep Space Station 63, towards the PN IC 418. We derived a 3He/H abundance in the range 1.74±0.8×10-3 to 5.8±1.7×10-3, depending on whether part of the line arises in an outer ionized halo. The lower value for 3He/H ratio approaches values predicted by stellar models which include thermohaline mixing, but requires that large amounts of 3He are produced inside low-mass stars which enrich the interstellar medium (ISM). However, this over-predicts the 3He abundance in H II regions, the ISM, and proto-solar grains, which is known to be of the order of 10-5. This discrepancy questions our understanding of the evolution of the 3He, from circumstellar environments to the ISM.

  20. The pulsating central star of the planetary nebula Kohoutek 1-16

    NASA Astrophysics Data System (ADS)

    Grauer, A. D.; Bond, H. E.

    1984-02-01

    High-speed photometry of the central star of the planetary nebula Kohoutek 1-16 shows it to be a low-amplitude pulsating variable. The dominant period is 28.3 minutes, with a semiamplitude that is usually about 0.01 mag. However, several additional periods sometimes appear in power spectra computed from light curves, and on two occasions a rapid drop into, or emergence from, a state in which no detectable variations were present was observed. Such 'mode switching' is typical of some of the ZZ Ceti-type white dwarf nonradial pulsators, but, at effective temperatures higher than 80,000 K, K1-16 is much too hot to be a ZZ Ceti variable. Spectroscopically and photometrically, the central star of K1-16 closely resembles the previously known hot pulsator PG 1159-035; these two objects represent a new pulsational instability mechanism for extremely hot degenerate or predegenerate stars. It is predicted that the evolutionary contraction of K1-16 will lead to a period decrease so rapid that it should be detectable over an interval of about 2 yr.

  1. Sculpting a Pre-Planetary Nebula with a Precessing Jet: IRAS 16342-3814

    NASA Technical Reports Server (NTRS)

    Sahai, R.; Le Mignant, D.; Sanchez Contreras, C.; Campbell, R. D.; Chaffee, F. H.

    2005-01-01

    We have imaged the bipolar pre-planetary nebula IRAS 16342-3814 with the Keck adaptive optics (AO) system in four near-infrared bands in the 1.6-4.7 (micro)m range. The lobes, which showed smoothly varying brightness distributions in previous optical images taken with the Hubble Space Telescope, have a limb-brightened appearance in the AO images, with a remarkable corkscrew structure inscribed on the lobe walls. A well-collimated, precessing jet with a diameter less than or approximately equal to 100 AU and a precession period less than or approximately equal to 50 yr, interacting with ambient circumstellar material, is most likely responsible for the corkscrew structure and the lobes, as indicated by a detailed comparison of our observations with published numerical simulations. The very red colors of the lobes in the near-infrared, coupled with their visibility at optical wavelengths, require that at least half, but not all, of the light of the central star be trapped by a compact circumstellar dust cloud heated to approximately 600-700 K and reradiated in the infrared. The lobes are thus illuminated both by the infrared light from this dust cloud as well as by the optical light from the central star.

  2. VLT/X-shooter Spectroscopy of a dusty planetary nebula discovered with Spitzer/IRS

    NASA Astrophysics Data System (ADS)

    Oliveira, I.; Overzier, R. A.; Pontoppidan, K. M.; van Dishoeck, E. F.; Spezzi, L.

    2011-02-01

    As part of a mid-infrared spectroscopic survey of young stars with the Spitzer Space Telescope, an unclassified red emission line object was discovered. Based on its high ionization state indicated by the Spitzer spectrum, this object could either be a dusty supernova remnant (SNR) or a planetary nebula (PN). In this research note, the object is classified and the available spectroscopic data are presented to the community for further analysis. UV/optical/NIR spectra were obtained during the science verification run of the VLT/X-shooter. A large number of emission lines are identified allowing the determination of the nature of this object. The presence of strong, narrow (Δv ~8 - 74 km s-1) emission lines, combined with very low line ratios of, e.g., [N ii]/Hα and [S ii]/Hα show that the object is a PN that lies at an undetermined distance behind the Serpens Molecular Cloud. This illustrates the potential of X-shooter as an efficient tool for constraining the nature of faint sources with unknown spectral properties or colors.

  3. Water Masers in W43A: Early Morphological Changes of a Future Planetary Nebula

    NASA Astrophysics Data System (ADS)

    Chong, Sze-Ning; Imai, Hiroshi; Diamond, Philip J.

    2015-05-01

    We present the distribution patterns of H2O maser features in the “water fountain” source (WF) W43A and show that they are closely related to the early morphological changes in a planetary nebula (PN). Using the Very Long Baseline Array, we have detected H2O maser features in W43A in 13 epochs across \\gt 10 yr. W43A is the only WF that has been observed for over a decade. We introduce a new cavity model scenario—a halo with a bipolar evacuated volume that has a partially enhanced wall—and compare it with the “traditional” precessing jet model particularly in terms of explaining the bow-shaped distribution patterns of H2O maser features in the most recent epochs and their temporal evolution. Long-term observations show that the distribution patterns require more than a single jet to form. Moreover, we have identified six groups of H2O maser features at both the redshifted and blueshifted sides with point symmetry. The six groups are believed to correspond to periodic mass profiles in the envelope and have recorded the mass-loss history. Together with a geometric similarity to the mid-infrared morphology of W43A, the results suggest that H2O masers can be used to trace the inner morphology and rapid temporal changes in evolved stars, especially where the PN shaping has just started.

  4. Formation and X-ray emission from hot bubbles in planetary nebulae - I. Hot bubble formation

    NASA Astrophysics Data System (ADS)

    Toalá, J. A.; Arthur, S. J.

    2014-10-01

    We carry out high-resolution two-dimensional radiation-hydrodynamic numerical simulations to study the formation and evolution of hot bubbles inside planetary nebulae. We take into account the evolution of the stellar parameters, wind velocity and mass-loss rate from the final thermal pulses during the asymptotic giant branch (AGB) through to the post-AGB stage for a range of initial stellar masses. The instabilities that form at the interface between the hot bubble and the swept-up AGB wind shell lead to hydrodynamical interactions, photoevaporation flows and opacity variations. We explore the effects of hydrodynamical mixing combined with thermal conduction at this interface on the dynamics, photoionization, and emissivity of our models. We find that even models without thermal conduction mix significant amounts of mass into the hot bubble. When thermal conduction is not included, hot gas can leak through the gaps between clumps and filaments in the broken swept-up AGB shell and this depressurises the bubble. The inclusion of thermal conduction evaporates and heats material from the clumpy shell, which expands to seal the gaps, preventing a loss in bubble pressure. The dynamics of bubbles without conduction is dominated by the thermal pressure of the thick photoionized shell, while for bubbles with thermal conduction it is dominated by the hot, shocked wind.

  5. Probing O-enrichment in C-rich dust planetary nebulae

    NASA Astrophysics Data System (ADS)

    García-Hernández, D. A.; Ventura, P.; Delgado-Inglada, G.; Dell'Agli, F.; Di Criscienzo, M.; Yagüe, A.

    2016-05-01

    The abundance of O in planetary nebulae (PNe) has been historically used as a metallicity indicator of the interstellar medium (ISM), where they originated; e.g. it has been widely used to study metallicity gradients in our Galaxy and beyond. However, clear observational evidence for O self-enrichment in low-metallicity Galactic PNe with C-rich dust has been recently reported. Here, we report asymptotic giant branch (AGB) nucleosynthesis predictions for the abundances of the CNO elements and helium in the metallicity range Z⊙/4 < Z < 2 Z⊙. Our AGB models, with diffusive overshooting from all the convective borders, predict that O is overproduced in low-Z low-mass (˜1-3 M⊙) AGB stars and nicely reproduce the recent O overabundances observed in C-rich dust PNe. This confirms that O is not always a good proxy of the original ISM metallicity and other chemical elements such as Cl or Ar should be used instead. The production of oxygen by low-mass stars should be thus considered in galactic-evolution models.

  6. Mid-infrared imaging of the bipolar planetary nebula M2-9 from SOFIA

    SciTech Connect

    Werner, M. W.; Sahai, R.; Davis, J.; Livingston, J.; Lykou, F.; DE Buizer, J.; Keller, L.; Adams, J.; Gull, G.; Henderson, C.; Herter, T.; Schoenwald, J.

    2014-01-10

    We have imaged the bipolar planetary nebula M2-9 using SOFIA's FORCAST instrument in six wavelength bands between 6.6 and 37.1 μm. A bright central point source, unresolved with SOFIA's ∼4''-5'' beam, is seen at each wavelength, and the extended bipolar lobes are clearly seen at 19.7 μm and beyond. The photometry between 10 and 25 μm is well fit by the emission predicted from a stratified disk seen at large inclination, as has been proposed for this source by Lykou et al. and by Smith and Gehrz. The principal new results in this paper relate to the distribution and properties of the dust that emits the infrared radiation. In particular, a considerable fraction of this material is spread uniformly through the lobes, although the dust density does increase at the sharp outer edge seen in higher resolution optical images of M2-9. The dust grain population in the lobes shows that small (<0.1 μm) and large (>1 μm) particles appear to be present in roughly equal amounts by mass. We suggest that collisional processing within the bipolar outflow plays an important role in establishing the particle size distribution.

  7. Using kinematic properties of pre-planetary nebulae to constrain engine paradigms

    NASA Astrophysics Data System (ADS)

    Blackman, Eric G.; Lucchini, Scott

    2014-05-01

    Some combination of binary interactions and accretion plausibly conspire to produce the ubiquitous collimated outflows from planetary nebulae (PN) and their presumed pre-PN (PPN) precursors. But which accretion engines are viable? The difficulty in observationally resolving the engines warrants the pursuit of indirect constraints. We show how kinematic outflow data for 19 PPN can be used to determine the minimum required accretion rates. We consider main-sequence (MS) and white dwarf (WD) accretors and five example accretion rates inferred from published models to compare with the minima derived from outflow momentum conservation. While our primary goal is to show the method in anticipation of more data and better theoretical constraints, taking the present results at face value already rules out modes of accretion: Bondi-Hoyle-Lyttleton (BHL) wind accretion and wind Roche lobe overflow (M-WRLOF, based on Mira parameters) are too feeble for all 19/19 objects for an MS accretor. For a WD accretor, BHL is ruled out for 18/19 objects and M-WRLOF for 15/19 objects. RLOF from the primary at the Red Rectangle level can accommodate 7/19 objects, though RLOF modes with higher accretion rates are not yet ruled out. Accretion modes operating from within common envelope evolution can accommodate all 19 objects, if jet collimation can be maintained. Overall, sub-Eddington rates for an MS accretor are acceptable but 8/19 would require super-Eddington rates for a WD. L61

  8. Automatic alignment of multi-temporal images of planetary nebulae using local optimization

    NASA Astrophysics Data System (ADS)

    Kazemzadeh, Farnoud; Hajian, Arsen R.

    2010-08-01

    Automatic alignment of time-separated astronomical images have historically proven to be difficult. The main reason for this difficulty is the amount of sporadic and unpredictable noise associated with astronomical images. A few examples of these effects are: image distortion due to optics, cosmic ray hits, transient background sources (super novae) and various artifact sources associated with the CCD imager itself. In this paper a new automated image registration method is introduced for aligning two time-separated images while minimizing the inherent errors and unpredictabilities. Using local optimization, the two images are aligned when the root mean square of the difference between the two images is minimized. The dataset consists of images of galactic planetary nebulae acquired by the Hubble Space Telescope. The aligned centroids inferred by the suggested method agree with the results from previously aligned images by inspection with high confidence. It is also demonstrated that this method is robust, sufficient, does not require extensive user input and it is highly sensitive to minor adjustments.

  9. Transformation from planetary nebula nucleus to white dwarf: a seismological study of stellar metamorphosis

    SciTech Connect

    Kawaler, S.D.

    1986-01-01

    The existence of several pulsating hot degenerates provides the exciting opportunity to study this transitory stage of stellar evolution with the techniques available from pulsation theory. Stellar models were evolved the planetary nebula-nucleus (PNN) phase to the cooling white dwarf phase using a variety of techniques; equations of linear adiabatic nonradial oscillations for these models were solved. The g-mode periods are determined within the degenerate core at high luminosities. The high radial overtone (20-40) and low order 1 (1-3) g-mode periods are comparable to those seen in the variable PG1159 stars. The period spacings agree as well, and appear to yield mode identifications. Rates of period change can be used to probe the mass, structure, composition, and energy loss mechanisms of these degenerates. The rates of period change for PNNs are strongly dependent on the rate of energy loss via neutrinos. The time scale for period change is about 10/sup 6/ years. Evolutionary changes in the rotation rate can be important also.

  10. Exploring the transition to planetary nebula using high-resolution techniques at infrared wavelengths

    NASA Astrophysics Data System (ADS)

    Wendolyn Blanco Cárdenas, Mónica

    2015-08-01

    A planetary nebula (PN) is the ionised envelope surrounding a white dwarf, the final fate of low- and intermediate-mass stars. This stellar phase is also important for its contribution to the interstellar medium, when PNe drive out s-process elements, molecules as well as different dust species, the building blocks of life. One of the most discussed topics in the PNe research field is their huge variety of morphologies and how the more complex forms are sculpted. The theoretical models predict the existence of collimating agents such as disks (steady and/or rotating), jets, and binary systems to sculpt these perplexing morphologies. However, the observations able to detect these shaping engines are often quite difficult to accomplish. Furthermore, the transition to PN hides the clues of these process, that is, when the AGB, post-AGBs, proto-PN, and the circumstellar environments of young PNe are compact and embeded in dust. In this work, we present our results implementing observational techniques and different analysis to inspect and resolve these structures by means of high-resolution imaging, high- and low-resolution spectroscopy at infrared wavelengths and using two VLT instruments: CRIRES (near-IR) and VISIR (mid-IR).

  11. A search for hydrogenated fullerenes in fullerene-containing planetary nebulae

    NASA Astrophysics Data System (ADS)

    Díaz-Luis, J. J.; García-Hernández, D. A.; Manchado, A.; Cataldo, F.

    2016-07-01

    Detections of C60 and C70 fullerenes in planetary nebulae (PNe) of the Magellanic Clouds and of our own Galaxy have raised the idea that other forms of carbon such as hydrogenated fullerenes (fulleranes like C60H36 and C60H18), buckyonions, and carbon nanotubes, may be widespread in the Universe. Here we present VLT/ISAAC spectra (R ∼⃒600) in the 2.9-4.1 µm spectral region for the Galactic PNe Tc 1 and M 1-20, which have been used to search for fullerene-based molecules in their fullerene-rich circumstellar environments. We report the non-detection of the most intense infrared bands of several fulleranes around ∼⃒3.4-3.6 μm in both PNe. We conclude that if fulleranes are present in the fullerene-containing circumstellar environments of these PNe, then they seem to be by far less abundant than C60 and C70. Our non-detections together with the (tentative) fulleranes detection in the proto-PN IRAS 01005+7910 suggest that fulleranes may be formed in the short transition phase between AGB stars and PNe but they are quickly destroyed by the UV radiation field from the central star.

  12. A robust expansion proper motion distance to the extraordinary planetary nebula KjPn 8

    NASA Astrophysics Data System (ADS)

    Boumis, P.; Meaburn, J.

    2014-04-01

    Since the discovery by Lopez, Vasquez and Rodriguez of the giant lobes projecting from the otherwise innocuous planetary nebula, KjPn 8, it has been imperative to obtain a robust distance (D) determination. This has now been achieved by comparing an image of the lobes taken in 2011 with the Greek Aristarchos telescope with that (POSSI-R) obtained in 1954: the baseline for expansive proper motions has therefore being extended to 57 yr. These proper motions, combined with previous radial velocity measurements and tilt of the most energetic outflow with respect to the sight line, as determined from HST imagery of the nebular core, give D = 1.8 ± 0.3 kpc. This value then lets the kinetic energy (approx 1047 erg) of the most recent and energetic outflow to be determined. It could be significant that this energy is consistent with an Intermediate Luminosity Optical Transient (ILOT) origin of the latest ejection as proposed for other similar objects by Soker and Kashi.

  13. Planetary Nebulae and their parent stellar populations. Tracing the mass assembly of M87 and Intracluster light in the Virgo cluster core

    NASA Astrophysics Data System (ADS)

    Arnaboldi, Magda; Longobardi, Alessia; Gerhard, Ortwin

    2016-08-01

    The diffuse extended outer regions of galaxies are hard to study because they are faint, with typical surface brightness of 1% of the dark night sky. We can tackle this problem by using resolved star tracers which remain visible at large distances from the galaxy centers. This article describes the use of Planetary Nebulae as tracers and the calibration of their properties as indicators of the star formation history, mean age and metallicity of the parent stars in the Milky Way and Local Group galaxies. We then report on the results from a deep, extended, planetary nebulae survey in a 0.5 deg2 region centered on the brightest cluster galaxy NGC 4486 (M87) in the Virgo cluster core, carried out with SuprimeCam@Subaru and FLAMES-GIRAFFE@VLT. Two planetary nebulae populations are identified out to 150 kpc distance from the center of M87. One population is associated with the M87 halo and the second one with the intracluster light in the Virgo cluster core. They have different line-of-sight velocity and spatial distributions, as well as different planetary nebulae specific frequencies and luminosity functions. The intracluster planetary nebulae in the surveyed region correspond to a luminosity of four times the luminosity of the Large Magellanic Cloud. The M87 halo planetary nebulae trace an older, more metal-rich, parent stellar population. A substructure detected in the projected phase-space of the line-of-sight velocity vs. major axis distance for the M87 halo planetary nebulae provides evidence for the recent accretion event of a satellite galaxy with luminosity twice that of M33. The satellite stars were tidally stripped about 1 Gyr ago, and reached apocenter at a major axis distance of 60-90 kpc from the center of M87. The M87 halo is still growing significantly at the distances where the substructure is detected.

  14. The Nucleus of the Planetary Nebula EGB 6 as a Post-Mira Binary

    NASA Astrophysics Data System (ADS)

    Bond, Howard E.; Ciardullo, Robin; Esplin, Taran L.; Hawley, Steven A.; Liebert, James; Munari, Ulisse

    2016-08-01

    EGB 6 is a faint, large, ancient planetary nebula (PN). Its central star, a hot DAOZ white dwarf (WD), is a prototype of a rare class of PN nuclei associated with dense, compact emission-line knots. The central star also shows excess fluxes in both the near-infrared (NIR) and mid-infrared (MIR). In a 2013 paper, we used Hubble Space Telescope (HST) images to show that the compact nebula is a point-like source, located 0.″16 (˜118 AU) from the WD. We attributed the NIR excess to an M dwarf companion star, which appeared to coincide with the dense emission knot. We now present new ground-based NIR spectroscopy, showing that the companion is actually a much cooler source with a continuous spectrum, apparently a dust-enshrouded low-luminosity star. New HST images confirm common proper motion of the emission knot and red source with the WD. The I-band, NIR, and MIR fluxes are variable, possibly on timescales as short as days. We can fit the spectral energy distribution (SED) with four blackbodies (the WD, a ˜1850 K NIR component, and MIR dust at 385 and 175 K). Alternatively, we show that the NIR/MIR SED is very similar to that of Class 0/I young stellar objects. We suggest a scenario in which the EGB 6 nucleus is descended from a wide binary similar to the Mira system, in which a portion of the wind from an AGB star was captured into an accretion disk around a companion star; a remnant of this disk has survived to the present time and is surrounded by gas photoionized by UV radiation from the WD. Based in part on data obtained with the NASA/ESA Hubble Space Telescope, obtained by the Space Telescope Science Institute. STScI is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. Also based in part on observations with the 1.5 m telescope operated by the SMARTS Consortium at Cerro Tololo Inter-American Observatory.

  15. The Nucleus of the Planetary Nebula EGB 6 as a Post-Mira Binary

    NASA Astrophysics Data System (ADS)

    Bond, Howard E.; Ciardullo, Robin; Esplin, Taran L.; Hawley, Steven A.; Liebert, James; Munari, Ulisse

    2016-08-01

    EGB 6 is a faint, large, ancient planetary nebula (PN). Its central star, a hot DAOZ white dwarf (WD), is a prototype of a rare class of PN nuclei associated with dense, compact emission-line knots. The central star also shows excess fluxes in both the near-infrared (NIR) and mid-infrared (MIR). In a 2013 paper, we used Hubble Space Telescope (HST) images to show that the compact nebula is a point-like source, located 0.″16 (∼118 AU) from the WD. We attributed the NIR excess to an M dwarf companion star, which appeared to coincide with the dense emission knot. We now present new ground-based NIR spectroscopy, showing that the companion is actually a much cooler source with a continuous spectrum, apparently a dust-enshrouded low-luminosity star. New HST images confirm common proper motion of the emission knot and red source with the WD. The I-band, NIR, and MIR fluxes are variable, possibly on timescales as short as days. We can fit the spectral energy distribution (SED) with four blackbodies (the WD, a ∼1850 K NIR component, and MIR dust at 385 and 175 K). Alternatively, we show that the NIR/MIR SED is very similar to that of Class 0/I young stellar objects. We suggest a scenario in which the EGB 6 nucleus is descended from a wide binary similar to the Mira system, in which a portion of the wind from an AGB star was captured into an accretion disk around a companion star; a remnant of this disk has survived to the present time and is surrounded by gas photoionized by UV radiation from the WD. Based in part on data obtained with the NASA/ESA Hubble Space Telescope, obtained by the Space Telescope Science Institute. STScI is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. Also based in part on observations with the 1.5 m telescope operated by the SMARTS Consortium at Cerro Tololo Inter-American Observatory.

  16. THE DETECTION OF C60 IN THE WELL-CHARACTERIZED PLANETARY NEBULA M1-11

    SciTech Connect

    Otsuka, Masaaki; Kemper, F.; Hyung, S.; Sargent, B. A.; Meixner, M.; Tajitsu, A.; Yanagisawa, K.

    2013-02-10

    We performed multiwavelength observations of the young planetary nebula (PN) M1-11 and obtained its elemental abundances, dust mass, and the evolutionary status of the central star. The AKARI/IRC, VLT/VISIR, and Spitzer/IRS spectra show features due to carbon-rich dust, such as the 3.3, 8.6, and 11.3 {mu}m features due to polycyclic aromatic hydrocarbons (PAHs), a smooth continuum attributable to amorphous carbon, and the broad 11.5 and 30 {mu}m features often ascribed to SiC and MgS, respectively. We also report the presence of an unidentified broad feature at 16-22 {mu}m, similar to the feature found in Magellanic Cloud PNe with either C-rich or O-rich gas-phase compositions. We identify for the first time in M1-11 spectral lines at 8.5 (blended with PAH), 17.3, and 18.9 {mu}m that we attribute to the C{sub 60} fullerene. This identification is strengthened by the fact that other Galactic PNe in which fullerenes are detected have similar central stars, similar gas-phase abundances, and a similar dust composition to M1-11. The weak radiation field due to the relatively cool central stars in these PNe may provide favorable conditions for fullerenes to survive in the circumstellar medium. Using the photoionization code CLOUDY, combined with a modified blackbody, we have fitted the {approx}0.1-90 {mu}m spectral energy distribution (SED) and determined the dust mass in the nebula to be {approx}3.5 Multiplication-Sign 10{sup -4} M {sub Sun }. Our chemical abundance analysis and SED model suggest that M1-11 is perhaps a C-rich PN with C/O ratio in the gas phase of +0.19 dex, and that it evolved from a 1-1.5 M {sub Sun} star.

  17. Heavy Element Abundances in Planetary Nebulae from Deep Optical Echelle Spectroscopy

    NASA Astrophysics Data System (ADS)

    Mashburn, Amanda; Sterling, Nicholas C.; Dinerstein, Harriet L.; Garofali, Kristen; Jensema, Rachael; Turbyfill, Amanda; Wieser, Hannah-Marie N.; Reed, Evan C.; Redfield, Seth

    2016-01-01

    We present the abundances of neutron(n)-capture elements (atomic number Z > 30) and iron determined from deep optical echelle spectroscopy of 14 Galactic planetary nebulae (PNe). The spectra were obtained with the 2D-coudé spectrograph on the 2.7-m Harlan J. Smith telescope at McDonald Observatory. The abundances of n-capture elements can be enhanced in PNe due to slow n-capture nucleosynthesis in the progenitor asymptotic giant branch (AGB) stars. The high spectral resolution of these data (R = 36,700) allow most n-capture element emission lines to be resolved from other nebular and telluric features. We detect Kr in all of the observed PNe (with multiple ions detected in several objects), while Br, Rb, and Xe were each detected in 4--5 objects. Using the new Kr ionization correction factors (ICFs) of Sterling et al. (2015, ApJS, 218, 25), we find [Kr/O] abundances ranging from 0.05 to 1.1 dex. We utilize approximate ICFs for the other n-capture elements, and find slightly lower enrichments for Br and Rb (-0.1 to 0.7 dex), while Xe is enhanced relative to solar by factors of two to 30. The [Xe/Kr] ratios range from -0.3 to 1.4 dex, indicating a significant range in neutron exposures in PN progenitor stars. Interestingly, the largest [Xe/Kr] ratio is found in the thick-disk PN NGC 6644, which has a lower metallicity than the other observed PNe. We detect iron emission lines in all but one target. Fe can be depleted into dust grains in ionized nebulae, and its abundance thus provides key information regarding dust-to-gas ratios and grain destruction processes. We find that [Fe/O] ranges from -1.3 to -0.7 dex in the observed PNe, a smaller spread of depletion factors than found in recent studies (Delgado-Inglada & Rodriguez 2014, ApJ, 784, 173) though this may be due in part to our smaller sample. These data are part of a larger study of heavy elements in PNe, which will provide more accurate determinations of n-capture element abundances than previous estimates in

  18. Mid-IR and radio images of IC 418: dust in a young planetary nebula.

    NASA Astrophysics Data System (ADS)

    Meixner, M.; Skinner, C. J.; Keto, E.; Zijlstra, A.; Hoare, M. G.; Arens, J. F.; Jernigan, J. G.

    1996-09-01

    We present three new images of the young, carbon rich planetary nebula, IC 418: 11.3μm dust emission, a [Ne II]12.8μm line emission and 6cm free-free continuum. All three images show different morphologies. In order to investigate these spatial differences and the mechanisms of dust emission in IC 418, we compare our data to two radiative transfer models with different radial density distributions. Model 1 has a thin shell that drops off as r^-3^, resulting in a high density ionized region surrounded by an ionized halo. While, model 2 has a thicker shell that drops off as r^-2^ resulting in the ionization front stopping in the thick shell and a high density ionized region immediately surrounded by a neutral shell. Both models use a mixture of silicon carbide (SiC) and amorphous carbon (AC) dust grains with dust to gas ratios of ~2x10^-5^ and ~6x10^-4^, respectively and the standard power law distribution in sizes (a^-3.5^; 0.005μmnebula. However, model 1 better explains all of the many previous observations of IC 418 at different wavelengths. We suggest a three layer onion model for IC 418: a ~6" radius high density ionized region surrounded by a ~20" radius low density ionized halo, enclosed by a completely photodissociated neutral halo extended beyond a ~80

  19. THE CHANDRA X-RAY SURVEY OF PLANETARY NEBULAE (CHANPLANS): PROBING BINARITY, MAGNETIC FIELDS, AND WIND COLLISIONS

    SciTech Connect

    Kastner, J. H.; Montez, R. Jr.; Rapson, V.; Balick, B.; Frew, D. J.; De Marco, O.; Parker, Q. A.; Miszalski, B.; Sahai, R.; Blackman, E.; Frank, A.; Chu, Y.-H.; Guerrero, M. A.; Zijlstra, A.; Behar, E.; Bujarrabal, V.; Corradi, R. L. M.; Nordhaus, J.; Sandin, C. E-mail: soker@physics.technion.ac.il; and others

    2012-08-15

    We present an overview of the initial results from the Chandra Planetary Nebula Survey (CHANPLANS), the first systematic (volume-limited) Chandra X-Ray Observatory survey of planetary nebulae (PNe) in the solar neighborhood. The first phase of CHANPLANS targeted 21 mostly high-excitation PNe within {approx}1.5 kpc of Earth, yielding four detections of diffuse X-ray emission and nine detections of X-ray-luminous point sources at the central stars (CSPNe) of these objects. Combining these results with those obtained from Chandra archival data for all (14) other PNe within {approx}1.5 kpc that have been observed to date, we find an overall X-ray detection rate of {approx}70% for the 35 sample objects. Roughly 50% of the PNe observed by Chandra harbor X-ray-luminous CSPNe, while soft, diffuse X-ray emission tracing shocks-in most cases, 'hot bubbles'-formed by energetic wind collisions is detected in {approx}30%; five objects display both diffuse and point-like emission components. The presence (or absence) of X-ray sources appears correlated with PN density structure, in that molecule-poor, elliptical nebulae are more likely to display X-ray emission (either point-like or diffuse) than molecule-rich, bipolar, or Ring-like nebulae. All but one of the point-like CSPNe X-ray sources display X-ray spectra that are harder than expected from hot ({approx}100 kK) central stars emitting as simple blackbodies; the lone apparent exception is the central star of the Dumbbell nebula, NGC 6853. These hard X-ray excesses may suggest a high frequency of binary companions to CSPNe. Other potential explanations include self-shocking winds or PN mass fallback. Most PNe detected as diffuse X-ray sources are elliptical nebulae that display a nested shell/halo structure and bright ansae; the diffuse X-ray emission regions are confined within inner, sharp-rimmed shells. All sample PNe that display diffuse X-ray emission have inner shell dynamical ages {approx}< 5 Multiplication-Sign 10{sup

  20. The extinction and dust-to-gas structure of the planetary nebula NGC 7009 observed with MUSE

    NASA Astrophysics Data System (ADS)

    Walsh, J. R.; Monreal-Ibero, A.; Barlow, M. J.; Ueta, T.; Wesson, R.; Zijlstra, A. A.

    2016-04-01

    Context. Dust plays a significant role in planetary nebulae. Dust ejected with the gas in the asymptotic giant branch (AGB) phase is subject to the harsh environment of the planetary nebula (PN) while the star is evolving towards a white dwarf. Dust surviving the PN phase contributes to the dust content of the interstellar medium. Aims: The morphology of the internal dust extinction has been mapped for the first time in a PN, the bright nearby Galactic nebula NGC 7009. The morphologies of the gas, dust extinction and dust-to-gas ratio are compared to the structural features of the nebula. Methods: Emission line maps in H Balmer and Paschen lines were formed from analysis of MUSE cubes of NGC 7009 observed during science verification of the instrument. The measured electron temperature and density from the same cube were employed to predict the theoretical H line ratios and derive the extinction distribution across the nebula. After correction for the interstellar extinction to NGC 7009, the internal AV/NH has been mapped for the first time in a PN. Results: The extinction map of NGC 7009 has considerable structure, broadly corresponding to the morphological features of the nebula. The dust-to-gas ratio, AV/NH, increases from 0.7 times the interstellar value to >5 times from the centre towards the periphery of the ionized nebula. The integrated AV/NH is about 2× the mean ISM value. A large-scale feature in the extinction map is a wave, consisting of a crest and trough, at the rim of the inner shell. The nature of this feature is investigated and instrumental and physical causes considered; no convincing mechanisms were identified to produce this feature, other than AGB mass loss variations. Conclusions: Extinction mapping from H emission line imaging of PNe with MUSE provides a powerful tool for revealing the properties of internal dust and the dust-to-gas ratio. Based on observations collected at the European Organisation for Astronomical Research in the Southern

  1. International Ultraviolet Explorer observations of the white dwarf nucleus of the very old, diffuse planetary nebula, IW-2

    NASA Technical Reports Server (NTRS)

    Bruhweiler, F. C.; Feibelman, Walter A.

    1993-01-01

    UV low-dispersion spectra of the central star of the faint planetary nebula, IW-2, were obtained with the IUE. The apparent large diameter of the very diffuse nebula, about half that of the moon, as seen on the Palomar Sky Survey plates by Ishida and Weinberger (1987), indicates this object to be potentially quite evolved, and nearby. The IUE spectra clearly reveal a hot stellar continuum extending over the entire wavelength range of the short-wavelength prime camera (1200-2000 A). This object with V = 17.7 +/- 0.4 is definitely one of the faintest stars ever successfully observed with the IUE. Comparisons of the IUE observed fluxes with those from white dwarf model atmospheres suggest extinction near E(B - V) = 0.45 for a white dwarf of T(eff) roughly 100,000 K. Constraints from estimates of the nebular emission measure and observed visual magnitude also argue for a white dwarf of T(eff) roughly 100,000 K at a distance of 300 to 350 pc. The nucleus of IW-2 is one of the most evolved stars to be identified with a planetary nebula.

  2. ARE PROTO-PLANETARY NEBULAE SHAPED BY A BINARY? RESULTS OF A LONG-TERM RADIAL VELOCITY STUDY

    SciTech Connect

    Hrivnak, Bruce J.; Lu Wenxian; Bohlender, David; Morris, S. C.; Woodsworth, Andrew W.; Scarfe, C. D. E-mail: wen.lu@valpo.edu E-mail: David.Bohlender@nrc-cnrc.gc.ca

    2011-06-10

    The shaping of the nebula is currently one of the outstanding unsolved problems in planetary nebula (PN) research. Several mechanisms have been proposed, most of which require a binary companion. However, direct evidence for a binary companion is lacking in most PNs. We have addressed this problem by obtaining precise radial velocities of seven bright proto-planetary nebulae (PPNs), objects in transition from the asymptotic giant branch to the PN phases of stellar evolution. These have F-G spectral types and have the advantage over PNs of having more and sharper spectral lines, leading to better precision. Our observations were made in two observing intervals, 1991-1995 and 2007-2010, and we have included in our analysis some additional published and unpublished data. Only one of the PPNs, IRAS 22272+5435, shows a long-term variation that might tentatively be attributed to a binary companion, with P > 22 yr, and from this, limiting binary parameters are calculated. Selection effects are also discussed. These results set significant restrictions on the range of possible physical and orbital properties of any binary companions: they have periods greater than 25 yr or masses of brown dwarfs or super-Jupiters. While not ruling out the binary hypothesis, it seems fair to say that these results do not support it.

  3. Rapid photometric and spectroscopic evolution of the young planetary nebula Hen 3-1357 and its central star SAO 244567

    NASA Astrophysics Data System (ADS)

    Arkhipova, V. P.; Ikonnikova, N. P.; Kniazev, A. Yu.; Rajoelimanana, Andry

    2013-03-01

    We present the results of spectroscopic and photometric observations for the young compact planetary nebula Hen 3-1357 and its central star SAO 244567. High-resolution spectroscopy has allowed the expansion velocity of the nebula, V exp = 8.4 ± 1.5 km s-1, and the heliocentric velocity of the object, V r = +12.6 ± 1.7 km s-1, to be determined. The gas shell parameters ( N e , T e ), the extinction in the H β line, and the O, N, Ne, Ar, S, Cl, He, and C abundances have been determined from low-resolution spectra taken in 1992 and 2011. We have found significant changes in the relative intensities of forbidden lines in the spectrum of Hen 3-1357 within the last 20 years: the low-excitation [O I], [O II], and [N II] lines became stronger relative to H β by a factor of ˜2, while the [O III] lines weakened by a factor of ˜ 2, suggesting a decrease in the excitation class of the nebula. The V-band photometry performed under the ASAS-3 program revealed a decline in the yearly mean brightness of SAO 244 567 from 2001 to 2009 by 0_.^m 5 and rapid variability with an amplitude of a few tenths of a magnitude. Published observational data in a wide spectral range, from the near ultraviolet to the radio band, suggest an appreciable weakening of the flux from the star and the nebula.

  4. A search for water maser emission toward obscured post-AGB star and planetary nebula candidates

    NASA Astrophysics Data System (ADS)

    Gómez, J. F.; Rizzo, J. R.; Suárez, O.; Palau, A.; Miranda, L. F.; Guerrero, M. A.; Ramos-Larios, G.; Torrelles, J. M.

    2015-06-01

    Context. Water maser emission at 22 GHz is a useful probe for studying the transition between the nearly spherical mass loss in the asymptotic giant branch (AGB) to a collimated one in the post-AGB phase. In their turn, collimated jets in the post-AGB phase could determine the shape of planetary nebulae once photoionization starts. Aims: We intend to find new cases of post-AGB stars and planetary nebulae (PNe) with water maser emission, including some especially interesting and rare types: water fountains (evolved objects with high velocity collimated jets traced by water masers) or water-maser-emitting PNe. Since previous studies have shown a higher detection rate of water maser emission in evolved objects that are optically obscured, we selected a sample that contains a significant fraction of post-AGB and young PN candidate sources showing signs of strong obscuration. Methods: We searched for water maser emission in 133 evolved objects using the radio telescopes in Robledo de Chavela, Parkes, and Green Bank. Results: We detected water maser emission in 15 sources of our sample, of which seven are reported here for the first time (IRAS 13483-5905, IRAS 14249-5310, IRAS 15408-5413, IRAS 17021-3109, IRAS 17348-2906, IRAS 17393-2727, and IRAS 18361-1203). We identified three water fountain candidates: IRAS 17291-2147, with a total velocity spread of ≃96 km s-1 in its water maser components and two sources (IRAS 17021-3109 and IRAS 17348-2906) that show water maser emission whose velocity lies outside the velocity range covered by OH masers. We have also identified IRAS 17393-2727 as a possible new water-maser-emitting PN. Conclusions: The detection rate is higher in obscured objects (14%) than in those with optical counterparts (7%), which is consistent with previous results. Water maser emission seems to be common in objects that are bipolar in the near-IR (43% detection rate in such sources). The water maser spectra of water fountain candidates like IRAS 17291

  5. Barium Isotope Heterogeneities in Planetary Materials: Applications to Incomplete Mixing of the Solar Nebula

    NASA Astrophysics Data System (ADS)

    Ranen, M. C.; Jacobsen, S. B.

    2006-05-01

    A persistent view among geochemists is that the Solar System formed as a hot, well mixed disk of dust and gas that had the same initial isotopic composition of heavy elements throughout. Thus, all meteorite parent bodies and terrestrial planets would have identical stable isotopic ratios of refractory, heavy elements. In order to explain the initial isotope ratios of various extinct nuclides, both injection of supernova and AGB star material to the proto-solar molecular cloud or disk within a few million years of formation has been proposed. A common view is that these r-process and s-process contributions were homogenized throughout the disk. The existence of pre-solar grains in meteorites shows that grains with extremely large isotopic differences have been preserved. Some rare, refractory inclusions in carbonaceous chondrites have relatively large r-process excesses while a large portion of pre-solar grains found in chondrites are almost pure s-process material. The survival of these grains means that the nebula could not be as homogenized as previously thought. Thus, it is plausible for various planets and planetesimals to have slightly different inventories of r- and s-process nuclides. Small isotopic differences between bulk meteorites and the Earth have been measured for both Mo and Zr (Yin et al. 2002). Boyet and Carlson (2005) measured a 20 ppm difference in 142Nd between the Earth and chondrites which could either be due to decay of 146Sm or an r-process enrichment in chondritic meteorites compared to the Earth, consistent with the Mo and Zr data. We have measured Ba isotopes in various chondrites to further investigate heavy element isotope heterogeneities in bulk planetary bodies. Barium is an ideal element to study because it has many isotopes, some of which are formed only in the s-process. All chondrites show r-process excesses of up to 40 ppm in 138Ba compared to the Earth. This is likely an r-process excess due to incomplete mixing of r- and s

  6. The structure of the planetary nebula NGC 2371 in the visible and mid-infrared

    NASA Astrophysics Data System (ADS)

    Ramos-Larios, Gerardo; Phillips, J. P.

    2012-09-01

    We investigate the structure of the planetary nebula NGC 2371 using [O III] λ5007 imaging taken with the Jacobus Kapteyn 1.0 m telescope, and [N II] λ6584, [O III] λ5007 and Hα results acquired with the Hubble Space Telescope. These are supplemented with archival mid-infrared (MIR) observations taken with the Spitzer Space Telescope. We note the presence of off-axis low-ionization spokes along a position angle of 65°, and associated collars of enhanced [O III] emission. The spokes appear to consist of dense condensations having low-excitation tails, possibly arising due to ultraviolet shadowing and/or ram-pressure stripping of material. Line ratios imply that most of the emission arises through photoionization, and is unlikely to derive from post-shock cooling regions. An analysis of these features in the MIR suggests that they may also be associated with high levels of emission from polycyclic aromatic hydrocarbons (PAHs), together with various permitted and forbidden line transitions. Such high levels of PAH emission, where they are confirmed, may develop as a result of preferentially enhanced far-ultraviolet pumping of the molecules, or shattering of larger grains within local shocks. Although H2 emission may also contribute to these trends, it is argued that shock-excited transitions would lead to markedly differing results. We finally note that thin filaments and ridges of [O III] emission may indicate the presence of shock activity at the limits of the interior envelope, as well as at various positions within the shell itself. We also note that radially increasing fluxes at 3.6, 5.8 and 8.0 μm, relative to the emission at 4.5 μm, may arise due to enhanced PAH emission in external photodissociative regions.

  7. A multiwavelength analysis of planetary nebulae in the Large Magellanic Cloud

    NASA Astrophysics Data System (ADS)

    Reid, Warren A.

    2014-03-01

    This paper examines, compares and plots optical, near- and mid-infrared (MIR) photometric data for 605 planetary nebulae (PNe) in the Large Magellanic Cloud (LMC). With the aid of multiwavelength surveys such as the Spitzer legacy programme Surveying the Agents of a Galaxy's Evolution, the Two Micron All Sky Survey and the Magellanic Cloud Photometric Survey, plots have been constructed to expose the relative contributions from molecular hydrogen, polycyclic aromatic hydrocarbons, forbidden emission lines, warm dust continuum and stellar emission at various bands. Besides identifying trends, these plots have helped to reveal PN mimics including six previously known PNe in the outer LMC which are re-classified as other object types. Together with continuing follow-up optical observations, the data have enabled a substantial reduction in the number of PNe previously tagged as `likely' and `possible'. The total number of LMC PNe is adjusted to 715 but with a greater degree of confidence in regard to classification. In each colour-colour plot, the more highly evolved LMC PNe are highlighted for comparison with younger, brighter PNe. The faintest and most evolved PNe typically cluster in areas of colour-colour space occupied by ordinary stars. Possible reasons for the wide disparity in infrared colour-colour ratios, such as evolution and dust composition, are presented for evaluation. A correlation is found between the optical luminosity of PNe, emission-line ratios and the MIR dust luminosity at various bands. Luminosity functions using the four Infrared Array Camera and Multiband Imaging Photometer of Spitzer (MIPS) [24] bands are directly compared, revealing an increasing accumulation of PNe within the brightest two magnitudes at longer wavelengths. A correlation is also found between the MIPS [24] band and the [O III] 5007 and Hβ fluxes.

  8. Constraints on Common Envelope Magnetic Fields from Observations of Jets in Planetary Nebulae

    NASA Astrophysics Data System (ADS)

    De Marco, Orsola; Tocknell, J.; Wardle, M.

    2014-01-01

    The common envelope (CE) interaction describes the swallowing of a nearby companion by a growing, evolving star. CEs that take place during the asymptotic giant branch phase of the primary and may lead to the formation of a planetary nebula (PN) with a post-CE close binary in the middle. We have used published observations of masses and kinematics of jets in four post-CE PN to infer physical characteristics of the CE interaction. In three of the four systems studied, Abell 63, ETHOS 1 and the Necklace PN, the kinematics indicate that the jets were launched a few thousand years before the CE and we favour a scenario where this happened before Roche lobe overflow, although better models of wind accretion and wind Roche lobe overflow are needed. The magnetic fields inferred to launch pre-CE jets are of the order of a few Gauss. In the fourth case, NGC 6778, the kinematics indicate that the jets were launched about 3000 years after the CE interaction. Magnetic fields of the order of a few hundreds to a few thousands Gauss are inferred in this case, approximately in line with predictions of post-CE magnetic fields. However, we remark that in the case of this system, we cannot find a reasonable scenario for the formation of the two jet pairs observed: the small orbital separation would preclude the formation of even one accretion disk able to supply the necessary accretion rate to cause the observed jets. Additional and improved observations of post-CE PN will provide a powerful tool to constrain the CE interaction.

  9. Spectroscopic Study of HD 179821 (IRAS 19114+0002): Proto-Planetary Nebula or Supergiant?

    NASA Technical Reports Server (NTRS)

    Reddy, B. E.; Hrivnak, Bruce J.

    1999-01-01

    A detailed chemical composition analysis of the bright post-AGB candidate HD 179821 (IRAS 19114 + 0002) is presented. The LTE analysis, based on high-resolution (R approximately equal 50,000) and high-quality (S/N approximately equal 300) spectra, yields atmospheric parameters T(sub eff) = 6750 K, log g = 0.5, and xi(sub t) = 5.25 km/s. The elemental abundance results of HD 179821 are found to be [Fe/H] = -0.1, [C/Fe] = +0.2, [N/Fe] = +1.3, [O/Fe] = +0.2, [alpha-process/Fe] = +0.5, and [s-process/Fe] = +0.4. These values clearly differ from the elemental abundances of Population I F supergiants. The C, N, and O abundances and the total CNO abundance value relative to Fe, [C+N+O/Fe] = +0.5, indicate that the photosphere of HD 179821 is contaminated with both the H- and He-burning products of the AGB phase. The evidence for He burning through the 3.alpha process and deep AGB mixing also comes from the observed overabundances of s-process elements. Remarkably, the abundance of the element Na is found to be very large, [Na/Fe] = +0.9. The ratio O/C = 2.6 indicates that the atmosphere is oxygen rich. The results of this abundance study support the argument that HD 179821 is a proto-planetary nebula,. probably with an intermediate-mass progenitor. However, the strength of the O I triplet lines at 7774 A and the distance derived from the interstellar Na I D1 and D2 components imply that the star is a luminous object (M(sub bol) approximately -8.9 +/- 1) and thus a massive supergiant. Thus, while this study contributes important new observational results for this star, an unambiguous determination of its evolutionary status has yet to be achieved.

  10. High-dispersion Spectrum of the Halo Planetary Nebula DdDm 1

    NASA Astrophysics Data System (ADS)

    Otsuka, Masaaki; Hyung, Siek; Lee, Seong-Jae; Izumiura, Hideyuki; Tajitsu, Akito

    2009-11-01

    Using the High Dispersion Spectrograph (HDS) at the Subaru Telescope, we secured the high-resolution line spectra in the 3600-7500 Å wavelength range of the Galactic halo planetary nebula DdDm 1. We also analyzed the Hubble Space Telescope Faint Object Spectrograph data in the 1200-6730 Å wavelength range. The diagnostic results indicate the electron temperatures of T epsilon~ 11,000-14,000 K and the electron number densities of N epsilon~ 2000-10,500 cm-3. In spite of high gaseous temperatures, we have not detected high excitation lines, e.g., He II. We derived abundance based on the ionic concentration of permitted and forbidden lines and the photoionization model. A comparison of the ionic concentrations from forbidden lines to recombination lines shows the abundance discrepancy between them. We tested various possibilities, e.g., temperature fluctuation and high-density blob components, to explain the discrepancy. The high-density components or density fluctuation might be partly responsible for the discrepancy. DdDm 1 shows a low carbon abundance that corresponds to metal-poor stars, [Fe/H] <=-1. Assuming a distance of 10 kpc to DdDm 1, theoretical models suggest that the central star has T effsime 39,000 K and Lsime 2000-3000 L sun. The relatively high gas temperatures appear to be caused by very low heavy elemental abundances or insufficient coolants in the shell gas. Its progenitor, born in an extremely carbon-poor environment as an initial mass of about 0.9 M sun, had probably experienced only the first dredge-up. Based on data collected at the Subaru Telescope, which is operated by the National Astronomical Observatory of Japan. Prop. ID S05B-178S (M. Otsuka).

  11. A Survey for Water Maser Emission toward Planetary Nebulae: New Detection in IRAS 17347-3139

    NASA Astrophysics Data System (ADS)

    de Gregorio-Monsalvo, Itziar; Gómez, Yolanda; Anglada, Guillem; Cesaroni, Riccardo; Miranda, Luis F.; Gómez, José F.; Torrelles, José M.

    2004-02-01

    We report on a water maser survey toward a sample of 27 planetary nebulae (PNe) using the Robledo de Chavela and Medicina single-dish antennas, as well as the Very Large Array (VLA). Two detections have been obtained: the already known water maser emission in K3-35, and a new cluster of masers in IRAS 17347-3139. This low rate of detections is compatible with the short lifetime of water molecules in PNe (~100 yr). The water maser cluster at IRAS 17347-3139 are distributed on a ellipse of size ~=0.2"×0.1", spatially associated with compact 1.3 cm continuum emission (simultaneously observed with the VLA). From archive VLA continuum data at 4.9, 8.4, and 14.9 GHz, a spectral index α=0.76+/-0.03 (Sν~να) is derived for this radio source, which is consistent with either a partially optically thick ionized region or an ionized wind. However, the latter scenario can be ruled out by mass-loss considerations, thus indicating that this source is probably a young PN. The spatial distribution and the radial velocities of the water masers are suggestive of a rotating and expanding maser ring, tracing the innermost regions of a torus formed at the end of the asymptotic giant branch phase. Given that the 1.3 cm continuum emission peak is located near one of the tips of the major axis of the ellipse of masers, we speculate on a possible binary nature of IRAS 17347-3139, where the radio continuum emission could belong to one of the components and the water masers would be associated with a companion.

  12. A catalogue of integrated Hα fluxes for 1258 Galactic planetary nebulae

    NASA Astrophysics Data System (ADS)

    Frew, David J.; Bojičić, Ivan S.; Parker, Q. A.

    2013-05-01

    We present a catalogue of new integrated Hα fluxes for 1258 Galactic planetary nebulae (PNe), with the majority, totalling 1234, measured from the Southern Hα Sky Survey Atlas (SHASSA) and/or the Virginia Tech Spectral-line Survey (VTSS). Aperture photometry on the continuum-subtracted digital images was performed to extract Hα+[N II] fluxes in the case of SHASSA, and Hα fluxes from VTSS. The [N II] contribution was then deconvolved from the SHASSA flux using spectrophotometric data taken from the literature or derived by us. Comparison with previous work shows that the flux scale presented here has no significant zero-point error. Our catalogue is the largest compilation of homogeneously derived PN fluxes in any waveband yet measured, and will be an important legacy and fresh benchmark for the community. Amongst its many applications, it can be used to determine statistical distances for these PNe, determine new absolute magnitudes for delineating the faint end of the PN luminosity function, provide baseline data for photoionization and hydrodynamical modelling, and allow better estimates of Zanstra temperatures for PN central stars with accurate optical photometry. We also provide total Hα fluxes for another 75 objects which were formerly classified as PNe, as well as independent reddening determinations for ˜270 PNe, derived from a comparison of our Hα data with the best literature Hβ fluxes. In an appendix, we list corrected Hα fluxes for 49 PNe taken from the literature, including 24 PNe not detected on SHASSA or VTSS, re-calibrated to a common zero-point.

  13. A test for asymptotic giant branch evolution theories: planetary nebulae in the Large Magellanic Cloud

    NASA Astrophysics Data System (ADS)

    Ventura, P.; Stanghellini, L.; Dell'Agli, F.; García-Hernández, D. A.; Di Criscienzo, M.

    2015-10-01

    We used a new generation of asymptotic giant branch (AGB) stellar models that include dust formation in the stellar winds to find the links between evolutionary models and the observed properties of a homogeneous sample of Large Magellanic Cloud (LMC) planetary nebulae (PNe). Comparison between the evolutionary yields of elements such as CNO and the corresponding observed chemical abundances is a powerful tool to shed light on evolutionary processes such as hot bottom burning (HBB) and third dredge-up (TDU). We found that the occurrence of HBB is needed to interpret the nitrogen-enriched (log (N/H) + 12 > 8) PNe. In particular, N-rich PNe with the lowest carbon content are nicely reproduced by AGB models of mass M ≥ 6 M⊙, whose surface chemistry reflects the pure effects of HBB. PNe with log (N/H) + 12 < 7.5 correspond to ejecta of stars that have not experienced HBB, with initial mass below ˜3 M⊙. Some of these stars show very large carbon abundances, owing to the many TDU episodes experienced. We found from our LMC PN sample that there is a threshold to the amount of carbon accumulated at AGB surfaces, log (C/H) + 12 < 9. Confirmation of this constraint would indicate that, after the C-star stage is reached, AGBs experience only a few thermal pulses, which suggests a rapid loss of the external mantle, probably owing to the effects of radiation pressure on carbonaceous dust particles present in the circumstellar envelope. The implications of these findings for AGB evolution theories and the need to extend the PN sample currently available are discussed.

  14. THE BORN-AGAIN PLANETARY NEBULA A78: AN X-RAY TWIN OF A30

    SciTech Connect

    Toalá, J. A.; Guerrero, M. A.; Marquez-Lugo, R. A.; Fang, X.; Schönberner, D.; Ramos-Larios, G.

    2015-01-20

    We present the XMM-Newton discovery of X-ray emission from the planetary nebula (PN) A78, the second born-again PN detected in X-rays apart from A30. These two PNe share similar spectral and morphological characteristics: they harbor diffuse soft X-ray emission associated with the interaction between the H-poor ejecta and the current fast stellar wind and a point-like source at the position of the central star (CSPN). We present the spectral analysis of the CSPN, using for the first time an NLTE code for expanding atmospheres that takes line blanketing into account for the UV and optical spectra. The wind abundances are used for the X-ray spectral analysis of the CSPN and the diffuse emission. The X-ray emission from the CSPN in A78 can be modeled by a single C VI emission line, while the X-ray emission from its diffuse component is better described by an optically thin plasma emission model with a temperature of kT = 0.088 keV (T ≈ 1.0 × 10{sup 6} K). We estimate X-ray luminosities in the 0.2-2.0 keV energy band of L {sub X,} {sub CSPN} = (1.2 ± 0.3) × 10{sup 31} erg s{sup –1} and L {sub X,} {sub DIFF} = (9.2 ± 2.3) × 10{sup 30} erg s{sup –1} for the CSPN and diffuse components, respectively.

  15. Optical and infrared imaging and spectroscopy of the multiple-shell planetary nebula NGC 6369

    NASA Astrophysics Data System (ADS)

    Ramos-Larios, G.; Guerrero, M. A.; Vázquez, R.; Phillips, J. P.

    2012-03-01

    NGC 6369 is a double-shell planetary nebula consisting of a bright annular inner shell with faint bipolar extensions and a filamentary envelope. We have used ground- and space-based narrow-band optical and near-infrared (near-IR) images, broad-band mid-IR images, optical long-slit echelle spectra and mid-IR spectra to investigate its physical structure. These observations indicate that the inner shell of NGC 6369 can be described as a barrel-like structure shape with polar bubble-like protrusions, and reveal evidence for H2 and strong polycyclic aromatic hydrocarbons emission from a photodissociative region (PDR) with molecular inclusions located outside the bright inner shell. High-resolution Hubble Space Telescope narrow-band images reveal an intricate excitation structure of the inner shell and a system of 'cometary' knots. The knotty appearance of the envelope, the lack of kinematical evidence for shell expansion and the apparent presence of emission from ionized material outside the PDR make us suggest that the envelope of NGC 6369 is not a real shell, but a flattened structure at its equatorial regions. We report the discovery of irregular knots and blobs of diffuse emission in low-excitation and molecular line emission that are located up to 80 arcsec from the central star, well outside the main nebular shells. We also show that the filaments associated to the polar protrusions have spatial extents consistent with post-shock cooling regimes, and likely represent regions of interaction of these structures with surrounding material.

  16. DETECTION OF DIFFUSE X-RAY EMISSION FROM PLANETARY NEBULAE WITH NEBULAR O VI

    SciTech Connect

    Ruiz, N.; Guerrero, M. A.; Jacob, R.; Schoenberner, D.; Steffen, M.

    2013-04-10

    The presence of O VI ions can be indicative of plasma temperatures of a few Multiplication-Sign 10{sup 5} K that are expected in heat conduction layers between the hot shocked stellar wind gas at several 10{sup 6} K and the cooler (10{sup 4} K) nebular gas of planetary nebulae (PNe). We have used FUSE observations of PNe to search for nebular O VI emission or absorption as a diagnostic of the conduction layer to ensure the presence of hot interior gas. Three PNe showing nebular O VI, namely IC 418, NGC 2392, and NGC 6826, have been selected for Chandra observations and diffuse X-ray emission is indeed detected in each of these PNe. Among the three, NGC 2392 has peculiarly high diffuse X-ray luminosity and plasma temperature compared with those expected from its stellar wind's mechanical luminosity and terminal velocity. The limited effects of heat conduction on the plasma temperature of a hot bubble at the low terminal velocity of the stellar wind of NGC 2392 may partially account for its high plasma temperature, but the high X-ray luminosity needs to be powered by processes other than the observed stellar wind, probably the presence of an unseen binary companion of the central star of the PN (CSPN) of NGC 2392. We have compiled relevant information on the X-ray, stellar, and nebular properties of PNe with a bubble morphology and found that the expectations of bubble models including heat conduction compare favorably with the present X-ray observations of hot bubbles around H-rich CSPNe, but have notable discrepancies for those around H-poor [WR] CSPNe. We note that PNe with more massive central stars can produce hotter plasma and higher X-ray surface brightness inside central hot bubbles.

  17. PLANETARY NEBULAE IN THE ELLIPTICAL GALAXY NGC 4649 (M 60): KINEMATICS AND DISTANCE REDETERMINATION

    SciTech Connect

    Teodorescu, A. M.; Mendez, R. H.; Bernardi, F.; Thomas, J.; Das, P.; Gerhard, O. E-mail: mendez@ifa.hawaii.edu

    2011-07-20

    Using a slitless spectroscopy method with (1) the 8.2 m Subaru telescope and its FOCAS Cassegrain spectrograph and (2) the ESO Very Large Telescope unit 1 (Antu) and its FORS2 Cassegrain spectrograph, we have detected 326 planetary nebulae (PNs) in the giant Virgo elliptical galaxy NGC 4649 (M 60) and measured their radial velocities. After rejecting some PNs more likely to belong to the companion galaxy NGC 4647, we have built a catalog with kinematic information for 298 PNs in M 60. Using these radial velocities, we have concluded that they support the presence of a dark matter halo around M 60. Based on an isotropic, two-component Hernquist model, we estimate the dark matter halo mass within 3R{sub e} to be 4 x 10{sup 11} M{sub sun}, which is almost one-half of the total mass of about 10{sup 12} M{sub sun} within 3R{sub e}. This total mass is similar to that estimated from globular cluster, XMM-Newton, and Chandra observations. The dark matter becomes dominant outside. More detailed dynamical modeling of the PN data is being published in a companion paper. We have also measured the m(5007) magnitudes of many of these PNs and built a statistically complete sample of 218 PNs. The resulting PN luminosity function (PNLF) was used to estimate a distance modulus of 30.7 {+-} 0.2 mag, equivalent to 14 {+-} 1 Mpc. This confirms an earlier PNLF distance measurement based on a much smaller sample. The PNLF distance modulus remains smaller than the surface brightness fluctuation distance modulus by 0.4 mag.

  18. METAL-RICH PLANETARY NEBULAE IN THE OUTER REACHES OF M31

    SciTech Connect

    Balick, B.; Kwitter, K. B.; Corradi, R. L. M.; Henry, R. B. C. E-mail: kkwitter@williams.edu E-mail: henry@ou.edu

    2013-09-01

    Spectroscopic data of two relatively [O III]-luminous planetary nebulae (PNe) have been obtained with the 10.4 m Gran Telescopio Canarias. M174 and M2496 are each {approx}1 Degree-Sign from the center of M31 along opposite sides of its minor axis. The ensemble of these 2 distant PNe plus 16 similarly luminous outer-disk PNe published previously by Kwitter et al. forms a homogeneous group in luminosity, metal content, progenitor mass, age, and kinematics. The main factual findings of our work are (1) O/H (and other low-mass {alpha} elements and their ratios to O) is uniformly solar-like in all 18 PNe ((12 + log(O/H)) = 8.62 {+-} 0.14); (2) the general sky distribution and kinematics of the ensemble much more closely resemble the rotation pattern of the classical disk of M31 than its halo or bulge; (3) the O/H gradient is surprisingly flat beyond R{sub g} {approx} 20 kpc. The PNe are too metal-rich to be bona fide members of M31's disk or halo, and (4) the abundance patterns of the sample are distinct from those in the spiral galaxies M33, M81, and NGC 300. Using standard PN age diagnostic methods, we suggest that all of the PNe formed {approx}2 Gyr ago in a starburst of metal-rich interstellar medium that followed an M31-M33 encounter about 3 Gyr ago. We review supporting evidence from stellar studies. Other more prosaic explanations, such as dwarf galaxy assimilation, are unlikely.

  19. C/O abundance ratios, iron depletions, and infrared dust features in galactic planetary nebulae

    SciTech Connect

    Delgado-Inglada, Gloria; Rodríguez, Mónica E-mail: mrodri@inaoep.mx

    2014-04-01

    We study the dust present in 56 Galactic planetary nebulae (PNe) through their iron depletion factors, their C/O abundance ratios (in 51 objects), and the dust features that appear in their infrared spectra (for 33 objects). Our sample objects have deep optical spectra of good quality, and most of them also have ultraviolet observations. We use these observations to derive the iron abundances and the C/O abundance ratios in a homogeneous way for all the objects. We compile detections of infrared dust features from the literature and we analyze the available Spitzer/IRS spectra. Most of the PNe have C/O ratios below one and show crystalline silicates in their infrared spectra. The PNe with silicates have C/O <1, with the exception of Cn 1-5. Most of the PNe with dust features related to C-rich environments (SiC or the 30 μm feature usually associated to MgS) have C/O ≳ 0.8. Polycyclic aromatic hydrocarbons are detected over the full range of C/O values, including 6 objects that also show silicates. Iron abundances are low in all the objects, implying that more than 90% of their iron atoms are deposited into dust grains. The range of iron depletions in the sample covers about two orders of magnitude, and we find that the highest depletion factors are found in C-rich objects with SiC or the 30 μm feature in their infrared spectra, whereas some of the O-rich objects with silicates show the lowest depletion factors.

  20. Nucleosynthesis Predictions for Intermediate-Mass AGB Stars: Comparison to Observations of Type I Planetary Nebulae

    NASA Technical Reports Server (NTRS)

    Karakas, Amanda I.; vanRaai, Mark A.; Lugaro, Maria; Sterling, Nicholas C.; Dinerstein, Harriet L.

    2008-01-01

    Type I planetary nebulae (PNe) have high He/H and N/O ratios and are thought to be descendants of stars with initial masses of approx. 3-8 Stellar Mass. These characteristics indicate that the progenitor stars experienced proton-capture nucleosynthesis at the base of the convective envelope, in addition to the slow neutron capture process operating in the He-shell (the s-process). We compare the predicted abundances of elements up to Sr from models of intermediate-mass asymptotic giant branch (AGB) stars to measured abundances in Type I PNe. In particular, we compare predictions and observations for the light trans-iron elements Se and Kr, in order to constrain convective mixing and the s-process in these stars. A partial mixing zone is included in selected models to explore the effect of a C-13 pocket on the s-process yields. The solar-metallicity models produce enrichments of [(Se, Kr)/Fe] less than or approx. 0.6, consistent with Galactic Type I PNe where the observed enhancements are typically less than or approx. 0.3 dex, while lower metallicity models predict larger enrichments of C, N, Se, and Kr. O destruction occurs in the most massive models but it is not efficient enough to account for the greater than or approx. 0.3 dex O depletions observed in some Type I PNe. It is not possible to reach firm conclusions regarding the neutron source operating in massive AGB stars from Se and Kr abundances in Type I PNe; abundances for more s-process elements may help to distinguish between the two neutron sources. We predict that only the most massive (M grester than or approx.5 Stellar Mass) models would evolve into Type I PNe, indicating that extra-mixing processes are active in lower-mass stars (3-4 Stellar Mass), if these stars are to evolve into Type I PNe.

  1. ALPHA ELEMENT ABUNDANCES IN A LARGE SAMPLE OF GALACTIC PLANETARY NEBULAE

    SciTech Connect

    Milingo, J. B.; Kwitter, K. B.; Souza, S. P.; Henry, R. B. C. E-mail: kkwitter@williams.ed E-mail: henry@mail.nhn.ou.ed

    2010-03-10

    In this paper, we present emission line strengths, abundances, and element ratios (X/O for Ne, S, Cl, and Ar) for a sample of 38 Galactic disk planetary nebulae (PNe) consisting primarily of Peimbert classification Type I. Spectrophotometry for these PNe incorporates an extended optical/near-IR range of lambdalambda3600-9600 A including the [S III] lines at 9069 A and 9532 A, setting this relatively large sample apart from typical spectral coverage. We have utilized Emission Line Spectrum Analyzer, a five-level atom abundance routine, to determine T{sub e} , N{sub e} , ionization correction factors, and total element abundances, thereby continuing our work toward a uniformly processed set of data. With a compilation of data from >120 Milky Way PNe, we present results from our most recent analysis of abundance patterns in Galactic disk PNe. With a wide range of metallicities, galactocentric distances, and both Type I and non-Type I objects, we have examined the alpha elements against H II regions and blue compact galaxies (H2BCGs) to discern signatures of depletion or enhancement in PNe progenitor stars, particularly the destruction or production of O and Ne. We present evidence that many PNe have higher Ne/O and lower Ar/Ne ratios compared to H2BCGs within the range of 8.5-9.0 for 12 + log(O/H). This suggests that Ne is being synthesized in the low- and intermediate-mass progenitors. Sulfur abundances in PNe continue to show great scatter and are systematically lower than those found in H2BCG at a given metallicity. Although we find that PNe do show some distinction in alpha elements when compared to H2BCG, within the Peimbert classification types studied, PNe do not show significant differences in alpha elements amongst themselves, at least to an extent that would distinguish in situ nucleosynthesis from the observed dispersion in abundance ratios.

  2. ABUNDANCES OF GALACTIC ANTICENTER PLANETARY NEBULAE AND THE OXYGEN ABUNDANCE GRADIENT IN THE GALACTIC DISK

    SciTech Connect

    Henry, R. B. C.; Morrison, Michael A.; Kwitter, Karen B.; Jaskot, Anne E.; Balick, Bruce; Milingo, Jacquelynne B. E-mail: morrison@nhn.ou.ed E-mail: ajaskot@umich.ed E-mail: jmilingo@gettysburg.ed

    2010-11-20

    We have obtained spectrophotometric observations of 41 anticenter planetary nebulae (PNe) located in the disk of the Milky Way. Electron temperatures and densities, as well as chemical abundances for He, N, O, Ne, S, Cl, and Ar were determined. Incorporating these results into our existing database of PN abundances yielded a sample of 124 well-observed objects with homogeneously determined abundances extending from 0.9 to 21 kpc in galactocentric distance. We performed a detailed regression analysis which accounted for uncertainties in both oxygen abundances and radial distances in order to establish the metallicity gradient across the disk to be 12 + log(O/H) = (9.09 {+-} 0.05) - (0.058 {+-} 0.006) x R{sub g} , with R{sub g} in kpc. While we see some evidence that the gradient steepens at large galactocentric distances, more objects toward the anticenter need to be observed in order to confidently establish the true form of the metallicity gradient. We find no compelling evidence that the gradient differs between Peimbert Types I and II, nor is oxygen abundance related to the vertical distance from the galactic plane. Our gradient agrees well with analogous results for H II regions but is steeper than the one recently published by Stanghellini and Haywood over a similar range in galactocentric distance. A second analysis using PN distances from a different source implied a flatter gradient, and we suggest that we have reached a confusion limit which can only be resolved with greatly improved distance measurements and an understanding of the natural scatter in oxygen abundances.

  3. Planetary nebulae search in the outskirts of M33: looking for the farthest candidates

    NASA Astrophysics Data System (ADS)

    Galera Rosillo, Rebeca; Corradi, Romano L. M.; Mampaso Recio, Antonio

    2015-08-01

    The nearby disc galaxy M33 is one of the best laboratories for testing chemical evolution models in galaxies and for understanding disc formation mechanisms. In this galaxy, planetary nebulae (PNe) were previously extensively studied only within a galactocentric radius of 8 kpc.In the framework of a broad study of the population of PNe in Local Group disc galaxies, we present the results of a deep narrow-band imaging of the outer regions of M33, performed using the Wide Field Camera at the 2.5 m Isaac Newton Telescope (INT).The INT images were obtained in the narrow-band filters selecting the [OIII] 5007 Å and Hα 6563 Å lines, plus broad-band filters SDSS g and i. A photometric catalog of around 150000 sources covering a total area of 5 square degrees, and extending out to 2 deg (30 kpc at the adopted distance of 840 kpc) from the centre of the galaxy is presented.PNe candidates are selected in the [OIII]-g vs Hα-r colour-colour diagram as bright emitters in the narrowband filters. A number of candidates with similar colours to those of known PNe, and with an apparent [OIII] magnitude > 21 have been selected for future follow-up. Three of these have been already spectroscopically confirmed at the William Herschel Telescope (WHT).Our survey will improve the knowledge of the PNe population in the outskirts of M33, constraining the properties of its metal-poor halo and of the extended disc substructures that have been proposed to be related to a relatively recent interaction with M31.

  4. Rotating Stars and the Formation of Bipolar Planetary Nebulae. II. Tidal Spin-up

    NASA Astrophysics Data System (ADS)

    García-Segura, G.; Villaver, E.; Manchado, A.; Langer, N.; Yoon, S.-C.

    2016-06-01

    We present new binary stellar evolution models that include the effects of tidal forces, rotation, and magnetic torques with the goal of testing planetary nebulae (PNs) shaping via binary interaction. We explore whether tidal interaction with a companion can spin-up the asymptotic giant brach (AGB) envelope. To do so, we have selected binary systems with main-sequence masses of 2.5 M ⊙ and 0.8 M ⊙ and evolve them allowing initial separations of 5, 6, 7, and 8 au. The binary stellar evolution models have been computed all the way to the PNs formation phase or until Roche lobe overflow (RLOF) is reached, whatever happens first. We show that with initial separations of 7 and 8 au, the binary avoids entering into RLOF, and the AGB star reaches moderate rotational velocities at the surface (∼3.5 and ∼2 km s‑1, respectively) during the inter-pulse phases, but after the thermal pulses it drops to a final rotational velocity of only ∼0.03 km s‑1. For the closest binary separations explored, 5 and 6 au, the AGB star reaches rotational velocities of ∼6 and ∼4 km s‑1, respectively, when the RLOF is initiated. We conclude that the detached binary models that avoid entering the RLOF phase during the AGB will not shape bipolar PNs, since the acquired angular momentum is lost via the wind during the last two thermal pulses. This study rules out tidal spin-up in non-contact binaries as a sufficient condition to form bipolar PNs.

  5. C/O Abundance Ratios, Iron Depletions, and Infrared Dust Features in Galactic Planetary Nebulae

    NASA Astrophysics Data System (ADS)

    Delgado-Inglada, Gloria; Rodríguez, Mónica

    2014-04-01

    We study the dust present in 56 Galactic planetary nebulae (PNe) through their iron depletion factors, their C/O abundance ratios (in 51 objects), and the dust features that appear in their infrared spectra (for 33 objects). Our sample objects have deep optical spectra of good quality, and most of them also have ultraviolet observations. We use these observations to derive the iron abundances and the C/O abundance ratios in a homogeneous way for all the objects. We compile detections of infrared dust features from the literature and we analyze the available Spitzer/IRS spectra. Most of the PNe have C/O ratios below one and show crystalline silicates in their infrared spectra. The PNe with silicates have C/O <1, with the exception of Cn 1-5. Most of the PNe with dust features related to C-rich environments (SiC or the 30 μm feature usually associated to MgS) have C/O >~ 0.8. Polycyclic aromatic hydrocarbons are detected over the full range of C/O values, including 6 objects that also show silicates. Iron abundances are low in all the objects, implying that more than 90% of their iron atoms are deposited into dust grains. The range of iron depletions in the sample covers about two orders of magnitude, and we find that the highest depletion factors are found in C-rich objects with SiC or the 30 μm feature in their infrared spectra, whereas some of the O-rich objects with silicates show the lowest depletion factors.

  6. First Results from HST19 GO12600: CNO Abundances in Seven Milky Way Planetary Nebulae

    NASA Astrophysics Data System (ADS)

    Kwitter, Karen B.; Dufour, Reginald J.; Shaw, Richard A.; Henry, Richard B. C.; Balick, Bruce; Corradi, Romano

    2014-06-01

    In HST Cycle 19 we observed 10 Milky Way planetary nebulae (PNe) from 1150-10270Å with STIS to obtain accurate abundances of carbon, nitrogen and oxygen. The ultimate goal of the project is to assess carbon production in the low-to-intermediate-mass (LIMS) progenitors of PNe with near-solar metallicity 0.5-1.2 x solar), but varying N/O 0.1-3), comparing observational data with theoretical models of carbon yields. Seven of our objects had data of sufficient quality to allow good empirical abundance determinations: IC2165, IC3568, NGC2440, NGC3242, NGC5315, NGC5882, and NGC7662. Each PN was observed with seven grating setting combinations with identical slit positions and slit sizes across the entire UV-optical spectral region. We created one-dimensional spectra from the two-dimensional STIS spectral images, taking care to extract the identical spatial region from each spectrum for a given object. This was done to produce one-dimensional spectral lines integrated along the slit, resulting in the highest signal-to-noise measurements for analysis. We measured line fluxes with IRAF and calculated nebular diagnostics and abundances with ELSA. The crucial value in using STIS is the ability to observe the ultraviolet lines of important CNO ions with higher signal-to-noise than in previous studies. In all objects we detected lines of C+, C+2, and C+3. We also detected N+ and N+4 in all objects; in four of the seven we also detected N+2 and N+3. We will present these data and compare them with previous determinations and analyses (largely from the old IUE datasets and studies). We gratefully acknowledge support from HST and from Williams College.

  7. VARIABILITY IN PROTO-PLANETARY NEBULAE. I. LIGHT CURVE STUDIES OF 12 CARBON-RICH OBJECTS

    SciTech Connect

    Hrivnak, Bruce J.; Lu Wenxian; Maupin, Richard E.; Spitzbart, Bradley D. E-mail: wen.lu@valpo.ed E-mail: bspitzbart@cfa.harvard.ed

    2010-02-01

    We have carried out long-term (14 years) V and R photometric monitoring of 12 carbon-rich proto-planetary nebulae. The light and color curves display variability in all of them. The light curves are complex and suggest multiple periods, changing periods, and/or changing amplitudes, which are attributed to pulsation. A dominant period has been determined for each and found to be in the range of approx150 days for the coolest (G8) to 35-40 days for the warmest (F3). A clear, linear inverse relationship has been found in the sample between the pulsation period and the effective temperature and also an inverse relationship between the amplitude of light variation and the effective temperature. These are consistent with the expectation for a pulsating post-asymptotic giant branch (post-AGB) star evolving toward higher temperature at constant luminosity. The published spectral energy distributions and mid-infrared images show these objects to have cool (200 K), detached dust shells and published models imply that intensive mass loss ended 400-2000 years ago. The detection of periods as long as 150 days in these requires a revision in the published post-AGB evolution models that couple the pulsation period to the mass loss rate and that assume that intensive mass loss ended when the pulsation period had decreased to 100 days. This revision will have the effect of extending the timescale for the early phases of post-AGB evolution. It appears that real time evolution in the pulsation periods of individual objects may be detectable on the timescale of two or three decades.

  8. HIGH-DISPERSION SPECTRUM OF THE HALO PLANETARY NEBULA DdDm 1

    SciTech Connect

    Otsuka, Masaaki; Hyung, Siek; Lee, Seong-Jae; Izumiura, Hideyuki; Tajitsu, Akito

    2009-11-01

    Using the High Dispersion Spectrograph (HDS) at the Subaru Telescope, we secured the high-resolution line spectra in the 3600-7500 A wavelength range of the Galactic halo planetary nebula DdDm 1. We also analyzed the Hubble Space Telescope Faint Object Spectrograph data in the 1200-6730 A wavelength range. The diagnostic results indicate the electron temperatures of T {sub e}psilonapprox 11,000-14,000 K and the electron number densities of N {sub e}psilonapprox 2000-10,500 cm{sup -3}. In spite of high gaseous temperatures, we have not detected high excitation lines, e.g., He II. We derived abundance based on the ionic concentration of permitted and forbidden lines and the photoionization model. A comparison of the ionic concentrations from forbidden lines to recombination lines shows the abundance discrepancy between them. We tested various possibilities, e.g., temperature fluctuation and high-density blob components, to explain the discrepancy. The high-density components or density fluctuation might be partly responsible for the discrepancy. DdDm 1 shows a low carbon abundance that corresponds to metal-poor stars, [Fe/H] <=-1. Assuming a distance of 10 kpc to DdDm 1, theoretical models suggest that the central star has T {sub eff}approx = 39,000 K and Lapprox = 2000-3000 L {sub sun}. The relatively high gas temperatures appear to be caused by very low heavy elemental abundances or insufficient coolants in the shell gas. Its progenitor, born in an extremely carbon-poor environment as an initial mass of about 0.9 M {sub sun}, had probably experienced only the first dredge-up.

  9. Ultraviolet spectrum and probable chemical composition of the high-excitation planetary nebula M1-1.

    PubMed

    Aller, L H; Keyes, C D; Feibelman, W A

    1986-05-01

    One of the highest excitation planetary nebulae known, M1-1, was studied with the image-tube scanner on the Shane 3-m telescope at Lick Observatory and with the International Ultraviolet Explorer. Large fractions of abundant elements such as C, N, O, S, and Ar exist in unobservable stages of ionization. Hence, it is difficult to establish the chemical composition of this nebula. The logarithmic abundance values of various elements compared with those of the Sun appear to be as follows: [Table: see text] Here log N(H) = 12. In contrast to NGC 6537, the composition of M1-1 does not appear to differ markedly from that of the Sun. N may be enhanced but there is no enhancement of He or C. In spite of its high excitation and its presumed origin from a relatively massive star, M1-1 shows no evidence for pronounced nuclear processing. PMID:16593688

  10. Ultraviolet spectrum and probable chemical composition of the high-excitation planetary nebula M1-1

    PubMed Central

    Aller, Lawrence H.; Keyes, Charles D.; Feibelman, Walter A.

    1986-01-01

    One of the highest excitation planetary nebulae known, M1-1, was studied with the image-tube scanner on the Shane 3-m telescope at Lick Observatory and with the International Ultraviolet Explorer. Large fractions of abundant elements such as C, N, O, S, and Ar exist in unobservable stages of ionization. Hence, it is difficult to establish the chemical composition of this nebula. The logarithmic abundance values of various elements compared with those of the Sun appear to be as follows: [Table: see text] Here log N(H) = 12. In contrast to NGC 6537, the composition of M1-1 does not appear to differ markedly from that of the Sun. N may be enhanced but there is no enhancement of He or C. In spite of its high excitation and its presumed origin from a relatively massive star, M1-1 shows no evidence for pronounced nuclear processing. PMID:16593688

  11. Planetary Nebulae in the Solar Neighbourhood: Statistics, Distance Scale and Luminosity Function

    NASA Astrophysics Data System (ADS)

    Frew, David J.

    2008-07-01

    An accurate census of the nearest planetary nebulae (PNe) is needed for calculations of the total number, space density, scale height, and birth rate of PNe in the Galaxy, to understand the dynamics of an evolving nebula and its relationship to the cooling history of the central star, and also to provide an unbiased sample to investigate the frequency of binary central stars and their role in the formation and shaping of these objects. This study presents the most refined volume-limited survey of PNe known to date. Integrated H-alpha fluxes for over 400 mostly evolved PNe are presented, based primarily on data from the Southern H-alpha Sky Survey Atlas (SHASSA) and the Virginia Tech Spectral-Line Survey (VTSS). Aperture photometry on the digital images was performed to extract H-alpha+[NII] fluxes. The [NII] contribution was then de-convolved using literature data, new data from slit spectra, or spectrophotometric data from the Wisconsin H-Alpha Mapper (WHAM) also obtained as part of this project. Comparison with previous work shows that the flux scale presented here has no significant zero-point error. The H-alpha fluxes are used to determine new Zanstra temperatures for those PNe with accurate central star photometry, calculating surface-brightness distances for each PN in the sample, and in conjunction with accurate [OIII] fluxes, new absolute PN magnitudes for delineating the faint end of the PN luminosity function. A spectroscopic survey of a range of MASH PNe is also presented. New emission-line intensities for 60 PNe are given, including a preliminary discussion of the chemical abundances of this sample. New distances have been determined for a large number of PNe, by either critically examining the literature, or by deriving new extinction and kinematic distances where suitable. For all PNe not amenable to these approaches, distances were estimated from a new H-alpha surface brightness-radius (SB-r) relation. The Hα SB-r relation covers >6 dex in SB, and

  12. Morphological Changes, Evidence for a Collimating Disk, and Extremely Young Jetlike Components in the Planetary Nebula IC 4997

    NASA Astrophysics Data System (ADS)

    Miranda, Luis F.; Torrelles, José M.

    1998-03-01

    We present VLA-A radio continuum observations at 3.6 cm and 2 cm of the extremely young, double-shell planetary nebula IC 4997. A comparison of the new 3.6 cm map with that obtained in 1995 July shows that morphological changes have occurred in the nebula in ~=1.3 yr. These changes reveal themselves by the presence in the outer shell of several new bright compact regions, most of which are located along the major nebular axis. The observed changes suggest that a variable highly collimated stellar wind impinges on the outer shell and causes variation of the physical conditions in compact nebular regions. This mechanism is probably related to the origin of the microstructure in IC 4997. The inner shell has been resolved at 2 cm and shows an elliptical morphology with a deconvolved size of ~=0.12" × 0.09" (P.A. ~= 56°). Evidence for an extended, flat equatorial disk (size ~=1.4" × 0.22", P.A. ~= 125°) is found at 2 cm. The derived spectral index α(3.6-2 cm) map of the nebula reveals a compact (size ~= 0.5" × 0.2", P.A. ~= 125°), dense [Ne ~= (2-6) × 105 cm-3], optically thick (τ3.6 cm ~= 1-8) band that probably represents the innermost, densest regions of the extended disk. This disk can be identified as the collimating agent of both the inner and outer shells. In addition, extremely young bipolar jetlike features are observed along the major axis of the inner shell, exhibiting the typical properties of jetlike outflows in planetary nebulae.

  13. A near infrared imaging polarimetry investigation of the bipolar proto-planetary nebula - OH231.8+4.2

    NASA Astrophysics Data System (ADS)

    Ahmad, Amir

    Proto-Planetary-Nebulae (PPNe) are a class of short-lived transitionary objects. They represent a period of a round a few 1000 years of stellar evolution between the Asymptotic Giant Branch (AGB) and Planetary Nebula (PN) phase. This part of the Hertzsprung-Russell (HR) diagram is not very well understood from theory, although it represents an important phase of low and intermediate mass (0.8 Msun < M < 8 Msun) stellar evolution. The unsolved problems are the formation and destruction of dust grains, the nature of their coupling to the gas, the physical processes driving the mass-loss, as well as the occurrence of bipolarity and formation of a disk-like torus. The AGB circumstellar envelope (CSE) is mostly spherical whereas the majority of PNe are bipolar. It is thought that the transition from spherical to axisymmetry takes places during the PPN phase. Near infrared (NIR) imaging polarimetry tells us about the dust density, as well as the grain size distribution. It lets us determine the morphological structure of the nebula and gives us some indication about the mass loss. Here we present NIR imaging polarimetry of OH231.8+4.2 (Rotten Egg nebula). It is a very well studied object thought to be at the end of the AGB but is unusual in the sense that, its central star is thought to be a "classical" Mira. We present NIR linear and circular polarimetry of the bipolar outflow of the nebula in the broad band at J (1.25 microns), H (1.65 microns) and K (2.2 microns). We use a Monte Carlo (MC) light scattering code to model the NIR intensities, colours and polarisation levels for this PPN, the results of which are presented. We detect high linear polarisation in OH231.8+4.2 (~ 50%) in the lobes of the nebula at J, H and K. We also detect maximum circular polarisation of (~ 1.7%) in the J band which is probably the first detection in a PPN. Based on our MC modelling we suggest that the majority of particles in OH231.8+4.2 are Rayleigh-like and are responsible for the high

  14. Detection of O VII Lambda 1522 in IUE Spectra of Planetary Nebula Nuclei and Other Hot Stars

    NASA Technical Reports Server (NTRS)

    Feibelman, Walter A.

    1999-01-01

    We present the first detection of O VII lambda 1522 emission or absorption from archival IUE spectra in 14 planetary nebula nuclei and three PG 1159-type stars. The n = 5 approaching 6 transition of O VII was determined by Kruk & Werner and observed by them in the spectrum of the very hot PG 1159-type star H1504+65 from data obtained with the Hopkins Ultraviolet Telescope (HUT). Emission-line fluxes or absorption equivalent widths as well as radial velocities for the program stars are presented. The precise rest wavelength for the 5 approaching 6 transition requires further investigation.

  15. Water Fountains in the Sky: Streaming Water Jets from Aging Star Provide Clues to Planetary-Nebula Formation

    NASA Astrophysics Data System (ADS)

    2002-06-01

    Astronomers using the National Science Foundation's Very Long Baseline Array (VLBA) radio telescope have found that an aging star is spewing narrow, rotating streams of water molecules into space, like a jerking garden hose that has escaped its owner's grasp. The discovery may help resolve a longstanding mystery about how the stunningly beautiful objects called planetary nebulae are formed. Artist's Conception of W43A. Artist's conception of W43A, with the aging star surrounded by a disk of material and a precessing, twisted jet of molecules streaming away from it in two directions. Credit: Kirk Woellert/National Science Foundation. The astronomers used the VLBA, operated by the National Radio Astronomy Observatory, to study a star called W43A. W43A is about 8,500 light-years from Earth in the direction of the constellation Aquila, the eagle. This star has come to the end of its normal lifetime and, astronomers believe, is about to start forming a planetary nebula, a shell of brightly glowing gas lit by the hot ember into which the star will collapse. "A prime mystery about planetary nebulae is that many are not spherical even though the star from which they are ejected is a sphere," said Phillip Diamond, director of the MERLIN radio observatory at Jodrell Bank in England, and one of the researchers using the VLBA. "The spinning jets of water molecules we found coming from this star may be one mechanism for producing the structures seen in many planetary nebulae," he added. The research team, led by Hiroshi Imai of Japan's National Astronomical Observatory (now at the Joint Institute for VLBI in Europe, based in the Netherlands), also includes Kumiko Obara of the Mizusawa Astrogeodynamics Observatory and Kagoshima University; Toshihiro Omodaka, also of Kagoshima University; and Tetsuo Sasao of the Japanese National Astronomical Observatory. The scientists reported their findings in the June 20 issue of the scientific journal Nature. As stars similar to our Sun

  16. New Galactic Planetary Nebulae and the role of Central Star Binarity

    NASA Astrophysics Data System (ADS)

    Miszalski, B.

    2009-09-01

    The Galactic population of planetary nebulae (PNe) offers great potential in improving our understanding of many astrophysical problems on both large and small scales. They are revealed out to large distances by their bright emission line spectra from which their radial velocities and chemical abundances can be measured. As members of the old stellar population, PNe are particularly abundant towards the Galactic bulge where their kinematics are a valuable, relatively unbiased tracer of the dynamics of the region. Chemical abundance variations may also be traced by PNe to place constraints on chemodynamical models of the Galaxy. On much smaller scales their central stars (CSPN) are a powerful window into the poorly understood late stages of binary stellar evolution. The capacity of PNe to perform these studies is critically dependent on the size of the population. The current Galactic population of PNe was substantially increased by the Macquarie/AAO/Strasbourg Halpha (MASH) PNe catalogue. A supplement to MASH, the MASH-II catalogue, is presented with more than 360 new Galactic PNe found after a thorough search of all 233 AAO/UKST SuperCOSMOS Halpha Survey fields in digital format. Novel, semi-automated data processing and multi-wavelength visualisation techniques are developed to maximise the sensitivity of the search. MASH-II PNe are notable for being either small, star-like PNe of relatively high surface brightness, or very large, extremely low surface brightness PNe. Over 90% of the catalogue is confirmed spectroscopically during extensive observing campaigns and the catalogue is available via the VizieR catalogue service at the Centre de Donn´ees Astronomiques de Strasbourg (CDS). This thesis is based on the exploitation of the MASH and MASH-II PNe catalogues that have provided the largest and most representative sample of PNe towards the Galactic bulge. This offers a unique opportunity to contribute towards two different, largely unexplored research domains

  17. A deep survey of heavy element lines in planetary nebulae - I. Observations and forbidden-line densities, temperatures and abundances

    NASA Astrophysics Data System (ADS)

    Tsamis, Y. G.; Barlow, M. J.; Liu, X.-W.; Danziger, I. J.; Storey, P. J.

    2003-10-01

    We present deep optical spectrophotometry of 12 Galactic planetary nebulae (PNe) and three Magellanic Cloud PNe. Nine of the Galactic PNe were observed by scanning the slit of the spectrograph across the nebula, yielding relative line intensities for the entire nebula that are suitable for comparison with integrated nebular fluxes measured in other wavelength regions. In this paper we use the fluxes of collisionally excited lines (CELs) from the nebulae to derive electron densities and temperatures, and ionic abundances. We find that the nebular electron densities derived from optical CEL ratios are systematically higher than those derived from the ratios of the infrared (IR) fine-structure (FS) lines of [OIII]. The latter have lower critical densities than the typical nebular electron densities derived from optical CELs, indicating the presence of significant density variations within the nebulae, with the IR CELs being biased towards lower density regions. We find that for several nebulae the electron temperatures obtained from [OII] and [NII] optical CELs are significantly affected by recombination excitation of one or more of the CELs. When allowance is made for recombination excitation, much better agreement is obtained with the electron temperatures obtained from optical [OIII] lines. We also compare electron temperatures obtained from the ratio of optical nebular to auroral [OIII] lines with temperatures obtained from the ratio of [OIII] optical lines to [OIII] IR FS lines. We find that when the latter are derived using electron densities based on the [OIII]52 μm/88 μm line ratio, they yield values that are significantly higher than the optical [OIII] electron temperatures. In contrast to this, [OIII] optical/IR temperatures derived using the higher electron densities obtained from optical [ClIII]λ5517/λ5537 ratios show much closer agreement with optical [OIII] electron temperatures, implying that the observed [OIII] optical/IR ratios are significantly

  18. The planetary nebulae populations in five galaxies: abundance patterns and evolution

    NASA Astrophysics Data System (ADS)

    Stasińska, G.; Richer, M. G.; McCall, M. L.

    1998-08-01

    We have collected photometric and spectroscopic data on planetary nebulae (PNe) in 5 galaxies: the Milky Way (bulge), M 31 (bulge), M 32, the LMC and the SMC. We have computed the abundances of O, Ne and N and compared them from one galaxy to another. In each Galaxy, the distribution of oxygen abundances has a large dispersion. The average O/H ratio is larger in the M 31 and the Galactic bulge PNe than in those in the Magellanic Clouds. In a given galaxy, it is also larger for PNe with [O III] luminosities greater than 100 L_⊙, which are likely to probe more recent epochs in the galaxy history. We find that the M 31 and the Galactic bulge PNe extend the very tight Ne/H-O/H correlation observed in the Galactic disk and Magellanic Clouds PNe towards higher metallicities. We note that the anticorrelation between N/O and O/H that was known to occur in the Magellanic Clouds and in the disk PNe is also marginally found in the PNe of the Galactic bulge. Furthermore, we find that high N/O ratios are higher for less luminous PNe. In M 32, all PNe have a large N/O ratio, indicating that the stellar nitrogen abundance is enhanced in this galaxy. We have also compared the PN evolution in the different galactic systems by constructing diagrams that are independent of abundances, and have found strikingly different behaviours of the various samples. In order to help in the interpretation of these data, we have constructed a grid of expanding, PN photoionization models in which the central stars evolve according to the evolutionary tracks of Bl{öcker (1995). These models show that the apparent spectroscopic properties of PNe are extremely dependent, not only on the central stars, but also on the masses and expansion velocities of the nebular envelopes. The main conclusion of the confrontation of the observed samples with the model grids is that the PN populations are indeed not the same in the various parent galaxies. Both stars and nebulae are different. In particular, the

  19. Compact planetary nebulae in the Galactic disk: Analysis of the central stars

    NASA Astrophysics Data System (ADS)

    Moreno-Ibáñez, Manuel; Villaver, Eva; Shaw, Richard A.; Stanghellini, Letizia

    2016-09-01

    Context. We have obtained multi-wavelength observations of compact Galactic planetary nebulae (PNe) to probe post-asymptotic giant branch (AGB) evolution from the onset of nebular ejection. Here we analyze new observations from HST to derive the masses and evolutionary status of their central stars (CSs). Aims: Our objective here is to derive the masses of the CSs hosted by compact PNe in order to better understand the relationship between the CS properties and those of the surrounding nebulae. We also compare this sample with others we obtained using the same technique in different metallicity environments: the Large and Small Magellanic Clouds. Methods: This paper is based on HST/WFC3 images of 51 targets obtained in a snapshot survey (GO-11657). The high spatial resolution of HST allows us to resolve these compact PNe and distinguish the CS emission from that of their surrounding PNe. We derive CS bolometric luminosities and effective temperatures using the Zanstra technique, from a combination of HST photometry and ground-based spectroscopic data. The targets were imaged through the filters F200LP, F350LP, and F814W from which we derive Johnson V and I magnitudes. We infer CS masses by placing the stars on a temperature-luminosity diagram and compare their location with the best available, single star post-AGB evolutionary tracks. Results: We present new, unique photometric measurements of 50 CSs, and we derive effective temperatures and luminosities for most of them. Central star masses for 23 targets were derived with the evolutionary track technique; the remaining masses were indeterminate most likely because of underestimates of the stellar temperature, or because of substantial errors in the adopted statistical distances to these objects. We expect these problems will be largely overcome when the Gaia distance catalog becomes available. We find that objects with the higher ratios of Zanstra temperatures T(H i)/T( He ii ) tend to have lower-mass progenitors

  20. Variability of the planetary nebula NGC 6572 and its central star during the interval covered by optical observations

    NASA Astrophysics Data System (ADS)

    Arkhipova, V. P.; Kostyakova, E. B.; Burlak, M. A.; Esipov, V. F.; Ikonnikova, N. P.

    2014-10-01

    Estimates of relative line intensities available in the literature and integrated H β fluxes of the planetary nebula NGC 6572 during the time covered by optical observations (1938-2013) are compared to search for possible variations. Line intensities measured from observations obtained at the Crimean Station of the Sternberg Astronomical Institute in 2013 are presented, as well as previously unpublished photographic spectroscopic data obtained 1972-2005. Our analysis of all the available data shows that the line intensities do not vary within the observational uncertainties, with the possible exception of the [OIII] 4959 and 5007 Å lines, which show a tendency for their intensity increase with time. This can be interpreted as a manifestation of a temperature increase of the central star, or radial stratification of the [OIII] emission in the nebula, with the latter explanation being less probable. However, stratification is clearly visible in the [OII] and [NII] line intensities. The integrated H β flux is most probably constant at F(H β) = (1.50 ± 0.03) × 10-10 erg cm-2 s-1. A refined estimate of the interstellar extinction toward NGC 6572 has been obtained from radio and optical data, c(H β) = 0.42 ± 0.03. The MAST spectroscopy data were used to derive the central star's UBV magnitudes in 2004. Integrated photoelectric UBV observations of the nebula and central star for 1971-2005 are presented.

  1. Imaging of four planetary nebulae in the Magellanic Clouds using the Hubble Space Telescope Faint Object Camera

    NASA Technical Reports Server (NTRS)

    Blades, J. C.; Barlow, M. J.; Albrecht, R.; Barbieri, C.; Boksenberg, A.; Crane, P.; Deharveng, J. M.; Disney, M. J.; Jakobsen, P.; Kamperman, T. M.

    1992-01-01

    Using the Faint Object Camera on-board the Hubble Space Telescope, we have obtained images of four planetary nebulae (PNe) in the Magellanic Clouds, namely N2 and N5 in the SMC and N66 and N201 in the LMC. Each nebula was imaged through two narrow-band filters isolating forbidden O III 5007 and H-beta, for a nominal exposure time of 1000 s in each filter. In forbidden O III, SMC N5 shows a circular ring structure, with a peak-to-peak diameter of 0.26 arcsec and a FWHM of 0.35 arcsec while SMC N2 shows an elliptical ring structure with a peak-to-peak diameter of 0.26 x 0.21. The expansion ages corresponding to the observed structures in SMC N2 and N5 are of the order of 3000 yr. LMC N201 is very compact, with a FWHM of 0.2 arcsec in H-beta. The Type I PN LMC N66 is a multipolar nebula, with the brightest part having an extent of about 2 arcsec and with fainter structures extending over 4 arcsec.

  2. Spitzer Search for Dust Disks around Central Stars of Planetary Nebulae

    NASA Astrophysics Data System (ADS)

    Bilíková, Jana; Chu, You-Hua; Gruendl, Robert A.; Su, Kate Y. L.; De Marco, Orsola

    2012-05-01

    Two types of dust disks have been discovered around white dwarfs (WDs): small dust disks within the Roche limits of their WDs and large dust disks around hot WDs extending to radial distances of 10-102 AU. The majority of the latter WDs are central stars of planetary nebulae (CSPNs). We have therefore used archival Spitzer Infrared Array Camera (IRAC) and Multiband Imaging Photometer for Spitzer (MIPS) observations of PNs to search for CSPNs with IR excesses and to make a comparative investigation of dust disks around stars at different evolutionary stages. We have examined available images of 72 resolved PNs in the Spitzer archive and found 56 of them large enough for the CSPN to be resolved from the PN. Among these, only 42 CSPNs are visible in IRAC and/or MIPS images and selected for photometric measurements. From the spectral energy distributions (SEDs) of these CSPNs, we find 19 cases with clear IR excess. Of these, seven are [WC]-type stars, two have apparent visual companions that account for the observed excess emission, two are symbiotic CSPNs, and in eight cases the IR excess originates from an extended emitter, likely a dust disk. For some of these CSPNs, we have acquired follow-up Spitzer MIPS images, Infrared Spectrograph spectra, and Gemini NIRI and Michelle spectroscopic observations. The SEDs and spectra show a great diversity in the emission characteristics of the IR excesses, which may imply different mechanisms responsible for the excess emission. For CSPNs whose IR excesses originate from dust continuum, the most likely dust production mechanisms are (1) breakup of bodies in planetesimal belts through collisions and (2) formation of circumstellar dust disks through binary interactions. A better understanding of post-asymptotic giant branch binary evolution as well as debris disk evolution along with its parent star is needed to distinguish between these different origins. Future observations to better establish the physical parameters of the

  3. Deep Optical Spectroscopy of Planetary Nebulae: The Search for Neutron-Capture Elements

    NASA Astrophysics Data System (ADS)

    Sterling, Nicholas C.; Garofali, K.; Dinerstein, H. L.; Hwang, S.; Redfield, S.

    2013-01-01

    We present deep, high-resolution (R=36,700) optical spectra of five planetary nebulae (PNe), taken with the 2D-coude echelle spectrograph on the 2.7-m Harlan J. Smith Telescope at McDonald Observatory. These observations are part of a larger optical survey of PNe, designed to unambiguously detect emission lines from neutron(n)-capture elements (atomic number Z>30). The abundances of these elements are of particular interest in PNe, since they can be produced by slow n-capture nucleosynthesis (the ``s-process'') during the asymptotic giant branch (AGB) stage of evolution of PN progenitor stars. The first large-scale investigation of n-capture element abundances in PNe (Sterling & Dinerstein 2008, ApJS, 174, 157) surveyed [Kr III] and [Se IV] transitions in the K band spectra of more than 80 PNe. However, the abundances derived from these data relied on ionization corrections that were often large and uncertain due to the detection of only one ion per element. Transitions of other Se and Kr ions, as well as many other trans-iron species, reside at optical wavelengths. High-resolution spectra are essential to unequivocally identify these lines and resolve potential blends with other species. The spectra we present are rich in emission features, with between 125 and 600 distinct lines detected in each PN. Emission from at least one Kr ion is detected in all five objects, and two (Hb 12 and J 900) exhibit emission from multiple Kr ions. We detected multiple Xe ions in J 900, as well as Se, Br, and Rb lines. Hb 12 also exhibits Xe emission, and the first detection of [Se II] in a PN to our knowledge. The spectra display a wealth of other emission lines, including permitted features of second-row elements and forbidden transitions of several iron-peak elements (e.g., Cr, Mn, Fe, Co, Ni, and Cu). Our survey makes it possible to derive more accurate Se and Kr abundances in PNe, and reveals the enrichment of other trans-iron elements. This enables more accurate s

  4. The planetary nebulae and H II regions in NGC 6822 revisited. Clues to AGB nucleosynthesis

    NASA Astrophysics Data System (ADS)

    García-Rojas, Jorge; Peña, Miriam; Flores-Durán, Sheila; Hernández-Martínez, Liliana

    2016-02-01

    Aims: The chemical behaviour of an ample sample of planetary nebulae (PNe) in NGC 6822 is analysed. Methods: Spectrophotometric data of 11 PNe and two H ii regions were obtained with the OSIRIS spectrograph attached to the Gran Telescopio Canarias. Data for other 13 PNe and three H ii regions were retrieved from the literature. Physical conditions and chemical abundances of O, N, Ne, Ar, and S were derived in a consistent way for 19 PNe and 4 H ii regions. Results: Abundances in the PNe sample are widely distributed showing 12 + log (O/H) from 7.4 to 8.2 and 12 + log (Ar/H) from 4.97 to 5.80. Two groups of PNe can be differentiated: one old with low metallicity (12 + log (O/H) <8.0 and 12 + log (Ar/H) < 5.7) and another younger one with metallicities similar to the values for H ii regions. The old objects are distributed in a larger volume than the young ones. An important fraction of PNe (over 30%) was found to be highly N-rich (Peimbert Type I PNe). Such PNe occur at any metallicity. In addition, about 60% of the sample presents high ionization (He++/He ≥ 0.1), possessing a central star with effective temperature higher than 100 000 K. Possible biases in the sample are discussed. From comparison with stellar evolution models by Karakas (2010) and Fishlock et al. (2014) of the observed N/O abundance ratios, our PNe should have had initial masses that are lower than 4 M⊙, although if the comparison is made with Ne vs. O abundances, the initial masses should have been lower than 2 M⊙. It appears that these models of stars of 2-3 M⊙ are producing too much 22Ne in the stellar surface at the end of the AGB. On the other hand, the comparison with another set of stellar evolution models with a different treatment of convection and on the assumptions about the overshoot of the convective core during the core H-burning phase, provided there is reasonable agreement between the observed and predicted N/O and Ne/H ratios if initial masses of more massive stars are

  5. The high-velocity outflow in the proto-planetary nebula Hen 3-1475

    NASA Astrophysics Data System (ADS)

    Riera, A.; García-Lario, P.; Manchado, A.; Bobrowsky, M.; Estalella, R.

    2003-04-01

    The proto-planetary nebula Hen 3-1475 shows a remarkable highly collimated optical jet with an S-shaped string of three pairs of knots and extremely high velocities. We present here a detailed analysis of the overall morphology, kinematic structure and the excitation conditions of these knots based on deep ground-based high dispersion spectroscopy complemented with high spatial resolution spectroscopy obtained with STIS onboard HST, and WFPC2 [N II] images. The spectra obtained show double-peaked, extremely wide emission line profiles, and a decrease of the radial velocities with distance to the source in a step-like fashion. We find that the emission line ratios observed in the intermediate knots are consistent with a spectrum arising from the recombination region of a shock wave with shock velocities ranging from 100 to 150 km s-1. We propose that the ejection velocity is varying as a function of time with a quasi-periodic variability (with timescale of the order of 100 years) and the direction of ejection is also varying with a precession period of the order of 1500 years. Some slowing down with distance along the axis of the Hen 3-1475 jet may be due to the entrainment process and/or to the enviromental drag. This scenario is supported by geometric and kinematic evidence: firstly, the decrease of the radial velocities along the Hen 3-1475 jet in a step like fashion; secondly, the kinematic structure observed in the knots; thirdly, the point-symmetric morphology together with the high proper motions shown by several knots; and finally the fact that the shock velocity predicted from the observed spectra of the shocked knots is much slower than the velocities at which these knots move outwards with respect to the central source. Based on observations made during service time with the 2.5 m Isaac Newton Telescope operated on La Palma by the Isaac Newton Group of Telescopes in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de

  6. SPITZER SEARCH FOR DUST DISKS AROUND CENTRAL STARS OF PLANETARY NEBULAE

    SciTech Connect

    Bilikova, Jana; Chu Youhua; Gruendl, Robert A.; Su, Kate Y. L.; De Marco, Orsola

    2012-05-01

    Two types of dust disks have been discovered around white dwarfs (WDs): small dust disks within the Roche limits of their WDs and large dust disks around hot WDs extending to radial distances of 10-10{sup 2} AU. The majority of the latter WDs are central stars of planetary nebulae (CSPNs). We have therefore used archival Spitzer Infrared Array Camera (IRAC) and Multiband Imaging Photometer for Spitzer (MIPS) observations of PNs to search for CSPNs with IR excesses and to make a comparative investigation of dust disks around stars at different evolutionary stages. We have examined available images of 72 resolved PNs in the Spitzer archive and found 56 of them large enough for the CSPN to be resolved from the PN. Among these, only 42 CSPNs are visible in IRAC and/or MIPS images and selected for photometric measurements. From the spectral energy distributions (SEDs) of these CSPNs, we find 19 cases with clear IR excess. Of these, seven are [WC]-type stars, two have apparent visual companions that account for the observed excess emission, two are symbiotic CSPNs, and in eight cases the IR excess originates from an extended emitter, likely a dust disk. For some of these CSPNs, we have acquired follow-up Spitzer MIPS images, Infrared Spectrograph spectra, and Gemini NIRI and Michelle spectroscopic observations. The SEDs and spectra show a great diversity in the emission characteristics of the IR excesses, which may imply different mechanisms responsible for the excess emission. For CSPNs whose IR excesses originate from dust continuum, the most likely dust production mechanisms are (1) breakup of bodies in planetesimal belts through collisions and (2) formation of circumstellar dust disks through binary interactions. A better understanding of post-asymptotic giant branch binary evolution as well as debris disk evolution along with its parent star is needed to distinguish between these different origins. Future observations to better establish the physical parameters of

  7. Observing Infrared Emission Lines of Neutron-Capture Species in Planetary Nebulae: New Detections with IGRINS

    NASA Astrophysics Data System (ADS)

    Dinerstein, Harriet L.; Sterling, N. C.; Kaplan, Kyle F.; Bautista, Manuel A.

    2015-08-01

    As the former envelopes of evolved stars, planetary nebulae (PNe) present an opportunity to study slow neutron-capture reactions (the “s-process”) during the AGB. Such studies differ from those of AGB stars in two ways. First, PNe represent the end point of self-enrichment and dredge-up in the star and most of its mass return to the ISM, enabling us to infer the nucleosynthetic yield of a specific element. Second, some s-process products are observable in PNe but difficult or impossible to observe in cool stars. These include some species with nuclear charge Z in the 30’s for which the major synthesis sites are uncertain. Optical emission lines of trans-iron species have been observed in some PNe, but are faint and can suffer from blending with lines of more abundant elements (Péquignot & Baluteau 1994, A&A, 283, 593; Sharpee et al. 2007, ApJ, 659, 1265). Observing infrared transitions from low energy states has proven to be a fruitful alternate approach. We used K-band lines of Se (Z=34) and Kr (Z=36) to study the demographics of their abundances in a large sample of Milky Way PNe (Dinerstein 2001, ApJ, 550, L223; Sterling & Dinerstein 2008, ApJ, 174, 158; Sterling, Porter, & Dinerstein 2015, submitted). An L-band emission line of Zn identified by Dinerstein & Geballe (2001, ApJ, 562, 515) and further observed by Smith, Zijlstra, & Dinerstein 2014 (MNRAS, 441, 3161), can be used as a tracer of the Fe-group, enabling determinations of the key stellar population diagnostic ratio [alpha/Fe] in PNe (see poster by Dinerstein et al., Focus Meeting 4). Using IGRINS, a high spectral resolution H and K band spectrometer (Park & Jaffe et al. 2014, Proc SPIE, 9147), we have discovered several new lines not previously reported in any astronomical object. Our detection of an H-band line of Rb (Z=37) confirms previous claims of optical Rb detections and indicates enrichment by a factor of ~4 in the PN NGC 7027 (Sterling, Dinerstein, Kaplan, & Bautista, in preparation

  8. Formation of Polycyclic Aromatic Hydrocarbons exhibiting (5,7)-member ring defects in Planetary Nebulae

    NASA Astrophysics Data System (ADS)

    Öttl, S.; Huber, S. E.; Kimeswenger, S.; Probst, M.

    2014-04-01

    Polycyclic aromatic hydrocarbons (PAHs) are nowadays widely accepted as one of the carriers of the ubiquitous aromatic infrared (IR) bands. The IR spectra of many planetary nebulae (PNe) are dominated by mid-IR emission features, attributed to the IR fluorescence of PAHs. Recent observations of PNe show the simultaneous presence of mid-IR features attributed to neutral fullerene molecules (i.e. C60) and PAHs (García-Hernández et al. 2010). In general, PNe show evidence of mixed chemistry with emission from PAHs, silicate dust, fullerenes and contributions from other molecular components. The still unidentified IR features seen in PNe require further laboratory and observational investigations. We present a theoretical study of the IR spectra of PAHs containing (5,7)-member ring defects. Using density functional theory, we investigate the effects such defects have on the IR spectra of pyrene (C16H10) and coronene (C24H12). In addition, we explore parts of the potential energy surface of the neutral species and discuss alternative formation pathways, especially in the environment of PNe. Coronene and pyrene can be seen as limiting or prototypical cases in various respects. They are among the smallest hydrocarbons that can exhibit (5,7)-ring defects. Previous work (Yu et al. 2012) has raised the suspicion that effects of such defects might be more intriguing with decreasing size of the PAHs. Our investigations represent the limiting cases with respect to the size of the PAHs. To study these small systems is thought to be an important step towards a substantial understanding of the role of (5,7)-ring defects for the IR spectra of PAHs. The formation of these (5,7)-ring defects in PAHs may be well supported in PNe. The environment strongly enables the transition from the ground state to the defect state. Therefore the knowledge of the IR spectra of these molecules will support the investigations in understanding the unidentified IR emission bands in PNe.

  9. FARADAY ROTATION IN THE TAIL OF THE PLANETARY NEBULA DeHt 5

    SciTech Connect

    Ransom, R. R.; Kothes, R.; Wolleben, M.; Landecker, T. L.

    2010-12-01

    We present 1420 MHz polarization images of a 5{sup 0} x 5{sup 0} region around the planetary nebula (PN) DeHt 5. The images reveal narrow Faraday-rotation structures on the visible disk of DeHt 5, as well as two wider, tail-like, structures 'behind' DeHt 5. Though DeHt 5 is an old PN known to be interacting with the interstellar medium (ISM), a tail has not previously been identified for this object. The innermost tail is {approx}3 pc long and runs away from the northeast edge of DeHt 5 in a direction roughly opposite that of the sky-projected space velocity of the white dwarf central star, WD 2218+706. We believe this tail to be the signature of ionized material ram-pressure stripped and deposited downstream during a >74,000 yr interaction between DeHt 5 and the ISM. We estimate the rotation measure (RM) through the inner tail to be -15 {+-} 5 rad m{sup -2}, and, using a realistic estimate for the line-of-sight component of the ISM magnetic field around DeHt 5, derive an electron density in the inner tail of n{sub e} = 3.6 {+-} 1.8 cm{sup -3}. Assuming the material is fully ionized, we estimate a total mass in the inner tail of 0.68 {+-} 0.33 M{sub sun} and predict that 0.49 {+-} 0.33 M{sub sun} was added during the PN-ISM interaction. The outermost tail consists of a series of three roughly circular components, which have a collective length of {approx}11.0 pc. This tail is less conspicuous than the inner tail and may be the signature of the earlier interaction between the WD 2218+706 asymptotic giant branch (AGB) progenitor and the ISM. The results for the inner and outer tails are consistent with hydrodynamic simulations and may have implications for the PN missing-mass problem as well as for models which describe the impact of the deaths of intermediate-mass stars on the ISM.

  10. Searching for planetary nebulae at the Galactic halo via J-PAS and J-PLUS

    NASA Astrophysics Data System (ADS)

    Goncalves, Denise R.; Aparício-Villegas, Teresa; Akras, Stavros; Borges Fernandes, Marcelo; J-PAS Collaboration

    2015-08-01

    The Javalambre-Physics of the Accelerating Universe Astrophysical Survey (J-PAS) is a narrow-band imaging, very wide field cosmological survey to be carried out from a dedicated 2.5m telescope and a 4.7 sq.deg camera with 1.2Gpix. It will last 5 years and will observe 8500 sq.deg of Northern sky to a 5-σ magnitude depth for point sources, equivalent to i ~23.3 over an aperture of 2 arcsec2. The J-PAS filter system consists of 54 contiguous narrow band filters of 145-Å FWHM, from 3,500 to 10,000Å. Two broad-band filters will be added at the extremes, UV and IR, plus 3 SDSS g, r, and i filters. The Javalambre Photometric Local Universe Survye (J-PLUS) will be an auxiliary survey ofJ-PAS (mainly for calibration) with a dedicated 0.80m telescope. J-PLUS comprises 12 filters, including g, r, i and z SDSS ones. Though about 2,500 planetary nebulae (PNe, confirmed spectroscopically) are known in the Galaxy, only 14 objects have been convincingly identified as halo PNe. They were classified as such from their location, kinematics and chemistry. Halo PNe are able to reveal precious information for the study of low- and intermediate-mass star evolution and the early chemical conditions of the Galaxy. The characteristic low continuum and intense line emissions of PNe make them good objects to be searched by J-PAS, and even by J-PLUS. For instance, the halo PNe BoBn 1, DdDm 1 and PS 1, located somewhere between 11 and 24 kpc from the Sun, have B magnitudes of 16, 14 and 13.4, respectively. Such values are easily encompassed by J-PAS/J-PLUS, given the typical limit magnitude of the survey. Though covering a significantly smaller sky area, data from the ALHAMBRA survey were used to test our J-PAS/J-PLUS strategy to search for PNe. Our first results will be shown in this poster.

  11. Near-infrared photometry of Galactic planetary nebulae with the VVV Survey

    NASA Astrophysics Data System (ADS)

    Weidmann, W. A.; Gamen, R.; van Hoof, P. A. M.; Zijlstra, A.; Minniti, D.; Volpe, M. G.

    2013-04-01

    Context. Planetary nebulae (PNe) are powerful tracers of evolved stellar populations. Among the 3000 known PNe in the Galaxy, about 600 are located within the 520 square-degree area covered by the VVV survey. The VVV photometric catalogue provides an important new dataset for the study of PNe, with high-resolution imaging in five near-infrared bands. Aims: There are various colour-colour diagrams that can be obtained from the VVV filters. We investigate the location of PNe in these diagrams and the separation from other types of objects. This includes the new Y-J vs. Z-Y diagram. Methods: Aperture photometry of known PNe in the VVV area was retrieved from source catalogues. Care was taken to minimise any confusion with field stars. The colours of the PNe we are determined for (H-Ks), (J-H), (Z-Y), and (Y-J), and compared to stars and to other types of emission line objects. Cloudy photo-ionisation models were used to predict colours for typical PNe. Results: We present near-infrared photometry for 353 known PNe. The best separation from other objects is obtained in the (H-Ks) vs. (J-H) diagram. We calculated the emission-line contribution to the in-band flux based on a model for NGC 6720: we find that this is highest in the Z and Y bands at over 50%, lower in the J band at 40%, and lowest in the H and Ks bands at 20%. A new view of PNe in the wavelength domain of the Z and Y bands is shown. Photo-ionisation models are used to explore the observed colours in these bands. The Y band is shown to be dominated by He I 1.083 μm and He II 1.012 μm, and colours involving this band are very sensitive to the temperature of the ionizing star. Conclusions: The VVV survey represents a unique dataset for studying crowded and obscured regions in the Galactic plane. The diagnostic diagrams presented here allow one to study the properties of known PNe and to uncover objects not previously classified. Tables 3-5 are only available in electronic form at the CDS via anonymous ftp to

  12. THE GALACTIC STRUCTURE AND CHEMICAL EVOLUTION TRACED BY THE POPULATION OF PLANETARY NEBULAE

    SciTech Connect

    Stanghellini, Letizia; Haywood, Misha E-mail: Misha.Haywood@obspm.f

    2010-05-10

    Planetary nebulae (PNe) derive from the evolution of {approx}1-8 M{sub sun} mass stars, corresponding to a wide range of progenitor ages, and thus are essential probes of the chemical evolution of galaxies, and indispensable to constrain the results from chemical models. We use an extended and homogeneous data set of Galactic PNe to study the metallicity gradients and the Galactic structure and evolution. The most up-to-date abundances, distances (calibrated with Magellanic Cloud PNe), and other parameters have been employed, together with a novel homogeneous morphological classification, to characterize the different PN populations. We confirm that morphological classes have a strong correlation with Peimbert's type PN, and also with their distribution on the Galactic landscape. We studied the {alpha}-element distribution within the Galactic disk, and found that the best selected disk population (i.e., excluding bulge and halo component), together with the most reliable PN distance scale yields to a radial oxygen gradient of {Delta}log(O/H)/{Delta}R{sub G} = -0.023 {+-} 0.006 dex kpc{sup -1} for the whole disk sample, and of {Delta}log(O/H)/{Delta}R{sub G} = -0.035 {+-} 0.024, -0.023 {+-} 0.005, and -0.011 {+-} 0.013 dex kpc{sup -1}, respectively for Type I, II, and III PNe, i.e., for high-, intermediate-, and low-mass progenitors. Neon gradients for the same PN types confirm the trend. Accurate statistical analysis shows moderately high uncertainties in the slopes, but also confirms the trend of steeper gradient for PNe with more massive progenitors, indicating a possible steepening with time of the Galactic disk metallicity gradient for what the {alpha}-elements are concerned. We found that the metallicity gradients are almost independent on the distance scale model used, as long as these scales are equally well calibrated with the Magellanic Clouds. The PN metallicity gradients presented here are consistent with the local metallicity distribution; furthermore

  13. The Detection of Neutron-Capture Elements in Magellanic Cloud Planetary Nebulae

    NASA Astrophysics Data System (ADS)

    Mashburn, Amanda; Sterling, Nicholas C.; Roederer, Ian U.

    2015-01-01

    We present deep, high-resolution 0.8--2.5 μm spectra of ten Magellanic Cloud planetary nebulae (PNe). These data were obtained with the FIRE spectrometer (Simcoe et al. 2013, PASP, 125, 270) on the 6.5-m Baade Telescope at Las Campanas Observatory. The primary goal of these observations is to detect fine-structure emission lines of the neutron(n)-capture elements Se and Kr. These elements can be produced by s-process nucleosynthesis in thermally-pulsing asymptotic giant branch (AGB) stars, the progenitors of PNe, and are enriched along with carbon in AGB envelopes by convective dredge-up. Extragalactic PNe are particularly valuable for studying s-process enrichments, since their distances are well-determined (unlike most Galactic PNe). Before our study, n-capture element detections had been reported in only one extragalactic PN, Hen 2-436 in the Sagittarius Dwarf (Wood et al. 2006, BAAS, 38, 1113; Otsuka et al. 2011, ApJ, 729, 39). Remarkably, we detect [Kr III] 2.199 and/or [Se IV] 2.287 μm in seven of the ten PNe (six of seven in the LMC and one of three in the SMC). At our resolution of R=4800, these lines are resolved from nearby H2 lines and therefore are unaffected by blending. A preliminary abundance analysis indicates that several of these PNe exhibit s-process enrichments, as expected given their high C/O ratios. The well-known distances to the LMC and SMC allow s-process enrichment factors to be studied as a function of PN luminosity and potentially initial progenitor mass. Moreover, this sample will provide new insights into n-capture nucleosynthesis at low metallicities. Beyond the Se and Kr lines, the spectra are incredibly rich, with typically 100-200 emission lines detected in LMC PNe and up to 100 in SMC objects, including lines of H2, [P II], [S II], [S III], [Cl II], [Fe II], and a number of as yet unidentified features. Our results demonstrate the utility of nebular spectroscopy for studying n-capture nucleosynthesis in extragalactic

  14. Population Signatures in Planetary Nebulae from Abundances of Fe-group and Neutron-Capture Elements

    NASA Astrophysics Data System (ADS)

    Dinerstein, Harriet L.; Geballe, Thomas R.; Sterling, N. C.

    2015-08-01

    There are two categories of elements for which abundances are measured in planetary nebulae (PNe). The first are species whose abundances may be modified by nuclear reactions in the star prior to PN formation, such as He, C, N, and nuclei made by slow neutron captures (Karakas & Lattanzio 2014, PASA, 31, 30). In contrast, elements unaffected by evolution should indicate the star’s initial composition. These include S, Ar, Cl, and (with certain exceptions) O and Ne, most of which are alpha species. A long-missing piece of the puzzle has been the abundances of the Fe-group elements. We cannot determine a meaningful elemental abundance from the gas-phase Fe lines seen in PNe, since Fe is heavily depleted into dust. Another approach is to use a different element as a proxy for Fe. Dinerstein & Geballe (2001, ApJ, 562, 515) identified a line at 3.625 μm as due to Zn, the least refractory Fe-group element. Observations of this line in Milky Way PNe yield -1 ≤ [Zn/H] ≤ 0 (Smith, Zijlstra, & Dinerstein 2014, MNRAS, 441, 3161; Dinerstein et al. 2015, in preparation). Substituting Zn for Fe, PNe can be placed in the [alpha/Fe] vs. [Fe/H] diagram used to characterize stellar populations. Dividing our sample into probable thin and thick disk members using the kinematic criterion of Peimbert’s Type II and III classes (1978, IAU Symp. 76, 215), we find that they occupy similar regions in [alpha/Fe] vs. [Fe/H] phase space as the stars of those populations. Elevated [alpha/Fe] values at subsolar [Fe/H], which tend to be higher for thick than thin disk PNe, cause degeneracies that make alpha species ambiguous metallicity indicators. This is important for self-enrichment studies, since if the initial abundance of an element is lower than projected from an alpha species, internal synthesis may be required to produce even a solar final abundance. Low observed abundances of the n-capture element Se suggest that many Type III PNe may have subsolar initial abundances of n

  15. An Infrared Ring Nebula around MSX5C G358.5391+00.1305: The True Nature of Suspected Planetary Nebula Wray 17-96 Determined via Direct Imaging and Spectroscopy

    NASA Astrophysics Data System (ADS)

    Egan, Michael P.; Clark, J. Simon; Mizuno, Donald R.; Carey, Sean J.; Steele, Iain A.; Price, Stephan D.

    2002-06-01

    The Midcourse Space Experiment (MSX) Galactic plane survey discovered a nearly perfectly circular ring nebula around the suspected planetary nebula Wray 17-96. Using near-IR spectral typing and modeling of the mid-IR nebula, we find that Wray 17-96 is more likely a candidate to be a luminous blue variable (LBV) surrounded by a large spherical ejecta shell. It is very similar to the G79.29+0.46 LBV candidate in Cygnus and the Pistol Star. The K-band spectrum and the mid-IR data indicate a stellar temperature of 13,000 K. The most likely distance to the source is 4.5 kpc, leading to a luminosity of 1.8×106 Lsolar. We suggest that the nebula consists of multiple shells and that an evolution from oxygen-rich to carbon-rich chemistry may be indicated.

  16. Spatio-kinematic modelling of Abell 65, a double-shelled planetary nebula with a binary central star

    NASA Astrophysics Data System (ADS)

    Huckvale, L.; Prouse, B.; Jones, D.; Lloyd, M.; Pollacco, D.; López, J. A.; O'Brien, T. J.; Sabin, L.; Vaytet, N. M. H.

    2013-09-01

    We present the first detailed spatio-kinematical analysis and modelling of the planetary nebula Abell 65, which is known to host a post-common envelope, binary, central star system. As such, this object is of great interest in studying the link between nebular morphology and central star binarity. [O III]5007 Å and Hα+[N II]6584 Å longslit spectra and imagery of Abell 65 were obtained with the Manchester Échelle Spectrometer on the 2.1-m telescope at the San Pedro Martír Observatory (MES-SPM). Further [O III]5007 Å longslit spectra were obtained with the Ultraviolet and Visual Échelle Spectrograph on the Very Large Telescope (VLT-UVES). These data were used to develop a spatio-kinematical model for the [O III]5007 Å emission from Abell 65. A `best-fitting' model was found by comparing synthetic spectra and images rendered from the model to the data. The model comprises an outer shell and an inner shell, with kinematical ages of 15000 ± 5000 yr kpc-1 and 8000 ± 3000 yr kpc-1, respectively. Both shells have peanut-shaped bipolar structures with symmetry axes at inclinations of (55 ± 10)° (to the line of sight) for the outer shell and (68 ± 10)° for the inner shell. The near alignment between the nebular shells and the binary orbital inclination [of (68 ± 2)°] is strongly indicative that the binary is responsible for shaping the nebula. Abell 65 is one of a growing number of planetary nebulae (seven to date, including Abell 65 itself) for which observations and modelling support the shaping influence of a central binary.

  17. New models for the evolution of post-asymptotic giant branch stars and central stars of planetary nebulae

    NASA Astrophysics Data System (ADS)

    Miller Bertolami, Marcelo Miguel

    2016-04-01

    Context. The post-asymptotic giant branch (AGB) phase is arguably one of the least understood phases of the evolution of low- and intermediate- mass stars. The two grids of models presently available are based on outdated micro- and macrophysics and do not agree with each other. Studies of the central stars of planetary nebulae (CSPNe) and post-AGB stars in different stellar populations point to significant discrepancies with the theoretical predictions of post-AGB models. Aims: We study the timescales of post-AGB and CSPNe in the context of our present understanding of the micro- and macrophysics of stars. We want to assess whether new post-AGB models, based on the latter improvements in TP-AGB modeling, can help us to understand the discrepancies between observation and theory and within theory itself. In addition, we aim to understand the impact of the previous AGB evolution for post-AGB phases. Methods: We computed a grid of post-AGB full evolutionary sequences that include all previous evolutionary stages from the zero age main sequence to the white dwarf phase. We computed models for initial masses between 0.8 and 4 M⊙ and for a wide range of initial metallicities (Z0 = 0.02, 0.01, 0.001, 0.0001). This allowed us to provide post-AGB timescales and properties for H-burning post-AGB objects with masses in the relevant range for the formation of planetary nebulae (~0.5-0.8 M⊙). We included an updated treatment of the constitutive microphysics and included an updated description of the mixing processes and winds that play a key role during the thermal pulses (TP) on the AGB phase. Results: We present a new grid of models for post-AGB stars that take into account the improvements in the modeling of AGB stars in recent decades. These new models are particularly suited to be inputs in studies of the formation of planetary nebulae and for the determination of the properties of CSPNe from their observational parameters. We find post-AGB timescales that are at

  18. Space Telescope Imaging Spectrograph Ultraviolet Spectra of Large Magellanic Cloud Planetary Nebulae: A Study of Carbon Abundances and Stellar Evolution

    NASA Astrophysics Data System (ADS)

    Stanghellini, Letizia; Shaw, Richard A.; Gilmore, Diane

    2005-03-01

    We acquired spectra of 24 LMC planetary nebulae (PNs) in the 1150-3000 Å range in order to determine carbon and other ionic abundances. The sample more than doubles the number of LMC PNs with high-quality UV spectra in this wavelength range and whose optical images are available in the Hubble Space Telescope archive. The Space Telescope Imaging Spectrograph was used with a very large aperture to obtain virtually slitless spectra; thus, the monochromatic images in the major nebula emission lines are also available. The analysis of the data shows extremely high quality spectra. This paper presents the emission lines identified and measured and the calculation of the ionic abundances of the emitting carbon and other ions, as well as total carbon abundance. P Cygni profiles have been found in a fraction of the nebulae, and the limiting velocities of the stellar winds estimated. The total carbon abundance can be inferred reliably in most nebulae. We found that the average carbon abundance in round and elliptical PNs is one order of magnitude larger than that of the bipolar PNs, while elliptical and round PNs with a bipolar core have a bimodal behavior. This results confirm that bipolarity in LMC PNs is tightly correlated with high-mass progenitors. When compared with predicted yields, we found that the observed abundance ratio shows a shift toward higher carbon abundances, which may be due to initial conditions assumed in the models not appropriate for LMC PNs. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555.

  19. Problems for the WELS classification of planetary nebula central stars: self-consistent nebular modelling of four candidates

    NASA Astrophysics Data System (ADS)

    Basurah, Hassan M.; Ali, Alaa; Dopita, Michael A.; Alsulami, R.; Amer, Morsi A.; Alruhaili, A.

    2016-05-01

    We present integral field unit (IFU) spectroscopy and self-consistent photoionization modelling for a sample of four southern Galactic planetary nebulae (PNe) with supposed weak emission-line central stars. The Wide Field Spectrograph on the ANU 2.3 m telescope has been used to provide IFU spectroscopy for NGC 3211, NGC 5979, My 60, and M 4-2 covering the spectral range of 3400-7000 Å. All objects are high-excitation non-Type I PNe, with strong He II emission, strong [Ne V] emission, and weak low-excitation lines. They all appear to be predominantly optically thin nebulae excited by central stars with Teff > 105 K. Three PNe of the sample have central stars which have been previously classified as weak emission-line stars (WELS), and the fourth also shows the characteristic recombination lines of a WELS. However, the spatially resolved spectroscopy shows that rather than arising in the central star, the C IV and N III recombination line emission is distributed in the nebula, and in some cases concentrated in discrete nebular knots. This may suggest that the WELS classification is spurious, and that, rather, these lines arise from (possibly chemically enriched) pockets of nebular gas. Indeed, from careful background subtraction we were able to identify three of the sample as being hydrogen rich O(H)-Type. We have constructed fully self-consistent photoionization models for each object. This allows us to independently determine the chemical abundances in the nebulae, to provide new model-dependent distance estimates, and to place the central stars on the Hertzsprung-Russell diagram. All four PNe have similar initial mass (1.5 < M/M⊙ < 2.0) and are at a similar evolutionary stage.

  20. A DETAILED MORPHO-KINEMATIC MODEL OF THE ESKIMO, NGC 2392: A UNIFYING VIEW WITH THE CAT'S EYE AND SATURN PLANETARY NEBULAE

    SciTech Connect

    Garcia-Diaz, Ma. T.; Lopez, J. A.; Steffen, W.; Richer, M. G. E-mail: jal@astrosen.unam.mx E-mail: richer@astrosen.unam.mx

    2012-12-20

    The three-dimensional and kinematic structure of the Eskimo nebula, NGC 2392, has been notoriously difficult to interpret in detail given its complex morphology, multiple kinematic components and its nearly pole-on orientation along the line of sight. We present a comprehensive, spatially resolved, high-resolution, long-slit spectroscopic mapping of the Eskimo planetary nebula. The data consist of 21 spatially resolved, long-slit echelle spectra tightly spaced over the Eskimo and along its bipolar jets. This data set allows us to construct a velocity-resolved [N II] channel map of the nebula with a resolution of 10 km s{sup -1} that disentangles its different kinematic components. The spectroscopic information is combined with Hubble Space Telescope images to construct a detailed three-dimensional morpho-kinematic model of the Eskimo using the code SHAPE. With this model we demonstrate that the Eskimo is a close analog to the Saturn and the Cat's Eye nebulae, but rotated 90 Degree-Sign to the line of sight. Furthermore, we show that the main characteristics of our model apply to the general properties of the group of elliptical planetary nebulae with ansae or FLIERS, once the orientation is considered. We conclude that this kind of nebula belongs to a class with a complex common evolutionary sequence of events.

  1. Distances for galactic planetary nebulae using mean forbidden O II doublet ratio electron densities

    NASA Astrophysics Data System (ADS)

    Kingsburgh, Robin L.; Barlow, M. J.

    1992-07-01

    Forbidden O II 3726, 3729-A double ratios and electron densities are presented for 68 galactic PN. For 45 of the objects, the doublet ratios represent integrations over the whole of the nebula. Calibrations recently derived from the Magellanic Cloud PN are used to derive distances for the majority of the nebulae. The typical forbidden O II density at the transition point between an optically thick and thin nebula is 4500/cu cm. An extensive comparison is made between the distances derived and previously published distances and distance scales. It is shown that the present distances, based on Magellanic Cloud calibrations, yield consistency with independent distance estimates. They also exhibit much greater self-consistency between central star masses derived from luminosity vs Teff comparisons on the one hand, and from absolute magnitude vs evolutionary age comparisons on the other. For the PN in this sample, rms electron densities, filling factors, and absolute radii are also derived.

  2. The Herschel Planetary Nebula Survey (HerPlaNS). I. Data overview and analysis demonstration with NGC 6781

    NASA Astrophysics Data System (ADS)

    Ueta, T.; Ladjal, D.; Exter, K. M.; Otsuka, M.; Szczerba, R.; Siódmiak, N.; Aleman, I.; van Hoof, P. A. M.; Kastner, J. H.; Montez, R.; McDonald, I.; Wittkowski, M.; Sandin, C.; Ramstedt, S.; De Marco, O.; Villaver, E.; Chu, Y.-H.; Vlemmings, W.; Izumiura, H.; Sahai, R.; Lopez, J. A.; Balick, B.; Zijlstra, A.; Tielens, A. G. G. M.; Rattray, R. E.; Behar, E.; Blackman, E. G.; Hebden, K.; Hora, J. L.; Murakawa, K.; Nordhaus, J.; Nordon, R.; Yamamura, I.

    2014-05-01

    Context. This is the first of a series of investigations into far-IR characteristics of 11 planetary nebulae (PNe) under the Herschel Space Observatory open time 1 program, Herschel Planetary Nebula Survey (HerPlaNS). Aims: Using the HerPlaNS data set, we look into the PN energetics and variations of the physical conditions within the target nebulae. In the present work, we provide an overview of the survey, data acquisition and processing, and resulting data products. Methods: We performed (1) PACS/SPIRE broadband imaging to determine the spatial distribution of the cold dust component in the target PNe and (2) PACS/SPIRE spectral-energy-distribution and line spectroscopy to determine the spatial distribution of the gas component in the target PNe. Results: For the case of NGC 6781, the broadband maps confirm the nearly pole-on barrel structure of the amorphous carbon-rich dust shell and the surrounding halo having temperatures of 26-40 K. The PACS/SPIRE multiposition spectra show spatial variations of far-IR lines that reflect the physical stratification of the nebula. We demonstrate that spatially resolved far-IR line diagnostics yield the (Te, ne) profiles, from which distributions of ionized, atomic, and molecular gases can be determined. Direct comparison of the dust and gas column mass maps constrained by the HerPlaNS data allows to construct an empirical gas-to-dust mass ratio map, which shows a range of ratios with the median of 195 ± 110. The present analysis yields estimates of the total mass of the shell to be 0.86 M⊙, consisting of 0.54 M⊙ of ionized gas, 0.12 M⊙ of atomic gas, 0.2 M⊙ of molecular gas, and 4 × 10-3 M⊙ of dust grains. These estimates also suggest that the central star of about 1.5 M⊙ initial mass is terminating its PN evolution onto the white dwarf cooling track. Conclusions: The HerPlaNS data provide various diagnostics for both the dust and gas components in a spatially resolved manner. In the forthcoming papers of the

  3. Automatic Generation of Algorithms for the Statistical Analysis of Planetary Nebulae Images

    NASA Technical Reports Server (NTRS)

    Fischer, Bernd

    2004-01-01

    which use numerical approximations even in cases where closed-form solutions exist. AutoBayes is implemented in Prolog and comprises approximately 75.000 lines of code. In this paper, we take one typical scientific data analysis problem-analyzing planetary nebulae images taken by the Hubble Space Telescope-and show how AutoBayes can be used to automate the implementation of the necessary anal- ysis programs. We initially follow the analysis described by Knuth and Hajian [KHO2] and use AutoBayes to derive code for the published models. We show the details of the code derivation process, including the symbolic computations and automatic integration of library procedures, and compare the results of the automatically generated and manually implemented code. We then go beyond the original analysis and use AutoBayes to derive code for a simple image segmentation procedure based on a mixture model which can be used to automate a manual preproceesing step. Finally, we combine the original approach with the simple segmentation which yields a more detailed analysis. This also demonstrates that AutoBayes makes it easy to combine different aspects of data analysis.

  4. Multiple outflows in the bipolar planetary nebula M1-16: A molecular line study

    NASA Technical Reports Server (NTRS)

    Sahai, Raghvendra; Wootten, Alwyn; Schwarz, Hugo E.; Wild, W.

    1994-01-01

    Extensive observations of the molecular gas in the young, compact planetary nebula M1-16 have been made, using the Swedish-ESO-Submillimeter Telescope. A map of the CO J = 2-1 emission shows that the molecular envelope contains both a slow and a fast outflow with expansion velocities of 19 km/s and greater than 34 km/s, respectively. The slow outflow is mildly elliptical, while the fast molecular outflow is bipolar. This fast outflow is roughly aligned with the very fast outflows recently found in the optical, while the long axis of the slow elliptical outflow is roughly orthogonal to the optical outflow axis. The kinematic timescales for the CO fast outflow and the optical very fast outflow agree closely, supporting the view that the former represents material in the slow outflow accelerated by the very fast outflow. The kinematic signature of a disk expanding with about 15.5 km/s can also be seen in the CO J = 2-1 data. The mass-loss rate (a) for the slow outflow is greater than or equal to 2.8 x 10(exp -5) solar mass/yr and possibly as large as 9 x 10(exp -5) solar mass/yr, (b) for the fast outflow is greater than or equal to 5 x 10(exp -6) solar mass/yr, and (c) for the very fast optically visible outflow is approximately equal 5 x 10(exp -7) solar mass/yr. The disk mass is approximately equal 6 x 10(exp -3) solar mass. Grain photoelectric heating results in temperatures of 20-70 K in molecular gas of the slow outflow. The (13)C/(12)C abundance ratio in M1-16 is found to be 0.33, quite possibly the highest found for any evolved object. Upper limits for the (18)O/(16)O and (17)O/(16)O ratios were found to be consistent with the values found in AGB stars. A search for other molecular species in M1-16 resulted in the detection of the high-excitation species HCN, CN, (13)CN, HCO(+), and H(13)CO(+) and possibly N2H(+). Both the HCO(+)/HCN and CN/HCN line-intensity ratios are enhanced, the former by a very large factor, over the values found in the envelopes of AGB

  5. Planetary nebulae as observational constraints in chemical evolution models for NGC 6822

    NASA Astrophysics Data System (ADS)

    Hernández-Martínez, L.; Carigi, L.; Peña, M.; Peimbert, M.

    2011-11-01

    Aims: Chemical evolution models are useful for understanding the formation and evolution of stars and galaxies. Model predictions will be more robust when more observational constraints are used. We present chemical evolution models for the dwarf irregular galaxy NGC 6822 using chemical abundances of old and young planetary nebulae (PNe) and H ii regions as observational constraints. We use two sets of chemical abundances, one derived from collisionally excited lines (CELs) and one from recombination lines (RLs). We use our models as a tool to distinguish between both procedures for abundance determinations. Methods: In our chemical evolution code the chemical contribution of low and intermediate mass stars is time-delayed, while for the massive stars the chemical contribution follows the instantaneous recycling approximation. Our models have two main free parameters: the mass-loss rate of a well-mixed outflow and the upper mass limit, Mup, of the initial mass function (IMF). To reproduce the gaseous mass and the present-day O/H value we need to vary the outflow rate and the Mup value. Results: We calculate two models with different Mup values that reproduce the constraints adequately. The abundances of old PNe agree with our models and support the star-formation history derived independently from photometric data. Both require an early well-mixed wind, lasting 5.3 Gyr, to reproduce the observed gaseous mass in the galaxy. In addition, by assuming a fraction of binaries producing SNIa of 1%, the models fit the Fe/H abundance ratio as derived from A supergiants. The first model (M4C), which assumes Mup = 40 M⊙, fits within errors smaller than 2σ the O/H, Ne/H, S/H, Ar/H and Cl/H abundances obtained from CELs for old and young PNe and H ii regions. The second model (M1R), which adopts Mup = 80 M⊙, reproduces within 2σ errors the O/H, C/H, Ne/H and S/H abundances adopted from RLs. Both models reproduce the increase of the O, Ne, S, and Ar elements during the

  6. The physics and kinematics of the evolved, interacting planetary nebula PN G342.0-01.7

    NASA Astrophysics Data System (ADS)

    Ali, A.; Amer, M. A.; Dopita, M. A.; Vogt, F. P. A.; Basurah, H. M.

    2015-11-01

    Integral field spectroscopy has been obtained for very few evolved planetary nebulae (PNe). Here we aim to study the physical and kinematical characteristics of the unstudied old planetary nebula PN G342.0-01.7, which shows evidence of interaction with its surrounding interstellar medium. We used integral field spectra from the Wide Field Spectrograph on the ANU 2.3 m telescope to provide spectroscopy across the whole object covering the spectral range 3400-7000 Å. We formed narrow-band images to investigate the excitation structure. The spectral analysis shows that the object is a distant Peimbert Type I planetary nebula (PN) of low excitation, formally of excitation class of 0.5. The low electron density, high dynamical age, and low surface brightness of the object confirm that it is observed fairly late in its evolution. It shows clear evidence for dredge-up of CN-processed material characteristic of its class. In addition, the low peculiar velocity of 7 km s-1 shows it to be a member of the young disk component of our Galaxy. We further determined an average expansion velocity of Vexp = 20.2 ± 1.3 km s-1, a local standard of rest radial velocity RVLSR = -27.7 ± 1.7 km s-1, and a distance of 2.06 ± 0.6 kpc for the object. We built a self-consistent photoionisation model for the PN matching the observed spectrum, the Hβ luminosity, and the diameter. On the basis of this we derive an effective temperature log Teff ~ 5.05 and luminosity 1.85 < log L< 2.25. The temperature is much higher than might have been expected using the excitation class, proving that this can be misleading in classifying evolved PNe. PN G342.0-01.7 is in interaction with its surrounding interstellar medium through which the object is moving in the south-west direction. This interaction drives a slow shock into the outer PN ejecta. A shock model suggests that it only accounts for about 10% of the total luminosity, but has an important effect on the global spectrum of the PN.

  7. IUE observations of proto-planetary and variable planetary nebulae. I - V1016 Cygni, HM Sagittae, and HBV 475. II - A search for variability in IC 4997 and NGC 6905

    NASA Technical Reports Server (NTRS)

    Feibelman, W. A.

    1982-01-01

    The IUE satellite has undertaken UV observations of the proto-planetary nebulae V1016 Cyg, HM Sge, and HBV 475, yielding emission line fluxes, line ratios, line profiles, electron densities, and distances from these objects. While levels of increasing excitation and ionization as a function of time are shown by the data for the first two nebulae, the trend for HBV 475 is found to lead in the opposite direction. The formation of a shell is suggested by dramatic changes in the HM Sge UV line profiles over the last four years, including the disappearance of W-R features and the incipient splitting of the semi-forbidden C III 1909 A line. An additional IUE search for UV variability in the planetary nebulae IC 4997 and NGC 6905 has yielded emission line fluxes, line ratios and profiles, and central star temperatures, as well as stratification effects data for several ions in NGC 6905

  8. Analysis of Co-spatial UV-Optical STIS Spectra of Seven Planetary Nebulae From HST Cycle 19 GO 12600

    NASA Astrophysics Data System (ADS)

    Miller, Timothy R.; Henry, Richard B. C.; Dufour, Reginald J.; Kwitter, Karen B.; Shaw, Richard A.; Balick, Bruce; Corradi, Romano

    2016-01-01

    We present an analysis of seven spatially resolved planetary nebulae (PNe), NGC 2440, NGC 3242, NGC 5315, NGC 5882, NGC 7662, IC 2165, and IC 3568, from observations in the Cycle 19 program GO 12600 using HST STIS. These seven observations cover the wavelength range 1150-10,270 Å with 0.2 and 0.5 arcsec wide slits, and are co-spatial to within 0.1 arcsec along a 25 arcsec length across each nebula. The wavelength and spatial coverage enabled a detailed study of physical conditions and abundances from UV and optical line emissions (compared to only optical lines) for these seven PNe. The first UV lines of interest are those of carbon. The resolved lines of C III] 1906.68 and 1908.73 yielded a direct measurement of the density within the volume occupied by doubly-ionized carbon and other similar co-spatial ions as well as contributed to an accurate measurement of the carbon abundance. Each PN spectrum was divided into smaller spatial regions or segments in order to assess inferred density variations among the regions along the entire slit. There is a clear difference in the inferred density for several regions of each PNe. Variations in electron temperature and chemical abundances were also probed and shown to be completely homogeneous within the errors. Lastly, these nebulae were modeled in detail with the photoionization code CLOUDY. This modeling constrained the central star parameters of temperature and luminosity and tested the effects different density profiles have on these parameters. We gratefully acknowledge generous support from NASA through grants related to the Cycle 19 program GO 12600, as well as from the University of Oklahoma.

  9. NON-DETECTION OF MAGNETIC FIELDS IN THE CENTRAL STARS OF THE PLANETARY NEBULAE NGC 1360 AND LSS 1362

    SciTech Connect

    Leone, Francesco; Privitera, Giovanni; Martinez Gonzalez, MarIa J.; Corradi, Romano L. M.; Sainz, Rafael Manso

    2011-04-20

    The presence of magnetic fields is an attractive hypothesis for shaping planetary nebulae (PNe). We report on observations of the central star of the two PNe NGC 1360 and LSS 1326. We performed spectroscopy on circularly polarized light with the Focal Reducer and Low Dispersion Spectrograph at the Very Large Telescope of the European Southern Observatory. Contrary to previous reports, we find that the effective magnetic field, which is the average over the visible stellar disk of longitudinal components of the magnetic fields, is null within errors for both stars. We conclude that direct evidence of magnetic fields on the central stars of PNe is still missing-either the magnetic field is much weaker (<600 G) than previously reported, or more complex (thus leading to cancellations), or both. Certainly, indirect evidence (e.g., MASER emission) fully justify further efforts to point out the strength and morphology of such magnetic fields.

  10. (F)UV spectral analysis of 15 extremely hot, hydrogen-rich central stars of planetary nebulae

    NASA Astrophysics Data System (ADS)

    Ziegler, Marc; Rauch, Thomas; Werner, Klaus; Kruk, Jeffrey W.

    2012-08-01

    We present results of a (F)UV spectral analysis of 15 hot, hydrogen-rich central stars of planetary nebulae (CSPNe) of DAO-type (A 7, A 31, A 35, A 39, NGC 3587, NGC 6720, NGC 6853, NGC 7293, PuWe 1, Sh 2-174) and O(H)-type (A 36, Lo 1, LSS 1362, NGC 1360, NGC 4361). The sample covers a wide range of parameters (T eff ~ 70-130 kK, log g = 5.4-7.4). It represents different stages of post-AGB evolution. The derived stellar parameters are crucial constraints for AGB nucleosynthesis and stellar evolutionary calculations. Detailed spectral analyses using fully line-blanketed NLTE model atmospheres including 23 elements from hydrogen to nickel are performed. Additional modeling of the ISM line absorption enables to unambigiously identify nearly all observed lines and to improve both, the photospheric as well as the ISM model.

  11. Radial metallicity gradients in spiral galaxies from H II regions and planetary nebulae: probing galactic chemical evolution

    NASA Astrophysics Data System (ADS)

    Stanghellini, Letizia

    2015-08-01

    Radial metallicity gradients, typically observed in spiral galaxies, are excellent constraints for chemical evolution models. The contemporary studies of the two stellar populations, whose progenitors have formed at different times, yield to the chemical and time constraining of the models. In this context, planetary nebula and HII region analysis proved to be ideal two-epochs test populations. We present an assortment of galaxies whose oxygen abundances have been determined both with weak- and strong-line methods, and whose radial metallicity gradients and their evolution in time have disclosed very interesting correlations with the galaxy characteristics. New results from our Gemini/GMOS observations, and a review of the best literature data, set the stage for a better understanding of spiral galaxy evolution.

  12. POSSIBLE STELLAR STREAMS IN THE EDGE-ON SPIRAL NGC 891 DISCOVERED FROM KINEMATICS OF PLANETARY NEBULAE

    SciTech Connect

    Shih, Hsin-Yi; Mendez, Roberto H. E-mail: mendez@ifa.hawaii.ed

    2010-12-10

    We have found 125 planetary nebulae (PNs) in NGC 891, using an [O III] {lambda}5007 on-band/off-band filter technique with the Faint Object Camera and Spectrograph (FOCAS) at the Cassegrain focus of the Subaru telescope, Mauna Kea. Radial velocities were measured for all detected sources, using a method of slitless spectroscopy which we briefly describe. The radial velocities allow us to study the motions of different stellar populations in NGC 891. The PN kinematics show rotation at large distances from the galactic plane. Of particular interest is the strong asymmetry of PN distribution at large height, which we interpret as two possible stellar streams that could be orbiting the galaxy at large angles to the main structure. These streams, if real, are probably remnants of a previous minor merging episode. This idea finds support in recent reports of clump-like, incompletely mixed structures from deep HST/ACS images of this galaxy.

  13. Is the central binary system of the planetary nebula Henize 2-428 a type Ia supernova progenitor?

    NASA Astrophysics Data System (ADS)

    García-Berro, Enrique; Soker, Noam; Althaus, Leandro G.; Ribas, Ignasi; Morales, Juan C.

    2016-05-01

    We critically discuss the recent observations of the binary system at the center of the bipolar planetary nebula Henize 2-428. We find that the proposed explanation of two equal-mass degenerate objects with a total mass larger than the Chandrasekhar limiting mass that supposedly will merge in less than a Hubble time, possibly leading to a SN Ia, is controversial. This hypothesis relies on the assumption that the variability of the He II 5412 Å spectral line is due to two absorption components. Instead, we propose that it can be accounted for by a broad absorption line from the central system on top of which there is a narrow emission line from the nebula. This prompted us to study if the binary system can be made of a degenerate star and a low-mass main sequence companion, or of two degenerate objects of smaller mass. We find that although both scenarios can account for the existence of two symmetric broad minima in the light curve, the second one agrees better with observations. We thus argue that the claim that Henize 2-428 provides observational evidence supporting the double-degenerate scenario for SN Ia is premature.

  14. Exploring Sulfur & Argon Abundances in Planetary Nebulae as Metallicity- Indicator Surrogates for Iron in the Interstellar Medium

    NASA Astrophysics Data System (ADS)

    Kwitter, Karen B.; Henry, Richard C.

    1999-02-01

    Our primary motivation for studying S and Ar distributions in planetary nebulae (PNe) across the Galactic disk is to explore the possibility of a surrogacy between (S+Ar)/O and Fe/O for use as a metallicity indicator in the interstellar medium. The chemical history of the Galaxy is usually studied through O and Fe distributions among objects of different ages. Historically, though, Fe and O have not been measured in the same systems: Fe is easily seen in stars but hard to detect in nebulae; the reverse is true for O. We know that S and Ar abundances are not affected by PN progenitor evolution, and we therefore seek to exploit both their unaltered abundances and ease of detectability in PNe to explore their surrogacy for Fe. If proven valid, this surrogacy carries broad and important ramifications for bridging the gap between stellar and interstellar abundances in the Galaxy, and potentially beyond. Observed S/O and Ar/O gradients will also provide constraints on theoretical stellar yields of S and Ar, since they can be compared with chemical evolution models (which incorporate theoretically-predicted stellar yields, an initial mass function, and rates of star formation and infall) to help place constraints on model parameters.

  15. The collimated outflows of the planetary nebula Hu 1-2: proper motion and radial velocity measurements

    NASA Astrophysics Data System (ADS)

    Miranda, L. F.; Blanco, M.; Guerrero, M. A.; Riera, A.

    2012-04-01

    Hu 1-2 is a planetary nebula that contains an isolated knot located north-west of the main nebula, which could be related to a collimated outflow. We present a subarcsecond Hα+[N II] image and a high-resolution, long-slit spectrum of Hu 1-2 that allow us to identify the south-eastern counterpart of the north-western knot and to establish their high-velocity (>340 km s-1), collimated bipolar outflow nature. The detection of the north-western knot in Palomar Observatory Sky Atlas (POSS) red plates allows us to carry out a proper motion analysis by combining three POSS red plates and two narrow-band Hα+[N II] CCD images, with a time baseline of ≃57 yr. A proper motion of 20 ± 6 mas yr-1 along position angle 312°± 15° and a dynamical age of 1375? yr are obtained for the bipolar outflow. The measured proper motion and the spatio-kinematical properties of the bipolar outflow yield a lower limit of 2.7 kpc for the distance to Hu 1-2. The Andalucia Faint Object Spectrograph and Camera (ALFOSC) is provided by the Instituto de Astrofísica de Andalucía (IAA) under a joint agreement with the University of Copenhagen and NOTSA. The IACUB uncrossed echelle spectrograph was built in a collaboration between the IAC and the Queen's University of Belfast.

  16. Mid- and Far-Infrared Photometry of Galactic Planetary Nebulae with the AKARI All-Sky Survey

    NASA Astrophysics Data System (ADS)

    Phillips, J. P.; Márquez-Lugo, R. A.

    2011-04-01

    We provide mid- and far-infrared photometry of 857 Galactic planetary nebulae (PNe) using data derived from the AKARI All-Sky Survey. These include fluxes at 9 and 18 μm obtained with the Infrared Camera (IRC), and at 65, 90, 140 and 160 μm using the far-Infrared Surveyor (FIS). It is noted that the IR luminosities of the youngest PNe are comparable to the total luminosities of the central stars, and subsequently decline to 5×102 L⊙ where D > 0.08 pc. This is consistent with an evolution of PNe dust opacities, and appreciable absorption in young and proto-PNe. We also note that there is little evidence for the evolution in IR/radio flux ratios suggested by previous authors. The fall-off of dust temperatures with increasing nebular diameter is similar to that determined in previous studies, whilst levels of Lyα heating are <0.5 of the total energy budget of the grains. There appears to be an evolution in the infrared excess (IRE) as nebulae expand, with the largest values occurring in the most compact PNe.

  17. EXPANSION OF HYDROGEN-POOR KNOTS IN THE BORN-AGAIN PLANETARY NEBULAE A30 AND A78

    SciTech Connect

    Fang, X.; Guerrero, M. A.; Marquez-Lugo, R. A.; Toalá, J. A.; Chu, Y.-H.; Gruendl, R. A.; Blair, W. P.; Hamann, W.-R.; Oskinova, L. M.; Todt, H.

    2014-12-20

    We analyze the expansion of hydrogen-poor knots and filaments in the born-again planetary nebulae A30 and A78 based on Hubble Space Telescope (HST) images obtained almost 20 yr apart. The proper motion of these features generally increases with distance to the central star, but the fractional expansion decreases, i.e., the expansion is not homologous. As a result, there is not a unique expansion age, which is estimated to be 610-950 yr for A30 and 600-1140 yr for A78. The knots and filaments have experienced complex dynamical processes: the current fast stellar wind is mass loaded by the material ablated from the inner knots; the ablated material is then swept up until it shocks the inner edges of the outer, hydrogen-rich nebula. The angular expansion of the outer filaments shows a clear dependence on position angle, indicating that the interaction of the stellar wind with the innermost knots channels the wind along preferred directions. The apparent angular expansion of the innermost knots seems to be dominated by the rocket effect of evaporating gas and by the propagation of the ionization front inside them. Radiation-hydrodynamical simulations show that a single ejection of material followed by a rapid onset of the stellar wind and ionizing flux can reproduce the variety of clumps and filaments at different distances from the central star found in A30 and A78.

  18. The Mutliple Lobes and Geometric Model of Hubble 12: A Young Planetary Nebula with two pairs of H2 Knots

    NASA Astrophysics Data System (ADS)

    Hsia, Chih-Hao; Chau, Wayne; Zhang, Yong; Kwok, Sun

    2015-08-01

    Hubble 12 (Hb 12) is a member of the rare group of planetary nebulae (PNs) exhibiting nested shells. Its intrinsic structures and shaping mechanism are still not fully understood. We present new near-infrared narrow-band imaging observations of Hb 12 using Wide-field InfraRed Camera on the Canada-France-Hawaii Telescope (CFHT). Combining Hubble Space Telescope optical imaging and CFHT observations, we find a number of co-axial rings aligned with the bipolar lobes and two pairs of separate knots with different orientations. These rings are thought to be the manifestation of a time-variable, collimated fast wind of bipolar lobes interacting with surrounding asymptotic giant branch circumstellar medium. The existence of knots with different orientations suggests that this PN hosts a bipolar, rotating, episodic jet (BRET). We construct a three-dimensional model that allows the visualization of the nebula viewed from different orientations, and infer that this PN might have intrinsic structures similar to the young multipolar PNs, Hen 2-320 and M 2-9.

  19. The determination of the masses of Magellanic Cloud planetary nebulae using forbidden O II doublet ratio electron densities

    NASA Astrophysics Data System (ADS)

    Barlow, M. J.

    1987-07-01

    Spectrophotometric data, including [O II] 3726, 3729 Å doublet ratios, are presented for 32 planetary nebulae (PN) in the Magellanic Clouds. It is argued that the electron densities derived from these ratios provide a much better diagnostic for the determination of nebular masses than previously assumed. The optically thick PN are found to all have electron densities greater than 6000 cm-3, while the optically thin PN all have electron densities below 5000 cm-3. The optically thin PN show a range of only a factor of 2.0 in their derived masses, and have a mean ionized mass of 0.27±0.06 M_sun;. The absolute Hβ fluxes of the optically thick nebulae show a range of only a factor of 1.8. The application of these results to Galactic PN would yield distances which are generally larger than those previously estimated. A method of distance determination is proposed for optically thin PN that uses integrated nebular [O II] electron densities rather than angular diameters.

  20. On the variations of O III forbidden line intensities in the spectrum of the planetary nebula IC 4997

    NASA Astrophysics Data System (ADS)

    Egikyan, A. G.

    1997-10-01

    The causes of asynchronous variations in the intensities of forbidden O III lines in the spectrum of the planetary nebula IC 4997 are considered. It is shown that the strengthening of the 4363-A line with a simultaneous weakening of the N1 and N2 lines can be explained by a severalfold increase of the mass-loss rate from the nucleus, up to 1-2 x 10 exp -7 solar mass/yr, over several years. The ionization model of the nebula under the combined effect of nucleus emission and the emission from a variable hot stellar wind with electron temperature of 500,000 K is used to calculate the theoretical line intensities. The calculations included 12 levels of O III. In the region of O III line formation, the electron density of 10 exp 6/cu cm and Te, which varies from 12,000 to 15,000 K, yield theoretical line intensities that are in best agreement with observations. The X-ray luminosity of the stellar wind from the nucleus at energies not less than 0.2 keV is on the order of 10 exp 35 erg/s, but the interstellar extinction rules out the possibility of observing this object.

  1. Mid­Infrared Imaging of the Bipolar Planetary Nebula M2-­9 from SOFIA

    NASA Astrophysics Data System (ADS)

    Sahai, R.; Werner, M. W.; Davis, J.; Livingston, J.; Lykou, F.; de Buizer, J.; Morris, M.; Keller, L.; Adams, J.; Gull, G.; Henderson, C.; Herter, T.; Schoenwald, J.

    2014-04-01

    We have imaged the bi-polar planetary nebula M2-9 using SOFIA's FORCAST instrument in six wavelength bands between 6.6 and 37.1 micron. A bright central point source, unresolved with SOFIA's ~4" beam, is seen at each wavelength, and the extended bipolar lobes are clearly seen at 19.7 μm and beyond. The photometry between 10 and 25 micron is well fit by a model of the type previously proposed for this source by Lykou et al and Chesneau et al. The principal new results in this paper relate to the distribution and properties of the dust that emits the infrared radiation. In particular, a considerable fraction of this material is spread uniformly through the lobes, although the dust density does increase at the sharp outer edge seen in higher resolution optical images of M2-9. The dust grain population in the source is unusual in that small (<0.1 micron) and large (>1 micron) particles appear to be present in roughly equal quantities by mass. We suggest that collisional processing within the bipolar outflow plays an important role in determining the particle size distribution. These early results show the promise of the SOFIA airborne observatory as a platform for studying planetary nebulae. This work is based on observations made with the NASA/DLR Stratospheric Observatory for Infrared Astronomy (SOFIA), operated by USRA and DSI. Portions of the work were carried out at the Jet Propulsion Laboratory, operated by the California Institute of Technology under a contract with NASA.

  2. Planetary Nebula Spectrograph survey of S0 galaxy kinematics - II. Clues to the origins of S0 galaxies

    NASA Astrophysics Data System (ADS)

    Cortesi, A.; Merrifield, M. R.; Coccato, L.; Arnaboldi, M.; Gerhard, O.; Bamford, S.; Napolitano, N. R.; Romanowsky, A. J.; Douglas, N. G.; Kuijken, K.; Capaccioli, M.; Freeman, K. C.; Saha, K.; Chies-Santos, A. L.

    2013-06-01

    The stellar kinematics of the spheroids and discs of S0 galaxies contain clues to their formation histories. Unfortunately, it is difficult to disentangle the two components and to recover their stellar kinematics in the faint outer parts of the galaxies using conventional absorption line spectroscopy. This paper therefore presents the stellar kinematics of six S0 galaxies derived from observations of planetary nebulae, obtained using the Planetary Nebula Spectrograph. To separate the kinematics of the two components, we use a maximum-likelihood method that combines the discrete kinematic data with a photometric component decomposition. The results of this analysis reveal that: the discs of S0 galaxies are rotationally supported; however, the amount of random motion in these discs is systematically higher than in comparable spiral galaxies; and the S0s lie around one magnitude below the Tully-Fisher relation for spiral galaxies, while their spheroids lie nearly one magnitude above the Faber-Jackson relation for ellipticals. All of these findings are consistent with a scenario in which spirals are converted into S0s through a process of mild harassment or `pestering,' with their discs somewhat heated and their spheroid somewhat enhanced by the conversion process. In such a scenario, one might expect the properties of S0s to depend on environment. We do not see such an effect in this fairly small sample, although any differences would be diluted by the fact that the current location does not necessarily reflect the environment in which the transformation occurred. Similar observations of larger samples probing a broader range of environments, coupled with more detailed modelling of the transformation process to match the wide range of parameters that we have shown can now be measured, should take us from these first steps to the definitive answer as to how S0 galaxies form.

  3. HuDo 1 and HuBi 1: two planetary nebulae ionized by cool [WC] central stars

    NASA Astrophysics Data System (ADS)

    Peña, M.

    2005-10-01

    As part of our spectroscopic survey of planetary nebulae with [WC] nuclei (Peña et al. 2001), low- and high-resolution spectra of the planetary nebulae HuDo 1 (PNG 060.4+01.5, PM1-310) and HuBi 1 (PNG 012.2+04.9, PM1-188) were secured and analyzed. Both objects are ionized by very late [WC] central stars. We found that the objects belong to the galactic disk, with heliocentric radial velocities of -12 km s-1 (HuDo 1) and 57 km s-1 (HuBi1). Both objects are heavily extinguished showing a logarithmic reddening, c(Hβ), of 2.04 for HuDo 1 and 1.22 for HuBi 1. Our data cover a wide wavelength range; therefore we obtained several plasma line ratios to estimate physical conditions and abundances. The derived electron temperature and density for HuBi 1 are 9,400±1,500 K and 800 cm-3. This density is very low for a nebula around a [WC]-late star. HuDo 1 has Ne = 3300 cm-3. We find log(O/H)+12 = 8.43 and 8.57, and N/O = 0.2 and 0.1 for HuDo 1 and HuBi 1 respectively, typical of disk PNe. Intense nebular He I recombination lines are detected for HuBi 1, this being the only PN excited by a very late [WC] star showing such an emission. The He+ abundance derived for HuBi 1 is 0.11, which is indicating a large He enhancement in HuBi 1. >From the analysis of the stellar emission lines a [WC 10] spectral type is derived for both stars. This is consistent with a stellar temperature of about 30,000 K, although the HuBi 1 central star should be slightly hotter for providing the large amount of He0 ionizing photons required to explain the nebular He I lines. Nebular and stellar parameters of HuDo 1 and HuBi 1 can be compared with those of other [WC 10] objects, such as M 4-18, He 2-113 and CPD-5608031. >From this, we can conclude that, in spite of the fact that all the objects have the same spectral type, the central stars of HuDo 1 and HuBi 1 should be intrinsically fainter, and consequently of lower mass. This is an additional evidence showing that stars of different masses can go

  4. SHAPEMOL: a 3D code for calculating CO line emission in planetary and protoplanetary nebulae. Detailed model-fitting of the complex nebula NGC 6302

    NASA Astrophysics Data System (ADS)

    Santander-García, M.; Bujarrabal, V.; Koning, N.; Steffen, W.

    2015-01-01

    Context. Modern instrumentation in radioastronomy constitutes a valuable tool for studying the Universe: ALMA has reached unprecedented sensitivities and spatial resolution, while Herschel/HIFI has opened a new window (most of the sub-mm and far-infrared ranges are only accessible from space) for probing molecular warm gas (~50-1000 K). On the other hand, the software SHAPE has emerged in the past few years as a standard tool for determining the morphology and velocity field of different kinds of gaseous emission nebulae via spatio-kinematical modelling. Standard SHAPE implements radiative transfer solving, but it is only available for atomic species and not for molecules. Aims: Being aware of the growing importance of the development of tools for simplifying the analyses of molecular data from new-era observatories, we introduce the computer code shapemol, a complement to SHAPE, with which we intend to fill the so-far under-developed molecular niche. Methods: shapemol enables user-friendly, spatio-kinematic modelling with accurate non-LTE calculations of excitation and radiative transfer in CO lines. Currently, it allows radiative transfer solving in the 12CO and 13CO J = 1-0 to J = 17-16 lines, but its implementation permits easily extending the code to different transitions and other molecular species, either by the code developers or by the user. Used along SHAPE, shapemol allows easily generating synthetic maps to test against interferometric observations, as well as synthetic line profiles to match single-dish observations. Results: We give a full description of how shapemol works, and we discuss its limitations and the sources of uncertainty to be expected in the final synthetic profiles or maps. As an example of the power and versatility of shapemol, we build a model of the molecular envelope of the planetary nebula NGC 6302 and compare it with 12CO and 13CO J = 2-1 interferometric maps from SMA and high-J transitions from Herschel/HIFI. We find the

  5. SULFURIZATION OF IRON IN THE DYNAMIC SOLAR NEBULA AND IMPLICATIONS FOR PLANETARY COMPOSITIONS

    SciTech Connect

    Ciesla, Fred J.

    2015-02-10

    One explanation for the enhanced ratio of volatiles to hydrogen in Jupiter’s atmosphere compared to a a gas of solar composition is that the planet accreted volatile-bearing clathrates during its formation. Models, however, suggest that S would be over abundant if clathrates were the primary carrier of Jupiter’s volatiles. This led to the suggestion that S was depleted in the outer nebula due to the formation troilite (FeS). Here, this depletion is quantitatively explored by modeling the coupled dynamical and chemical evolution of Fe grains in the solar nebula. It is found that disks that undergo rapid radial expansion from an initially compact state may allow sufficient production of FeS and carry H{sub 2}S-depleted gas outward where ices would form, providing the conditions needed for S-depleted clathrates to form. However, this expansion would also carry FeS grains to this region, which could also be incorporated into planetesimals. Thus for clathrates to be a viable source of volatiles, models must account for the presence of both H{sub 2}S in FeS in the outer solar nebula.

  6. The abundance discrepancy - recombination line versus forbidden line abundances for a northern sample of galactic planetary nebulae

    NASA Astrophysics Data System (ADS)

    Wesson, R.; Liu, X.-W.; Barlow, M. J.

    2005-09-01

    We present deep optical spectra of 23 galactic planetary nebulae, which are analysed in conjunction with archival infrared and ultraviolet spectra. We derive nebular electron temperatures based on standard collisionally excited line (CEL) diagnostics as well as the hydrogen Balmer jump and find that, as expected, the Balmer jump almost always yields a lower temperature than the [OIII] nebular-to-auroral line ratio. We also make use of the weak temperature dependence of helium and OII recombination line ratios to further investigate the temperature structure of the sample nebulae. We find that, in almost every case, the derived temperatures follow the relation , which is the relation predicted by two-component nebular models in which one component is cold and hydrogen-deficient. Te(OII) may be as low as a few hundred Kelvin, in line with the low temperatures found for the hydrogen-deficient knots of Abell 30 by Wesson, Liu and Barlow. Elemental abundances are derived for the sample nebulae from both CELs and optical recombination lines (ORLs). ORL abundances are higher than CEL abundances in every case, by factors ranging from 1.5 to 12. Five objects with O2+ abundance discrepancy factors greater than 5 are found. DdDm 1 and Vy 2-2 are both found to have a very large abundance discrepancy factor of 11.8. We consider the possible explanations for the observed discrepancies. From the observed differences between Te(OIII) and Te(BJ), we find that temperature fluctuations cannot resolve the abundance discrepancies in 22 of the 23 sample nebulae, implying some additional mechanism for enhancing ORL emission. In the one ambiguous case, the good agreement between abundances derived from temperature-insensitive infrared lines and temperature-sensitive optical lines also points away from temperature fluctuations being present. The observed recombination line temperatures, the large abundance discrepancies and the generally good agreement between infrared and optical CEL

  7. Parameters of Selected Central Stars of Planetary Nebulae from Consistent Optical and UV Spectral Analysis

    NASA Astrophysics Data System (ADS)

    Kaschinski, Cornelius Bernhard

    Low mass stars have zero age main sequence masses of roughly 0.8-8.0 solar masses. Once their H and He source is depleted, low mass stars reaching the tip of the asymptotic giant branch (AGB) eject their envelopes becoming Central Stars of Planetary Nebulae (CSPNs). In the main part of this thesis we investigate the stellar parameters of a selected samples of CSPNS in order to further examine the validity of the commonly accepted core mass-luminosity relation of CSPNs. The necessity of such a critical examination was highlighted by a mismatch between the derived stellar parameters from hydrodynamical self-consistent UV analysis and those from a plane-parallel model fit to photospheric H and He absorption lines. The consistently derived masses from the UV analysis showed a wider spread than the masses derived from the optical analysis, which were obtained using theoretical post-AGB evolutionary tracks. This investigation was carried out using the non-local thermodynamic equilibrium atmosphere code "WM-basic", which has been previously used as the basis for the earlier consistent UV analysis performed on the sample of selected CSPNs. First, we improved the code by implementing the Stark broadening effect, so as to model optical H and He lines simultaneously along with the UV spectrum. This allowed a self-consistent re-analysis of the most and least massive of the CSPNs sampled. Using the UV parameter set we then reproduced not only the observed UV spectra but also produced optical line profiles which are nearly identical to those from optical stellar parameter models. The consistent models using the optical parameter set reproduce neither spectrum accurately. The lack of consistency between stellar and wind parameters of the optical parameter set is also evident from a different approach based on an investigation of the dynamical wind parameters. In a subsequent study, we further improved the WM-basic code by implementing the treatment of clumping. The strength of

  8. LIMITS ON [O III] 5007 EMISSION FROM NGC 4472'S GLOBULAR CLUSTERS: CONSTRAINTS ON PLANETARY NEBULAE AND ULTRALUMINOUS BLACK HOLE X-RAY BINARIES IN GLOBULAR CLUSTERS

    SciTech Connect

    Peacock, Mark B.; Zepf, Stephen E.; Maccarone, Thomas J.

    2012-06-20

    We have searched for [O III] 5007 emission in high-resolution spectroscopic data from FLAMES/GIRAFFE Very Large Telescope observations of 174 massive globular clusters (GCs) in NGC 4472. No planetary nebulae (PNe) are observed in these clusters, constraining the number of PNe per bolometric luminosity, {alpha} < 0.8 Multiplication-Sign 10{sup -7} PN/L{sub Sun }. This is significantly lower than the rate predicted from stellar evolution, if all stars produce PNe. Comparing our results to populations of PNe in galaxies, we find most galaxies have a higher {alpha} than these GCs (more PNe per bolometric luminosity-though some massive early-type galaxies do have similarly low {alpha}). The low {alpha} required in these GCs suggests that the number of PNe per bolometric luminosity does not increase strongly with decreasing mass or metallicity of the stellar population. We find no evidence for correlations between the presence of known GC PNe and either the presence of low-mass X-ray binaries (LMXBs) or the stellar interaction rates in the GCs. This, and the low {alpha} observed, suggests that the formation of PNe may not be enhanced in tight binary systems. These data do identify one [O III] emission feature, this is the (previously published) broad [O III] emission from the cluster RZ 2109. This emission is thought to originate from the LMXB in this cluster, which is accreting at super-Eddington rates. The absence of any similar [O III] emission from the other clusters favors the hypothesis that this source is a black hole LMXB, rather than a neutron star LMXB with significant geometric beaming of its X-ray emission.

  9. On the Nonthermal κ-distributed Electrons in Planetary Nebulae and H II Regions: The κ Index and Its Correlations with Other Nebular Properties

    NASA Astrophysics Data System (ADS)

    Zhang, Yong; Zhang, Bing; Liu, Xiao-Wei

    2016-01-01

    Recently, a suspicion arose that the free electrons in planetary nebulae (PNs) and H ii regions might have nonthermal energy distributions. In this scenario, a κ index is introduced to characterize the electron energy distributions, with smaller κ values indicating larger deviations from Maxwell-Boltzmann distributions. Assuming that this is the case, we determine the κ values for a sample of PNs and H ii regions by comparing the intensities of [O iii] collisionally excited lines and the hydrogen Balmer jump. We find the average κ indices of PNs and H ii regions to be 27 and 32, respectively. Correlations between the resultant κ values and various physical properties of the nebulae are examined to explore the potential origin of nonthermal electrons in photoionized gaseous nebulae. However, no positive result is obtained. Thus, the current analysis does not lend support to the idea that κ-distributed electrons are present in PNs and H ii regions.

  10. Discovery of Rubidium, Cadmium, and Germanium Emission Lines in the Near-infrared Spectra of Planetary Nebulae

    NASA Astrophysics Data System (ADS)

    Sterling, N. C.; Dinerstein, Harriet L.; Kaplan, Kyle F.; Bautista, Manuel A.

    2016-03-01

    We identify [Rb iv] 1.5973 and [Cd iv] 1.7204 μm emission lines in high-resolution (R = 40,000) near-infrared spectra of the planetary nebulae (PNe) NGC 7027 and IC 5117, obtained with the Immersion GRating INfrared Spectrometer (IGRINS) on the 2.7 m telescope at McDonald Observatory. We also identify [Ge vi] 2.1930 μm in NGC 7027. Alternate identifications for these features are ruled out based on the absence of other multiplet members and/or transitions with the same upper levels. Ge, Rb, and Cd can be enriched in PNe by s-process nucleosynthesis during the asymptotic giant branch stage of evolution. To determine ionic abundances, we calculate [Rb iv] collision strengths and use approximations for those of [Cd iv] and [Ge vi]. Our identification of [Rb iv] 1.5973 μm is supported by the agreement between Rb3+/H+ abundances found from this line and the 5759.55 Å feature in NGC 7027. Elemental Rb, Cd, and Ge abundances are derived with ionization corrections based on similarities in ionization potential ranges between the detected ions and O and Ne ionization states. Our analysis indicates abundances 2-4 times solar for Rb and Cd in both nebulae. Ge is subsolar in NGC 7027, but its abundance is uncertain due to the large and uncertain ionization correction. The general consistency of the measured relative s-process enrichments with predictions from models appropriate for these PNe (2.0-2.5 M⊙, [Fe/H] = -0.37) demonstrates the potential of using PN compositions to test s-process nucleosynthesis models. This paper includes data taken at The McDonald Observatory of The University of Texas at Austin.

  11. The High-Excitation Planetary Nebula NCG 246: Optical and Near-Ultraviolet Observations and Two-dimensional Numerical Models

    NASA Technical Reports Server (NTRS)

    Szentgyorgyi, Andrew; Raymond, John; Franco, Jose; Villaver, Eva; Lopez-Martin, Luis

    2003-01-01

    We have imaged the planetary nebula (PN) NGC 246 in the near-ultraviolet wavelengths [Ne v] 342.6 nm, the Bowen fluorescence line of 0 111 at 344.4 nm, and a nearby line-free region centered on 338.6 nm, as well as H(alpha), [O III] 500.7 nm, and [S II] 673.0 and 671.5 nm. Imaging in the 344.4 nm line is necessary to deconvolve contamination of the [Ne v] images by O III 342.9 nm. The emission from the shell and inner parts of the nebula is detected in [Ne v]. The radial profiles of the [Ne v] brightness decrease with radius from the exciting star, indicating that the bulk of the emission from this ion is due to the hard UV stellar radiation field, with a (probably) marginal contribution from collisional ionization in a shock between the PN shell and the interstellar medium (ISM). In contrast, the radial profiles of the emission in H(alpha), [0 III] 500.7 nm, and [S II] are flatter and peak at the location of the shell. The emission of [S II] probably traces the interaction of the PN with the ambient ISM. We also present two-dimensional numerical simulations for this PN-ISM interaction. The simulations consider the stellar motion with respect to the ambient ISM, with a velocity of 85 km/s , and include the time evolution of the wind parameters and UV radiation field from the progenitor star.

  12. SWIFT/UVOT PHOTOMETRY OF THE PLANETARY NEBULA WeBo 1: UNMASKING A FAINT HOT COMPANION STAR

    SciTech Connect

    Siegel, Michael H.; Hoversten, Erik; Stark, Michele; Bond, Howard E.; Breeveld, Alice A. E-mail: hoversten@swift.psu.edu E-mail: bond@stsci.edu

    2012-08-15

    We present an analysis of over 150 ks of data on the planetary nebula WeBo 1 (PN G135.6+01.0) obtained with the Swift Ultraviolet Optical Telescope (UVOT). The central object of this nebula has previously been described as a late-type K giant barium star with a possible hot companion, most likely a young pre-white dwarf. UVOT photometry shows that while the optical photometry is consistent with a large cool object, the near-ultraviolet (NUV) photometry shows far more UV flux than could be produced by any late-type object. Using model stellar atmospheres and a comparison to UVOT photometry for the pre-white dwarf PG 1159-035, we find that the companion has a temperature of at least 40,000 K and a radius of, at most, 0.056 R{sub Sun }. While the temperature and radius are consistent with a hot compact stellar remnant, they are lower and larger, respectively, than expected for a typical young pre-white dwarf. This likely indicates a deficiency in the assumed UV extinction curve. We find that higher temperatures more consistent with expectations for a pre-white dwarf can be derived if the foreground dust has a strong 'blue bump' at 2175 A and a lower R{sub V}. Our results demonstrate the ability of Swift to both uncover and characterize hot hidden companion stars and to constrain the UV extinction properties of foreground dust based solely on UVOT photometry.

  13. Discovery of Rubidium, Cadmium, and Germanium Emission Lines in the Near-infrared Spectra of Planetary Nebulae

    NASA Astrophysics Data System (ADS)

    Sterling, N. C.; Dinerstein, Harriet L.; Kaplan, Kyle F.; Bautista, Manuel A.

    2016-03-01

    We identify [Rb iv] 1.5973 and [Cd iv] 1.7204 μm emission lines in high-resolution (R = 40,000) near-infrared spectra of the planetary nebulae (PNe) NGC 7027 and IC 5117, obtained with the Immersion GRating INfrared Spectrometer (IGRINS) on the 2.7 m telescope at McDonald Observatory. We also identify [Ge vi] 2.1930 μm in NGC 7027. Alternate identifications for these features are ruled out based on the absence of other multiplet members and/or transitions with the same upper levels. Ge, Rb, and Cd can be enriched in PNe by s-process nucleosynthesis during the asymptotic giant branch stage of evolution. To determine ionic abundances, we calculate [Rb iv] collision strengths and use approximations for those of [Cd iv] and [Ge vi]. Our identification of [Rb iv] 1.5973 μm is supported by the agreement between Rb3+/H+ abundances found from this line and the 5759.55 Å feature in NGC 7027. Elemental Rb, Cd, and Ge abundances are derived with ionization corrections based on similarities in ionization potential ranges between the detected ions and O and Ne ionization states. Our analysis indicates abundances 2–4 times solar for Rb and Cd in both nebulae. Ge is subsolar in NGC 7027, but its abundance is uncertain due to the large and uncertain ionization correction. The general consistency of the measured relative s-process enrichments with predictions from models appropriate for these PNe (2.0–2.5 M⊙, [Fe/H] = ‑0.37) demonstrates the potential of using PN compositions to test s-process nucleosynthesis models. This paper includes data taken at The McDonald Observatory of The University of Texas at Austin.

  14. Investigating the Near-Infrared Properties of Planetary Nebulae II. Medium Resolution Spectra. 2; Medium Resolution Spectra

    NASA Technical Reports Server (NTRS)

    Hora, Joseph L.; Latter, William B.; Deutsch, Lynne K.

    1998-01-01

    We present medium-resolution (R approximately 700) near-infrared (lambda = 1 - 2.5 micrometers) spectra of a sample of planetary nebulae (PNe). A narrow slit was used which sampled discrete locations within the nebulae; observations were obtained at one or more positions in the 41 objects included in the survey. The PN spectra fall into one of four general categories: H1 emission line-dominated PNe, H1 and H2 emission line PNe, H2 emission line-dominated PNe, and continuum-dominated PNe. These categories correlate with morphological type, with the elliptical PNe falling into the first group, and the bipolar PNe primarily in the H2 and continuum emission groups. The categories also correlate with C/O ratio, with the O-rich objects falling into the first group and the C-rich objects in the groups. Other spectral features were observed in all catagories, such as continuum emission from the central star, and warm dust continuum emission towards the long wavelength end of the spectra. H2 was detected in four PNe in this survey for the first time. An analysis was performed using the H2 line ratios in all of the PN spectra in the survey where a sufficient number of lines were observed to determine the ortho-to-para ratio and the rotational and vibrational excitation temperatures of the H-2 in those objects. One unexpected result from this analysis is that the H-2 is excited by absorption of ultraviolet photons in most of the PNe, although there are several PNe in which collisional excitation plays an important role. The correlation between bipolar morphology and H2 emission has been strengthened with the new detections of H2 in this survey.

  15. Binary Central Stars of Planetary Nebulae Discovered through Photometric Variability. IV. The Central Stars of HaTr 4 and Hf 2-2

    NASA Astrophysics Data System (ADS)

    Hillwig, Todd C.; Bond, Howard E.; Frew, David J.; Schaub, S. C.; Bodman, Eva H. L.

    2016-08-01

    We explore the photometrically variable central stars of the planetary nebulae HaTr 4 and Hf 2-2. Both have been classified as close binary star systems previously based on their light curves alone. Here, we present additional arguments and data confirming the identification of both as close binaries with an irradiated cool companion to the hot central star. We include updated light curves, orbital periods, and preliminary binary modeling for both systems. We also identify for the first time the central star of HaTr 4 as an eclipsing binary. Neither system has been well studied in the past, but we utilize the small amount of existing data to limit possible binary parameters, including system inclination. These parameters are then compared to nebular parameters to further our knowledge of the relationship between binary central stars of planetary nebulae and nebular shaping and ejection.

  16. The FUSE Spectrum of the Planetary Nebula SwSt 1: Evidence for Inhomogeneities in the Gas and Dust

    NASA Astrophysics Data System (ADS)

    Sterling, N. C.; Dinerstein, Harriet L.; Bowers, C. W.; Redfield, Seth

    2005-05-01

    We present Far Ultraviolet Spectroscopic Explorer (FUSE) observations of the young, compact planetary nebula (PN) SwSt 1 along the line of sight to its central star HD 167362. We detect circumstellar absorption lines from several species against the continuum of the central star. The physical parameters of the nebula derived from the FUSE data differ significantly from those found from emission lines. We derive an electron density ne=8800+4800-2400 cm-3 from the column density ratio of the excited S III fine-structure levels, which is at least a factor of 3 lower than all prior estimates. The gaseous iron abundance derived from the UV lines is quite high ([Fe/S]=-0.35+/-0.12), which implies that iron is not significantly depleted into dust. In contrast, optical and near-infrared emission lines indicate that Fe is more strongly depleted: [Fe/H]=-1.64+/-0.24 and [Fe/S]=-1.15+/-0.33. We do not detect nebular H2 absorption, to a limit N(H2)<7×1014 cm-2, at least 4 orders of magnitude lower than the column density estimated from infrared H2 emission lines. Taken together, the lack of H2 absorption, low ne, and high gaseous Fe abundance derived from the FUSE spectrum provide strong evidence that dense structures (which can shield molecules and dust from the destructive effects of energetic stellar photons) are not present along the line of sight to the central star. On the other hand, there is substantial evidence for dust, molecular material, and dense gas elsewhere in SwSt 1. Therefore, we conclude that the nebula must have an inhomogeneous structure. We detect nebular absorption at 1040.94 and 1041.69 Å from the two excited fine-structure levels of neutral oxygen. These levels give rise to far-infrared emission lines at 63 and 145 μm, which are often used to infer gas properties, particularly temperature, under the assumption that they are collisionally excited. We find that the O I fine-structure levels in SwSt 1 have an inverted population ratio. This requires a

  17. OT1_rrubin_1: Herschel's Opportunity to Solve the Nebular Abundance Problem While Creating a Legacy Planetary Nebulae Dataset

    NASA Astrophysics Data System (ADS)

    Rubin, R.

    2010-07-01

    Abundance surveys of a large sample of Galactic planetary nebulae (PNe) have led to the discovery of a group of super-metal-rich nebulae whose spectra show prominent optical recombination lines (ORLs) from C, N, O, and Ne ions. The heavy element abundances derived from ORLs for several PNe are a factor >10 higher than those derived from the traditional method based on collisionally excited lines (CELs). This ratio is called the abundance discrepancy factor (adf). A promising proposition to explain the nebular abundance problem posits that these nebulae contain (at least) two distinct regions - one of "normal" electron temperature, Te (~10000 K) and chemical composition (~solar) and another of very low Te (< 1000) that is H-deficient, thus having high metal abundances relative to H. The latter component emits strong heavy element ORLs and IR fine-structure (FS) CELs but essentially no optical/UV CELs. Efforts to directly detect these inclusions in PNe have been unsuccessful to date. However, there is mounting circumstantial evidence for their existence, such as presented in our recent paper that modeled the high-adf PN NGC 6153 using a 3-D photoionization code. The models that included the low Te, H-deficient knots fit most observations far better than did those models without the clumps. With the launch of Herschel, there is finally the capability to perform a test we've been dreaming of. Measurements have shown that the adf varies with position in a PN and is highest close to the central star. The very low Te inclusions must be cooled via FS IR lines. We propose to use Herschel to map the FS IR lines in 5 bright PNe on the largest adf list, to find if these lines peak where the adf peaks. These spectra will also provide a feast for our other team expertise/interests: a legacy dataset of molecular lines to explore PDRs, how the central star interacts with the AGB ejecta and shapes the PN, how the shocks are produced, what comprises the chemistry of the molecular

  18. The hydrogen-deficient knot of the `born-again' planetary nebula Abell 58 (V605 Aql)

    NASA Astrophysics Data System (ADS)

    Wesson, R.; Barlow, M. J.; Liu, X.-W.; Storey, P. J.; Ercolano, B.; De Marco, O.

    2008-02-01

    We have analysed deep optical spectra of the `born-again' planetary nebula Abell 58 and its hydrogen-deficient knot, surrounding V605 Aql, which underwent a nova-like eruption in 1919. Our analysis shows that the extinction towards the central knot is much higher than previously thought, with c(Hβ) = 2.0. The outer nebula is less reddened, with c(Hβ) = 1.04. We find that the outer nebula has a Ne/O ratio higher than the average PN value. The electron temperature we derive for the central knot varies widely depending on the diagnostic used. The [OIII] nebular-to-auroral transition ratio gives a temperature of 20800K, while the ratio of the [NII] nebular and auroral lines gives Te = 15200K. The helium line ratios λ5876/λ4471 and λ6678/λ4471 imply temperatures of 350 and 550K, respectively. Weakly temperature-sensitive OII recombination line ratios imply similarly low electron temperatures. Abundances derived from recombination lines are vastly higher than those found from collisionally excited lines, with the abundance discrepancy factor (ADF) for O2+ reaching 89 - the second highest known value after that found for the hydrogen-deficient knots in Abell 30. The observed temperature diagnostics and abundances support the idea that, like Abell 30, the knot of Abell 58 contains some very cold ionized material. Although the central star is carbon-rich (C/O > 1), the knot is found to be oxygen-rich, a situation not predicted by the single-star `born-again' theory of its formation. We compare the known properties of Abell 58 to those of Abell 30, Sakurai's Object and several novae and nova remnants. We argue that the abundances in the ejecta observed in A30 and A58 have more in common with neon novae than with Sakurai's Object, which is believed to have undergone a final helium flash. In particular, the C/O ratio of less than unity and the presence of substantial quantities of neon in the ejecta of both Abell 30 and Abell 58 are not predicted by very late thermal

  19. A SPITZER/IRS SPECTRUM OF THE 2008 LUMINOUS TRANSIENT IN NGC 300: CONNECTION TO PROTO-PLANETARY NEBULAE

    SciTech Connect

    Prieto, Jose L.; Sellgren, Kris; Thompson, Todd A.; Kochanek, Christopher S.

    2009-11-10

    We present a Spitzer/IRS low-resolution mid-infrared (mid-IR) spectrum (5-14 mum) of the luminous transient discovered in the nearby galaxy NGC 300 in 2008 May. This transient had peak luminosity M{sub V} approx = -13, showed an optical spectrum dominated by relatively narrow Balmer and Ca II lines in emission, and its progenitor was identified in pre-explosion images as a dust-enshrouded approx10 M {sub sun} star, characteristics that make it a twin of SN 2008S. The Spitzer spectrum, obtained three months after discovery, shows that the transient is very luminous in the mid-IR. Furthermore, the spectrum shows strong, broad emission features at 8 mum and 12 mum that are observed in Galactic carbon-rich proto-planetary nebulae. Combining these data with published optical and near-IR photometry obtained at the same epoch, we find that the mid-IR excess traced by the Spitzer spectrum accounts for approx20% of the total energy output. This component can be well explained by emission from approx3 x 10{sup -4} M{sub sun} of pre-existing progenitor dust at temperature T approx 400 K. The spectral energy distribution of the transient also shows a near-IR excess that can be explained by emission from newly formed dust in the ejecta. Alternatively, both the near-IR and mid-IR excesses can together be explained by a single pre-existing geometrically thick dust shell. In light of the new observations obtained with Spitzer, we revisit the analysis of the optical spectra and kinematics, which were compared to the massive yellow-hypergiant IRC+10420 in previous studies. We show that proto-planetary nebulae share many properties with the NGC 300 transient and SN 2008S. We conclude that even though the explosion of a massive star (M approx> 10 M{sub sun}) cannot be ruled out, an explosive event on a massive (M approx 6-10 M{sub sun}) carbon-rich AGB/super-AGB or post-AGB star is consistent with all observations of the transients and their progenitors presented thus far.

  20. VLA observations of stellar planetary nebulae. [using Very Large Array at National Radio Astronomy Observatory

    NASA Technical Reports Server (NTRS)

    Johnson, H. M.; Balick, B.; Thompson, A. R.

    1979-01-01

    Coordinates, dimensions, 4885-MHz flux densities, and brightness temperatures of K3-2, NGC 6833, Ps 1, II 5117, Me 2-2, Hb 12, Vy 1-1, and M1-5 are reported. In two other cases, H3-29 and H3-75, confused extended structure was detected in which the nebula could not be identified with certainty. He 2-467, M1-2, and Peterson's H-alpha object in M15 were also included in the observations but not detected with an upper limit of less than 10 mJy. The observations are compared with some of the previous optical and radio data, such as log S(H-beta). Distances are computed from the present data with standard assumptions. Corresponding linear radii range below 0.1 pc, among the smallest in previous distributions of radius.

  1. The gas turbulence in planetary nebulae: quantification and multi-D maps from long-slit, wide-spectral range echellograms

    NASA Astrophysics Data System (ADS)

    Sabbadin, F.; Turatto, M.; Benetti, S.; Ragazzoni, R.; Cappellaro, E.

    2008-09-01

    Context: This methodological paper is part of a short series dedicated to the long-standing astronomical problem of de-projecting the bi-dimensional, apparent morphology of a three-dimensional distribution of gas. Aims: We focus on the quantification and spatial recovery of turbulent motions in planetary nebulae (and other classes of expanding nebulae) by means of long-slit echellograms over a wide spectral range. Methods: We introduce some basic theoretical notions, discuss the observational methodology, and develop an accurate procedure disentangling all broadening components (instrumental resolution, thermal motions, turbulence, gradient of the expansion velocity, and fine structure of hydrogen-like ions) of the velocity profile in all spatial positions of each spectral image. This allows us to extract random, non-thermal motions at unprecedented accuracy, and to map them in 1-, 2- and 3-dimensions. Results: We discuss general and specific applications of the method. We present the solution to practical problems in the multi-dimensional turbulence-analysis of a testing-planetary nebula (NGC 7009), using the three-step procedure (spatio-kinematics, tomography, and 3D rendering) developed at the Astronomical Observatory of Padua (Italy). In addition, we introduce an observational paradigm valid for all spectroscopic parameters in all classes of expanding nebulae. Conclusions: Unsteady, chaotic motions at a local scale constitute a fundamental (although elusive) kinematical parameter of each planetary nebula, providing deep insights on its different shaping agents and mechanisms, and on their mutual interaction. The detailed study of turbulence, its stratification within a target and (possible) systematic variation among different sub-classes of planetary nebulae deserve long-slit, multi-position angle, wide-spectral range echellograms containing emissions at low-, medium-, and high-ionization, to be analyzed pixel-to-pixel with a straightforward and versatile

  2. A Spectroscopic study of the envelope of the hybrid nova V458 Vul and the surrounding planetary nebula

    NASA Astrophysics Data System (ADS)

    Tarasova, T. N.

    2015-10-01

    Spectroscopic observations of the hybrid V458 Vul obtained between days 9 and 778 after the brightness maximumare analyzed. Short-period, daily profile variations of forbidden [FeVII] iron lines were detected in the nebular phase, as well as a long-period (about 60-day) cyclic variation that was correlated with the photometric and X-ray cycles. The abundances of helium, neon, and iron in the nova's envelope have been estimated. The helium, neon, and iron abundances exceed the solar values by factors of 4.4, 4.8, and 3.7. The envelope mass is 1.4 × 10-5 Mʘ. The electron temperatures and number densities have been calculated for the Northwestern and Southeastern knots of the planetary nebula. The temperature derived for the Northwestern knot is T e = 10 000 K and the electron number density, n e = 600 cm-3; for the Southeastern knot, T e = 13 000 K and n e = 750 cm-3.

  3. Polycyclic aromatic hydrocarbons and molecular hydrogen in oxygen-rich planetary nebulae: the case of NGC 6720

    NASA Astrophysics Data System (ADS)

    Cox, N. L. J.; Pilleri, P.; Berné, O.; Cernicharo, J.; Joblin, C.

    2016-02-01

    Evolved stars are primary sources for the formation of polycyclic aromatic hydrocarbons (PAHs) and dust grains. Their circumstellar chemistry is usually designated as either oxygen rich or carbon rich, although dual-dust chemistry objects, whose infrared spectra reveal both silicate- and carbon-dust features, are also known. The exact origin and nature of this dual-dust chemistry is not yet understood. Spitzer-Infrared Spectrograph (IRS) mid-infrared spectroscopic imaging of the nearby, oxygen-rich planetary nebula NGC 6720 reveals the presence of the 11.3 μm aromatic (PAH) emission band. It is attributed to emission from neutral PAHs, since no band is observed in the 7-8 μm range. The spatial distribution of PAHs is found to closely follow that of the warm clumpy molecular hydrogen emission. Emission from both neutral PAHs and warm H2 is likely to arise from photodissociation regions associated with dense knots that are located within the main ring. The presence of PAHs together with the previously derived high abundance of free carbon (relative to CO) suggest that the local conditions in an oxygen-rich environment can also become conducive to in situ formation of large carbonaceous molecules, such as PAHs, through a bottom-up chemical pathway. In this scenario, the same stellar source can enrich the interstellar medium with both oxygen-rich dust and large carbonaceous molecules.

  4. AN ENVELOPE DISRUPTED BY A QUADRUPOLAR OUTFLOW IN THE PRE-PLANETARY NEBULA IRAS 19475+3119

    SciTech Connect

    Hsu, Ming-Chien; Lee, Chin-Fei E-mail: cflee@asiaa.sinica.edu.tw

    2011-07-20

    IRAS 19475+3119 is a quadrupolar pre-planetary nebula (PPN), with two bipolar lobes, one in the east-west (E-W) direction and one in the southeast-northwest (SE-NW) direction. We have observed it in CO J = 2-1 with the Submillimeter Array at {approx}1'' resolution. The E-W bipolar lobe is known to trace a bipolar outflow and it is detected at high velocity. The SE-NW bipolar lobe appears at low velocity, and could trace a bipolar outflow moving in the plane of the sky. Two compact clumps are seen at low velocity around the common waist of the two bipolar lobes, spatially coincident with the two emission peaks in the NIR, tracing dense envelope material. They are found to trace the two limb-brightened edges of a slowly expanding torus-like circumstellar envelope produced in the late asymptotic giant branch phase. This torus-like envelope originally could be either a torus or a spherical shell, and it appears as it is now because of the two pairs of cavities along the two bipolar lobes. Thus, the envelope appears to be disrupted by the two bipolar outflows in the PPN phase.

  5. Polycyclic aromatic hydrocarbons and molecular hydrogen in oxygen-rich planetary nebulae: the case of NGC 6720

    PubMed Central

    Cox, N. L. J.; Pilleri, P.; Berné, O.; Cernicharo, J.; Joblin, C.

    2015-01-01

    Evolved stars are primary sources for the formation of polycyclic aromatic hydrocarbons (PAHs) and dust grains. Their circumstellar chemistry is usually designated as either oxygen-rich or carbon-rich, although dual-dust chemistry objects, whose infrared spectra reveal both silicate- and carbon-dust features, are also known. The exact origin and nature of this dual-dust chemistry is not yet understood. Spitzer-IRS mid-infrared spectroscopic imaging of the nearby, oxygen-rich planetary nebula NGC 6720 reveals the presence of the 11.3 μm aromatic (PAH) emission band. It is attributed to emission from neutral PAHs, since no band is observed in the 7–8 μm range. The spatial distribution of PAHs is found to closely follow that of the warm clumpy molecular hydrogen emission. Emission from both neutral PAHs and warm H2 is likely to arise from photo-dissociation regions associated with dense knots that are located within the main ring. The presence of PAHs together with the previously derived high abundance of free carbon (relative to CO) suggest that the local conditions in an oxygen-rich environment can also become conducive to in-situ formation of large carbonaceous molecules, such as PAHs, via a bottom-up chemical pathway. In this scenario, the same stellar source can enrich the interstellar medium with both oxygen-rich dust and large carbonaceous molecules. PMID:26924856

  6. Central Star Properties and C-N-O Abundances in Eight Galactic Planetary Nebulae from New HST/STIS Observations

    NASA Astrophysics Data System (ADS)

    Henry, Richard B. C.; Balick, Bruce; Dufour, Reginald J.; Kwitter, Karen B.; Shaw, Richard A.; Corradi, Romano

    2015-01-01

    We present detailed photoionization models of eight Galactic planetary nebulae (IC2165, IC3568, NGC2440, NGC3242, NGC5315, NGC5882, NGC7662, & PB6) based on recently obtained HST STIS spectra. Our interim goal is to infer Teff, luminosity, and current and progenitor masses for each central star, while the ultimate goal is to constrain published stellar evolution models which predict nebular CNO abundances. The models were produced by using the code CLOUDY to match closely the measured line strengths derived from high-quality HST STIS spectra (see poster by Dufour et al., this session) extending in wavelength from 1150-10270 Angstroms. The models assumed a blackbody SED. Variable input parameters included Teff, a radially constant nebular density, a filling factor, and elemental abundances. For the eight PNs we found a birth mass range of 1.5-2.9 Msun, a range in log(L/Lsun) of 3.10-3.88, and a Teff range of 51-150k K. Finally, we compare CNO abundances of the eight successful models with PN abundances of these same elements that are predicted by published stellar evolution models. We gratefully acknowledge generous support from NASA through grants related to the Cycle 19 program GO12600.

  7. The expansion proper motions of the extraordinary giant lobes of the planetary nebula KjPn 8 revisited

    NASA Astrophysics Data System (ADS)

    Boumis, P.; Meaburn, J.

    2013-04-01

    The primary aim is to establish a firm value for the distance to the extraordinary planetary nebula KjPn 8. Secondary aims are to measure the ages of the three giant lobes of this object as well as estimate the energy in the eruption, that caused the most energetic outflow, for comparison with that of an intermediate-luminosity optical transient (ILOT). For these purposes a mosaic of images in the Hα + [N II] optical emission lines has been obtained with the new Aristarchos telescope in 2011 for comparison with the images of the KjPn 8 giant lobes present on the Palomar Observatory Sky Survey (POSSI-R) 1954 and POSSII-R 1991 plates. Expansion proper motions of features over this 57 yr baseline in the outflows are present. Using these, a firm distance to KjPn 8 of 1.8 ± 0.3 kpc has been derived for now the angle of the latest outflow to the sky has been established from Hubble Space Telescope imagery of the nebular core. Previously, the uncertain predictions of a bow-shock model were used for this purpose. The dynamical ages of the three separate outflows that form the giant lobes of KjPn 8 are also directly measured as 3200, 7200 and ≥5 × 104 yr, respectively, which confirms their sequential ejection. Moreover, the kinetic energy of the youngest and most energetic of these is measured as ≈1047 erg which is compatible with an ILOT origin.

  8. A kinematic determination of the structure of the double ring planetary nebula NGC 2392, the Eskimo

    NASA Technical Reports Server (NTRS)

    O'Dell, C. R.; Weiner, Larry D.; Chu, You-Hua

    1990-01-01

    Slit spectra and existing 'velocity cube' data have been used to determine the structure of the double ring PN NGC 2392. The inner shell is a stellar wind-sculpted prolate spheroid with a ratio of axes of 2:1 and the approaching end of the long axis pointed 20 deg from the line of sight in P.A. = 200 deg. The outer ring is caused by an outer disk with density dropping off with distance from the central star and with distance from its plane, which is the same as the equatorial band of high density in the inner shell. The outer disk contains a ring of higher density knots at a distance of 16 arcsec and is losing material through free expansion, forming an outer envelope of increasing velocity. Forbidden S II spectra are used to determine the densities in all of the major regions of the nebula. It is argued that the filamentary cores at the centers of the knots seen in the outer ring originate in the sublimation of bodies formed at the same time as the parent star.

  9. The rocket-ultraviolet spectrum of the planetary nebula NGC 7027

    NASA Technical Reports Server (NTRS)

    Bohlin, R. C.; Stecher, T. P.; Marionni, P. A.

    1975-01-01

    An ultraviolet spectrum of NGC 7027, obtained with a rocket-borne telescope, is analyzed. Absolute values are presented for the observed fluxes, and upper limits are given for the strongest predicted lines that were not observed. The results are corrected for interstellar extinction using the observed and calculated line ratios between H-beta and the hydrogenic recombination line of He II at 1640 A. The corrected C IV resonance line at 1549 A is found to be in good agreement with the intensity calculated from models, but the intercombination line of C III at 1909 A is found to be too bright by a factor of 10. This discrepancy is reduced to a factor of 4 by taking dielectric recombination into account and is eliminated by using the solar carbon abundance, which implies attenuation in the C IV line. It is shown that no appreciable number of absorbing grains can exist in the C IV-producing region of the nebula since the optical depth is of the order of 10,000 at the line center.

  10. Echelle spectroscopy and photoionization modelling of the entire planetary nebula NGC 6210

    NASA Astrophysics Data System (ADS)

    Bohigas, J.; Escalante, V.; Rodríguez, M.; Dufour, R. J.

    2015-02-01

    High-resolution spectroscopy of NGC 6210, show that recombination line abundances of O+2 and Ne+2 are two to three times larger than forbidden line abundances, Te(O+2) is smaller than Te(N+) and possibly Te(S+), the ionized mass is ≃0.07 M⊙ and the progenitor zero-age main-sequence mass is 1.2-2 M⊙. If electrons are in equilibrium, recombination lines are likely produced in a cold low-density medium. A photoionization model (CLOUDY 13.03) with a positive density gradient and two exciting sources, reproduced most of the optical spectrum, the temperature distribution of the nebula, He II 4686/He I 5876, [O II]3726/[O III]5007 and [O II]3726/3729, but not the other density sensitive line ratios. Including fluorescence and recombination, we found good agreement with observed C II and C III line intensities, O II and O III model intensities which are 2.6 and 7.8 times smaller than observed and large erratic differences with observations in C III, N II and N III lines. UV and IR data suggest that [O II] emission is from a region ˜ 6 times less dense than assumed by the model and that IR lines are produced in a medium where the density is ˜1000 cm-3. There may be a lower density medium beyond a dense ring described by the photoionization model, as well as a cold low-density component. A multicomponent model is required to reproduce the entire spectrum of NGC 6210.

  11. Millimeter Observations of CS, HCO+, and CO toward Five Planetary Nebulae: Following Molecular Abundances with Nebular Age

    NASA Astrophysics Data System (ADS)

    Edwards, J. L.; Cox, E. G.; Ziurys, L. M.

    2014-08-01

    Millimeter and sub-millimeter observations of CO, CS, and HCO+ have been conducted toward five planetary nebulae (PNe: K4-47, NGC 6537 (Red Spider), M2-48, NGC 6720 (Ring), and NGC 6853 (Dumbbell)), spanning an age range of 900-10,000 yr, using the Sub-Millimeter Telescope and the 12 m antenna of the Arizona Radio Observatory. The J = 5 → 4, J = 3 → 2, and J = 2 → 1 transitions of CS at 245, 147, and 98 GHz, as well as the J = 3 → 2 and J = 1 → 0 lines of HCO+ at 268 and 89 GHz, were detected toward each source. At least three rotational transitions of CO have also been observed, including the J = 6 → 5 and J = 4 → 3 lines at 691 and 461 GHz. CS had not been definitively identified previously in PNe, and new detections of HCO+ were made in four of the five nebulae. From a radiative transfer analysis of the CO and CS data, kinetic temperatures of T K ~ 10-80 K and gas densities of n(H2) ~ 0.1-1 × 106 cm-3 were determined for the molecular material in these sources. Column densities for CO, CS, and HCO+ were N tot ~ 0.2-5 × 1016 cm-2, N tot ~ 0.4-9 × 1012 cm-2, and N tot ~ 0.3-5 × 1012 cm-2, respectively, with fractional abundances, relative to H2, of f ~ 0.4-2 × 10-4, f ~ 1-4 × 10-8, and f ~ 1 × 10-8, with the exception of M2-48, which had f(HCO+) ~ 10-7. Overall, the molecular abundances do not significantly vary over a duration of 10,000 yr, in contrast to predictions of chemical models. The abundances reflect the remnant asymptotic giant branch shell material, coupled with photochemistry in the early PN phase. These observations also suggest that PNe eject substantial amounts of molecular material into the diffuse interstellar medium.

  12. Millimeter observations of CS, HCO{sup +}, and CO toward five planetary nebulae: following molecular abundances with nebular age

    SciTech Connect

    Edwards, J. L.; Ziurys, L. M.; Cox, E. G.

    2014-08-20

    Millimeter and sub-millimeter observations of CO, CS, and HCO{sup +} have been conducted toward five planetary nebulae (PNe: K4-47, NGC 6537 (Red Spider), M2-48, NGC 6720 (Ring), and NGC 6853 (Dumbbell)), spanning an age range of 900-10,000 yr, using the Sub-Millimeter Telescope and the 12 m antenna of the Arizona Radio Observatory. The J = 5 → 4, J = 3 → 2, and J = 2 → 1 transitions of CS at 245, 147, and 98 GHz, as well as the J = 3 → 2 and J = 1 → 0 lines of HCO{sup +} at 268 and 89 GHz, were detected toward each source. At least three rotational transitions of CO have also been observed, including the J = 6 → 5 and J = 4 → 3 lines at 691 and 461 GHz. CS had not been definitively identified previously in PNe, and new detections of HCO{sup +} were made in four of the five nebulae. From a radiative transfer analysis of the CO and CS data, kinetic temperatures of T {sub K} ∼ 10-80 K and gas densities of n(H{sub 2}) ∼ 0.1-1 × 10{sup 6} cm{sup –3} were determined for the molecular material in these sources. Column densities for CO, CS, and HCO{sup +} were N {sub tot} ∼ 0.2-5 × 10{sup 16} cm{sup –2}, N {sub tot} ∼ 0.4-9 × 10{sup 12} cm{sup –2}, and N {sub tot} ∼ 0.3-5 × 10{sup 12} cm{sup –2}, respectively, with fractional abundances, relative to H{sub 2}, of f ∼ 0.4-2 × 10{sup –4}, f ∼ 1-4 × 10{sup –8}, and f ∼ 1 × 10{sup –8}, with the exception of M2-48, which had f(HCO{sup +}) ∼ 10{sup –7}. Overall, the molecular abundances do not significantly vary over a duration of 10,000 yr, in contrast to predictions