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Sample records for faint planetary nebulae

  1. 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.

  2. 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.

  3. Orion Nebula and Planetary Nebulae

    NASA Astrophysics Data System (ADS)

    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. 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.

  5. 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

  6. 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.

  7. Shock modelling of Planetary Nebulae

    NASA Astrophysics Data System (ADS)

    Cuesta, L.; Phillips, J. P.; Mampaso, A.

    1994-06-01

    The kinematics of Planetary Nebulae are analyzed in terms of the solutions to the equations of hydrodynamic equilibrium developed by J. Canto. We apply our analysis to the Planetary Nebulae NGC 6905 and NGC 6537. A detailed spectroscopic study of these objects reveals the existence of high nuclear velocities, together with complex kinematic structures and unusual emission line intensities. Shock ionization clearly plays a key role in these nebulae. Remarkably good agreement is obtained when comparing the synthetic maps and spectra resulting from the shock solutions with the observational data.

  8. Deprojection of planetary nebula images

    NASA Astrophysics Data System (ADS)

    Volk, Kevin; Leahy, Denis A.

    1993-11-01

    Several optical or radio images of planetary nebulae have been deprojected using the algorithm described in Leahy & Volk (1993). For each image 16 radial cuts from the center of the nebula were independently deprojected assuming either spherical symmetry or a weighting of the emissivity distribution towards the plane of the sky. The deprojection was carried out using the optical line images of Balick (1987) for the Ring Nebula (NGC 6720, PN G063.1+13.9) and NGC 40 (PN G120.0+09.8) and for the 15 GHz radio image of M3-35 (PN G071.6-02.3) from Aaquist & Kwok (1991). These three nebulae were chosen due to their generally ellipsoidal shapes as seen projected on the sky, but in all three cases the deprojection indicates that the nebuale are neither oblate or prolate ellipsoidal shells. Instead, these nebulae have two main regions of emission roughly oppositely positioned around the central star each of which covers a solid angle of approximately pi steradians, and most of the emission is in more or less cylindrical bands with very little emissivity at the 'poles' of the nebulae. The nebulae are therefore more barrel-shaped than ellipsoid-shaped. While the possibility that planetary nebulae are cylindrical in shape has been studied in the past, these results indicate that the body of the nebula is far more patchy than had been postulated which may resolve some of the difficulties that the hypothesis of cylindrical symmetry has had. Such shapes are more complicated than the simplest form of the interacting winds model of planetary nebula formation predicts, but can be explained if the progenitor red giant wind was rather asymmetrical.

  9. Neutral matter in planetary nebulae

    NASA Technical Reports Server (NTRS)

    Dinerstein, Harriet L.

    1991-01-01

    A review of current studies of neutral envelopes is presented with particular attention given to the use of the envelopes as test cases for understanding the ionization and thermal structure of photodissociation regions. The study of near-IR H2 emission is discussed with detailed spectra given for a few planetary nebulae, and airborne observations of far-IR atomic lines are discussed. These two methods can discern photodissociation regions with warm gas and UV flux is fairly prominent. The use of resonance-absorption-line spectroscopy is also reviewed with respect to the analysis of the Na D lines, and thereby allows the measurement of integrated columns of material through the shell. The methods provide evidence for the notion that planetary nebulae consist of more than just ionized material; large amounts of neutral and molecular material are being confirmed, which has important implications for the mass-loss episode of the nebulae.

  10. 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

  11. 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)

  12. s-process enrichment in the planetary nebula NGC 3918

    NASA Astrophysics Data System (ADS)

    García-Rojas, J.; Madonna, S.; Luridiana, V.; Sterling, N. C.; Morisset, C.

    2015-05-01

    We present deep, high-resolution (R˜40000) UVES at VLT spectrophotometric data of the planetary nebula NGC 3918. This is one of the deepest spectra ever taken of a planetary nebula. We have identified and measured more than 700 emission lines and, in particular, we have detected very faint lines of several neutron-capture elements (s-process elements: Kr, Xe and Rb) that enable us to compute their chemical abundances with unprecedented accuracy, thus constraining the efficiency of the s-process and convective dredge-up.

  13. The planetary nebula NGC 6826

    NASA Technical Reports Server (NTRS)

    Feibelman, W. A.

    1981-01-01

    Monochromatic photographs have established the NGC 6826 nebula as the third member of a group of very rare triple-shell planetaries (Feibelman, 1971, 1974). Kaler (1974) also characterized NGC 6826 as a giant halo planetary. Numerous errors and confusing statements regarding its size, structure and stratification are discussed, and the correct dimensions of the nebula are reported: the inner ring is 12.7 arcsec x 8.7 arcsec (Feibelman, 1971); the outer ring is 27 arcsec x 24 arcsec according to Curtis (1918), 25.7 arcsec x 24.4 arcsec according to Feibelman (1971), and 36 arcsec x 36 arcsec according to Coleman et al. (1975). The halo measurements range in diameter from 110 arcsec (Duncan, 1937) to 130 arcsec (Kaler, 1974) to 142 arcsec (Millikan, 1974). Values for the distance of NGC 6826 range from 0.75-1.16 kpc (Cahn and Kaler, 1971) to 2.265 kpc (Cudworth, 1974).

  14. 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.

  15. Birth and early evolution of planetary nebulae

    NASA Astrophysics Data System (ADS)

    Parthasarathy, M.

    2000-06-01

    Birth and early evolution of planetary nebulae is described. The study of the young planetary nebula Hen 1357 (Stingray Nebula) with HST is discussed. The observed characteristics of few interesting PPNe and PNe are described. The presence of multiple arcs or rings, knots, jets, collimated and bipolar out flows and disks shows the complex nature of mass loss process during the AGB and post-AGB phases of evolution.

  16. Where Do Messy Planetary Nebulae Come From?

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2017-03-01

    If you examined images of planetary nebulae, you would find that many of them have an appearance that is too messy to be accounted for in the standard model of how planetary nebulae form. So what causes these structures?Examples of planetary nebulae that have a low probability of having beenshaped by a triple stellar system. They are mostly symmetric, with only slight departures (labeled) that can be explained by instabilities, interactions with the interstellar medium, etc. [Bear and Soker 2017]A Range of LooksAt the end of a stars lifetime, in the red-giant phase, strong stellar winds can expel the outer layers of the star. The hot, luminous core then radiates in ultraviolet, ionizing the gas of the ejected stellar layers and causing them to shine as a brightly colored planetary nebula for a few tens of thousands of years.Planetary nebulae come in a wide variety of morphologies. Some are approximately spherical, but others can be elliptical, bipolar, quadrupolar, or even more complex.Its been suggested that non-spherical planetary nebulae might be shaped by the presence of a second star in a binary system with the source of the nebula but even this scenario should still produce a structure with axial or mirror symmetry.A pair of scientists from Technion Israel Institute of Technology, Ealeal Bear and Noam Soker, argue that planetary nebulae with especially messy morphologies those without clear axial or point symmetries may have been shaped by an interacting triple stellar system instead.Examples of planetary nebulae that might have been shaped by a triple stellar system. They have some deviations from symmetry but also show signs of interacting with the interstellar medium. [Bear and Soker 2017]Departures from SymmetryTo examine this possibility more closely, Bear and Soker look at a sample of thousands planetary nebulae and qualitatively classify each of them into one of four categories, based on the degree to which they show signs of having been shaped by a

  17. Using Planetary Nebulae to Teach Physics

    NASA Astrophysics Data System (ADS)

    Kwitter, Karen B.

    2011-05-01

    We have developed an interactive website, "Gallery of Planetary Nebula Spectra," (www.williams.edu/Astronomy/research/PN/nebulae/) that contains high-quality optical-to-near-infrared spectra, atlas information, and bibliographic references for more than 160 planetary nebulae that we have observed in the Milky Way Galaxy. To make the material more accessible to students, I have created three undergraduate-level exercises that explore physics-related aspects of planetary nebulae. "Emission Lines and Central Star Temperature” uses the presence or absence of emission lines from species with different ionization potentials to rank the temperatures of the exciting stars in a selection of nebulae. "Interstellar Reddening” uses the observed Balmer decrement in a sample of planetary nebulae at different Galactic latitudes to infer the distribution of interstellar dust in the Milky Way. Finally, "Determining the Gas Density in Planetary Nebulae,” which I will focus on here, uses the observed intensity ratio of the 6717 Å and 6731 Å emission lines from singly ionized sulfur to determine the electron density in the nebular gas. These exercises demonstrate that planetary nebula spectra are useful real-world examples illustrating a variety of physical principles, including the behavior of blackbodies, wavelength-dependent particle scattering, recombination-line ratios, atomic physics, and statistical mechanics.

  18. 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

  19. The Planetary Nebula System of M33

    NASA Astrophysics Data System (ADS)

    Ciardullo, Robin; Durrell, Patrick R.; Laychak, Mary Beth; Herrmann, Kimberly A.; Moody, Kenneth; Jacoby, George H.; Feldmeier, John J.

    2004-10-01

    We report the results of a photometric and spectroscopic survey for planetary nebulae (PNs) over the entire body of the Local Group spiral galaxy M33. We use our sample of 152 PNs to show that the bright end of the galaxy's [O III] λ5007 planetary nebula luminosity function (PNLF) has the same sharp cutoff seen in other galaxies. The apparent magnitude of this cutoff, along with the IRAS DIRBE foreground extinction estimate of E(B-V)=0.041, implies a distance modulus for the galaxy of (m-M)0=24.86+0.07-0.11 (0.94+0.03-0.05 Mpc). Although this value is ~15% larger than the galaxy's Cepheid distance, the discrepancy likely arises from differing assumptions about the system's internal extinction. Our photometry, which extends more than 3 mag down the PNLF, also reveals that the faint end of M33's PNLF is nonmonotonic, with an inflection point ~2 mag below the PNLF's bright limit. We argue that this feature is due to the galaxy's large population of high core mass planetaries and that its amplitude may eventually be a useful diagnostic for studies of stellar populations. Fiber-coupled spectroscopy of 140 of the PN candidates confirms that M33's PN population rotates along with the old disk, with a small asymmetric drift of ~10 km s-1. Remarkably, the population's line-of-sight velocity dispersion varies little over ~4 optical disk scale lengths, with σrad~20 km s-1. We show that this is due to a combination of factors, including a decline in the radial component of the velocity ellipsoid at small galactocentric radii and a gradient in the ratio of the vertical to radial velocity dispersion. We use our data to derive the dynamical scale length of M33's disk and the disk's mass-to-light ratio. Our most likely solution suggests that the surface mass density of M33's disk decreases exponentially, but with a scale length that is ~2.3 times larger than that of the system's IR luminosity. The large scale length also implies that the disk's V-band mass-to-light ratio changes

  20. Size distribution of planetary nebulae

    NASA Astrophysics Data System (ADS)

    Asvarov, Abdul; Allahverdiyev, Ahad

    2015-08-01

    Despite a very long history of investigations, the nature and origin of planetary nebulae (PNe) are not fully understood. It is obvious that the observational properties of PNe are influenced by the properties of the central star and the conditions in the environment. In this presentation in order to understand the effects of these components we have modeled the evolution of radio luminosity and the expansion of PNe in the framework of different hypothesis on the origin of these objects. In this we have used the observational data on the central stars and clustered this data into gourps with the similar parameters of the central stars. For the each of these groups of PNe we have built statistical dependences radio luminosity - diameter, number of PNe - diameter which are then compared to the modeled ones. Unfortunately, the comparison of simulations with observations did not allow us to choose between the known models of the evolution of the PN shell. However with the increase of statistics the approach considered in this presentation may become more productive.

  1. 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.

  2. 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.

  3. A Mid-IR Search for Planetary Nebulae

    NASA Astrophysics Data System (ADS)

    Wachter, Stefanie

    2015-01-01

    Motivated by the dearth of relatively faint, compact planetary nebulae (PNe) in uncrowded fields that could serve as potential spectral calibration sources for the Euclid Mission, we have conducted a search for PNe at high Galactic latitudes based on WISE data. Previous studies have largely focused on the Galactic Plane or searched for mid-IR counterparts to optically selected PNe. We instead identify the WISE mid-IR color locus of PNe and investigate the cataloged sources fulfilling these color criteria. We will present preliminary results from this study, including new PNe candidates.

  4. Reddening of planetary nebulae - NGC 2392

    NASA Technical Reports Server (NTRS)

    Zipoy, D. M.

    1976-01-01

    A method for finding the reddening of planetary nebulae is proposed which makes use of the fact that the color of a hot star is an insensitive function of its temperature. Spectrophotometric data of NGC 2392 are presented and used to compute its color excess by the present method as well as older methods; the present method appears to be viable. These results combined with previous measurements tend to support the idea that reddening is variable over the surface of the nebula.

  5. 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.

  6. 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.

    2016-11-01

    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 (Optical System for Imaging and low-Intermediate-Resolution Integrated Spectroscopy/Gran Telescopio Canarias) with the goal of analysing 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.

  7. 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.

  8. 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.

  9. Trigonometric Parallaxes of Central Stars of Planetary Nebulae

    DTIC Science & Technology

    2007-02-01

    TRIGONOMETRIC PARALLAXES OF CENTRAL STARS OF PLANETARY NEBULAE Hugh C. Harris,1 Conard C. Dahn, Blaise Canzian, Harry H. Guetter, S. K. Leggett,2...parallaxes of 16 nearby planetary nebulae are presented, including reduced errors for seven objects with previous initial results and results for six new...unresolved close companions are detected. Key words: astrometry — planetary nebulae: general — stars: AGB and post-AGB — stars: distances 1. INTRODUCTION

  10. 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

  11. 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

  12. Hot Gas in Planetary Nebulae

    NASA Technical Reports Server (NTRS)

    Gruendl, Robert A.; Chu, You-Hua; Guerrero, Martin

    2003-01-01

    It was successfully obtained the FUSE spectra of all targets awarded. The analysis of the spectra has been a complex task due to the superposition of the P-Cygni profile from the wind of the central star and absorption components from low ionization and molecular species in the nebular shell. In six of the eight targets there are narrow O VI absorption components that may arise from the interface layer between the hot (l0(exp 6) K) interior gas and the surrounding warm (l0(exp 4) K) dense nebular shell. To better determine whether these narrow O VI absorption lines arise from the interface region we have obtained ground-based high-dispersion spectroscopic observations of the central star and nebula to pin-point the precise line-of-sight velocity of the nebular emission lines. The comparison between these optical spectra with the far-UV spectra obtained with FUSE is complete. The analysis shows that in most cases the narrow O VI absorption components have velocities slightly redshifted from the emission lines which arise from the approaching side of the nebular shell. Preliminary results have been published in two papers.

  13. Chemical Abundances of Compact Planetary Nebulae

    NASA Astrophysics Data System (ADS)

    Lee, Ting-Hui; Shaw, Richard A.; Stanghellini, letizia; Riley, Ben

    2015-08-01

    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 deep sample of PN chemical abundances. We obtained optical spectra of PNe with the Southern Astrophysical Research (SOAR) Telescope and Goodman High-Throughput Spectrograph between 2012 and 2015. These data were used to calculate the nebulae diagnostics such as electron temperature and density for each PN, and to derive the elemental abundances of He, N, O Ne, S and Ar. These abundances are vital to understanding the nature of the PNe, and their low- to intermediate-mass progenitor stars.

  14. KINEMATIC DISTANCES OF GALACTIC PLANETARY NEBULAE

    SciTech Connect

    Yang, A. Y.; Tian, W. W.; Zhu, H.; Wu, D.; Leahy, D. A. E-mail: ayyang@bao.ac.cn

    2016-03-15

    We construct H i absorption spectra for 18 planetary nebulae (PNs) and their background sources using data from the International Galactic Plane Survey. We estimate the kinematic distances of these PNs, among which 15 objects’ kinematic distances are obtained for the first time. The distance uncertainties of 13 PNs range from 10% to 50%, which is a significant improvement with uncertainties of a factor of two or three smaller than most previous distance measurements. We confirm that PN G030.2−00.1 is not a PN because of its large distance found here.

  15. Silicon and magnesium in planetary nebulae

    NASA Technical Reports Server (NTRS)

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

    1981-01-01

    The IUE satellite spectra of some planetary nebulae show features due to silicon and magnesium: Si III wavelengths 1883, 1892; Si IV wavelengths 1394, 1403; Mg II wavelengths 2796, 2804 and Mg V wavelengths 2784, 2929. With the aid of modeling techniques, the corresponding elemental abundances are found. In addition to previous observations of NGC 7662 and IC 418, data were found for NGC 2440, Hu 1-2, IC 2003 and IC 2165. Silicon appears depleted by up to an order of magnitude relative to the sun. Large variations of magnesium abundance are found, which are likely to reflect differing degrees of depletion due to grain formation.

  16. 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

  17. 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

  18. 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.

  19. Morpho-kinematic modeling of planetary nebulae

    NASA Astrophysics Data System (ADS)

    Chan, Tsz-Pan (Henry)

    2009-11-01

    The Planetary Nebulae (PNe) are the transition phase between asymptotic giant branch (AGB) star and white dwarfs for stars with masses between 1 and 8 M⊙. They were originally thought to be well-studied and can be explained with simple models. With the advance of imaging technology especially on Space Telescope (HST), the shapes of PNe have been found to be much more complex than we assumed to be. We aimed to investigate on the basic but mysterious intrinsic three-dimensional structures using the newly developed modeling software. Astronomers usually use the morphological classification on group and classify different properties of PNe. Over the past century many attempts have been made for this classification to seek for explaining and understanding the threedimensional structure that is responsible for the observed images. There have been two beliefs in explaining the variety of shapes of PNe and among them the most amazing one is that the morphologies can be accounted by different orientations of a single structure (Khromov & Kohoutek, 1968). Motivated by the study of Ring Nebula on its intrinsic structure, we investigated the possibility that different types of morphology in PNe can be explained by a single model. We used the newly developed modeling code SHAPE (Steffen et al., 2006), which cooperates the use of spatial information as well as its kinematics, and aimed to quantitatively investigate the basic structure inside PNe. We investigated two classical nebulae: NGC 2346 and NGC 2440. We proposed a simple but adequate model for these nebulae. Stimulated optical images and the p-v arrays were derived by the modeling code SHAPE to make comparison with the observed data to seek for the correctness of the model. Hubble velocity field and inverse square law density distribution were assumed throughout the modeling process. This model provides insights in seeking further adequate intrinsic structure of PNe.

  20. 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).

  1. Birth and early evolution of a planetary nebula

    NASA Astrophysics Data System (ADS)

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

    1998-04-01

    The final expulsion of gas by a star as it forms a planetary nebula - the ionized shell of gas often observed surrounding a young white dwarf - is one of the most poorly understood stages of stellar evolution,. Such nebulae form extremely rapidly (about 100 years for the ionization) and so the formation process is inherently difficult to observe. Particularly puzzling is how a spherical star can produce a highly asymmetric nebula with collimated outflows. Here we report optical observations of the Stingray nebula,, which has become an ionized planetary nebula within the past few decades. We find that the collimated outflows are already evident, and we have identified the nebular structure that focuses the outflows. We have also found a companion star, reinforcing previous suspicions that binary companions play an important role in shaping planetary nebulae and changing the direction of successive outflows.

  2. 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.

  3. 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.

  4. The distances of highly evolved planetary nebulae

    NASA Astrophysics Data System (ADS)

    Phillips, J. P.

    2005-02-01

    The central stars of highly evolved planetary nebulae (PNe) are expected to have closely similar absolute visual magnitudes MV. This enables us to determine approximate distances to these sources where one knows their central star visual magnitudes, and levels of extinction. We find that such an analysis implies values of D which are similar to those determined by Phillips; Cahn, Kaler & Stanghellin; Acker, and Daub. However, our distances are very much smaller than those of Zhang; Bensby & Lundstrom, and van de Steene & Zijlstra. The reasons for these differences are discussed, and can be traced to errors in the assumed relation between brightness temperature and radius. Finally, we determine that the binary companions of such stars can be no brighter than MV~ 6mag, implying a spectral type of K0 or later in the case of main-sequence stars.

  5. 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.

  6. 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

  7. The ionization structure of planetary nebulae. IX - NGC 1535

    NASA Technical Reports Server (NTRS)

    Barker, Timothy

    1989-01-01

    The ionization structure of planetary nebula NGC 1535 was investigated using spectrophotometric observations of emission-line intensities over the spectral range 1400-7200 A, which were carried out in five positions in this nebula. The results obtained on the ionic abundances of He, O, N, Ne, C, and Ar in NGC 1535 suggest that it is a planetary nebula that formed initially in a somewhat metal-poor region and has undergone little or no enhancement of its original abundances by mixing with nuclear-processed material.

  8. s-process enrichment in the planetary nebula NGC 3918. Results from deep echelle spectrophotometry

    NASA Astrophysics Data System (ADS)

    Madonna, Simone; Garcia-Rojas, Jorge; Luridiana, Valentina; Sterling, Nicholas C.; Morisset, Christophe

    2015-08-01

    Approximately half of the elements with atomic number Z > 30 are created by slow neutron-capture process in the stellar interior of low- and intermediate- mass stars on the asymptotic giant branch (AGB), during the phase of thermal pulses. These elements, collectively called s-process elements, are dredged up onto the surface of the star and later ejected into the medium by stellar winds, giving us the opportunity of observing them in planetary nebulae. In this work we study the chemical content of the planetary nebula NGC 3918 through deep, high-resolution (R~40000) spectrophotometric data taken with UVES at VLT. We identify and measure more than 750 emission lines, some of which are faint lines of the s-process elements Rb, Kr, and Xe. The abundances of these elements are calculated with unprecedented accuracy, thus constraining the efficiency of the s-process and convective dredge-up in the progenitor star of NGC 3918.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. The SPM Kinematic Catalogue of Planetary Nebulae

    NASA Astrophysics Data System (ADS)

    López, J. A.; Richer, M.; Riesgo, H.; Steffen, W.; Meaburn, J.; García-Segura, G.; Escalante, K.

    2006-06-01

    We present a progress report on the San Pedro Mártir Kinematic Catalogue of Planetary Nebulae. Both, galactic PNe from the disk, bulge and halo populations, and PNe from galaxies in the local group from a diverse range of metallicities have been observed. Most of the observations have been made with the 2.1-m SPM telescope and the Manchester Echelle Spectrometer (Meaburn et al. 2003, RevMexAA, 39, 185). The data consists of spatially resoved long slit spectra at resolutions of ˜ 10 km s^{-1}. For most galactic targets more than one slit positions has been observed. The interpretation of the 3D structures and outflows derived from the kinematic data is being performed with the aid of SHAPE (see the contributions by Steffen, López, & Escalante, Steffen & López in this symposium). This unique database of high dispersion spectra will allow a firm characterisation of nebular shell properties in relation to progenitors from diverse stellar populations.

  14. New young planetary nebulae in IPHAS

    NASA Astrophysics Data System (ADS)

    Viironen, K.; Mampaso, A.; Corradi, R. L. M.; Rodríguez, M.; Greimel, R.; Sabin, L.; Sale, S. E.; Unruh, Y.; Delgado-Inglada, G.; Drew, J. E.; Giammanco, C.; Groot, P.; Parker, Q. A.; Sokoloski, J.; Zijlstra, A.

    2009-07-01

    Aims: We search for very small-diameter galactic planetary nebulae (PNe) representing the earliest phases of PN evolution. The IPHAS catalogue of Hα-emitting stars provides a useful basis for this study since all sources present in this catalogue must be of small angular diameter. Methods: The PN candidates are selected based on their location in two colour-colour diagrams: IPHAS (r' - Hα) vs. (r' - i'), and 2MASS (J - H) vs. (H - K_s). Spectroscopic follow-up was carried out on a sample of candidates to confirm their nature. Results: We present a total of 83 PN candidates. We were able to obtain spectra or find the classification from the literature for 35 candidates. Five of these objects are likely to be new PNe, including one large bipolar PN discovered serendipitously close to an emission-line star. PN distances deduced from extinction-distance relations based on IPHAS field-star photometry are presented for the first time. These yield distance estimates for our objects in the range 2 kpc and 6 kpc. From the data in hand, we conclude that four of the discovered objects are probably young PNe.

  15. Ionization structure of multiple-shell planetary nebulae. I. NGC 2438

    NASA Astrophysics Data System (ADS)

    Öttl, S.; Kimeswenger, S.; Zijlstra, A. A.

    2014-05-01

    Context. In recent times an increasing number of extended haloes and multiple shells around planetary nebulae have been discovered. These faint extensions to the main nebula trace the mass-loss history of the star, modified by the subsequent evolution of the nebula. Integrated models predict that some haloes may be recombining, and thus are not in ionization equilibrium. But parameters such as the ionization state and thus the contiguous excitation process are only poorly known. The haloes are very extended, but faint in surface brightness -103 times lower than the main nebula. The observational limits call for an extremely well studied main nebula, to model the processes in the shells and haloes of one object. NGC 2438 is a perfect candidate to explore the physical characteristics of the halo. Aims: The aim is to derive a complete data set of the main nebula. This allows us to derive the physical conditions from photoionization models, such as temperature, density and ionization, and clumping. These models are used to derive whether the halo is in ionization equilibrium. Methods: Long-slit spectroscopic data at various positions in the nebula were obtained at the ESO 3.6 m and the SAAO 1.9 m telescope. These data were supplemented by imaging data from the HST archive and from the ESO 3.6 m telescope and by archival VLA observations. The use of diagnostic diagrams draws limits for physical properties in the models. The photoionization code CLOUDY was used to model the nebular properties and to derive a more accurate distance and ionized mass. Results: We derive an accurate extinction EB - V = 0.16, and distance of 1.9 ± 0.2 kpc. This locates the nebula behind the nearby open cluster M46 and rules out membership. The low-excitation species are found to be dominated by clumps. The emission line ratios show no evidence for shocks. The filling factor increases with radius in the nebula. The electron densities in the main nebula are ~250 cm-3, dropping to ~10-30 in the

  16. 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.

  17. 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.

  18. An Interactive Gallery of Planetary Nebula Spectra

    NASA Astrophysics Data System (ADS)

    Kwitter, K. B.; Henry, R. B. C.

    2002-12-01

    We have created a website containing high-quality moderate-resolution spectra of 88 planetary nebulae (PNe) from 3600 to 9600 Å, obtained at KPNO and CTIO. Spectra are displayed in a zoomable window, and there are templates available that show wavelength and ion identifications. In addition to the spectra themselves, the website also contains a brief discussion of PNe as astronomical objects and as contributors to our understanding of stellar evolution, and a table with atlas information for each object along with a link to an image. This table can be re-ordered by object name, galactic or equatorial coordinates, distance from the sun, the galactic center, or the galactic plane. We envision that this website, which concentrates a large amount of data in one place, will be of interest to a variety of users. PN researchers might need to check the spectrum of a particular object of interest; the non-specialist astronomer might simply be interested in perusing such a collection of spectra; and finally, teachers of introductory astronomy can use this database to illustrate basic principles of atomic physics and radiation. To encourage such use, we have written two simple exercises at a basic level to introduce beginning astronomy students to the wealth of information that PN spectra contain. We are grateful to Adam Wang of the Williams College OIT and to his summer student teams who worked on various apects of the implementation of this website. This work has been supported by NSF grant AST-9819123 and by Williams College and the University of Oklahoma.

  19. IFU spectroscopy of southern planetary nebulae - III

    NASA Astrophysics Data System (ADS)

    Ali, A.; Dopita, M. A.; Basurah, H. M.; Amer, M. A.; Alsulami, R.; Alruhaili, A.

    2016-10-01

    In this paper, we describe integral field spectroscopic observations of four southern Galactic planetary nebulae (PNe), M3-4, M3-6, Hen2-29 and Hen2-37 covering the spectral range 3400-7000 Å. We derive the ionization structure, the physical conditions, the chemical compositions and the kinematical characteristics of these PNe and find good agreement with previous studies that relied upon the long-slit technique in their co-spatial area. From their chemical compositions as well as their spatial and kinematic characteristics, we determined that Hen2-29 is of the Peimbert type I (He- and N-rich), while the other three are of type II. The strength of the nebular He II line reveals that M3-3, Hen2-29 and Hen2-37 are of mid to high excitation classes while M3-6 is a low-excitation PN. A series of emission-line maps extracted from the data cubes were constructed for each PN to describe its overall structure. These show remarkable morphological diversity. Spatially resolved spectroscopy of M3-6 shows that the recombination lines of C II, C III, C IV and N III are of nebular origin, rather than arising from the central star as had been previously proposed. This result increases doubts regarding the weak emission-line star (WELS) classification raised by Basurah et al. In addition, they reinforce the probability that most genuine cases of WELS arise from irradiation effects in close binary central stars.

  20. 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.

    2017-02-01

    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 seven 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.

  1. Observations and 3D hydrodynamical models of planetary nebulae with Wolf-Rayet type central stars

    NASA Astrophysics Data System (ADS)

    Rechy-García, J. S.; Velázquez, P. F.; Peña, M.; Raga, A. C.

    2017-01-01

    We present high-resolution, long-slit spectroscopic observations of two planetary nebulae, M 1-32 and M 3-15, with [WC] central stars located near the Galactic bulge. The observations were obtained with the 2.1-m telescope of the Observatorio Astronómico Nacional, San Pedro Mártir. M 1-32 shows wide wings on the base of its emission lines and M 3-15 has two very faint high-velocity knots. In order to model both planetary nebulae, we built a three-dimensional model consisting of a jet interacting with an equatorially concentrated slow wind, emulating the presence of a dense torus, using the Yguazú hydrodynamical code. From our hydrodynamical models, we obtained position-velocity diagrams in the [N II]λ6583 line for comparison with the observations. We find that the spectral characteristics of M 1-32 and M 3-15 can be explained with the same physical model - a jet moving inside an asymptotic giant branch wind - using different parameters (physical conditions and position angles of the jet). In agreement with our model and observations, these objects contain a dense torus seeing pole-on and a bipolar jet escaping through the poles. Then, we propose to classify this kind of objects as spectroscopic bipolar nebulae, although they have been classified morphologically as compact, round, or elliptical nebulae or with `close collimated lobes'.

  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. The open cluster NGC 2818 and its associated planetary nebula

    SciTech Connect

    Pedreros, M. )

    1989-12-01

    New CCD UBV photometry of the open cluster NGC 2818 central region indicates that previously derived values of distance and reddening for the cluster have been considerably overestimated, leading to erroneous values for the physical parameters of its associated planetary nebula (PK 261 + 8.1 deg). The analysis of the new data yields E(B-V) = 0.18 + or - 0.03 and V(0)-M(v) = 11.80 + or - 0.2 (2.3 + or - 0.2 kpc) for the cluster's color excess and distance modulus, respectively. If cluster membership is assumed for the planetary nebula, the above estimates result in physical parameters that compare better with those of a typical planetary nebula in the Galaxy and the Magellanic Clouds. 26 refs.

  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. 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

  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. Photodestruction of PAHs in Planetary Nebulae

    NASA Astrophysics Data System (ADS)

    Boechat-Roberty, H. M.; Neves, R.; Pilling, S.; de Souza G. G., B.; Lago, A.

    It is known that polycyclic aromatic hydrocarbons (PAHs) are mainly formed in the dust shells of late stages of AGB type carbon rich stars. After the ejection of H-rich envelope those stars become the proto-planetary nebulae (PPNs). The chemistry in PPNs has been strongly modified by the UV photons coming from the hot central star and by the X-rays associated with its high-velocity winds. Benzene (C6H6) and small PAHs like Anthracene (C14H10) were effectively detected in the PPNs CRL 618 (Cernicharo et al. 2001) and Red Rectangle (Vijh, Witt & Gordon 2004) respectively. The goal of this work is to experimentally study photoabsorption, photoionization and photodissociation processes of the benzene, biphenyl (C12H10), naphthalene (C10H8), phenanthrene (C14H10) and methyl-anthracene (C14H9(CH3)). The measurements were taken at the Brazilian Synchrotron Light Laboratory (LNLS), using soft X-ray and UV photons from a toroidal grating monochromator TGM beamline (12-310 eV). The experimental set-up consists of a high vacuum chamber with a Time-Of-Flight Mass Spectrometer (TOF-MS). Mass spectra were obtained using PhotoElectron PhotoIon Coincidence (PEPICO) technique. Kinetic energy distributions and abundances for each ionic fragment have been obtained from the analysis of the corresponding peak shapes in the mass spectra. Dissociative and non-dissociative photoionization cross sections for some molecules were also determined (see for example: Boechat-Roberty, Pilling & Santos 2005). We have observed that PAHs molecules are extreme resistant to UV photons, confirming that PAHs absorb the UV photons and after some internal energetic rearrangements, they can emit in the IR range. However, these molecules are destroyed by soft X-rays photons producing several ionic fragments, some of them with great kinetic energy. In the mass spectra of the Benzene and methyl-anthracene molecules, the observed ionic fragments C4H2+, C6H2+, C4HCH3 and C2HCH3, could correspond to the same

  8. Discovery of planetary nebulae using predictive mid-infrared diagnostics

    NASA Astrophysics Data System (ADS)

    Parker, Quentin A.; Cohen, Martin; Stupar, Milorad; Frew, David J.; Green, Anne J.; Bojicic, Ivan; Guzman-Ramirez, Lizette; Sabin, Laurence; Vogt, Frédéric

    2012-12-01

    We demonstrate a newly developed mid-infrared (MIR) planetary nebula (PN) selection technique. It is designed to enable efficient searches for obscured, previously unknown, PN candidates present in the photometric source catalogues of Galactic plane MIR sky surveys. Such selection is now possible via new, sensitive, high-to-medium resolution, MIR satellite surveys such as those from the Spitzer Space Telescope and the all-sky Wide-field Infrared Survey Explorer satellite missions. MIR selection is based on how different colour-colour planes isolate zones (sometimes overlapping) that are predominately occupied by different astrophysical object types. These techniques depend on the reliability of the available MIR source photometry. In this pilot study, we concentrate on MIR point-source detections and show that it is dangerous to take the MIR GLIMPSE (Galactic Legacy Infrared Mid-Plane Survey Extraordinaire) photometry from Spitzer for each candidate at face value without examining the actual MIR image data. About half of our selected sources are spurious detections due to the applied source detection algorithms being affected by complex MIR backgrounds and the deblending of diffraction spikes around bright MIR point sources into point sources themselves. Nevertheless, once this additional visual diagnostic checking is performed, valuable MIR-selected PN candidates are uncovered. Four turned out to have faint, compact, optical counterparts in our Hα survey data missed in previous optical searches. We confirm all of these as true PNe via our follow-up optical spectroscopy. This lends weight to the veracity of our MIR technique. It demonstrates sufficient robustness that high-confidence samples of new Galactic PN candidates can be extracted from these MIR surveys without confirmatory optical spectroscopy and imaging. This is problematic or impossible when the extinction is large.

  9. Evolution of the central stars of young planetary nebulae

    NASA Astrophysics Data System (ADS)

    Hajduk, M.; van Hoof, P. A. M.; Zijlstra, A. A.

    2015-01-01

    Aims: The evolution of central stars of planetary nebulae was so far documented in just a few cases. However, spectra collected a few decades ago may provide a good reference for studying the evolution of central stars using the emission line fluxes of their nebulae. We investigated evolutionary changes of the [O iii] 5007 Å line flux in the spectra of planetary nebulae. Methods: We compared nebular fluxes collected during a decade or longer. We used literature data and newly obtained spectra. A grid of cloudy models was computed using existing evolutionary models, and the models were compared with the observations. Results: An increase of the [O iii] 5007 Å line flux is frequently observed in young planetary nebulae hosting H-rich central stars. The increasing nebular excitation is the response to the increasing temperature and hardening radiation of the central stars. We did not observe any changes in the nebular fluxes in the planetary nebulae hosting late-type Wolf-Rayet (WR) central stars. This may indicate a slower temperature evolution (which may stem from a different evolutionary status) of late-[WR] stars. Conclusions: In young planetary nebulae with H-rich central stars, the evolution can be followed using optical spectra collected during a decade or longer. The observed evolution of H-rich central stars is consistent with the predictions of the evolutionary models provided in the literature. Late-[WR] stars possibly follow a different evolutionary path. Reduced spectra from the Torun and SAAO observatories 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/573/A65

  10. 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.

  11. Search for variability of five central stars of planetary nebulae

    NASA Astrophysics Data System (ADS)

    Paunzen, E.; Netopil, M.; Rode-Paunzen, M.

    2017-01-01

    The central stars of planetary nebulae are interesting objects which are important to understand the very late stages of stellar evolution. They exhibit variability due to binarity, stellar winds, and pulsation. We searched for variability in five of such objects and found only upper limits. However, also this null result is important for the understanding of these stars.

  12. Fainting

    MedlinePlus

    ... tunnel vision) or noises are fading into the background. Causes Fainting may occur while or after you: ... a seizure or heart rhythm disturbance), and to figure out the cause of the fainting episode. If ...

  13. 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

  14. 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.

  15. The peculiar planetary nebula 75+35 deg 1

    NASA Astrophysics Data System (ADS)

    Feibelman, Walter A.

    1987-04-01

    The high galactic latitude planetary nebula 75+35°1 was observed in the low-dispersion mode of the IUE. The UV spectrum is characterized by a strong continuum that matches the energy distribution of a blackbody curve of 90,000K±5000K. A color temperature of 94,000K±4000K is derived. The spectral type mimics that of an O7.5 V star. A very strong N V λ1240 feature with a P Cygni profile is present. There is no trace of C III] λ1909 which is usually the strongest emission line in planetary nebulae. A very slight depression in the λ2200 region suggests very little interstellar absorption with an upper limit of E(B-V) = 0.025 mag, as would be expected for a high galactic latitude object. The ultraviolet observations, in context with the optical data, indicate that this object is not a typical planetary.

  16. New Faint Ring-Like Structures Found in Planetary Nebulae

    NASA Astrophysics Data System (ADS)

    Ramos-Larios, G.; Santamaría, E.; Marquez-Lugo, A.; Guerrero, M. A.; Sabin, L.

    2014-04-01

    Many PNe show rings and shells related to the remnants of the circumstellar envelopes of the asymptotic giant branch phase (AGB). After an extensive search in the HST and Spitzer archives we found ring-like structures in several PNe. Following the image analysis described by Corradi et al. (2004), and unsharp masking techniques it was possible to effectively remove the underlying halo emission, enhancing the ring structures. We mention in the results some hypotheses about the origins of these rings.

  17. a Study of HCO+ and CS in Planetary Nebulae

    NASA Astrophysics Data System (ADS)

    Edwards, Jessica L.; Ziurys, L. M.; Woolf, N. J.

    2011-06-01

    Millimeter-wave observations have been conducted towards a sample of planetary nebulae (PNe) using the 12-meter and Sub-millimeter telescopes of the Arizona Radio Observatory. HCO+ was observed in the J=3-2 transition at 1 mm and the J=1-0 transition at 3 mm. CS was observed in the J=5-4, J=3-2, and J=2-1 transitions at 1, 2, and 3 mm, respectively. Both molecules have been detected in NGC 6537 (Red Spider Nebula), K4-47, and M2-48, as well as NGC 6720 (Ring Nebula) and NGC 6853 (Dumbbell Nebula), which are both over 7,000 years old. Although a number of molecular line surveys of circumstellar envelopes have been done and one conducted towards a very young PNe, the molecular content of planetary nebulae is not well characterized. It was previously thought that the high ultraviolet radiation field of the central star would destroy any molecules leftover from the circumstellar envelope; however, molecules clearly exist well into the PNe stage. These data are currently being analyzed and molecular abundances being determined, which will be compared to those seen in diffuse interstellar material. The implications of these observations will be discussed in relation to the molecular content of diffuse clouds and the origins of the diffuse interstellar bands.

  18. 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.

  19. Multiple outflows in the planetary nebula NGC 6058

    NASA Astrophysics Data System (ADS)

    Guillén, P. F.; Vázquez, R.; Miranda, L. F.; Zavala, S.; Contreras, M. E.; Ayala, S.; Ortiz-Ambriz, A.

    2013-07-01

    We present narrow-band [O III]λ5007 and Hα images, as well as long-slit high-resolution echelle spectra of the planetary nebula NGC 6058. Our data reveal that NGC 6058 is a multipolar planetary nebula of ˜45 arcsec in extent that is formed by four bipolar outflows oriented at different position angles. Assuming homologous expansion for all the structures, and a distance of 3.5 kpc, we obtain polar velocities of ˜68 km s-1 for three of them. The estimated kinematical ages suggest that the three oldest outflows were ejected at intervals of ˜1100 and ˜400 yr, during which the ejection axis changed its orientation by ˜60° and ˜40°, respectively. Although an inner ring-like structure is suggested by the direct images, the kinematics shows that no equatorial ring or toroid exists in the nebula. On the contrary, the long-slit spectra reveal that the ring-like structure corresponds to a fourth outflow that is oriented almost perpendicular to the other three. This fourth outflow is the youngest one and appears to be interacting with the other three, creating a protruding zone that sweeps material in a region almost perpendicular to the major axes of the oldest outflows. This structure also presents two bright arcuate regions along the direction of the older outflows, and on opposite sides of the central star. From our model, we suggest that NGC 6058 could be at an intermediate evolutionary stage between starfish planetary nebulae and multipolar planetary nebula with apparent equatorial lobes.

  20. The ionization structure of planetary nebulae 10: NGC 2392

    NASA Technical Reports Server (NTRS)

    Barker, Timothy

    1989-01-01

    Spectrophotometric observations of emission-line intensities over the spectral range 1400 to 7200 A were made in six positions in the planetary nebula NGC 2392. Standard equations used to correct for the existence of elements in other than the optically observable ionization stages give consistent results for the different positions that are in excellent agreement with abundances calculated using ultraviolet lines, and there is no evidence for any abundance gradient in the nebula. The logarithmic abundances agree well with determinations by Aller and Keyes.

  1. A window on the efficiency of the s-process in AGB stars: chemical abundances of n-capture elements in the planetary nebula NGC 3918

    NASA Astrophysics Data System (ADS)

    Madonna, S.; García-Rojas, J.; Luridiana, V.; Sterling, N. C.; Morisset, C.

    The chemical content of the planetary nebula NGC 3918 is investigated through deep, high-resolution (R˜40,000) UVES at VLT spectrophotometric data. We identify and measure more than 750 emission lines, making ours one of the deepest spectra ever taken for a planetary nebula. Among these lines we detect very faint lines of several neutron-capture elements (Se, Kr, Rb, and Xe), which enable us to compute their chemical abundances with unprecedented accuracy, thus constraining the efficiency of the ph s-process and convective dredge-up in the progenitor star of NGC 3918.

  2. 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.

  3. Continuous infrared emission of proto- and young-planetary nebulae

    NASA Technical Reports Server (NTRS)

    Szczerba, Ryszard

    1989-01-01

    Evolutionary sequences of planetary nebulae (PNe) were calculated beginning from the moment of shell ejection to its dissipation and IR spectra of the outgoing radiation were obtained for different stages of the evolution. To solve the coupled hydrodynamical and radiation transfer problem a computer code was used in which gas and dust are treated as two separate hydrodynamical components. The models, which are calculated for two grain materials (graphite and silicate) have a size distribution of particles based on that found for the interstellar medium. In the computations, the recent optical properties of graphite and astronomical silicate grains tabulated by Draine (1987) were employed. It was assumed that silicate of graphite grains exist below some critical temperature equal to 1300 or to 1700 K, respectively. Infrared model spectra are compared with the IR radiation emitted by some proto- and some young-planetary nebulae. The observed IR continua can be quite well matched with our models with grains having a reasonable size range.

  4. 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.

  5. Planetary nebulae near the Galactic Centre: chemical abundances

    NASA Astrophysics Data System (ADS)

    Cavichia, O.; Costa, R. D. D.; Maciel, W. J.; Mollá, M.

    2014-10-01

    In this work, we report physical parameters and abundances derived for a sample of high extinction planetary nebulae located in the Galactic bulge, near the Galactic Centre, based on low dispersion spectroscopy secured at the SOAR telescope using the Goodman spectrograph. The results show that the abundances of our sample are similar to those from other regions of the bulge. Nevertheless, the average abundances of the Galactic bulge do not follow the observed trend of the radial abundance gradient in the disk.

  6. 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.

  7. 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}.

  8. THE [O III] NEBULA OF THE MERGER REMNANT NGC 7252: A LIKELY FAINT IONIZATION ECHO

    SciTech Connect

    Schweizer, Francois; Kelson, Daniel D.; Villanueva, Edward V.; Seitzer, Patrick; Walth, Gregory L.

    2013-08-20

    We present images and spectra of a {approx}10 kpc-sized emission-line nebulosity discovered in the prototypical merger remnant NGC 7252 and dubbed the ''[O III] nebula'' because of its dominant [O III] {lambda}5007 line. This nebula seems to yield the first sign of episodic active galactic nucleus (AGN) activity still occurring in the remnant, {approx}220 Myr after the coalescence of two gas-rich galaxies. Its location and kinematics suggest it belongs to a stream of tidal-tail gas falling back into the remnant. Its integrated [O III] {lambda}5007 luminosity is 1.4 Multiplication-Sign 10{sup 40} erg s{sup -1}, and its spectrum features some high-excitation lines, including He II {lambda}4686. In diagnostic line-ratio diagrams, the nebula lies in the domain of Seyfert galaxies, suggesting that it is photoionized by a source with a power-law spectrum. Yet, a search for AGN activity in NGC 7252 from X-rays to radio wavelengths yields no detection, with the most stringent upper limit set by X-ray observations. The upper luminosity limit of L{sub 2-10{sub keV,0}}<5 Multiplication-Sign 10{sup 39} erg s{sup -1} estimated for the nucleus is {approx}10{sup 3} times lower than the minimum ionizing luminosity of {approx}> 5 Multiplication-Sign 10{sup 42} erg s{sup -1} necessary to excite the nebula. This large discrepancy suggests that the nebula is a faint ionization echo excited by a mildly active nucleus that has declined by {approx}3 orders of magnitude over the past 20,000-200,000 yr. In many ways this nebula resembles the prototypical ''Hanny's Voorwerp'' near IC 2497, but its size is 3 Multiplication-Sign smaller and its [O III] luminosity {approx}100 Multiplication-Sign lower. We propose that it be classified as an extended emission-line region (EELR). The [O III] nebula is then the lowest-luminosity ionization echo and EELR discovered so far, indicative of recent, probably sputtering AGN activity of Seyfert-like intensity in NGC 7252.

  9. Fainting

    MedlinePlus

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  10. Fainting

    MedlinePlus

    ... En Español Making a Change – Your Personal Plan Hot Topics Am I in a Healthy Relationship? Who ... reasons why teens faint: Physical triggers. Getting too hot or being in a crowded, poorly ventilated setting ...

  11. 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}.

  12. H2 in low-ionization structures of planetary nebulae

    NASA Astrophysics Data System (ADS)

    Akras, Stavros; Gonçalves, Denise R.; Ramos-Larios, Gerardo

    2017-02-01

    We report the detection of near-IR H2 emission from the low-ionization structures (knots) in two planetary nebulae. The deepest ever high-angular-resolution H2 (1-0) S(1) at 2.122 μm, H2 (2-1) S(1) at 2.248 μm and Brγ images of K 4-47 and NGC 7662, obtained using the Near InfraRed Imager and Spectrometer (NIRI) at Gemini-North, are analysed here. K 4-47 reveals a remarkable highly collimated bipolar structure not only in the optical but also in the molecular hydrogen emission. The H2 emission emanates from the walls of the bipolar outflows and also from the pair of knots at the tip of the outflows. The H2 (1-0) S(1)/(2-1) S(1) line ratio ranges from ∼7 to ∼10, suggesting the presence of shock interactions. Our findings can be explained by the interaction of a jet/bullet ejected from the central star with the surrounding asymptotic giant branch material. The strongest H2 line, (1-0) S(1), is also detected in several low-ionization knots located at the periphery of the elliptical planetary nebula NGC 7662, but only four of these knots are detected in the H2 (2-1) S(1) line. These four knots exhibit an H2 line ratio between 2 and 3.5, which suggests that the emission is caused by the UV ionizing flux of the central star. Our data confirm the presence of H2 gas in both fast- and slow-moving low-ionization knots, which has only been confirmed before in the nearby Helix nebula and Hu 1-2. Overall, the low-ionization structures of planetary nebulae are found to have similar traits to photodissociation regions.

  13. Binarity and the Abundance Discrepancy Problem in Planetary Nebulae

    NASA Astrophysics Data System (ADS)

    Corradi, Romano L. M.; García-Rojas, Jorge; Jones, David; Rodríguez-Gil, Pablo

    2015-04-01

    The discrepancy between abundances computed using optical recombination lines and collisionally excited lines is a major unresolved problem in nebular astrophysics. Here, we show that the largest abundance discrepancies are reached in planetary nebulae with close binary central stars. We illustrate this using deep spectroscopy of three nebulae with a post common-envelope (CE) binary star. Abell 46 and Ou 5 have O2+/H+ abundance discrepancy factors larger than 50, and as high as 300 in the inner regions of Abell 46. Abell 63 has a smaller discrepancy factor around 10, which is still above the typical values in ionized nebulae. Our spectroscopic analysis supports previous conclusions that, in addition to “standard” hot ({{T}e} ˜ 104 K) gas, there exists a colder ({{T}e} ˜ 103 K), ionized component that is highly enriched in heavy elements. These nebulae have low ionized masses, between 10-3 and 10-1 M⊙ depending on the adopted electron densities and temperatures. Since the much more massive red giant envelope is expected to be entirely ejected in the CE phase, the currently observed nebulae would be produced much later, during post-CE mass loss episodes when the envelope has already dispersed. These observations add constraints to the abundance discrepancy problem. We revise possible explanations. Some explanations are naturally linked to binarity such as, for instance, high-metallicity nova ejecta, but it is difficult at this stage to depict an evolutionary scenario consistent with all of the observed properties. We also introduce the hypothesis that these nebulae are the result of tidal destruction, accretion, and ejection of Jupiter-like planets.

  14. Interaction of planetary nebulae with the interstellar medium

    NASA Technical Reports Server (NTRS)

    Borkowski, Kazimierz J.; Sarazin, Craig L.; Soker, Noam

    1990-01-01

    The interaction of a moving planetary nebula (PN) with the interstellar medium is considered. The PN shell is compressed first in the direction of the stellar motion. This produces a dipole asymmetry in the surface brightness of the nebula, typically at a nebular density of about 40/cu cm if the nebula is located in the Galactic plane. In the later stages of the interaction, this part of the shell is significantly decelerated with respect to the central star, and the PN becomes strongly asymmetric in shape. This distortion and the subsequent stripping of the nebular gas away from the central star typically occurs at a low nebular density of about 6/cu cm. The morphology of PNs with central stars whose proper motions exceed 0.015 arcsec/yr was examined, and it was found that many of the extended nebulae are interacting with the interstellar medium (ISM). The sample doubles the number of known PNs interacting with the ISM. The morphology of nearby PNs was examined, and a number of strongly asymmetric nebuale were found.

  15. Optical spectrum of the planetary nebula M 2-24

    NASA Astrophysics Data System (ADS)

    Zhang, Y.; Liu, X.-W.

    2003-06-01

    We have obtained medium-resolution, deep optical long-slit spectra of the bulge planetary nebula (PN) M 2-24. The spectrum covers the wavelength range from 3610-7330 Å. Over two hundred emission lines have been detected. The spectra show a variety of optical recombination lines (ORLs) from C, N, O and Ne ions. The diagnostic diagram shows significant density and temperature variations across the nebula. Our analysis suggests that the nebula has a dense central emission core. The nebula was thus studied by dividing it into two regions: 1) a high ionization region characterized by an electron temperature of Te=16 300 K and a density of log Ne(cm-3) = 6.3; and 2) a low ionization region represented by Te=11 400 K and log Ne(cm-3) = 3.7. A large number of ORLs from C, N, O and Ne ions have been used to determine the abundances of these elements relative to hydrogen. In general, the resultant abundances are found to be higher than the corresponding values deduced from collisionally excited lines (CELs). This bulge PN is found to have large enhancements in two alpha -elements, magnesium and neon. Full Table 2 is available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.126.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/404/545

  16. [Fe III] EMISSION LINES IN THE PLANETARY NEBULA NGC 2392

    SciTech Connect

    Zhang, Y.; Chau, W.; Hsia, C.-H.; Kwok, S.; Fang, X.; Liu, X.-W.; Koning, N.

    2012-07-20

    NGC 2392 is a young double-shell planetary nebula (PN). Its intrinsic structure and shaping mechanism are still not fully understood. In this paper we present new spectroscopic observations of NGC 2392. The slits were placed at two different locations to obtain the spectra of the inner and outer regions. Several [Fe III] lines are clearly detected in the inner region. We infer that NGC 2392 might have an intrinsic structure similar to the bipolar nebula Mz 3, which also exhibits a number of [Fe III] lines arising from the central regions. In this scenario, the inner and outer regions of NGC 2392 correspond to the inner lobes and the outer outflows of Mz 3, respectively. We construct a three-dimensional morpho-kinematic model to examine our hypothesis. We also compare the physical conditions and chemical composition of the inner and outer regions, and discuss the implications on the formation of this type of PN.

  17. 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.

  18. 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

  19. The rapidly evolving planetary nebula Hen 3-1357

    NASA Astrophysics Data System (ADS)

    Gry, C.

    Hen 3-1357 (known as the 'Stingray Nebula') is the youngest Planetary Nebula known in the sky. It has become ionized within the past few decades and its central star seems to be still rapidly evolving in the H-R diagram towards hotter effective temperatures. With this proposal we want to determine the current effective temperature of the central star and the characteristics of the stellar wind thirteen years after its discovery with IUE. This will enable us to determine whether the rapid spectral changes observed in the last few years are the consequence of an episodic post-AGB mass loss event or the result of a continuous evolution in the H-R digram. In any of these cases, the observations will help us to understand this short and, thus, still poorly known transition phase which leads to the formation of a new PN.

  20. 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.

  1. 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.

  2. 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.

  3. Models of the Thermal Evolution of an Initially Hot Solar Nebula: Implications for Planetary Material

    NASA Technical Reports Server (NTRS)

    Cassen, P.

    2000-01-01

    We develop models of the thermal evolution of the solar nebula designed to test the hypothesis that planetary objects began to form as the nebula cooled from an initially hot state, and compare the results of the models with meteoritic and planetary data.

  4. The UKST survey of planetary nebulae in the Small Magellanic Cloud.

    NASA Astrophysics Data System (ADS)

    Morgan, D. H.

    1995-09-01

    This paper describes the results of a search for planetary nebulae on objective-prism plates which were taken with the UK 1.2-m Schmidt Telescope and cover the entire Small Magellanic Cloud. Co-ordinates and finding charts are given for nine new planetary nebula candidates. A total of 62 objects were detected and their spatial distribution is discussed.

  5. Probing the Properties of Two Galaxies with Planetary Nebulae

    NASA Astrophysics Data System (ADS)

    Fogel, J. K. J.; Jacoby, G. H.; Shaw, R. A.; Stanghellini, L.; Van de Steene, G. C.; Dopita, M.

    2002-12-01

    By measuring the abundances in nebulae, and distinguishing the enrichment of processed elements (primarily He, C, N, and O) from non-processed elements, (chiefly Ar, Ne, S) we are able to probe both the chemical enrichment around the planetary nebula and the population type of the progenitor star. Where we can also determine the evolutionary state, and therefore the mass, of the central star, we can also determine the time since the progenitor was formed. Because of these useful properties, studies of 18 PNs in the Large Magellanic Cloud (LMC) and six PNs in the Galactic bulge were undertaken to investigate the stellar population and PN properties in these contrasting environments. We also have spectra for eight more PN of sufficient quality to perform this analysis on them for a total of 14 planetaries out of the 95 new PN identified by Jacoby & Van de Steene. Neither of these sets of planetaries had been studied before because of the observational difficulties in obtaining high quality data. For the PNs in the Galactic center, the high extinction made it difficult to obtain the traditional optical diagnostic lines; while the study of LMC PNs required the high spatial resolution of HST to resolve the nebular structure. Moderate-dispersion spectra from MSSSO and spectral images from HST/STIS were used to examine in more detail the results of Stanghellini et al. (2000), where chemical enrichments were found in asymmetric PNs, relative to round or elliptical PNs. For the LMC planetaries, where we observed many diagnostic lines, it was straightforward to create models that matched the observed quantities very well, which then yielded a direct determination of the chemical abundances. Moderate dispersion spectra of the Galactic center PNs yielded far fewer measurable emission lines, and required extensive modeling using Gary Ferland's CLOUDY code to determine the chemical abundances. Jeffrey Fogel's research was supported by the NOAO/KPNO Research Experiences for

  6. A New Population of Galactic Bulge Planetary Nebulas

    NASA Astrophysics Data System (ADS)

    Stenborg, T. N.

    A new population of Galactic bulge planetary nebulas is presented. Nebula candidates were discovered by systematically reviewing archival [OIII] on/off band survey imaging of the central -5° ≤ l ≤ 5°, -5° ≤ b ≤ 5° region around the Galactic centre. An image segmentation and interleaving scheme was developed to facilitate this review. The resultant candidates (> 200) were then double checked against complementary archival Hα sky survey data to screen for obvious planetary nebula (PN) mimics or spurious image artefacts. Confirmatory spectroscopy of the PN candidates was pursued with thin slit, fibre multiobject and wide field spectrographs. Custom software was built to streamline interfacing with third-party spectroscopic management tools and a parallel greedy set cover algorithm implemented for efficient field selection in constrained multi-object observations. The combined imaging and spectroscopic evidence yielded true (4), probable (31) and possible (83) PNs toward the bulge. Secondary discoveries such as new PN mimics and late type stars were by-products of the confirmatory spectroscopy. Instances of literature PN duplication encountered during the investigation were noticed and documented. Spectral analysis of new PNs, including those obtained with a new optimised sky subtraction technique devised and demonstrated here, provided diagnostic data allowing radial velocity and Balmer decrement determination. Using a combined diameter and radial velocity criterion, bona fide bulge PNs were distinguished from new foreground PNs. Where Balmer decrements were available for new bulge PNs, differential aperture photometry was used to provide a modest data increment to Galactic bulge planetary nebula luminosity function (PNLF). The PNLF was revised with data from some new bulge PNs, but more significantly, by a series of corrections to the data derived from previously known bulge PNs (~225), such as improved filter transmission effects, statistically

  7. 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.

  8. 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.

  9. 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.

  10. The remarkably high excitation planetary nebula GC 6537

    PubMed Central

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

    1999-01-01

    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 ≈ 0.2 Å) 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

  11. Hydrodynamic instability of the solar nebula in the presence of a planetary core

    NASA Technical Reports Server (NTRS)

    Perri, F.; Cameron, A. G. W.

    1974-01-01

    When a planetary core composed of condensed matter accumulates in the primitive solar nebula, the gas in the nebula becomes gravitationally concentrated as an envelope about the planetary core. An analysis of models of such gaseous envelopes indicates that giant planets (such as Jupiter and Saturn) formed in a massive primitive solar nebula of the type constructed by Cameron and Pine (1973). When the mass of the accumulating planetary core becomes sufficiently great, the surrounding gaseous envelope will become hydrodynamically unstable against collapse onto the planetary core. Much of the surrounding gas also may be compressed onto the core by the background pressure of the gas.

  12. The planetary nebula Abell 48 and its [WN] nucleus

    NASA Astrophysics Data System (ADS)

    Frew, David J.; Bojičić, I. S.; Parker, Q. A.; Stupar, M.; Wachter, S.; DePew, K.; Danehkar, A.; Fitzgerald, M. T.; Douchin, D.

    2014-05-01

    We have conducted a detailed multi-wavelength study of the peculiar nebula Abell 48 and its central star. We classify the nucleus as a helium-rich, hydrogen-deficient star of type [WN4-5]. The evidence for either a massive WN or a low-mass [WN] interpretation is critically examined, and we firmly conclude that Abell 48 is a planetary nebula (PN) around an evolved low-mass star, rather than a Population I ejecta nebula. Importantly, the surrounding nebula has a morphology typical of PNe, and is not enriched in nitrogen, and thus not the `peeled atmosphere' of a massive star. We estimate a distance of 1.6 kpc and a reddening, E(B - V) = 1.90 mag, the latter value clearly showing the nebula lies on the near side of the Galactic bar, and cannot be a massive WN star. The ionized mass (˜0.3 M⊙) and electron density (700 cm-3) are typical of middle-aged PNe. The observed stellar spectrum was compared to a grid of models from the Potsdam Wolf-Rayet (PoWR) grid. The best-fitting temperature is 71 kK, and the atmospheric composition is dominated by helium with an upper limit on the hydrogen abundance of 10 per cent. Our results are in very good agreement with the recent study of Todt et al., who determined a hydrogen fraction of 10 per cent and an unusually large nitrogen fraction of ˜5 per cent. This fraction is higher than any other low-mass H-deficient star, and is not readily explained by current post-AGB models. We give a discussion of the implications of this discovery for the late-stage evolution of intermediate-mass stars. There is now tentative evidence for two distinct helium-dominated post-AGB lineages, separate to the helium- and carbon-dominated surface compositions produced by a late thermal pulse. Further theoretical work is needed to explain these recent discoveries.

  13. Near-infrared spectroscopy of planetary nebulae: How strong is the H2 emission?

    NASA Technical Reports Server (NTRS)

    Dinerstein, H. L.; Carr, J.; Harvey, P. M.; Lester, D. F.

    1986-01-01

    In an effort to understand the systematics of the H2 emission from planetary nebulae, a program of near-infared spectroscopy using the University of Texas infrared reticon spectrometer was started. This instrument has a 1x32 element InSb photodiode array as a detector. All of the observations reported were made on the McDonald Observatory 2.7 m telescope, with spectra resolving power lambda/delta lambda = 600. The spectral coverage allows the measurement strengths of Brackett gamma He I 2.113 microns, HE II 2.189 microns and the v = 1=0 S(1) line of H2 at 2.122 microns. One of the most important advantages of this instrument is that we are able to resolve H2 from the adjacent He I line. Most previous observations of planetaries have been made at spectral resolving powers of about 100, which blend these lines. The contribution of the He I line has generally been dismissed as being unimportant, but we show that this may not be valid. Our higher resolving power also improves the line-to-continuum contrast; in some cases, the continuum is the limiting factor in detecting faint lines.

  14. A search for photometric variability of hydrogen-deficient planetary-nebula nuclei

    NASA Astrophysics Data System (ADS)

    González Pérez, J. M.; Solheim, J.-E.; Kamben, R.

    2006-08-01

    Aims.We searched for photometric variability in a sample of hot, hydrogen-deficient planetary nebula nuclei (PNNi) with "PG 1159" or "O VI" spectral type, most of them embedded in a bipolar or elliptical planetary nebula envelope (PNe). These characteristics may indicate the presence of a hidden close companion and an evolution affected by episodes of interaction between them. Methods: .We obtained time-series photometry from a sample of 11 candidates using the Nordic Optical Telescope (NOT) with the Andalucía Faint Object Spectrograph and Camera (ALFOSC), modified with our own control software to be able to observe in a high-speed multi-windowing mode. The data were reduced on-line with the real time photometry (RTP) code, which allowed us to detect periodic variable stars with small amplitudes from CCD data in real time. We studied the properties of the observed modulation frequencies to investigate their nature. Results: .We report the first detection of low-amplitude pulsations in the PNNi VV 47, NGC 6852, and Jn 1. In addition, we investigated the photometric variability of NGC 246. Time-series analysis shows that the power spectra of VV 47, NGC 6852, and NGC 246 are variable on time scales of hours. Power spectra from consecutive nights of VV 47 and NGC 6852 show significant peaks in different frequency regions. The same type of variability is present in NGC 246 in 2 observing runs separated by 3 days. Changes are also found in the power spectra of VV 47 and NGC 246 during the same night. The VV 47 power spectra are peculiar since they present modulation frequencies in a wide range from 175 to 7600 μHz. This is different from the previously known pulsating PNNi where no frequencies are found above ~3000 μHz. The high-frequency modulation observed in VV 47 may be due to g-modes triggered by the ɛ-mechanism, observed for the first time.

  15. s-process enrichment in the planetary nebula NGC 3918. Results from deep echelle spectrophotometry

    NASA Astrophysics Data System (ADS)

    García-Rojas, J.; Madonna, S.; Luridiana, V.; Sterling, N. C.; Morisset, C.; Delgado-Inglada, G.; Toribio San Cipriano, L.

    2015-09-01

    The chemical content of the planetary nebula NGC 3918 is investigated through deep, high-resolution (R ˜ 40 000) UVES (Ultraviolet-Visual Echelle Spectrograph) at VLT (Very Large Telescope) spectrophotometric data. We identify and measure more than 750 emission lines, making ours one of the deepest spectra ever taken for a planetary nebula. Among these lines we detect very faint lines of several neutron-capture elements (Se, Kr, Rb, and Xe), which enable us to compute their chemical abundances with unprecedented accuracy, thus constraining the efficiency of the s-process and convective dredge-up in NGC 3918 progenitor star. We find that Kr is strongly enriched in NGC 3918 and that Se is less enriched than Kr, in agreement with the results of previous papers and with predicted s-process nucleosynthesis. We also find that Xe is not as enriched by the s-process in NGC 3918 as is Kr and, therefore, that neutron exposure is typical of modestly subsolar metallicity asymptotic giant branch (AGB) stars. A clear correlation is found when representing [Kr/O] versus log(C/O) for NGC 3918 and other objects with detection of multiple ions of Kr in optical data, confirming that carbon is brought to the surface of AGB stars along with s-processed material during third dredge-up episodes, as predicted by nucleosynthesis models. We also detect numerous refractory element lines (Ca, K, Cr, Mn, Fe, Co, Ni, and Cu) and a large number of metal recombination lines of C, N, O, and Ne. We compute physical conditions from a large number of diagnostics, which are highly consistent among themselves assuming a three-zone ionization scheme. Thanks to the high ionization of NGC 3918 we detect a large number of recombination lines of multiple ionization stages of C, N, O and Ne. The abundances obtained for these elements by using recently determined state-of-the-art ionization correction factor (ICF) schemes or simply adding ionic abundances are in very good agreement, demonstrating the quality

  16. Discovering Planetary Nebula Geometries: Explorations with a Hierarchy of Models

    NASA Technical Reports Server (NTRS)

    Huyser, Karen A.; Knuth, Kevin H.; Fischer, Bernd; Schumann, Johann; Granquist-Fraser, Domhnull; Hajian, Arsen R.

    2004-01-01

    Astronomical objects known as planetary nebulae (PNe) consist of a shell of gas expelled by an aging medium-sized star as it makes its transition from a red giant to a white dwarf. In many cases this gas shell can be approximately described as a prolate ellipsoid. Knowledge of the physics of ionization processes in this gaseous shell enables us to construct a model in three dimensions (3D) called the Ionization-Bounded Prolate Ellipsoidal Shell model (IBPES model). Using this model we can generate synthetic nebular images, which can be used in conjunction with Hubble Space Telescope (HST) images of actual PNe to perform Bayesian model estimation. Since the IBPES model is characterized by thirteen parameters, model estimation requires the search of a 13-dimensional parameter space. The 'curse of dimensionality,' compounded by a computationally intense forward problem, makes forward searches extremely time-consuming and frequently causes them to become trapped in local solutions. We find that both the speed and of the search can be improved by judiciously reducing the dimensionality of the search space. Our basic approach employs a hierarchy of models of increasing complexity that converges to the IBPES model. Earlier studies establish that a hierarchical sequence converges more quickly, and to a better solution, than a search relying only on the most complex model. Here we report results for a hierarchy of five models. The first three models treat the nebula as a 2D image, while the last two models explore its characteristics as a 3D object and enable us to characterize the physics of the nebula. This five-model hierarchy is applied to HST images of ellipsoidal PNe to estimate their geometric properties and gas density profiles.

  17. The latest eruption of planetary nebula IC 2165

    NASA Astrophysics Data System (ADS)

    Bohigas, J.; Rodríguez, M.; Dufour, R. J.

    2013-10-01

    Open slit high dispersion spectroscopic observations of the inner region of planetary nebula (PN) IC 2165 indicate that the object has a relatively uniform and high electron temperature, with its density being much larger close to the PN nucleus. Abundances imply that it is a non-type I PN. Calcium and iron have been heavily depleted into grains. The ionized mass is at least ˜ 0.05 M_⊙. A photoionization model (CLOUDY, version 10.00) assuming an inverse square law for the density and abundances typical of a non-type I PN, produced a fair replica of the spectrum and of all electron density and temperature sensitive line ratios, but not of the global properties of this object. All evidence indicates that IC 2165 was produced by a metal poor 2 M_⊙ A5 V star that took off some 2×10^9 yr ago.

  18. Two planetary nebulae with tori of different development.

    NASA Astrophysics Data System (ADS)

    Kerber, F.; Claeskens, J.-F.

    1997-02-01

    In this paper we discuss the morphology of two bipolar planetary nebulae (PNe) based on broad-band (ESO/SERC) and narrow-band ([OIII] and Halpha_) images. At first sight both objects are similar and show two pronounced bright knots - the usual signature of a torus seen edge-on. We demonstrate though that the two objects are not two of a kind at this point but are rather representing two different stages of evolution. The brightness distribution found in Wei1-5 is well explained by a homogeneous torus with a ratio of radius to thickness of 2. KeWe1 is a complicated object showing point symmetry. It can be understood in terms of an incomplete ring, probably a torus caught in the process of breaking up due to the action of a strong wind from the central star.

  19. 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.

  20. 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.

  1. Finding Variable Stars in Planetary Nebula using the ISIS Subtraction Software

    NASA Astrophysics Data System (ADS)

    Long, Jacob; Nault, K.; Hillwig, T. C.

    2013-01-01

    In order to explain the great variety of observed shapes among planetary nebulae, we are examining the theory that binary central stars of planetary nebulae are a significant factor in their shaping. We determine if the central star of planetary nebulae is binary by looking for photometric periodic variability, a common feature of close binary systems. Using existing data we evaluate the variability using the ISIS image subtraction software. We have detected variability in the central star of Pe 1-9, a previously known close binary system. We also show results for a number of additional targets.

  2. 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.

  3. 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.

  4. A new statistical distance scale for planetary nebulae

    NASA Astrophysics Data System (ADS)

    Ali, Alaa; Ismail, H. A.; Alsolami, Z.

    2015-05-01

    In the first part of the present article we discuss the consistency among different individual distance methods of Galactic planetary nebulae, while in the second part we develop a new statistical distance scale based on a calibrating sample of well determined distances. A set composed of 315 planetary nebulae with individual distances are extracted from the literature. Inspecting the data set indicates that the accuracy of distances is varying among different individual methods and also among different sources where the same individual method was applied. Therefore, we derive a reliable weighted mean distance for each object by considering the influence of the distance error and the weight of each individual method. The results reveal that the discussed individual methods are consistent with each other, except the gravity method that produces higher distances compared to other individual methods. From the initial data set, we construct a standard calibrating sample consists of 82 objects. This sample is restricted only to the objects with distances determined from at least two different individual methods, except few objects with trusted distances determined from the trigonometric, spectroscopic, and cluster membership methods. In addition to the well determined distances for this sample, it shows a lot of advantages over that used in the prior distance scales. This sample is used to recalibrate the mass-radius and radio surface brightness temperature-radius relationships. An average error of ˜30 % is estimated for the new distance scale. The newly distance scale is compared with the most widely used statistical scales in literature, where the results show that it is roughly similar to the majority of them within ˜±20 % difference. Furthermore, the new scale yields a weighted mean distance to the Galactic center of 7.6±1.35 kpc, which in good agreement with the very recent measure of Malkin 2013.

  5. The Shaping of Planetary Nebulae: Asymmetry in the External Wind

    NASA Astrophysics Data System (ADS)

    Dwarkadas, Vikram V.; Chevalier, Roger A.; Blondin, John M.

    1996-02-01

    We have modeled planetary nebulae (PNs) in the context of the interacting stellar winds model. If the two interacting winds have constant properties, the velocity of the PN shell tends toward a constant with time and the shape becomes self-similar. Additionally, if the velocity of the fast wind is much higher than the expansion velocity of the shell, the interior of the hot shocked bubble becomes isobaric. Using semi-analytical methods, complemented by hydrodynamic simulations, we have calculated the shapes of PNs in the self-similar stage. An asymmetric density profile is assumed for the slow outer wind. The asymmetry is modeled using different functions, which depend on the degree of asymmetry and the steepness of the density profile in the angular direction. We include the effects of the ambient wind velocity, which has not received much attention since the work of Kahn & West (1985). The fact that typical PN velocities (10-40 km s-1) are only marginally greater than typical red giant wind velocities (5-20 km s-1) indicates that this is an important parameter. The morphological appearance is a consequence of the density contrast, steepness of the density profile and velocity of the ambient medium; classification of PNs purely on the basis of the first two factors may be misleading. Moderate values of the density contrast result in a cusp at the equator. A higher density contrast coupled with a low velocity for the external medium gives rise to extremely bipolar nebulae. For large density contrasts and a significant value of the slow wind velocity, the surface density maximum of the shell shifts away from the equator, giving rise to peanut-shaped structures with pronounced equatorial bulges. If the external wind velocity is small compared to the expansion velocity of the nebula, the PNs tend to be more bipolar, even with a moderate density contrast. If the PN velocity is close to that of the external wind, the shape is relatively spherical. However, a velocity

  6. The Chandra Planetary Nebula Survey (ChanPlaNS). II. X-Ray Emission from Compact Planetary Nebulae

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

    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 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 (lsim 5 × 103 yr), and likewise compact (R neb <~ 0.15 pc), PNe with closed structures and high central electron densities (ne >~ 1000 cm-3), and is rarely associated with PNe that show H2 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.

  7. Formation of Explosive Comet in Proto-planetary Nebula

    NASA Astrophysics Data System (ADS)

    Gladysheva, O.

    2013-09-01

    The question about the formation of the comet's nucleus is examined, taking into account the peculiarities of the destruction of the Tunguska cosmic body. According to the suggested model, the comet's nucleus consists from ample quantity of organic coverings, one covering inserts into another covering, similar to Russian set of nesting dolls. The space between neighbouring coverings is filled by different size lumps and grains down to micron size. Comets were formed in the inner region of the solar system in the early stages of the evolution of the proto-planetary cloud. Proto-comets began to accumulate their mass on the periphery of protoplanetary nebula (far from the ecliptic), where the temperature decreases to <100 K. Then, under the influence of gravitation, comets many times crossed the plane of the ecliptic, performing relaxation oscillations. Coverings on comet surfaces formed during every crossing by the comet of the ecliptic area, where the temperature was high. During their oscillations, most comets were thrown out of the inner regions of the solar system by planetary perturbations in the Öpik-Oort cloud.

  8. Evidence for a [WR] or WEL-type binary nucleus in the bipolar planetary nebula Vy 1-2

    NASA Astrophysics Data System (ADS)

    Akras, S.; Boumis, P.; Meaburn, J.; Alikakos, J.; López, J. A.; Gonçalves, D. R.

    2015-09-01

    We present high-dispersion spectroscopic data of the compact planetary nebula Vy 1-2, where high expansion velocities up to 100 km s-1 are found in the Hα, [N II] and [O III] emission lines. Hubble Space Telescope images reveal a bipolar structure. Vy 1-2 displays a bright ring-like structure with a size of 2.4 arcsec × 3.2 arcsec and two faint bipolar lobes in the east-west direction. A faint pair of knots is also found, located almost symmetrically on opposite sides of the nebula at position angle = 305°. Furthermore, deep low-dispersion spectra are also presented and several emission lines are detected for the first time in this nebula, such as the doublet [Cl III] 5517, 5537, [K IV] 6101, C II 6461 and the doublet C IV 5801, 5812Å. By comparison with the solar abundances, we find enhanced N, depleted C and solar O. The central star must have experienced the hot-bottom burning (CN-cycle) during the second dredge-up phase, implying a progenitor star of M ≥ 3 M⊙. The very low C/O and N/O abundance ratios suggest a likely post-common envelope close binary system. A simple spherically symmetric geometry with either a blackbody or an H-deficient stellar atmosphere model is not able to reproduce the ionization structure of Vy 1-2. The effective temperature and luminosity of its central star indicate a young nebula located at a distance of ˜9.7 kpc with an age of ˜3500 yr. The detection of stellar emission lines, C II 6461, the doublet C IV λλ 5801, 5812 and O III 5592 Å, emitted from an H-deficient star, indicates the presence of a late-type Wolf-Rayet or a WEL-type central star.

  9. 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.

  10. IR Excesses of Four Central Stars of Planetary Nebulae

    NASA Astrophysics Data System (ADS)

    Bilikova, Jana; Chu, Y.; Gruendl, R. A.; Su, K. Y. L.

    2008-03-01

    An infrared excess of a star indicates the presence of an additional object that is cooler and dimmer and therefore undetectable at optical wavelengths, such as a low-mass companion, a planet, or a dust disk. Dust disks have been detected around post-AGB stars and a number of white dwarfs (WDs). An intermediate stage between these two, the central stars of planetary nebulae (CSPNs), have been neglected in the search for dust disks. PN researches focus more on the nebulosity than the CSPN, and any detected excess is usually assumed to originate from stellar ejecta without further investigation. The Helix Nebula's central star was the first one found to exhibit IR excess after careful subtraction of nebular emission, and the origin of this excess was found to be a dust continuum. To search for more cases of IR excess of CSPNs, we have surveyed 40 resolved PNe in the Spitzer archive. For the PNe with resolved central stars, we carried out photometric measurements, and combined them with supplemental optical and near-IR data to construct their spectral energy distributions (SEDs). We further modeled stellar emission using appropriate stellar temperature, distance, and de-reddened V or B magnitude. We find four CSPNs that exhibit IR excess - NGC 2346, NGC 2438, NGC 6804 and NGC 7139. The nature and the origin of the IR excess in these CSPNs is still unclear and needs to be verified spectroscopically. If it is indeed continuous in nature, it is likely due to the presence of a dust disk, which could be produced in a common-envelope binary evolution, or result from tidal breakup of asteroids or collisions among Kuiper-Belt-like objects.

  11. Synthesizing Planetary Nebulae for Large Scale Surveys: Predictions for LSST

    NASA Astrophysics Data System (ADS)

    Vejar, George; Montez, Rodolfo; Morris, Margaret; Stassun, Keivan G.

    2017-01-01

    The short-lived planetary nebula (PN) phase of stellar evolution is characterized by a hot central star and a bright, ionized, nebula. The PN phase forms after a low- to intermediate-mass star stops burning hydrogen in its core, ascends the asymptotic giant branch, and expels its outer layers of material into space. The exposed hot core produces ionizing UV photons and a fast stellar wind that sweeps up the surrounding material into a dense shell of ionized gas known as the PN. This fleeting stage of stellar evolution provides insight into rare atomic processes and the nucleosynthesis of elements in stars. The inherent brightness of the PNe allow them to be used to obtain distances to nearby stellar systems via the PN luminosity function and as kinematic tracers in other galaxies. However, the prevalence of non-spherical morphologies of PNe challenge the current paradigm of PN formation. The role of binarity in the shaping of the PN has recently gained traction ultimately suggesting single stars might not form PN. Searches for binary central stars have increased the binary fraction but the current PN sample is incomplete. Future wide-field, multi-epoch surveys like the Large Synoptic Survey Telescope (LSST) can impact studies of PNe and improve our understanding of their origin and formation. Using a suite of Cloudy radiative transfer calculations, we study the detectability of PNe in the proposed LSST multiband observations. We compare our synthetic PNe to common sources (stars, galaxies, quasars) and establish discrimination techniques. Finally, we discuss follow-up strategies to verify new LSST-discovered PNe and use limiting distances to estimate the potential sample of PNe enabled by LSST.

  12. 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.

  13. 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.

  14. 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.

  15. Estimating the binary fraction of central stars of planetary nebulae using the infrared excess method

    NASA Astrophysics Data System (ADS)

    Douchin, D.; De Marco, O.; Frew, D. J.; Jacoby, G. H.; Fitzgerald, M.; Jasniewicz, G.; Moe, M.; Passy, J. C.; Hillwig, T.; Harmer, D.

    2014-04-01

    There is no quantitative theory to explain why a high 80% of all planetary nebulae are non-spherical. The Binary Hypothesis states that a companion to the progenitor of a central star of planetary nebula is required to shape nebulae whose shapes are not spherical or mildly elliptical, implying that many single post-AGB stars do not make a PN at all. A way to test this hypothesis is to estimate the binary fraction of central stars of planetary nebula and to compare it with that of the main sequence population. Preliminary results from the infrared excess technique indicate that the binary fraction of central stars of planetary nebula is higher than that of the main sequence, implying that PNe could preferentially form via a binary channel. I will present new results from a search of red and infrared flux excess in an extended sample of central stars of planetary nebula and compare the improved estimate of the PN binary fraction with that of main sequence stars.

  16. Single Rotating Stars and the Formation of Bipolar Planetary Nebula

    NASA Astrophysics Data System (ADS)

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

    2014-04-01

    We have computed new stellar evolution models that include the effects of rotation and magnetic torques under different hypothesis. The goal is to test if a single star can sustain in the envelope the rotational velocities needed for the magneto hydrodynamical (MHD) simulations to shape bipolar Planetary Nebulae (PNe) when the high mass-loss rates take place. Stellar evolution models with main sequence masses of 2.5 and 5 Mo, and initial rotational velocities of 250 km/s have been followed all the way to 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 in increasing the rotational velocity of the envelope since the stellar angular momentum is removed efficiently by the wind. We have, as well, tested 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 rotating at the speeds needed by the 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.

  17. Single Rotating Stars and the Formation of Bipolar Planetary Nebula

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

    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 ⊙ and initial rotational velocities of 250 km s-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.

  18. PAH formation in O-rich planetary nebulae

    NASA Astrophysics Data System (ADS)

    Guzman-Ramirez, L.; Lagadec, E.; Jones, D.; Zijlstra, A. A.; Gesicki, K.

    2014-06-01

    Polycyclic aromatic hydrocarbons (PAHs) have been observed in O-rich planetary nebulae towards the Galactic bulge. This combination of oxygen-rich and carbon-rich material, known as dual-dust or mixed chemistry, is not expected to be seen around such objects. We recently proposed that PAHs could be formed from the photodissociation of CO in dense tori. In this work, using VISIR/VLT, we spatially resolved the emission of the PAH bands and ionized emission from the [S IV] line, confirming the presence of dense central tori in all the observed O-rich objects. Furthermore, we show that for most of the objects, PAHs are located at the outer edge of these dense/compact tori, while the ionized material is mostly present in the inner parts of these tori, consistent with our hypothesis for the formation of PAHs in these systems. The presence of a dense torus has been strongly associated with the action of a central binary star and, as such, the rich chemistry seen in these regions may also be related to the formation of exoplanets in post-common-envelope binary systems.

  19. 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.

  20. 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.

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

    NASA Astrophysics Data System (ADS)

    Lee, Ting-Hui; Shaw, Richard A.; Stanghellini, Letizia

    2014-08-01

    We propose to obtain SOAR/Goodman spectra of 20 Galactic disk planetary nebulae (PNe) to derive their elemental abundances. This is an ongoing optical/IR spectral survey of 150 compact PNe to build a complete sample of their chemical abundances in the Galactic disk. Our SOAR/Goodman observations in the 2012B and 2013A semesters have yielded high quality spectra for 27 PNe; we plan to observe an additional 20 southern-sky objects in 2014B. The optical spectra will be combined with Spitzer spectra of IR collisional lines to improve abundance constraints. 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 progenitor metallicity on stellar chemical yields.

  2. 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}.

  3. 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.

  4. High Dispersion UV Spectroscopy of the Planetary Nebula NGC 3918

    NASA Astrophysics Data System (ADS)

    Torres-Peimbert, Silvia

    NGC 3918 is one of the brightest PN in the sky. Carefully studied it might be the best PN to construct a very detailed model because it has a very homogeneous density distribution. Pena and Torres-Peimbert (1983) from an IUE high dispersion exposure of 120^m found that the resonance lines intensity ratio of NV 1239/1242 is equal to 1.2 ± 0.1 while that of CIV is normal (1.9 ± 0.2). This result should be verified, because if true, it implies that there is absorption by intervening hot gas of large N(NV)/N(ClV) column density ratio. This gas could be part of the general low density interstellar medium or could be in the form of a very extended envelope, perhaps produced by the first stage of mass loss from the progenitor star. We would like to secure more high dispersion IUE spectra of this planetary nebula to further investigate these problems.

  5. 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.

  6. 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.

  7. 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.

  8. Life after stellar death: Planetary Nebulae and Supernova Remnants

    NASA Astrophysics Data System (ADS)

    Boumis, P.

    2013-09-01

    Planetary nebulae (PNe) are powerful tracers of our Galaxy's star formation history. Their study can provide insight to the late stages of stellar evolution, the nucleosynthesis in low and intermediate mass stars (1-8Mo) and the chemical evolution of galaxies. Supernova explosions belong to the most spectacular events in the Universe. Supernova remnants (SNRs), which are the consequent results of these events and come from the late stages of massive stars (>8Mo), are among the strongest radio sources observed. They have a major influence on both the properties of the interstellar medium (ISM) and the evolution of galaxies as a whole. They enrich the ISM with heavy elements, release about 1051 ergs of energy, heat the ISM, compress the magnetic field, and efficiently accelerate, by their shock waves, energetic cosmic rays observed throughout the Galaxy. I will present results of our work on PNe and SNRs, which aims to (a) discover optical SNRs in the Galaxy, (b) study their morphology and kinematics, (c) characterize their properties (such as density, shock velocity etc.) and (d) provide information on their interaction with the ISM, using the "Aristarchos" among other telescopes.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. Fast winds in central stars of some planetary nebulae

    NASA Astrophysics Data System (ADS)

    Cerruti-Sola, M.; Perinotto, M.

    1989-10-01

    Winds from the central stars of the planetary nebulae NGC 1535, NGC 6210, NGC 7009, IC 418, and IC 4593 have been investigated with high-resolution IUE spectra. All these stars present P Cygni profiles in some of the following lines: N V 1240, O IV 1342, O V 1371, Si IV 1397, C IV 1549, and N IV 1719 A. These profiles have been analyzed with the SEI method developed by Lamers et al. (1987). The mass-loss rates of the winds are found to be 1.4 x 10 to the -9th, 2.2 x 10 to the -9th, 2.8 x 10 to the -9th, 6.3 x 10 to the -9th, and 4.2 x 10 to the -8th solar mass/yr for the above stars, respectively. Despite all efforts made in order to reach the maximum accuracy, the uncertainty of these determinations remains in some cases quite large. Nevertheless, it is possible to show that the mechanism producing the winds is likely to be the radiation pressure.

  15. Rings and arcs around evolved stars - I. Fingerprints of the last gasps in the formation process of planetary nebulae

    NASA Astrophysics Data System (ADS)

    Ramos-Larios, G.; Santamaría, E.; Guerrero, M. A.; Marquez-Lugo, R. A.; Sabin, L.; Toalá, J. A.

    2016-10-01

    Evolved stars such as asymptotic giant branch stars (AGB), post-AGB stars, proto-planetary nebulae (proto-PNe), and planetary nebulae (PNe) show rings and arcs around them and their nebular shells. We have searched for these morphological features in optical Hubble Space Telescope and mid-infrared Spitzer Space Telescope images of ˜650 proto-PNe and PNe and discovered them in 29 new sources. Adding those to previous detections, we derive a frequency of occurrence ≃8 per cent. All images have been processed to remove the underlying envelope emission and enhance outer faint structures to investigate the spacing between rings and arcs and their number. The averaged time lapse between consecutive rings and arcs is estimated to be in the range 500-1200 yr. The spacing between them is found to be basically constant for each source, suggesting that the mechanism responsible for the formation of these structures in the final stages of evolved stars is stable during time periods of the order of the total duration of the ejection. In our sample, this period of time spans ≤4500 yr.

  16. 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.

  17. Expansion analyses on low-excitation planetary nebulae with stellar images

    SciTech Connect

    Tamura, Shinichi; Shibata, K.M. Nobeyama Radio Observatory, Minamimaki )

    1990-11-01

    The paper presents the results of analyses on the expansion characteristics of the low-excitation and unresolved planetary nebulae, M1-5, M1-9, K3-66, and K3-67. The sample nebulae are divided into two groups. The first includes the real compact planetary nebulae M1-5 and M1-9 based on their single-Gaussian profiles. The second one includes nebulae that are unresolved because of their large distances. The nebulae K3-66 and K3-67 should belong to the second group since they show the double-Gaussian components in the emission-line profiles. Relationships between expansion velocities and I(forbidden O III 5007 A)/I(H-beta) and between electron densities and expansion velocities give the basis for the above arguments and reveal that the nebulae IC 4997, Vy2-2, and M3-27 obviously are in different phases of evolution from those of other low-excitation planetary nebulae. 24 refs.

  18. 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.

  19. 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.

  20. Extinction distances of Planetary Nebulae interacting with the interstellar medium

    NASA Astrophysics Data System (ADS)

    Pirzkal, N.; Kerber, F.; Roth, M.

    2000-12-01

    Distances to Planetary Nebulae (PNe) are notoriously unreliable. It is known that statistical methods such as the different versions of the Shklovsky--derived distance scales can not be applied to individual objects with any confidence. Various methods to estimate the distance of individual PN have been successfully applied in the past, e.g. using trigonometric parallaxes, radio and optical expansion rates, the central star's atmosphere, or the nature of companions in binary systems. However, these have the drawback of relying on some special properties of a PN, and require various combinations of very high S/N observations, of large time bases, and of extensive modeling. In the end, these methods can only be applied to a very small number of PNe. As a result, after more than 30 years of research, accurate and reliable distances are known for less than 5 2000 or so Galactic PNe. This is the largest single obstacle to a better understanding of the fundamental properties of PNe. One method which does not require us to make any assumptions about the PN and which can be applied to all PNe close to the Galactic plane is the extinction distance method. This method relies on the fact that most of the stars surrounding a target PN are either Main-Sequence stars or giants with known intrinsic colors. Using these, together with an a-priori dust extinction law, an extinction vs. distance relation can be determined for the field. We have applied this method to several PN fields which were observed in the B,V,Rc, and Ic bands. We report here on the first results and present extinction vs. distance relations in the direction of our target PNe. A discussion about the accuracy of the method and the derived distances is included.

  1. Neutron-capture Element Abundances in Magellanic Cloud Planetary Nebulae

    NASA Astrophysics Data System (ADS)

    Mashburn, A. L.; Sterling, N. C.; Madonna, S.; Dinerstein, Harriet L.; Roederer, I. U.; Geballe, T. R.

    2016-11-01

    We present near-infrared spectra of 10 planetary nebulae (PNe) in the Large and Small Magellanic Clouds (LMC and SMC), acquired with the FIRE and GNIRS spectrometers on the 6.5 m Baade and 8.1 m Gemini South Telescopes, respectively. We detect Se and/or Kr emission lines in eight of these objects, the first detections of n-capture elements in Magellanic Cloud PNe. Our abundance analysis shows large s-process enrichments of Kr (0.6-1.3 dex) in the six PNe in which it was detected, and Se is enriched by 0.5-0.9 dex in five objects. We also estimate upper limits to Rb and Cd abundances in these objects. Our abundance results for the LMC are consistent with the hypothesis that PNe with 2-3 M ⊙ progenitors dominate the bright end of the PN luminosity function in young gas-rich galaxies. We find no significant correlations between s-process enrichments and other elemental abundances, central star temperature, or progenitor mass, though this is likely due to our small sample size. We determine S abundances from our spectra and find that [S/H] agrees with [Ar/H] to within 0.2 dex for most objects, but is lower than [O/H] by 0.2-0.4 dex in some PNe, possibly due to O enrichment via third dredge-up. Our results demonstrate that n-capture elements can be detected in PNe belonging to nearby galaxies with ground-based telescopes, allowing s-process enrichments to be studied in PN populations with well-determined distances. This paper includes data obtained with the 6.5-m Magellan Telescopes located at Las Campanas Observatory, Chile, and with the Gemini-South Telescope at Cerro Pachon, Chile.

  2. 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.

  3. 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.

  4. Planetary Nebulae that Cannot Be Explained by Binary Systems

    NASA Astrophysics Data System (ADS)

    Bear, Ealeal; Soker, Noam

    2017-03-01

    We examine the images of hundreds of planetary nebulae (PNe) and find that for about one in six PNe the morphology is too “messy” to be accounted for by models of stellar binary interaction. We speculate that interacting triple stellar systems shaped these PNe. In this preliminary study, we qualitatively classify PNe by one of four categories. (1) PNe that show no need for a tertiary star to account for their morphology. (2) PNe whose structure possesses a pronounced departure from axial-symmetry and/or mirror-symmetry. We classify these, according to our speculation, as “having a triple stellar progenitor.” (3) PNe whose morphology possesses departure from axial-symmetry and/or mirror-symmetry, but not as pronounced as in the previous class, and are classified as “likely shaped by triple stellar system.” (4) PNe with minor departure from axial-symmetry and/or mirror-symmetry that could have been also caused by an eccentric binary system or the interstellar medium. These are classified as “maybe shaped by a triple stellar system.” Given a weight η t = 1, η l = 0.67, and η m = 0.33 to classes 2, 3, and 4, respectively, we find that according to our assumption about 13%–21% of PNe have been shaped by triple stellar systems. Although in some evolutionary scenarios not all three stars survive the evolution, we encourage the search for a triple stellar systems at the center of some PNe.

  5. HST/WFPC2 Observations of Asymmetric Planetary and Proto-Planetary Nebulae: NGC3132, HEN 401 and Roberts 22

    NASA Astrophysics Data System (ADS)

    Sahai, R.; Trauger, J.; Bujarrabal, V.; WFPC2 Id Team

    1997-12-01

    As part of a continuing effort to understand how planetary nebulae acquire their complex shapes and symmetries, we have obtained high-resolution images of the planetary nebula NGC3132, and the proto-planetary nebulae Hen 401 and Roberts 22, with the Wide Field Planetary Camera 2 (WFPC2) aboard the Hubble Space Telescope (HST). The images have been taken through a variety of narrow emission-line filters and a medium or broad continuum filter. All 3 objects have substantial quantities of cold, dense molecular gas detected via mm-wave CO line emission. The Hubble images reveal a rich and complex morphological structure of the circumstellar material in these objects. The NGC3132 images show a bright elliptical shape, surrounded by fainter filamentary, elliptical structures with position angles different from the main structure. New features uncovered by HST in this well-observed (from the ground) extended nebula, include a wide pillar-like structure lying roughly along the major axis of the nebula in [OIII]lambda5007 and Hα , but not in the low-excitation [OI]lambda6300 & [NII]lambda6584 lines. The latter show a thin equatorial band of material girdling the main nebula around its waist, and a fine jet-like feature extending radially outwards from the equatorial girdle. Both protoplanetary nebulae, Hen 401 and Roberts 22, seen mostly in scattered light from dust, are bipolar. The bipolar lobes in Hen 401 are long and cylindrical (length/width~14), with frayed ends; the visible central star is surrounded by a bipolar skirt-like structure, co-axial with the lobes. In Roberts 22, the lobes are shaped like a butterfly's wings, separated by a dark ``body'' of dense dust which hides the central star, and multiple shell structures can be seen in the fainter nebulosity surrounding the main lobes. We will discuss the implications of the remarkable structures seen in these 3 nebulae for current theories for the formation and shaping of planetary nebulae.

  6. Spectrophotometry of Jacoby's complete sample of planetary nebulae in the Magellanic Clouds

    SciTech Connect

    Boroson, T.A.; Liebert, J.

    1989-04-01

    Spectrophotometric observations have been obtained for all 68 planetary nebulae candidates in the Large and Small Magellanic Clouds from the complete sample of Jacoby. While most show line spectra characteristic of planetary nebulae, some 23 of the candidates could not be confirmed or have other explanations. A revised luminosity function is discussed. Many of the emission-line spectra are characterized by very strong forbidden N II and He II lines. One object (SMC 23) showing a peculiar forbidden line spectrum appears to be an extremely dense nebula, yet one may infer that the associated central star is hot and rather massive. Another nebula (LMC 26) shows forbidden lines but not detectable Balmer emission. Radial velocity measurements are discussed for most of the LMC objects, and may be useful diagnostics of the kinematics of the central bar. 30 refs.

  7. 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%.

  8. Extended halos and intracluster light using Planetary Nebulae as tracers in nearby clusters

    NASA Astrophysics Data System (ADS)

    Arnaboldi, Magda

    Since the first detection of intracluster planetary nebulae in 1996, imaging and spectroscopic surveys identified such stars to trace the radial extent and the kinematics of diffuse light in clusters. This topic of research is tightly linked with the studies of galaxy formation and evolution in dense environment, as the spatial distribution and kinematics of planetary nebulae in the outermost regions of galaxies and in the cluster cores is relevant for setting constraints on cosmological simulations. In this sense, extragalactic planetary nebulae play a very important role in the near-field cosmology, in order to measure the integrated mass as function of radius and the orbital distribution of stars in structures placed in the densest regions of the nearby universe.

  9. Binarity in the Central Stars of Planetary Nebulae and its Relationship to Stellar Evolution: An Observational Perspective

    NASA Astrophysics Data System (ADS)

    Hillwig, T. C.; Jacoby, G. H.; Jones, D.; De Marco, O.

    2017-03-01

    The existing status of our knowledge of binary central stars of planetary nebulae will be explored. Binary modeling of known systems is providing physical parameters that can be compared amongst the sample, with nebular characteristics, and with similar binaries with no associated planetary nebula. Correlations among these areas will be discussed, especially in relation to our understanding of stellar evolution.

  10. Carbonaceous compounds in carbon stars and planetary nebulae

    NASA Astrophysics Data System (ADS)

    Ryter, C.

    A recent count of the stars leaving the main sequence and the method to estimate the return of matter to the interstellar medium due to mass-loss is summarized. Stars of (1 - 5) M? would replenish the interstellar medium in (6 - 12) x 109 years. Carbonaceous compounds of the interstellar dust are believed to be formed in the atmosphere of carbon stars, but I bring evidences that the fraction of it made of very small particles and most frequently referred to as polycyclic aromatic hydrocarbons (PAH), which on average are believed to accommodate > 15% of the interstellar carbon, are not formed as soon as the dust condenses in the atmosphere of red giants. Some kind of processing seems to be required, very likely induced by the exposition of the dust to the ultraviolet radiation of the central star when the red giant becomes a planetary nebula. Heating of small grains by hard photons is believed to heat them to high enough a temperature to produce some morphological or crystallographic evolution, roughly from aliphatic to aromatic stucture. Further processing of the interstellar medium along the same line is suggested by observations of reflection nebulae, which display properties of the dust and gas at the site of star formation. Les résultats de comptages récents d'étoiles quittant la séquence principale et la méthode permettant d'évaluer le taux de perte de masse sont brièvement présentés. On trouve que les étoiles de 1 à 5 M⊙ reconstituent la masse du milieu interstellaire en (6 -12) x 109 années. Il est plausible que les géantes rouges forment d'abord les composants sHicés, puis lorsqu'elles atteignent la phase à carbone, qu'elles produisent la composante carbonée de la poussière interstellaire. Cette dernière comporte une importante fractions de très petites particules, le plus souvent considérées comme formées de grosses molécules polycycliques aromatiques (PAH), et qui contiennent au moins 15 % du carbone interstellaire. Bien qu

  11. Planetary nebulae as tracers of galaxy stellar populations

    NASA Astrophysics Data System (ADS)

    Buzzoni, Alberto; Arnaboldi, Magda; Corradi, Romano L. M.

    2006-05-01

    We address the general problem of the luminosity-specific planetary nebula (PN) number, better known as the `α' ratio, given by α=NPN/Lgal, and its relationship with the age and metallicity of the parent stellar population. Our analysis relies on population synthesis models that account for simple stellar populations (SSPs), and more elaborate galaxy models covering the full star formation range of the different Hubble morphological types. This theoretical framework is compared with the updated census of the PN population in Local Group (LG) galaxies and external ellipticals in the Leo group, and the Virgo and Fornax clusters. The main conclusions of our study can be summarized as follows. (i) According to the post-asymptotic giant branch (AGB) stellar core mass, PN lifetime in a SSP is constrained by three relevant regimes, driven by the nuclear (Mcore>~ 0.57Msolar), dynamical (0.57Msolar>~Mcore>~ 0.55Msolar) and transition (0.55Msolar>~Mcore>~ 0.52Msolar) time-scales. The lower limit for Mcore also sets the minimum mass for stars to reach the AGB thermal-pulsing phase and experience the PN event. (ii) Mass loss is the crucial mechanism to constrain the value of α, through the definition of the initial-to-final mass relation (IFMR). The Reimers mass-loss parametrization, calibrated on Pop II stars of Galactic globular clusters, poorly reproduces the observed value of α in late-type galaxies, while a better fit is obtained using the empirical IFMR derived from white dwarf observations in the Galaxy open clusters. (iii) The inferred PN lifetime for LG spirals and irregulars exceeds 10000yr, which suggests that Mcore<~ 0.65Msolar cores dominate, throughout. (iv) The relative PN deficiency in elliptical galaxies, and the observed trend of α with galaxy optical colours, support the presence of a prevailing fraction of low-mass cores (Mcore<~ 0.55Msolar) in the PN distribution and a reduced visibility time-scale for the nebulae as a consequence of the increased AGB

  12. 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.

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

    PubMed

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

    2010-09-03

    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.

  14. Physical properties of fullerene-containing Galactic planetary nebulae

    NASA Astrophysics Data System (ADS)

    Otsuka, Masaaki; Kemper, F.; Cami, J.; Peeters, E.; Bernard-Salas, J.

    2014-01-01

    We searched the Spitzer Space Telescope data archive for Galactic planetary nebulae (PNe), which show the characteristic 17.4 and 18.9 μm features due to C60, also known as buckminsterfullerene. Out of 338 objects with Spitzer/Infrared Spectrograph data, we found eleven C60-containing PNe, six of which (Hen2-68, IC2501, K3-62, M1-6, M1-9 and SaSt2-3) are new detections, not known to contain C60 prior to this work. The strongest 17.4 and 18.9 μm C60 features are seen in Tc1 and SaSt2-3, and these two sources also prominently show the C60 resonances at 7.0 and 8.5 μm. In the other nine sources, the 7.0 and 8.5 μm features due to C60 are much weaker. We analysed the spectra, along with ancillary data, using the photoionization code CLOUDY to establish the atomic line fluxes, and determine the properties of the radiation field, as set by the effective temperature of the central star. In addition, we measured the infrared spectral features due to dust grains. We find that the polycyclic aromatic hydrocarbon (PAH) profile over 6-9 μm in these C60-bearing carbon-rich PNe is of the more chemically processed class A. The intensity ratio of 3.3 to 11.3 μm PAH indicates that the number of C-atoms per PAH in C60-containing PNe is small compared to that in non-C60 PNe. The Spitzer spectra also show broad dust features around 11 and 30 μm. Analysis of the 30 μm feature shows that it is strongly correlated with the continuum, and we propose that a single carbon-based carrier is responsible for both the continuum and the feature. The strength of the 11 μm feature is correlated to the temperature of the dust, suggesting that it is at least partially due to a solid-state carrier. The chemical abundances of C60-containing PNe can be explained by asymptotic giant branch nucleosynthesis models for initially 1.5-2.5 M⊙ stars with Z = 0.004. We plotted the locations of C60-containing PNe on a face-on map of the Milky Way and we found that most of these PNe are outside the

  15. 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

  16. 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.

  17. The chemical composition of three planetary nebulae in the Magellanic Clouds

    NASA Technical Reports Server (NTRS)

    Dufour, R. J.; Killen, R. M.

    1977-01-01

    The paper studies the detailed spectral characteristics of the planetary nebulae N97 and N153 in the Large Magellanic Cloud (LMC), the planetary nebula N67 in the Small Magellanic Cloud (SMC), and the small H II regions N9, N61, and N81 in the SMC. Electron temperatures and densities for each nebula are derived from emission-line strengths determined by photographic spectrophotometry, and relative abundances are estimated for H, He, N, O, Ne, Ar, and S. The results show that: (1) N67 has a 60% overabundance in He/H while N97 and N153 have approximately normal He/H values; (2) all three planetaries have N/H values comparable to those of galactic planetaries but substantially higher than found in the H II regions of their respective Cloud; (3) the O/H values in the planetaries are similar to or lower than those in the H II regions of the respective Cloud; (4) the O/Ne, O/S, and O/Ar ratios in the two LMC planetaries are comparable to those in galactic planetaries; (5) the compositions of the small H II regions in the SMC are nearly identical to those of previously studied large H II regions in the same Cloud; and (6) the He/H ratio of the interstellar gas in the SMC is about 25% less than that in the Galaxy. It is concluded that most of the N abundance in both Clouds arose from nucleosynthesis sources other than planetary nebulae.

  18. 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

  19. 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.

  20. 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.

  1. The Eclipsing Central Stars of the Planetary Nebulae Lo 16 and PHR J1040-5417

    NASA Astrophysics Data System (ADS)

    Hillwig, Todd C.; Frew, David; Jones, David; Crispo, Danielle

    2017-01-01

    Binary central stars of planetary nebula are a valuable tool in understanding common envelope evolution. In these cases both the resulting close binary system and the expanding envelope (the planetary nebula) can be studied directly. In order to compare observed systems with common envelope evolution models we need to determine precise physical parameters of the binaries and the nebulae. Eclipsing central stars provide us with the best opportunity to determine high precision values for mass, radius, and temperature of the component stars in these close binaries. We present photometry and spectroscopy for two of these eclipsing systems; the central stars of Lo 16 and PHR 1040-5417. Using light curves and radial velocity curves along with binary modeling we provide physical parameters for the stars in both of these systems.

  2. Comparative Study Of Outer Halos Of Planetary Nebula NGC 246, NGC 1501, And NGC 2022

    NASA Astrophysics Data System (ADS)

    Arion, Douglas N.; Finnvik, S.; Troyer, Z.

    2012-01-01

    A number of planetary nebulae exhibit multiple shell structures, including concentric outer halos. Three such nebulae have been studied by obtaining deep images in [O III] to identify linkages between structures observed in the inner nebula and structures found in the outer halos. Three different planetaries were studied - NGC 246, 1501, and 2022, and all exhibit similar morphologies, suggesting similar evolutionary pathways. Of note are jet structures that appear to extend through all of the shell/halo layers, implying that the layers were ejected before the jets. Data were obtained on the 0.9m WIYN telescope at Kitt Peak National Observatory and the 1.52m Kuiper Telescope of the University of Arizona Steward Observatory. This work was supported in part by the Wisconsin Space Grant Consortium and a private bequest from Ms. Linda Staubitz.

  3. 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.

  4. Observational Confirmation of a Link Between Common Envelope Binary Interaction and Planetary Nebula Shaping

    NASA Astrophysics Data System (ADS)

    Hillwig, Todd C.; Jones, David; De Marco, Orsola; Bond, Howard E.; Margheim, Steve; Frew, David

    2016-12-01

    A current issue in the study of planetary nebulae with close binary central stars (CSs) is the extent to which the binaries affect the shaping of the nebulae. Recent studies have begun to show a high coincidence rate between nebulae with large-scale axial or point symmetries and close binary stars. In addition, combined binary-star and spatiokinematic modeling of the nebulae have demonstrated that all of the systems studied to date appear to have their central binary axis aligned with the primary axis of the nebula. Here we add two more systems to the list, the CSs and nebulae of NGC 6337 and Sp 1. We show both systems to be low inclination, with their binary axis nearly aligned with our line of sight. Their inclinations match published values for the inclinations of their surrounding nebulae. Including these two systems with the existing sample statistically demonstrates a direct link between the central binary and the nebular morphology. In addition to the systems’ inclinations we give ranges for other orbital parameters from binary modeling, including updated orbital periods for the binary CSs of NGC 6337 and Sp 1.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. An outflow model for bipolar planetary nebulae and the case of NGC 6302

    NASA Astrophysics Data System (ADS)

    Silvestro, G.; Robberto, M.

    NGC 6302 is a bright, bipolar planetary nebula that exhibits a wide range of excitation and ionization conditions, together with complex structure and kinematics. High-velocity (>300 km s-1) flows were detected in the nebula, which are believed to originate as a wind from the central star. The authors present a numerical analysis of the morphology of the inner outflow region, based on a generalization of the equations given by Cantò (1980) and Barral and Cantò (1981). A discussion of the interpretation of NGC 6302 within a model of disk-confined stellar wind is given.

  10. He 2-104 - A symbiotic proto-planetary nebula?

    NASA Technical Reports Server (NTRS)

    Schwarz, Hugo E.; Aspin, Colin; Lutz, Julie H.

    1989-01-01

    CCD observations are presented for He 2-104, an object previously classified as both PN and symbiotic star, which show that this is in fact a protoplanetary nebula (PPN) with a dynamical age of about 800 yr. The presence of highly collimated jets, extending over 75 arcsec on the sky, combined with an energy distribution showing a hot as well as a cool component, indicates that He 2-104 is a binary PPN. Since the primary is probably a Mira with a 400-d period (as reported by Whitelock, 1988), it is proposed that the system is a symbiotic PPN.

  11. Spectroscopic studies of four planetary nebulae with emission-line nuclei

    NASA Astrophysics Data System (ADS)

    Burlak, M. A.; Kniazev, A. Yu.

    2013-10-01

    Spectroscopic observations of four planetary nebulae (PNe) with emission-line central stars of different spectral types are presented: Cn 1-5, Pe 1-1, NGC 5873, and M1-19. The interstellar extinction, physical conditions ( n e , T e ), and abundances of several elements (He, N, O, Ne, S, Ar, Cl) have been determined for all nebulae. The nebula Cn 1-5 with fairly high abundances of helium and nitrogen is shown to belong to type I PNe. Possible variability of the intensities of low-excitation emission lines in NGC 5873 has been found; it can be related to variations of the stellar wind from the central star. The measured α-element abundance ratios (S/O, Ne/O, Ar/O, Cl/O) are in good agreement with those typical of HII regions.

  12. 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

  13. THE EXOTIC ECLIPSING NUCLEUS OF THE RING PLANETARY NEBULA SuWt 2

    SciTech Connect

    Exter, Katrina; Bond, Howard E.; Stassun, Keivan G.; Smalley, B.; Maxted, P. F. L.; Pollacco, D. L. E-mail: bond@stsci.ed

    2010-11-15

    SuWt 2 is a planetary nebula (PN) consisting of a bright ionized thin ring seen nearly edge-on, with much fainter bipolar lobes extending perpendicularly to the ring. It has a bright (12th magnitude) central star, too cool to ionize the PN, which we discovered in the early 1990s to be an eclipsing binary. Although it was anticipated that there would also be an optically faint, hot, ionizing star in the system, a spectrum from the International Ultraviolet Explorer (IUE) did not reveal a UV source. We present extensive ground-based photometry and spectroscopy of the central binary collected over the ensuing two decades, resulting in the determination that the orbital period of the eclipsing pair is 4.9 days, and that it consists of two nearly identical A1 V stars, each of mass {approx}2.7 M{sub sun}. The physical parameters of the A stars, combined with evolutionary tracks, show that both are in the short-lived 'blue-hook' evolutionary phase that occurs between the main sequence and the Hertzsprung gap, and that the age of the system is about 520 Myr. One puzzle is that the stars' rotational velocities are different from each other, and considerably slower than synchronous with the orbital period. It is possible that the center-of-mass velocity of the eclipsing pair is varying with time, suggesting that there is an unseen third orbiting body in the system. We propose a scenario in which the system began as a hierarchical triple, consisting of a {approx}2.9 M{sub sun} star orbiting the close pair of A stars. Upon reaching the asymptotic giant branch stage, the primary engulfed the pair into a common envelope, leading to a rapid contraction of the orbit and catastrophic ejection of the envelope into the orbital plane. In this picture, the exposed core of the initial primary is now a white dwarf of {approx}0.7 M{sub sun}, orbiting the eclipsing pair, which has already cooled below the detectability possible by IUE at our derived distance of 2.3 kpc and a reddening of E

  14. 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.

  15. Variation of Central Star Masses in Planetary Nebulae with Height above the Galactic Plane

    NASA Astrophysics Data System (ADS)

    Phillips, J. P.

    2004-04-01

    There are various reasons for suspecting that the progenitor masses of planetary nebulae (PNe) decline with height z above the Galactic plane. This, if true, would also imply a similar decrease in mean central star masses . We report here a further way in which such gradients may be determined. It will be shown that the distribution of planetary nebulae with respect to 5 GHz brightness temperature varies strongly with Galactic latitude. This variation is likely to arise from a change in the central star mass function N(M[CS]). High latitude sources appear to have a steeply varying function N(M[CS]), implying the presence of relatively few nebulae with high central star masses. By contrast, the low latitude sources have a much gentler fall-off in N(M[CS]), implying a larger proportion of high M[CS] nebulae. This is shown to imply significant gradients of mean mass with latitude b. We find that d/d |bLOW . b[LOW] . bLOW| ≃ .0×103M⊙ deg-1 for nebulae having 1.0/d |zLOW . z[LOW] . zLOW| ≃ .6×10-2 kpc-1 for nebulae with heights |z . z . z| > |zLOW . z[LOW] . zLOW| , and where one adopts the statistical distances of Phillips (2002).

  16. Abundances in Planetary Nebulae: an Autopsy of Low and Intermediate Mass Stars

    NASA Astrophysics Data System (ADS)

    Buell, James Francis

    In this work we report on the results of synthetic thermally pulsing asymptotic giant branch models (TP-AGB) and compare the results to the abundance ratios in a sample of planetary nebulae. We use updated the input parameters for mass-loss, the stellar luminosity, and dredge-up. We calculated models with masses between 0.8 solar masses and 8 solar masses. We also calculated models with (Fe/H) between -2.5 and 0.3. The effect of the first, second, and third dredge-up as well as hot-bottom burning are reported on. The analysis of a sample of Galactic bulge and disk planetary nebulae is also reported on.

  17. 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.

  18. The carbon-rich proto-planetary nebula IRAS 22272 + 5435

    NASA Technical Reports Server (NTRS)

    Hrivnak, Bruce J.; Kwok, Sun

    1991-01-01

    Ground-based photometry and spectroscopy is presented for IRAS 22272 + 5435, a 9th mag star with a large infrared excess. The flux distribution is 'double-peaked', with a visible and near-infrared component due to the reddened photosphere and a far-infrared component presumably due to a detached dust shell. About equal amounts of energy are detected from each. The spectrum is that of a peculiar G supergiant, Gp Ia. In addition, strong molecular bands of C3 and C2 are observed. The flux distribution is modeled and, together with published molecular-line radio observations, allows the determination of basic parameters of the central star and the dust shell. The source has the characteristics one would expect of a proto-planetary nebula, an object in transition from the asymptotic giant branch to the planetary nebula phase.

  19. The carbon-rich proto-planetary nebula IRAS 22272 + 5435

    SciTech Connect

    Hrivnak, B.J.; Kwok, Sun Calgary, University )

    1991-04-01

    Ground-based photometry and spectroscopy is presented for IRAS 22272 + 5435, a 9th mag star with a large infrared excess. The flux distribution is 'double-peaked', with a visible and near-infrared component due to the reddened photosphere and a far-infrared component presumably due to a detached dust shell. About equal amounts of energy are detected from each. The spectrum is that of a peculiar G supergiant, Gp Ia. In addition, strong molecular bands of C3 and C2 are observed. The flux distribution is modeled and, together with published molecular-line radio observations, allows the determination of basic parameters of the central star and the dust shell. The source has the characteristics one would expect of a proto-planetary nebula, an object in transition from the asymptotic giant branch to the planetary nebula phase. 31 refs.

  20. The carbon-rich proto-planetary nebula IRAS 22272 + 5435

    NASA Astrophysics Data System (ADS)

    Hrivnak, Bruce J.; Kwok, Sun

    1991-04-01

    Ground-based photometry and spectroscopy is presented for IRAS 22272 + 5435, a 9th mag star with a large infrared excess. The flux distribution is 'double-peaked', with a visible and near-infrared component due to the reddened photosphere and a far-infrared component presumably due to a detached dust shell. About equal amounts of energy are detected from each. The spectrum is that of a peculiar G supergiant, Gp Ia. In addition, strong molecular bands of C3 and C2 are observed. The flux distribution is modeled and, together with published molecular-line radio observations, allows the determination of basic parameters of the central star and the dust shell. The source has the characteristics one would expect of a proto-planetary nebula, an object in transition from the asymptotic giant branch to the planetary nebula phase.

  1. Spectroscopy of Planetary Nebulae at the Bright End of the Luminosity Function

    NASA Astrophysics Data System (ADS)

    Rilinger, Anneliese; Kwitter, Karen B.; Balick, Bruce; Corradi, R. L. M.; Galera Rosillo, Rebeca; Jacoby, George H.; Shaw, Richard A.

    2017-01-01

    We have obtained spectra of 8 luminous planetary nebulae (PNe) in M31 and 4 in the Large Magellanic Cloud with the goal of understanding their properties and those of their progenitor stars. These PNe are at or near the M* region (the most luminous PNe) in their respective galaxies. M31 PNe were observed at the Gran Telescopio Canarias using the OSIRIS spectrograph; LMC PNe were observed with the FORS2 spectrograph at the Very Large Telescope. Line intensities were measured in IRAF. Using our n-level atom program, ELSA (Johnson, et.al, 2006, Planetary Nebulae in our Galaxy and Beyond, 234, 439), we determined temperature, density, and elemental abundances for each nebula. We then modeled the nebulae and central stars with Cloudy (Ferland, et al. 1998, PASP, 110, 761). We plan to use these models of the central stars to estimate the masses and ages of the progenitor stars. We hope to discover whether the progenitor stars of M* PNe exhibit consistently different characteristics from those of other PNe progenitors.

  2. The post-common-envelope, binary central star of the planetary nebula Hen 2-11

    NASA Astrophysics Data System (ADS)

    Jones, D.; Boffin, H. M. J.; Miszalski, B.; Wesson, R.; Corradi, R. L. M.; Tyndall, A. A.

    2014-02-01

    We present a detailed photometric study of the central star system of the planetary nebula Hen 2-11, selected for study because of its low-ionisation filaments and bipolar morphology - traits which have been strongly linked with central star binarity. Photometric monitoring with NTT-EFOSC2 reveals a highly irradiated, double-eclipsing, post-common-envelope system with a period of 0.609 d. Modelling of the lightcurve indicates that the nebular progenitor is extremely hot, while the secondary in the system is probably a K-type main sequence star. The chemical composition of the nebula is analysed, showing Hen 2-11 to be a medium-excitation non-Type i nebula. A simple photoionisation model is constructed determining abundance ratios of C/O and N/O which would be consistent with the common-envelope cutting short the AGB evolution of the nebular progenitor. The detection of a post-common-envelope binary system at the heart of Hen 2-11 further strengthens the link between binary progeny and the formation of axisymmetric planetary nebulae with patterns of low-ionisation filaments, clearly demonstrating their use as morphological indicators of central star binarity. Extracted 1D spectra, reduced 2D spectra, and table of photometry 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/562/A89

  3. High-Resolution Near-Infrared Spectra of the Proto-Planetary Nebula, MWC 922

    NASA Astrophysics Data System (ADS)

    Whelan, David G.; Chojnowski, S.; Zasowski, G.; Wisniewski, J. P.; Nidever, D. L.; Majewski, S.; SDSS-III/APOGEE Team

    2014-01-01

    The detailed abundance and morphology properties of the diverse objects collectively labeled 'B[e] stars' remains uncertain. As part of a program targeting known emission line objects in order to compare to new emission-line sources discovered in the SDSS-III/APOGEE survey, the unclassified B[e] star MWC 922, a proto-planetary nebula also known as the Red Square Nebula, was observed. Our high-resolution (R ~ 22,500) H-band spectra from APOGEE reveal a number of metal lines, including low-ionization species of Fe, C, Si, and Co, although our current line list is insufficient to identify all of the emission lines observed. At least one Diffuse Interstellar Band (DIB) is present, consistent with previously observed high dust and PAH column densities toward this source. Whereas the Hydrogen recombination lines and the allowed metal lines are all fairly broad 100s km/s), the [Fe II] emission features have two components, consisting of a broad emission line with a narrow emission line superposed. We identify a large number of the observed lines and attribute the variations in line width to specific geometrical features in the nebula. This approach provides new insight into the excitation mechanisms for the two-component model that has been proposed for similar proto-planetary nebulae.

  4. 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.

  5. Properties of LMC planetary nebulae and parent populations in the MACHO database

    SciTech Connect

    Alves, D.R. |; Alcock, C.; Cook, K.H.

    1996-10-01

    The MACHO microlensing experiment's time-sampled photometry database contains blue and red lightcurves for nearly 9 million stars in the central bar region of the Large Magellanic Cloud (LMC). We have identified known LMC Planetary Nebulae (PN) in the database and find one, Jacoby 5, to be variable. We additionally present data on the ``parent populations`` of LMC PN, and discuss the star formation history of the LMC bar. 14 refs., 1 fig.

  6. 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.

  7. Ultraviolet and optical spectra of central stars of halo planetary nebulae

    NASA Astrophysics Data System (ADS)

    Pena, M.; Torres-Peimbert, S.; Ruiz, M. T.

    1992-11-01

    UV and optical spectrophotometric data on central stars of eight Population II planetary nebulae are analyzed. Visual magnitudes, spectral classification, color temperatures, and luminosities are derived from these data. All the stars in the sample exhibit an absorption-type spectrum, and most of them have normal H and He photospheric abundances, with the possible exception of M 2-29 and GJJC-1, which appear to be H-deficient.

  8. 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.

  9. Young planetary nebulae: Hubble Space Telescope imaging and new morphological classifications system

    NASA Astrophysics Data System (ADS)

    Sahai, R.; Villar, G. G., III; Morris, M.

    Using Hubble Space Telescope images of about 120 young planetary nebulae (PNe), most of which have not previously been published, we have devised a comprehensive morphological classification system for these objects, with minimal prejudice regarding their underlying physical cause. However, in many cases, physical causes are readily suggested by the primary 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). This system generalizes a recently-devised system for pre-planetary nebulae, which are the immediate progenitors of planetary nebulae. Unlike previous classification studies, we have focussed 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.

  10. Near- and mid-IR morphology of the water maser emitting planetary nebula K 3-35

    NASA Astrophysics Data System (ADS)

    Blanco, M. W.; Guerrero, M. A.; Miranda, L. F.; Lagadec, E.; Suárez, O.

    2014-01-01

    The shaping process of planetary nebulae (PNe) takes place during the short transition from the asymptotic giant branch (AGB) phase to the white dwarf stage. The young PN K 3-35 represents a unique case where a small-sized water maser ring has been linked to the launch of collimated outflows that shape the nebula. The contrasting optical and radio continuum morphologies of K 3-35 indicate that they disclose different structural components that are apparently unconnected. To bridge the gap between optical and radio continuum observations, we present here new broadband and narrowband near- and mid-IR images of K 3-35. These images, and their comparison with optical and radio continuum images, are revealing. The radio continuum and mid-IR images are dominated by a compact source at the core of K 3-35 whose emission gives evidence of very dense ionized material embedded within a dust cocoon. The emission from the core, obscured at optical wavelengths, is faintly detected in the Ks band. We suggest that the dust may shield the water molecules at the inner ring from the central star ionizing radiation. The precessing collimated outflows, very prominent in radio continuum, are also detected in mid-IR, very particularly in the [S iv] image. The mid-IR emission from these outflows consist mostly of ionized material, although the broadband filter at 11.85 μm seems to imply that a small amount of dust may be carried out by the outflow. The interactions of these outflows with the nebular shell result in shocks that excite the emission of H2 as well as low-excitation lines from ionized species, such as [N ii] at the tips of the outflows. Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere, Chile. Program: 085.D-0256(A).

  11. 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

  12. Astrometry With the Hubble Space Telescope: Trigonometric Parallaxes of Planetary Nebula Nuclei NGC 6853, NGC 7293, ABELL 31, and DeHt 5

    DTIC Science & Technology

    2009-12-01

    reserved. Printed in the U.S.A. ASTROMETRY WITH THE HUBBLE SPACE TELESCOPE: TRIGONOMETRIC PARALLAXES OF PLANETARY NEBULA NUCLEI NGC 6853, NGC 7293, ABELL 31...present absolute parallaxes and relative proper motions for the central stars of the planetary nebulae NGC 6853 (The Dumbbell), NGC 7293 (The Helix...Abell 31, and DeHt 5. This paper details our reduction and analysis using DeHt 5 as an example. We obtain these planetary nebula nuclei (PNNi

  13. PHOTOMETRY OF THE STINGRAY NEBULA (V839 ARA) FROM 1889 TO 2015 ACROSS THE IONIZATION OF ITS PLANETARY NEBULA

    SciTech Connect

    Schaefer, Bradley E.; Edwards, Zachary I.

    2015-10-20

    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{sup −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{sup −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.

  14. 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.

  15. A HUBBLE SPACE TELESCOPE Survey for Resolved Companions of Planetary Nebula Nuclei

    NASA Astrophysics Data System (ADS)

    Ciardullo, Robin; Bond, Howard E.; Sipior, Michael S.; Fullton, Laura K.; Zhang, C.-Y.; Schaefer, Karen G.

    1999-07-01

    We report the results of a Hubble Space Telescope ``snapshot'' survey aimed at finding resolved binary companions of the central stars of Galactic planetary nebulae (PNe). Using the the Wide Field and Planetary Camera and Wide Field Planetary Camera 2, we searched the fields of 113 PNe for stars whose close proximity to the central star suggests a physical association. In all, we find 10 binary nuclei that are very likely to be physically associated and another six that are possible binary associations. By correcting for interstellar extinction and placing the central stars' companions on the main sequence (or, in one case, on the white dwarf cooling curve), we derive distances to the objects, and thereby significantly increase the number of PNe with reliable distances. Comparison of our derived distances with those obtained from various statistical methods shows that all of the latter have systematically overestimated the distances, by factors ranging up to a factor of 2 or more. We show that this error is most likely due to the fact that the properties of our PNe with binary nuclei are systematically different from those of PNe used heretofore to calibrate statistical methods. Specifically, our PNe tend to have lower surface brightnesses at the same physical radius than the traditional calibration objects. This difference may arise from a selection effect: the PNe in our survey are typically nearby, old nebulae, whereas most of the objects that calibrate statistical techniques are low-latitude, high surface brightness, and more distant nebulae. As a result, the statistical methods that seem to work well with samples of distant PNe, for example, those in the Galactic bulge or external galaxies, may not be applicable to the more diverse population of local PNe. Our distance determinations could be improved with better knowledge of the metallicities of the individual nebulae and central stars, measurements of proper motions and radial velocities for additional

  16. Far-infrared emission line spectroscopy of planetary nebulae from the KAO

    NASA Technical Reports Server (NTRS)

    Dinerstein, Harriet L.

    1994-01-01

    The main focus of the overall project was to study the properties of planetary nebulae using far-infrared emission lines. The observations were conducted with the 'cooled grating spectrometer' or CGS, a moderate-resolution echelle spectrometer designed and built at the Ames Research Center. During the first few years of the program, the emphasis was on emission lines of doubly-ionized oxygen and nitrogen ((O III) 52 and 88 microns, (N III) 57 microns), which arise in the ionized regions of the nebulae. Starting around 1989, our emphasis shifted to observing fine-structure lines of neutral oxygen and singly-ionized carbon ((O I) 63 and 145 microns, (C II) 157 microns), which arise from predominantly neutral material outside the ionized regions. This program was typically assigned one or two observing flights per year. Because these studies required obtaining a substantial sample of objects in order to reach meaningful conclusions, publication of comprehensive papers summarizing all of the results is still pending. However, numerous interim reports based on the airborne results as well as on closely-related supporting observations have been published during the grant period. The bibliographic information for these reports is given in the publications section. An overall summary of the planetary nebula results was presented at the Airborne Astronomy Symposium (20th Anniversary of the KAO) on 8 July 1994; reprints will be provided when available. In parallel with the planetary nebula study, we also observed the (O III) and (N III) lines in several H II regions, and attempted (unsuccessfully) to detect these lines in several old nova remnants and the supernova remnant Cassiopeia A.

  17. Stingray Nebula

    NASA Technical Reports Server (NTRS)

    1996-01-01

    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).

  18. 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.

  19. Spectrophotometric observations of a peculiar nitrogen-rich planetary nebula NGC 2440

    NASA Astrophysics Data System (ADS)

    Louise, R.

    1982-06-01

    By using the Boller and Chivens spectrograph with a moderate dispersion (59 A/mm) in the red spectral region, 65 spectra covering the whole surface of the planetary nebula NGC 2440 were obtained. Intensities of H-alpha, forbidden N II lines 6548-6584 A and forbidden S II lines 6717-6731 A are derived using the IDS system available at the ESO in La Silla (Chile). The nebula is known to be a nitrogen-rich nebula (Peimbert, 1978) surrounded by secondary structures (Minkowski, 1964). The unusual high value of the forbidden N II lines/H-alpha in the central core (approximately 3.0) is certainly due to the nitrogen overabundance occurring in that part of the nebula. Its variations from the center to the outer regions are interpreted as a consequence of small-scale ionization structure (Capriotti, Cromwell and Williams, 1971). The observations show clearly an outward increase of both forbidden N II lines/H-alpha and I(6717)/I(6713) ratios.

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

    SciTech Connect

    Liebert, J.; Green, R.; Bond, H.E.; Holberg, J.B.; Wesemael, F. Mount Wilson and Las Campanas Observatories, Pasadena, CA Kitt Peak National Observatory, Tucson, AZ Space Telescope Science Institute, Baltimore, MD Arizona Univ., Tucson Montreal Universite, Montreal )

    1989-11-01

    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. 45 refs.

  1. A Planetary Nebula around Nova V458 Vulpeculae Undergoing Flash Ionization

    NASA Astrophysics Data System (ADS)

    Wesson, R.; Barlow, M. J.; Corradi, R. L. M.; Drew, J. E.; Groot, P. J.; Knigge, C.; Steeghs, D.; Gaensicke, B. T.; Napiwotzki, R.; Rodriguez-Gil, P.; Zijlstra, A. A.; Bode, M. F.; Drake, J. J.; Frew, D. J.; Gonzalez-Solares, E. A.; Greimel, R.; Irwin, M. J.; Morales-Rueda, L.; Nelemans, G.; Parker, Q. A.; Sale, S. E.; Sokoloski, J. L.; Somero, A.; Uthas, H.; Walton, N. A.; Warner, B.; Watson, C. A.; Wright, N. J.

    2008-11-01

    Nova V458 Vul erupted on 2007 August 8 and reached a visual magnitude of 8.1 a few days later. Hα images obtained 6 weeks before the outburst as part of the IPHAS Galactic plane survey reveal an 18th magnitude progenitor surrounded by an extended nebula. Subsequent images and spectroscopy of the nebula reveal an inner nebular knot increasing rapidly in brightness due to flash ionization by the nova event. We derive a distance of 13 kpc based on light travel time considerations, which is supported by two other distance estimation methods. The nebula has an ionized mass of 0.2 M⊙ and a low expansion velocity: this rules it out as ejecta from a previous nova eruption, and is consistent with it being a ~14,000 year old planetary nebula, probably the product of a prior common envelope (CE) phase of evolution of the binary system. The large derived distance means that the mass of the erupting WD component of the binary is high. We identify two possible evolutionary scenarios, in at least one of which the system is massive enough to produce a Type Ia supernova upon merging.

  2. The planetary nebula IPHASXJ211420.0+434136 (Ou5): insights into common-envelope dynamical and chemical evolution

    NASA Astrophysics Data System (ADS)

    Corradi, R. L. M.; Rodríguez-Gil, P.; Jones, D.; García-Rojas, J.; Mampaso, A.; García-Alvarez, D.; Pursimo, T.; Eenmäe, T.; Liimets, T.; Miszalski, B.

    2014-07-01

    While analysing the images of the IPHAS (INT/WFC Photometric Hα Survey of the northern Galactic plane) survey, we noticed that the central star of the candidate planetary nebula IPHASXJ211420.0+434136 (also named Ou5) was clearly variable. This is generally considered as an indication of binarity. To confirm it, we performed a photometric monitoring of the central star, and obtained images and spectra of the nebula. The nebular spectrum confirms that IPHASXJ211420.0+434136 is a planetary nebula of moderately high excitation. It has a remarkable morphology with two nested pairs of bipolar lobes and other unusual features. The light curve of the central star reveals that it is an eclipsing binary system with an orbital period of 8.74 h. It also displays a strong irradiation effect with an amplitude of 1.5 mag. The presence of multiple bipolar outflows adds constraints to the formation of these nebulae, suggesting the occurrence of discrete ejection events during, or immediately before, the common-envelope phase. IPHASXJ211420.0+434136 also adds evidence to the hypothesis that a significant fraction of planetary nebulae with close binary central stars have a peculiar nebular chemistry and a relatively low nebular mass. This may point to low-mass, low-metallicity progenitors, with additional effects related to the binary evolution. We also suggest that these objects may be relevant to understand the abundance discrepancy problem in planetary nebulae.

  3. Observations of the Bowen fluorescence mechanism and charge transfer in planetary nebulae. II

    NASA Astrophysics Data System (ADS)

    Liu, Xiao-Wei; Danziger, John; Murdin, Paul

    1993-06-01

    The study compares measurements of O(2+) Bowen fluorescence and charge transfer lines in nine planetary nebulae with theoretical predictions, taking into account contributions from the Bowen fluorescence mechanism, the charge transfer reaction between O(3+) and H(0), and radiative and dielectronic recombination. In general, good agreement is found. It is shown that excitation by absorption of the stellar continuum UV radiation is negligible for these lines. There is a good positive correlation between the strength of the charge transfer reaction and the degree of excitation of the nebulae. The relative charge transfer rate coefficients into singlet and triplet levels of O(2+), k(2p3p3DJ)/k(2p3p1P)(J = 1, 2, 3), are derived and on average are equal to 1.2, independent of the statistical weight 2J + 1 of the fine-structure level.

  4. Further observations of the planetary nebula in the globular cluster M22

    SciTech Connect

    Cudworth, K.M. )

    1990-06-01

    The proper motion of the central star of the newly-discovered planetary nebula in the globular cluster M22 strongly confirms cluster membership, in agreement with radial-velocity data from the discovery group. An accurate optical position of the central star differs by a few arcseconds from the IR source position derived by the discoverers. Photographic photometry of the star on plates spanning nearly a century shows that the star has probably brightened by about 0.2 mag since 1900, but there is no evidence of variations on shorter timescales. Dust within the nebula is probably responsible for the excess reddening of the background red companion to the central star. 12 refs.

  5. 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.

  6. 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.

  7. 2-45 Micron Infrared Spectroscopy of Carbon-Rich Proto-Planetary Nebulae

    NASA Technical Reports Server (NTRS)

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

    2000-01-01

    Infrared Space Observatory (ISO) 2-45 micron observations of seven proto-planetary nebulae (PPNs) and two other carbon-rich objects are presented. The unidentified emission features at 21 and 30 microns are detected in six sources, including four new detections of the 30 micron feature. This previously unresolved 30 micron feature is now resolved and found to consist of a broad feature peaking at 27.2 microns (the '30 micron' feature) and a narrower feature at 25.5 microns (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 infrared (UIR) emission features at 3.3, 6.2, 7.7, and 11.3 microns which are commonly observed in planetary nebulae and H II regions, are also seen in these PPNs. However, their strengths relative to the continuum plateaus at 8 and 12 microns are weaker than in planetary nebulae. The 6.9 micron feature, seen almost exclusively in PPNs, is strong. New millimeter CO and HCN observations were made; they support the carbon-rich nature of the objects and yield the expansion velocities of the gaseous envelopes. The spectral energy distributions of these PPNs were fitted with a radiative-transfer model, taking into account the emission features at 21, 26, and 30 microns. A significant fraction of the total energy output is emitted in these features: as high as 20% in the 30 micron feature and 8% in the 21 micron feature. The fact that so much energy is carried in these features suggests that the material responsible for these features must be made of abundant elements and most likely involves carbon. SiS, appears to be ruled out as the emitter of the 21 micron feature due to the absence of a predicted companion feature.

  8. Radiation-driven winds of hot stars. V - Wind models for central stars of planetary nebulae

    NASA Technical Reports Server (NTRS)

    Pauldrach, A.; Puls, J.; Kudritzki, R. P.; Mendez, R. H.; Heap, S. R.

    1988-01-01

    Wind models using the recent improvements of radiation driven wind theory by Pauldrach et al. (1986) and Pauldrach (1987) are presented for central stars of planetary nebulae. The models are computed along evolutionary tracks evolving with different stellar mass from the Asymptotic Giant Branch. We show that the calculated terminal wind velocities are in agreement with the observations and allow in principle an independent determination of stellar masses and radii. The computed mass-loss rates are in qualitative agreement with the occurrence of spectroscopic stellar wind features as a function of stellar effective temperature and gravity.

  9. 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.

  10. 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

  11. DISCOVERY OF COLLIMATED BIPOLAR OUTFLOWS IN THE PLANETARY NEBULA TH 2-A

    SciTech Connect

    Danehkar, A.

    2015-12-10

    We present a comprehensive set of spatially resolved, integral field spectroscopic mapping of the Wolf–Rayet planetary nebula Th 2-A, obtained using the Wide Field Spectrograph on the Australian National University 2.3-m telescope. Velocity-resolved Hα channel maps with a resolution of 20 km s{sup −1} allow us to identify different kinematic components within the nebula. This information is used to develop a three-dimensional morpho-kinematic model of the nebula using the interactive kinematic modeling tool shape. These results suggest that Th 2-A has a thick toroidal shell with an expansion velocity of 40 ± 10 km s{sup −1}, and a thin prolate ellipsoid with collimated bipolar outflows toward its axis reaching velocities in the range of 70–110 km s{sup −1}, with respect to the central star. The relationship between its morpho-kinematic structure and peculiar [WO]-type stellar characteristics deserves further investigation.

  12. A DETAILED SPATIOKINEMATIC MODEL OF THE CONICAL OUTFLOW OF THE MULTIPOLAR PLANETARY NEBULA NGC 7026

    SciTech Connect

    Clark, D. M.; Lopez, J. A.; Steffen, W.; Richer, M. G.

    2013-03-15

    We present extensive, long-slit, high-resolution coverage of the complex planetary nebula (PN) NGC 7026. We acquired 10 spectra using the Manchester Echelle Spectrometer at San Pedro Martir Observatory in Baja California, Mexico, and each shows exquisite detail, revealing the intricate structure of this object. Incorporating these spectra into the three-dimensional visualization and kinematic program SHAPE and using Hubble Space Telescope images of NGC 7026, we have produced a detailed structural and kinematic model of this PN. NGC 7026 exhibits remarkable symmetry consisting of three lobe pairs and four sets of knots, all symmetrical about the nucleus and displaying a conical outflow. Comparing the three-dimensional structure of this nebula to recent XMM-Newton X-ray observations, we investigate the extended X-ray emission in relation to the nebular structure. We find that the X-ray emission, while confined to the closed, northern lobes of this PN, shows an abrupt termination in the middle of the southeast lobe, which our long slit data show to be open. This is where the shocked fast wind seems to be escaping the interior of the nebula and the X-ray emission rapidly cools in this region.

  13. 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.

  14. Spectroscopy and Photoionization Model of Planetary Nebulae: NGC 6543 and NGC 7662

    NASA Astrophysics Data System (ADS)

    Puspitaningrum, Evaria; Lutfi Malasan, Hakim; Kawakita, Hideyo

    2016-11-01

    Spectroscopic observations in the wavelength range of λλ4000 — 8000 Å of the planetary nebulae (PN), NGC 6543 and NGC 7662, have been undertaken in 2014 using the compact spectrograph attached to the 28-cm Schmidt-Cassegrainian reflector at Koyama Astronomical Observatory. We derived physical parameters of NGC 6543 and NGC 7662 from the analyses of observed emission lines, i.e. electron temperature, density, and elemental abundances. To obtain more reliable physical quantities of NGC 6543 and NGC 7662, the use of photoionization model is needed. We use the computer code, CLOUDY C13.3 to build detailed photoionization models of NGC 6543 and NGC 7662. Model of NGC 6543 and 7662 can be constructed by providing sufficient information on physical parameters of the central stars and the nebula. In this work, input parameters to construct the photoionization model of NGC 6543 and NGC 7662 are distance, temperature and luminosity of central star and nebula parameters. The model results were compared with observational result taken in 2014. Observed and modeled temperatures were deduced from [O III] λλ(4959 + 5007) Å /λ4636 Å and the electron density from [S II] λλ 6716/6731 Å. There are some discrepancies between observed and modeled due to limitations inherent with the resolution and quality of spectroscopic data. Further spectroscopic observations with higher resolution of NGC 6543 and NGC 7662 is recommended.

  15. 2-D Spectroscopic Observations of O II Recombination Lines in the Planetary Nebula NGC 7009

    NASA Astrophysics Data System (ADS)

    Hwang, Sehyun; Dinerstein, H.; Hill, G.; MacQueen, P.; Adams, J.; Blanc, G.

    2007-12-01

    We present preliminary results from 2-D spatially-resolved spectroscopic observations of the planetary nebula NGC 7009, obtained in September 2007 on the McDonald Observatory 2.7m telescope utilizing the integral field unit (IFU) VIRUS-P (Visible Integral-field Replicable Unit Spectrograph-Prototype; Hill et al., 2006, New Astronomy Reviews, 50, 378). The instrument delivers simultaneous spectra in 247 fibers over the wavelength range 3550-5850Å at a spectral resolving power of 1000 at 5000Å. By taking three spatially dithered integrations, fully-sampled maps can be obtained for a region of 112"×112" with an angular resolution of 4.1". These observations are part of an observing program to investigate the enigma of the optical recombination lines (ORLs) such as those of O II, that appear to indicate higher oxygen abundances than the collisionally excited lines (CELs) from the same ion, in some planetary nebulae. In order to resolve this abundance discrepancy, Liu et al. (2000, MNRAS, 312, 585) proposed a dual-abundance model, which postulates that the nebulae which display this behavior contain cold, metal-rich, H-deficient inclusions where the ORLs are produced, embedded in hotter material of more normal composition from which the CELs arise. This model can provide a good fit to the integrated-light spectra, but the cold, metal-rich inclusions have yet to be spatially resolved or isolated. We have obtained fully-sampled maps of several planetary nebulae that display this anomaly, in an effort to find evidence for localized variations in the strengths of the ORLs relative to the CELs that would be expected if the cold, metal-rich gas is concentrated in spatially distinct clumps. In this poster we will present results from our observations to date, in particular from a recent VIRUS-P observing set of NGC 7009. [This research was supported by NSF grants AST-0408609/-0708245 to H.L.D., and VIRUS-P has been by the Cynthia and George Mitchell Foundation.

  16. Photoionized gaseous nebulae and magnetized stellar winds: The evolution and shaping of H II regions and planetary nebulae

    NASA Astrophysics Data System (ADS)

    Franco, José; García-Segura, Guillermo; Kurtz, Stan E.; López, José A.

    2001-05-01

    The early evolution of hydrogen+ (H II) regions is controlled by the properties of the star-forming cloud cores. The observed density distributions in some young H II regions indicate that the power-law stratifications can be steeper than r-2. Ionization fronts can overrun these gradients and the ionized outflows are strongly accelerated along these steep density distributions. Thus, photoionized regions can either reach pressure equilibrium inside the inner parts of the high-pressure cores [with sizes and densities similar to those observed in ultra compact (UC) H II regions], or create bright H II regions with extended emission. The density inhomogeneities engulfed within the ionization fronts create corrugations in the front, which in turn drive instabilities in the ionization-shock (I-S) front. These instabilities grow on short time scales and lead to the fragmentation of the dense shells generated by the shock fronts. Thus, new clumps are continuously created from the fragmented shell, and the resulting finger-like structures can explain the existence of elephant trunks and cometary-like globules in most H II regions. In the case of planetary nebulae (PNe), wind asymmetries and magnetic fields from rotating stars, along with precession of the rotation axis, can create the wide range of observed PNe morphologies and collimated outflows (jets). Magnetic collimation and jet formation in PNe become very efficient after the flow has passed through the reverse shock of the PN.

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

    NASA Astrophysics Data System (ADS)

    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 (). 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 ~1.76, which is above the Chandrasekhar limit (the maximum mass of a stable white dwarf) of 1.4. 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.

  18. 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.

  19. Young Planetary Nebulae: Hubble Space Telescope Imaging and a New Morphological Classification System

    NASA Astrophysics Data System (ADS)

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

    2011-04-01

    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.

  20. 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.

  1. A Revised Planetary Nebula Luminosity Function Distance to NGC 628 Using MUSE

    NASA Astrophysics Data System (ADS)

    Kreckel, K.; Groves, B.; Bigiel, F.; Blanc, G. A.; Kruijssen, J. M. D.; Hughes, A.; Schruba, A.; Schinnerer, E.

    2017-01-01

    Distance uncertainties plague our understanding of the physical scales relevant to the physics of star formation in extragalactic studies. The planetary nebulae luminosity function (PNLF) is one of very few techniques that can provide distance estimates to within ∼10% however, it requires a planetary nebula (PN) sample that is uncontaminated by other ionizing sources. We employ optical integral field unit spectroscopy using the Multi-Unit Spectroscopic Explorer on the Very Large Telescope to measure [O iii] line fluxes for sources unresolved on 50 pc scales within the central star-forming galaxy disk of NGC 628. We use diagnostic line ratios to identify 62 PNe, 30 supernova remnants, and 87 H ii regions within our fields. Using the 36 brightest PNe, we determine a new PNLF distance modulus of {29.91}-0.13+0.08 mag (9.59{}-0.57+0.35 Mpc), which is in good agreement with literature values, but significantly larger than the previously reported PNLF distance. We are able to explain the discrepancy and recover the previous result when we reintroduce SNR contaminants to our sample. This demonstrates the power of full spectral information over narrowband imaging in isolating PNe. Given our limited spatial coverage within the Galaxy, we show that this technique can be used to refine distance estimates, even when IFU observations cover only a fraction of a galaxy disk.

  2. 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

    2015-03-05

    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.

  3. 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.

  4. Galactic Planetary Nebulae and their central stars. I. An accurate and homogeneous set of coordinates

    NASA Astrophysics Data System (ADS)

    Kerber, F.; Mignani, R. P.; Guglielmetti, F.; Wicenec, A.

    2003-09-01

    We have used the 2nd generation of the Guide Star Catalogue (GSC-II) as a reference astrometric catalogue to compile the positions of 1086 Galactic Planetary Nebulae (PNe) listed in the Strasbourg ESO Catalogue (SEC), its supplement and the version 2000 of the Catalogue of Planetary Nebulae. This constitutes about 75% of all known PNe. For these PNe, the ones with a known central star (CS) or with a small diameter, we have derived coordinates with an absolute accuracy of ~0\\farcs35 in each coordinate, which is the intrinsic astrometric precision of the GSC-II. For another 226, mostly extended, objects without a GSC-II counterpart we give coordinates based on the second epoch Digital Sky Survey (DSS-II). While these coordinates may have systematic offsets relative to the GSC-II of up to 5 arcsecs, our new coordinates usually represent a significant improvement over the previous catalogue values for these large objects. This is the first truly homogeneous compilation of PNe positions over the whole sky and the most accurate one available so far. The complete Table \\ref{tab2} is only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/408/1029}

  5. 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.

  6. 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).

  7. 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.

  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. 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}.

  10. 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

  11. The chemical composition of planetary nebulae and HII regions in NGC 3109

    NASA Astrophysics Data System (ADS)

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

    2007-12-01

    Aims:We present deep spectrophotometry for a sample of 8 planetary nebulae (PNe) and 12 HII regions distributed throughout the dwarf irregular galaxy NGC 3109, in order to analyze the chemical composition of both types of nebulae. Methods: We describe the observations and data reduction, and present line intensities for the nebular emission lines detected. The physical conditions and the abundances of He, O, Ne, N, S and Ar are derived, using the classical T_e-based method. We confirm our previous identification of PNe and HII regions based on photometry, except for one object, which we argue is a compact HII region rather than a planetary nebula. Results: We find that the chemical composition of the interstellar medium in NGC 3109, as sampled by its HII regions, is remarkably uniform. The oxygen abundance is log O/H + 12 = 7.77 ± 0.07 in this galaxy, as compared to 8.05 ± 0.09 for the Small Magellanic Cloud (for which we rederived the metallicity in a homogeneous way). PNe show significantly higher oxygen abundances in NGC 3109: log O/H + 12 = 8.16 ± 0.19. Similarly to what has been suggested for some of the PNe in the Magellanic Clouds and other metal-poor galaxies, we argue that oxygen in the PNe in NGC 3109 is affected by dredge up in their progenitors. This could also be the case for neon, although the uncertainties for this element are bigger. Conclusions: From our analysis, we conclude that oxygen and neon are not always a safe indicator of the chemical composition of the interstellar medium at low metallicities. An alternative to the O and Ne enrichment in PNe is that the low metallicity in HII regions has been caused by dilution of the interstellar medium due to an interaction with a neighboring galaxy about a Gyr ago. The excitation patterns of the PNe in NGC 3109 are very different from the excitation patterns of PNe in other galaxies. This issue needs to be investigated further, as it implies that the evolution of PNe depends upon the properties of

  12. 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.

  13. 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.

  14. Alignment of the angular momentum vectors of planetary nebulae in the Galactic Bulge

    NASA Astrophysics Data System (ADS)

    Rees, B.; Zijlstra, A. A.

    2013-10-01

    We use high-resolution Hα images of 130 planetary nebulae (PNe) to investigate whether there is a preferred orientation for PNe within the Galactic Bulge. The orientations of the full sample have a uniform distribution. However, at a significance level of 0.01, there is evidence for a non-uniform distribution for those PNe with evident bipolar morphology. If we assume that the bipolar PNe have a unimodal distribution of the polar axis in Galactic coordinates, the mean Galactic position angle is consistent with 90°, i.e. along the Galactic Plane, and the significance level is better than 0.001 (the equivalent of a 3.7σ significance level for a Gaussian distribution). The shapes of PNe are related to angular momentum of the original star or stellar system, where the long axis of the nebula measures the angular momentum vector. In old, low-mass stars, the angular momentum is largely in binary orbital motion. Consequently, the alignment of bipolar nebulae that we have found indicates that the orbital planes of the binary systems are oriented perpendicular to the Galactic Plane. We propose that strong magnetic fields aligned along the Galactic Plane acted during the original star formation process to slow the contraction of the star-forming cloud in the direction perpendicular to the Plane. This would have produced a propensity for wider binaries with higher angular momentum with orbital axes parallel to the Galactic Plane. Our findings provide the first indication of a strong, organized magnetic field along the Galactic Plane that impacted on the angular momentum vectors of the resulting stellar population.

  15. The Nearby AGB Star L2 Puppis: The Birth Of a Planetary Nebula?

    NASA Astrophysics Data System (ADS)

    Kervella, P.; Montargès, M.; Lagadec, E.

    2015-12-01

    Adaptive optics observations in the infrared (VLT/NACO, Kervella et al. [6]) and visible (VLT/SPHERE, Kervella et al. [7]) domains revealed that the nearby AGB star L2 Pup (d = 64 pc) is surrounded by a dust disk seen almost edge-on. Thermal emission from a large dust "loop" is detected at 4 μm up to more than 10 AU from the star. We also detect a secondary source at a separation of 32 mas, whose nature is uncertain. L2 Pup is currently a relatively "young" AGB star, so we may witness the formation of a planetary nebula. The mechanism that breaks the spherical symmetry of mass loss is currently uncertain, but we propose that the dust disk and companion are key elements in the shaping of the bipolar structure. L2 Pup emerges as an important system to test this hypothesis.

  16. Abundances of sulfur in the Milky Way Disk from Peimbert Type II planetary nebulae

    NASA Astrophysics Data System (ADS)

    Milingo, Jacquelynne Brenda

    2000-08-01

    Sulfur abundance gradients and heavy element ratios for the Milky Way Disk are constructed based upon newly acquired spectrophotometry of Type II planetary nebulae (PN). These spectra extend from 3600-9600 angstroms allowing us to use the [SIII] 9069 and 9532 angstrom lines to improve upon earlier sulfur abundance estimates. Considering a significant portion of sulfur in PN exists in the S(+2) ionization stage (and higher) this method should allow us to extrapolate more reliable total element abundance from ionic abundances. Given the progenitor mass and location of Type II PN (close to the Galactic disk), this sample of objects is free of nucleosynthetic self-contamination and thus their S abundances in particular are expected to reflect levels of these elements in the interstellar medium at the time of PN progenitor formation. These sulfur abundances provide constraints for studying various aspects of GCE such as massive star yields and the distribution of S across the Milky Way disk.

  17. 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.

  18. 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.

  19. Spatial variations of physical and chemical properties of the planetary nebulae NGC 6302 and NGC 2440

    NASA Astrophysics Data System (ADS)

    Rauber, A. B.; Copetti, M. V. F.; Krabbe, A. C.

    2014-10-01

    We present an analysis of the physical and chemical conditions of the planetary nebulae NGC 6302 and NGC 2440 through spatially resolved spectroscopy. Long slit spectrophotometric data were obtained with the Goodman spectrograph attached to the 4.1 m SOAR telescope in several different declinations with the slit on the East-West direction. From them, maps and spatial profiles were constructed. Electron densities were calculated from the [S II] and [Ar IV] sensors, and electron temperatures from the [N II] and [O III] sensors. Small temperature fluctuations on the plane of the sky were obtained. Abundances of N^{+}, O^{+}, S^{+}, S^{2+}, O^{2+}, Ne^{2+}, Ar^{3+}, Ar^{4+} relative to H^{+} were determined from collisionally excited lines, and relative abundances of He^{+} and He^{2+} from recombination lines.

  20. 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.

  1. Limits to the Magnetic Field in the Planetary Nebula NGC 246 from Faraday Rotation

    NASA Astrophysics Data System (ADS)

    Rodríguez, L. F.; Carrasco-González, C.; Cantó, J.; Pasetto, A.; Raga, A. C.; Tafoya, D.

    2017-04-01

    We present radio continuum observations of the linearly polarized extragalactic source J0047-1150, whose line of sight traverses the galactic planetary nebula NGC 246. We determine the position angle of the electric vector at seven frequencies between 1.3 and 1.8 GHz, finding no evidence of Faraday rotation and setting a 4-σ upper limit to the rotation measure of 9.6 rad m-2, which implies an upper limit to the average line-of-sight component of the magnetic field in NGC 246 of 1.3 μG. However, we show that the rotation measure across a source with a dipolar magnetic field morphology practically cancels out. Therefore, if the magnetic field has this morphology, the local values of the magnetic field in NGC 246 could be much larger and will not be evident in a Faraday rotation experiment.

  2. 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.

  3. 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.

  4. AKARI/IRC NEAR-INFRARED SPECTRAL ATLAS OF GALACTIC PLANETARY NEBULAE

    SciTech Connect

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

    2016-04-15

    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. 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.

  6. Mid-infrared imaging of 18 planetary nebulae using the Spitzer Space Telescope

    NASA Astrophysics Data System (ADS)

    Phillips, J. P.; Ramos-Larios, G.

    2008-01-01

    We present 3.6-, 4.5-, 5.8- and 8.0-μm photometric mapping of 18 galactic planetary nebulae, based on observations taken with the Spitzer Space Telescope. These are shown to have morphologies which are sometimes quite different from those observed in the visible, with much of the emission arising outside the ionized shells. There is also evidence for a change in nebular sizes between the differing photometric bands. An analysis of mid-infrared (MIR) colours suggests that many nebulae have dust/polycyclic aromatic hydrocarbon (PAH) emission components, and it seems likely that longer wave MIR fluxes (in particular) are associated with PAH emission features. Such features are likely to be associated, in addition, with photodissociative regimes, where shock fragmentation of dust may lead to the replenishment of smaller PAH grains. Finally, we note that the source Ap 2-1 possesses a particularly interesting structure, and may represent a case in which the nebular shell is ploughing through an enveloping HII region. Similarly, it appears that central emission in M 2-48 may arise from a warm and dusty collimating disc.

  7. 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.

  8. 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.

  9. FAST, LOW-IONIZATION EMISSION REGIONS OF THE PLANETARY NEBULA M2-42

    SciTech Connect

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

    2016-02-15

    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{sup −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{sup −1} with respect to the nebular center. It is found that the mean density of the collimated outflows, 595 ± 125 cm{sup −3}, is five times lower than that of the main shell, 3150 cm{sup −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.

  10. 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.

  11. 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.

  12. 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).

  13. The influence of binarity on the morpho-kinematics of planetary nebulae

    NASA Astrophysics Data System (ADS)

    Jones, David; Tyndall, Amy A.; Lloyd, Myfanwy; Santander-García, Miguel

    2012-08-01

    The role of central star binarity in the shaping of planetary nebulae (PNe) has been the subject of much debate, with single stars believed to be incapable of producing the most highly collimated morphologies. However, observational support for binary-induced shaping has been sadly lacking. Here, we highlight the results of a continuing programme to spatio-kinematically model the morphologies of all PNe known to contain a close binary central star. Spatio-kinematical modelling is imperative for these objects, as it circumvents the degeneracy between morphology and orientation which can adversely affect determinations of morphology based on imaging alone. Furthermore, spatio-kinematical modelling accurately determines the orientation of the nebular shell, allowing the theoretically predicted perpendicular alignment, between nebular symmetry axis and binary orbital plane, to be tested. To date, every PN subjected to this investigation has displayed the predicted alignment, indicating that binarity has played an important role in the formation and evolution of these nebulae. The further results from this programme will be key, not only in determining whether binary interaction is responsible for shaping the studied PNe, but also in assessing the importance of binarity in the formation and evolution of all PNe in general.

  14. Millimeter observations of planetary nebulae. A contribution to the Planck pre-launch catalogue

    NASA Astrophysics Data System (ADS)

    Umana, G.; Leto, P.; Trigilio, C.; Buemi, C. S.; Manzitto, P.; Toscano, S.; Dolei, S.; Cerrigone, L.

    2008-05-01

    Aims: We present 43 GHz (7 mm) observations of a sample of radio-bright Planetary nebulae aimed to obtain, together with far-IR measurements (IRAS), reliable estimates of the fluxes emitted in the millimetre and sub-millimetre band, and, therefore, to test their detectability by the forthcoming ESA PLANCK mission. This spectral range, even though very important to constrain the physics of circumstellar environments, is still far from being completely exploited. Methods: The new millimetre 43 GHz observations were obtained by using the 32 m INAF-IRA Noto Radiotelescope. To estimate the millimetre and sub-millimetre fluxes, we extrapolated and summed the ionized gas (free-free radio emission) and dust (thermal emission) contributions in this frequency range. By comparison of the derived flux densities to the predicted sensitivity we investigate the possible detection of such source for all the channels of PLANCK Results: We conclude that almost 80% of our sample will be detected by PLANCK, with a higher detection rate in the higher frequency channels, where there is a good combination of brighter intrinsic flux from the sources and reduced extended Galactic foregrounds contamination despite poorer instrumental sensitivity. From the new 43 GHz, combined with single-dish 5 GHz observations from the literature, we derive radio spectral indexes, which are consistent with optically thin free-free nebula. This result indicates that the high frequency radio spectrum of our sample sources is dominated by thermal free-free, and other emissions, if present, are negligible.

  15. 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.

  16. He 2-104 - A link between symbiotic stars and planetary nebulae?

    NASA Technical Reports Server (NTRS)

    Lutz, Julie H.; Kaler, James B.; Shaw, Richard A.; Schwarz, Hugo E.; Aspin, Colin

    1989-01-01

    Ultraviolet, optical and infrared observations of He 2-104 are presented, and estimates for some of the physical properties of the nebular shell are made. It is argued that He 2-104 is in transition between the D-type symbiotic star and bipolar planetary nebula phases and, as such, represents a link between subclasses of these two types of objects. The model includes a binary system with a Mira variable and a hot, evolved star. Previous mass loss has resulted in the formation of a disk of gas and dust around the whole system, while the hot star has an accretion disk which produces the observed highly ionized emission line spectrum. Emission lines from cooler, lower density gas is also observed to come from the nebula. In addition, matter is flowing out of the system in a direction perpendicular to the disk with a high velocity and is impacting upon the previously-ejected red giant wind and/or the ambient interstellar medium.

  17. He 2-104: A link between symbiotic stars and planetary nebulae

    SciTech Connect

    Lutz, J.H.; Kaler, J.B.; Shaw, R.A.; Schwarz, H.E.; Aspin, C.

    1989-05-01

    Ultraviolet, optical and infrared observations of He 2-104 are presented, and estimates for some of the physical properties of the nebular shell are made. It is argued that He 2-104 is in transition between the D-type symbiotic star and bipolar planetary nebula phases and, as such, represents a link between subclasses of these two types of objects. The model includes a binary system with a Mira variable and a hot, evolved star. Previous mass loss has resulted in the formation of a disk of gas and dust around the whole system, while the hot star has an accretion disk which produces the observed highly ionized emission line spectrum. Emission lines from cooler, lower density gas is also observed to come from the nebula. In addition, matter is flowing out of the system in a direction perpendicular to the disk with a high velocity and is impacting upon the previously-ejected red giant wind and/or the ambient interstellar medium.

  18. He 2-104: A link between symbiotic stars and planetary nebulae

    NASA Technical Reports Server (NTRS)

    Lutz, Julie H.; Kaler, James B.; Shaw, Richard A.; Schwarz, Hugo E.; Aspin, Colin

    1989-01-01

    Ultraviolet, optical and infrared observations of He 2-104 are presented, and estimates for some of the physical properties of the nebular shell are made. It is argued that He 2-104 is in transition between the D-type symbiotic star and bipolar planetary nebula phases and, as such, represents a link between subclasses of these two types of objects. The model includes a binary system with a Mira variable and a hot, evolved star. Previous mass loss has resulted in the formation of a disk of gas and dust around the whole system, while the hot star has an accretion disk which produces the observed highly ionized emission line spectrum. Emission lines from cooler, lower density gas is also observed to come from the nebula. In addition, matter is flowing out of the system in a direction perpendicular to the disk with a high velocity and is impacting upon the previously-ejected red giant wind and/or the ambient interstellar medium.

  19. 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.

  20. Behind the Curtain: Revealing the Nebular Influence on X-ray Emission from Planetary Nebulae

    NASA Astrophysics Data System (ADS)

    Montez, Rodolfo, Jr.

    2017-01-01

    Planetary Nebulae (PNe), the ionized shells of gas surrounding dying low- to intermediate-mass stars, are interesting astrophysical plasma laboratories because of the range of plasma conditions that exist in close proximity. Early in the lifetime of PNe, a 106 K plasma---called a hot bubble---fills the 104 K nebular shell. The interaction of these two plasmas is the potential origin of cooler than expected hot bubble temperatures. Studying high-spatial resolution imaging by the Hubble Space Telescope and the Chandra X-ray Observatory offer an opportunity to study the interaction of these two plasmas. Yet the Chandra and HST observations of PN BD+30°3639 indicate distinct X-ray and optical morphologies that do not appear directly correlated. However, we have developed a method that uses Chandra imaging spectroscopy to study the spatial distribution of the hot bubble X-ray emission. Remarkably, applying this method to the X-ray observation reveals the influence of the surrounding nebula and mimics the optical morphology that is otherwise hidden in the X-ray images. We present the methodology, images derived using the method, and the distribution of the physical conditions that likely give rise to the observed effect. Further improvement of the method and establishing its limitations in the low-count regime will help establish the utility of this method for other low-count extended X-ray sources.

  1. 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).

  2. Planetary Nebulae in the Elliptical Galaxy NGC 821: Kinematics and Distance Determination

    NASA Astrophysics Data System (ADS)

    Teodorescu, A. M.; Méndez, R. H.; Bernardi, F.; Riffeser, A.; Kudritzki, R. P.

    2010-09-01

    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. Based on data collected at the Subaru Telescope, which is operated by the National Astronomical Observatory of Japan.

  3. 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.

  4. The Kinematics of the Permitted C ii λ6578 Line in a Large Sample of Planetary Nebulae

    NASA Astrophysics Data System (ADS)

    Richer, Michael G.; Suárez, Genaro; López, José Alberto; García Díaz, María Teresa

    2017-03-01

    We present spectroscopic observations of the C ii λ6578 permitted line for 83 lines of sight in 76 planetary nebulae at high spectral resolution, most of them obtained with the Manchester Echelle Spectrograph on the 2.1 m telescope at the Observatorio Astronómico Nacional on the Sierra San Pedro Mártir. We study the kinematics of the C ii λ6578 permitted line with respect to other permitted and collisionally excited lines. Statistically, we find that the kinematics of the C ii λ6578 line are not those expected if this line arises from the recombination of C2+ ions or the fluorescence of C+ ions in ionization equilibrium in a chemically homogeneous nebular plasma, but instead its kinematics are those appropriate for a volume more internal than expected. The planetary nebulae in this sample have well-defined morphology and are restricted to a limited range in Hα line widths (no large values) compared to their counterparts in the Milky Way bulge; both these features could be interpreted as the result of young nebular shells, an inference that is also supported by nebular modeling. Concerning the long-standing discrepancy between chemical abundances inferred from permitted and collisionally excited emission lines in photoionized nebulae, our results imply that multiple plasma components occur commonly in planetary nebulae.

  5. The Formation of a Multiple Planetary Nebula:Hubble Space Telescope/WFPC2 Observations of KJPN 8

    NASA Astrophysics Data System (ADS)

    López, J. A.; Meaburn, J.; Rodríguez, L. F.; Vázquez, R.; Steffen, W.; Bryce, M.

    2000-07-01

    KjPn 8 is an extreme polypolar planetary nebula with a large-scale structure characterized by a giant biconical envelope. Spasmodic bipolar ejections in changing directions have occurred over thousands of years to create this peculiar nebula. Narrowband images of the core of KjPn 8 have now been obtained with the Wide Field Planetary Camera 2 on board the Hubble Space Telescope (HST) and are reported here. The central star is finally revealed in these observations, and its compact nebular core is resolved into a remarkably young elliptical ring, currently expanding at only 16 km s-1. This ring is the ionized inner region of larger molecular CO and H2 counterparts, all sharing the same orientation. The highest speed and youngest outflows are perpendicular to this central ring, which is identified as the latest event in the creation of this nebula. It is shown that the formation history of KjPn 8 has involved two distinct and consecutive planetary nebulae-like events, probably originating from a binary core evolution with components of very similar mass. These characteristics indicate that KjPn 8 may be a rare object in our Galaxy and the first ever detected of this class.

  6. 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.

  7. DDT_dgarciah_3: Searching for complex fullerene-based molecules in the prototype fullerene Planetary Nebula IC 418

    NASA Astrophysics Data System (ADS)

    García-Hernández, D. A.

    2013-02-01

    The recent and unexpected detection of the most common fullerenes (C60 and C70) and proto-graphene in some Planetary Nebulae (PNe) raises the exciting possibility that other more complex fullerene-based molecules (e.g., carbon onions or multishell fullerenes, fullerene-adducts) might be ubiquitous in the Universe and continue to be serious candidates to explain many astrophysical phenomena. The presence of complex fullerene-based molecules such as carbon onions in the circumstellar shells of fullerene-containing PNe is strongly suggested by our recent analysis of the unusual diffuse interstellar bands detected towards two PNe where C60 had already been found. If complex fullerene-based molecules such as carbon onions are present in this peculiar class of stars, they could easily be detected in the far-IR range. Fullerene-containing PNe are usually very faint in the far-IR but our very recent detection of C60 fullerenes in PN IC 418 can now mitigate this unfortunate situation. Surprisingly, Herschel has not observed this very bright source - now considered the prototype fullerene-containing PN - as part of any approved program in previous cycles. Thus, a comprehensive far-IR study of the complex circumstellar environment where fullerenes and fullerene-based molecules may form is at present lacking. With this DDT proposal we aim at obtaining full range, high S/N, Herschel/PACS far-IR spectra of PN IC 418 to search for the spectral signatures of complex fullerene-based molecules such as multishell fullerenes (e.g., C60@C240, C240@C960), which are predicted to be detectable as relatively strong broad features in the far-IR range. If successful, these observations will constitute the first firm detection of the most complex molecules ever detected in space. In addition, we will search for the predicted hydrogenated amorphous carbon (HAC) associated feature at ~60 um to confirm/refute the HAC's processing/decomposition scenario as the preferred fullerene formation route

  8. Prospecting for Elements: Galactic Halo Planetary Nebulae Abundances and Virgo Spiral Galaxy Color Profiles

    NASA Astrophysics Data System (ADS)

    Howard, Joseph William

    Halo planetary nebulae. Using published spectral line data for nine halo planetary nebulae (HPNe), I have calculated photoionization models in an attempt to gain insight into the physical conditions and chemical abundances of these nebulae. The nine HPNE reported upon are K648, DdDm-1, NGC2242, NGC4361, PN243.8-37.1, PN006-41.9, M2-29, BB-1, and H4-1. The derived abundance ranges for the HPNe are: C 6.60-8.95, N 7.18-8.00, O 7.56-8.56, Ne 6.24-7.71, Ar 4.12-7.70, and S 4.90-7.00 (log(x) + 12). The temperature range for the central stars of these nebulae is 40,000 to 140,000K. Specifically, with a few exceptions, I find that all nine objects exhibit subsolar O/H; most show enhanced C/O and N/O, and a constant Ne/O ration. I also note the existence of comparatively larger abundance scatter in the HPNe as opposed to disk PNe, and suggest that this is consistent with the accretion model of halo formation formulated by Searle & Zinn. In addition, I test the effects on derived abundances and central star temperatures of a variety of model atmospheres as well as blackbodies for input ionizing spectra. I find that nebular line strengths are relatively insensitive to atmospheric details; thus blackbody spectra are suitable for central star continua. Near-infrared Virgo cluster spiral colors. Near-infrared (NIR) surface photometry in J (1.2μm), H (1.6μm) and K (2.2μm) have been obtained for a sample of Virgo cluster spirals; NGC4321, NGC4303, NGC4571, NGC4689, and NGC4254 which span a large range in HI deficiency. The spirals range from a normal gas content to a deficiency of a factor of 10 compared to normal galaxies. Using previous HII region abundance studies along with the NIR colors an attempt has been made to calibrate any correlation between the J-K index to the overall gas phase abundance gradients as a first step to probing the underlying stellar metallicity. Decomposition techniques have been used to produce estimates of spiral bulge/disk masses and luminosities

  9. 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

  10. 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.

  11. 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.

  12. Low-ionization structures in planetary nebulae - I. Physical, kinematic and excitation properties

    NASA Astrophysics Data System (ADS)

    Akras, Stavros; Gonçalves, Denise R.

    2016-01-01

    Though the low-ionization small-scale structures (LISs) such as knots, filaments and jets of planetary nebulae (PNe) are known for ˜30 yr, some of their observational properties are not well established. In consequence, our ability to include them in the wider context of the formation and evolution of PNe is directly affected. Why most structures have lower densities than the PN shells hosting them? Is their intense emission in low-ionization lines the key to their main excitation mechanism? Therefore, if considered altogether, can LISs line ratios, chemical abundances and kinematics enlighten the interplay between the different excitation and formation processes? Here we present a spectroscopic analysis of five PNe that possess LISs confirming that all nebular components have comparable electron temperatures, whereas the electron density is systematically lower in LISs than in the surrounding nebula. Chemical abundances of LISs versus other PN components do not show significant differences as well. By using diagnostic diagrams from shock models, we demonstrate that LISs' main excitation is due to shocks, whereas the other components are mainly photoionized. We also propose new diagnostic diagrams involving a few emission lines ([N II], [O III], [S II]) and log(fshocks/f*), where fshocks and f* are the ionization photon fluxes due to the shocks and the central star ionizing continuum, respectively. A robust relation differentiating the structures is found, with the shock-excited clearly having log(fshocks/f*) > -1; while the photoionized structures have log(fshocks/f*) < -2. A transition zone, with -2 < log(fshocks/f*) < -1, where both mechanisms are equally important, is also defined.

  13. 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.

  14. 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 ☉}.

  15. Three-dimensional photoionization modelling of the planetary nebula NGC 3918

    NASA Astrophysics Data System (ADS)

    Ercolano, B.; Morisset, C.; Barlow, M. J.; Storey, P. J.; Liu, X.-W.

    2003-04-01

    The three-dimensional Monte Carlo photoionization code MOCASSIN has been applied to construct a realistic model of the planetary nebula NGC 3918. Three different geometric models were tried, the first being the biconical density distribution already used some years ago by Clegg et al. In this model the nebula is approximated by a biconical structure of enhanced density, embedded in a lower-density spherical region. Spindle-like density distributions were used for the other two models (models A and B). Model A used a mass distribution slightly modified from one of Mellema's hydrodynamical models that had already been adopted by Corradi et al. for their observational analysis of NGC 3918. Our spindle-like model B instead used an analytical expression to describe the shape of the inner shell of this object as consisting of an ellipsoid embedded in a sphere. The effects of the interaction of the diffuse fields coming from two adjacent regions of different densities were investigated. These are found to be non-negligible, even for the relatively uncomplicated case of a biconical geometry. We found that the ionization structure of low-ionization species near the boundaries is particularly affected. It is found that all three models provided acceptable matches to the integrated nebular optical and ultraviolet spectrum. Large discrepancies were found between all of the model predictions of infrared fine-structure line fluxes and ISO SWS measurements. This was found to be largely due to an offset of ~14 arcsec from the centre of the nebula that affected all of the ISO observations of NGC 3918. For each model, we also produced projected emission-line maps and position-velocity diagrams from synthetic long-slit spectra, which could be compared to recent HST images and ground-based long-slit echelle spectra. This comparison showed that spindle-like model B provided the best match to the observations. Although the integrated emission-line spectrum of NGC 3918 can be reproduced

  16. New Detections of HNC in Planetary Nebulae: Evolution of the [HCN]/[HNC] Ratio

    NASA Astrophysics Data System (ADS)

    Schmidt, D. R.; Ziurys, L. M.

    2017-01-01

    New detections of HNC have been made toward 11 planetary nebulae (PNe), including K4-47, K3-58, K3-17, M3-28, and M4-14. These sources, which represent a wide range of ages and morphologies, had previously been observed in HCN by Schmidt & Ziurys. Measurements of the J=1\\to 0 and J=3\\to 2 transitions of HNC near 90 and 271 GHz were conducted using the new 12 m and the Sub-Millimeter Telescope of the Arizona Radio Observatory. HCN and HNC were also identified via their J=1\\to 0 lines toward eight positions across the Helix Nebula (NGC 7293). Column densities for HNC, determined from radiative transfer modeling, were Ntot(HNC) ∼ (0.06–4.0) × 1013 cm‑2, corresponding to fractional abundances with respect to H2 of f ∼ (0.02–1.4) × 10‑7. The HCN and HNC column densities across the Helix were found to be {N}{tot}({HCN}) ∼ (0.2–2.4) × 1012 cm‑2 and {N}{tot}({HNC}) ∼ (0.07–1.6) × 1012 cm‑2, with fractional abundances of (0.2–3.2) × 10‑7 and (0.09–2.2) × 10‑7. The [HCN]/[HNC] ratio varied between ∼1–8 for all PNe, with [HCN]/[HNC] ∼1–4 across the Helix. These values are greatly reduced from what has been found in asymptotic giant branch stars, where the ratio is typically >100. Both the abundance of HNC and the [HCN]/[HNC] ratio do not appear to vary significantly with nebular age across a time span of ∼10,000 years, in contrast to predictions of chemical models. The increase in HNC appears to arise in the proto-planetary stage, but becomes “frozen” once the PN phase is reached.

  17. X-Ray Imaging of Planetary Nebulae with Wolf-Rayet-type Central Stars: Detection of the Hot Bubble in NGC 40

    NASA Astrophysics Data System (ADS)

    Montez, Rodolfo, Jr.; Kastner, Joel H.; De Marco, Orsola; Soker, Noam

    2005-12-01

    We present the results of Chandra X-Ray Observatory observations of the planetary nebulae (PNs) NGC 40 and Hen 2-99. Both PNs feature late-type Wolf-Rayet central stars that are currently driving fast (~1000 km s-1), massive winds into denser, slow-moving (~10 km s-1) material ejected during recently terminated asymptotic giant branch (AGB) evolutionary phases. Hence, these observations provide key tests of models of wind-wind interactions in PNs. In NGC 40, we detect faint, diffuse X-ray emission distributed within a partial annulus that lies nested within a ~40" diameter ring of nebulosity observed in optical and near-infrared images. Hen 2-99 is not detected. The inferred X-ray temperature (TX~106 K) and luminosity (LX~2×1030 ergs s-1) of NGC 40 are the lowest measured thus far for any PN displaying diffuse X-ray emission. These results, combined with the ringlike morphology of the X-ray emission from NGC 40, suggest that its X-ray emission arises from a ``hot bubble'' that is highly evolved and is generated by a shocked, quasi-spherical fast wind from the central star, as opposed to AGB or post-AGB jet activity. In contrast, the lack of detectable X-ray emission from Hen 2-99 suggests that this PN has yet to enter a phase of strong wind-wind shocks.

  18. HIP 3678: a hierarchical triple stellar system in the centre of the planetary nebula NGC 246

    NASA Astrophysics Data System (ADS)

    Adam, C.; Mugrauer, M.

    2014-11-01

    We report the detection of a new low-mass stellar companion to the white dwarf HIP 3678 A, the central star of the planetary nebula NGC 246. The newly found companion is located about 1 arcsec (at projected separation of about 500 au) north-east of HIP 3678 A, and shares a common proper motion with the white dwarf and its known comoving companion HIP 3678 B. The hypothesis that the newly detected companion is a non-moving background object can be rejected on a significance level of more than 8σ, by combining astrometric measurements from the literature with follow-up astrometry, obtained with Wide Field Planetary Camera 2/Hubble Space Telescope and NACO/Very Large Telescope. From our deep NACO imaging data, we can rule out additional stellar companions of the white dwarf with projected separations between 130 up to 5500 au. In the deepest high-contrast NACO observation, we achieve a detection limit in the Ks band of about 20 mag, which allows the detection of brown dwarf companions with masses down to 36 Mjup at an assumed age of the system of 260 Myr. To approximate the masses of the companions HIP 3678 B and C, we use the evolutionary Baraffe et al. models and obtain about 0.85 M⊙ for HIP 3678 B and about 0.1 M⊙ for HIP 3678 C. According to the derived absolute photometry, HIP 3678 B should be a early to mid-K dwarf (K2-K5), while HIP 3678 C should be a mid M dwarf with a spectral type in the range between M5 and M6.

  19. 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.

  20. The light element abundance distribution in NGC 5128 from planetary nebulae

    NASA Astrophysics Data System (ADS)

    Walsh, J. R.; Jacoby, G. H.; Peletier, R. F.; Walton, N. A.

    2012-08-01

    Context. Planetary nebulae in the nearest large elliptical galaxy provide light element abundances difficult or impossible to measure by other means in a stellar system very different from the galaxies in the Local Group. Aims: The light element abundance pattern from many planetary nebulae (PNe) at a range of radial distances was measured from optical spectroscopy in the elliptical galaxy NGC 5128, which hosts the radio source Centaurus A. The PN abundances, in particular for oxygen, and the PN progenitor properties are related to the galaxy stellar properties. Methods: PNe in NGC 5128 covering the upper 4 mag of the luminosity function were selected from a catalogue. VLT FORS1 multi-slit spectra in blue and red ranges were obtained over three fields at 3, 9 and 15' projected radii (4, 8 and 17 kpc, for an adopted distance of 3.8 Mpc) and spectra were extracted for 51 PNe. Accurate electron temperature and density diagnostics are usually required for abundance determination, but were not available for most of the PNe. Cloudy photoionization models were run to match the spectra by a spherical, constant density nebula ionized by a black body central star. He, N, O and Ne abundances with respect to H were determined and, for brighter PN, S and Ar; central star luminosities and temperatures are also derived. Results: Emission line ratios for the 51 PNe are entirely typical of PN such as in the Milky Way. The temperature sensitive [O III]4363 Å line was weakly detected in 10 PNe, both [O II] and [O III] lines were detected in 30 PNe, and only the bright [O III]5007 Å line was detected in 7 PN. For 40 PNe with Cloudy models, from the upper 2 mag of the [O III] luminosity function, the most reliably estimated element, oxygen, has a mean 12 + log(O/H) of 8.52 with a narrow distribution. No obvious radial gradient is apparent in O/H over a range 2-20 kpc. Comparison of the PN abundances with the stellar population, from the spectra of the integrated stellar light on the

  1. INFRARED TWO-COLOR DIAGRAMS FOR AGB STARS, POST-AGB STARS, AND PLANETARY NEBULAE

    SciTech Connect

    Suh, Kyung-Won

    2015-08-01

    We present various infrared two-color diagrams (2CDs) for asymptotic giant branch (AGB) stars, post-AGB stars, and Planetary Nebulae (PNe) and investigate possible evolutionary tracks. We use catalogs from the available literature for the sample of 4903 AGB stars (3373 O-rich; 1168 C-rich; 362 S-type), 660 post-AGB stars (326 post-AGB; 334 pre-PN), and 1510 PNe in our Galaxy. For each object in the catalog, we cross-identify the IRAS, AKARI, Midcourse Space Experiment, and 2MASS counterparts. The IR 2CDs can provide useful information about the structure and evolution of the dust envelopes as well as the central stars. To find possible evolutionary tracks from AGB stars to PNe on the 2CDs, we investigate spectral evolution of post-AGB stars by making simple but reasonable assumptions on the evolution of the central star and dust shell. We perform radiative transfer model calculations for the detached dust shells around evolving central stars in the post-AGB phase. We find that the theoretical dust shell model tracks using dust opacity functions of amorphous silicate and amorphous carbon roughly coincide with the densely populated observed points of AGB stars, post-AGB stars, and PNe on various IR 2CDs. Even though some discrepancies are inevitable, the end points of the theoretical post-AGB model tracks generally converge in the region of the observed points of PNe on most 2CDs.

  2. Time-variable Non-thermal Emission in the Planetary Nebula IRAS 15103-5754

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

    The beginning of photoionization marks the transition between the post-AGB and planetary nebula (PN) phases of stars with masses ≲ 8 M ⊙ . This critical phase is difficult to observe, as it lasts only a few decades. The combination of jets and magnetic fields, the key agents of PN shaping, could give rise to synchrotron emission, but this has never been observed before in any PNe, since free-free emission from the ionized gas is expected to dominate its radio spectrum. In this paper we report radio continuum observations taken with the ATCA between 1 and 46 GHz of the young PN IRAS 15103-5754. Our observations in 2010-2011 show non-thermal emission compatible with synchrotron emission from electrons accelerated at a shock with spectral index α ≃ -0.54. However, in 2012, the spectral index α ≃ -0.28 is no longer compatible with synchrotron emission in these types of processes. Several hypotheses are discussed to explain this change. The more plausible ones are related to the presence of the newly photoionized region in this young PN: either energy loss of electrons due to Coulomb collisions with the plasma, or selective suppression of synchrotron radiation due to the Razin effect. We postulate that the observed flattening of non-thermal radio spectra could be a hallmark identifying the beginning of the PN phase.

  3. The Born-again Planetary Nebula A78: An X-Ray Twin of A30

    NASA Astrophysics Data System (ADS)

    Toalá, J. A.; Guerrero, M. A.; Todt, H.; Hamann, W.-R.; Chu, Y.-H.; Gruendl, R. A.; Schönberner, D.; Oskinova, L. M.; Marquez-Lugo, R. A.; Fang, X.; Ramos-Larios, G.

    2015-01-01

    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 × 106 K). We estimate X-ray luminosities in the 0.2-2.0 keV energy band of L X, CSPN = (1.2 ± 0.3) × 1031 erg s-1 and L X, DIFF = (9.2 ± 2.3) × 1030 erg s-1 for the CSPN and diffuse components, respectively.

  4. 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.

  5. THE SHAPING OF THE MULTIPOLAR PRE-PLANETARY NEBULA CRL 618 BY MULTIDIRECTIONAL BULLETS

    SciTech Connect

    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{sub ⊙}, 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  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. 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.

  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. 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.

  14. 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.

  15. The central star candidate of the planetary nebula Sh2-71: photometric and spectroscopic variability

    NASA Astrophysics Data System (ADS)

    Močnik, T.; Lloyd, M.; Pollacco, D.; Street, R. A.

    2015-07-01

    We present the analysis of several newly obtained and archived photometric and spectroscopic data sets of the intriguing and yet poorly understood 13.5 mag central star candidate of the bipolar planetary nebula Sh2-71. Photometric observations confirmed the previously determined quasi-sinusoidal light curve with a period of 68 d and also indicated periodic sharp brightness dips, possibly eclipses, with a period of 17.2 d. In addition, the comparison between U and V light curves revealed that the 68 d brightness variations are accompanied by a variable reddening effect of ΔE(U - V) = 0.38. Spectroscopic data sets demonstrated pronounced variations in spectral profiles of Balmer, helium and singly ionized metal lines and indicated that these variations occur on a time-scale of a few days. The most accurate verification to date revealed that spectral variability is not correlated with the 68 d brightness variations. The mean radial velocity of the observed star was measured to be ˜26 km s-1 with an amplitude of ±40 km s-1. The spectral type was determined to be B8V through spectral comparison with synthetic and standard spectra. The newly proposed model for the central star candidate is a Be binary with a misaligned precessing disc.

  16. UNUSUAL SHOCK-EXCITED OH MASER EMISSION IN A YOUNG PLANETARY NEBULA

    SciTech Connect

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

    2016-01-20

    We report on OH maser emission toward G336.644−0.695 (IRAS 16333−4807), which is a H{sub 2}O 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 H{sub 2}O masers, whereas the 1720 MHz masers show a variable spectrum, with several components spread over a higher velocity range (up to 36 km s{sup −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.

  17. Rummaging inside the Eskimo's parka: variable asymmetric planetary nebula fast wind and a binary nucleus?

    NASA Astrophysics Data System (ADS)

    Prinja, R. K.; Urbaneja, M. A.

    2014-05-01

    We report on high-resolution optical time series spectroscopy of the central star of the `Eskimo' planetary nebula NGC 2392. Data sets were secured with the European Southern Observatory (ESO) 2.3 m in 2006 March and Canada-France-Hawaii Telescope (CFHT) 3.6 m in 2010 March to diagnose the fast wind and photospheric properties of the central star. The He I and He II recombination lines reveal evidence for clumping and temporal structures in the fast wind that are erratically variable on time-scales down to ˜30 min (i.e. comparable to the characteristic wind flow time). We highlight changes in the overall morphology of the wind lines that cannot plausibly be explained by line-synthesis model predictions with a spherically homogeneous wind. Additionally, we present evidence that the ultravoilet line profile morphologies support the notion of a high-speed, high-ionization polar wind in NGC 2392. Analyses of deep-seated, near-photospheric absorption lines reveals evidence for low-amplitude radial velocity shifts. Fourier analysis points tentatively to an ˜0.12-d modulation in the radial velocities, independently evident in the ESO and CFHT data. We conclude that the overall spectroscopic properties support the notion of a (high-inclination) binary nucleus in NGC 2392 and an asymmetric fast wind.

  18. Stripping of a planetary nebula from the globular cluster M22

    NASA Technical Reports Server (NTRS)

    Borkowski, Kazimier J.; Tsvetanov, Zlatan; Harrington, J. P.

    1993-01-01

    High-spatial resolution imaging in the O III lambda 5007 line of a planetary nebula (PN) in the globular cluster M22 reveals a strongly asymmetric (half-moon shaped) nebular morphology. We confirm that this peculiar morphology is caused by the distortion of stellar ejecta by the ram pressure of the ambient interstellar medium (ISM) through which the cluster is moving with a high velocity of 200 km/s. Emission knots visible in the leading (upstream) nebular section confirm theoretical expectations that the shell should have been fragmented by the Rayleigh-Taylor instability. Stripping of the PN from M22 by the ambient ISM is the first direct evidence for removal of gas from globular clusters. M22 is at a favorable location for the ram-pressure stripping to be effective, only 400 pc below the Galactic plane, well within a 2 kpc thick layer of ionized gas enveloping the plane. Ionized (or possibly neutral) gas in this layer, with a hydrogen density of about 0.1 cu/cm, is responsible for the observed interaction.

  19. 3D Radiative Transfer models of Planetary Nebulae with CRONOS and CLOUDY

    NASA Astrophysics Data System (ADS)

    Niederwanger, F.; Öttl, Silvia; Kimeswenger, S.; Kissmann, R.; Reitberger, K.

    2014-04-01

    We present our ideas about a new setup for a full 3D radiative transfer hydrodynamic (RT-HD) computation for planetary nebulae (PNe). The setup is based on the 3D MHD code CRONOS, using low dissipative conservation numerical schemes for hydrodynamics and MHD (Kissmann et al. 2009), and on CLOUDY (Ferland et al. 2013). New to our ideas is the implementation of CLOUDY for the radiative terms. While in previous works internal cooling was calculated using analytical cooling curves from Dalgarno&McCray (1972) for the lower temperatures and from Gerritsen&Icke (1997) for the high temperature regime, we intend to use the sophisticated physics of CLOUDY in a similar way as for CLOUDY 3D (Morisset, 2011). The hydrodynamic calculations provide the density and velocity structure. Repeatedly, a CLOUDY model is calculated to derive cooling, absorption and radiative pressure acceleration terms for the hydro code. We show the feasibility of this setup for symmetric and asymmetric geometries of PNe. Euclidean grids are used to avoid imprinting. We present first tests for this setup and first results on the numerical stability. These simulations were run using different geometries, like e.g. disks. Another group is working on 3D models of particle acceleration in radiatively driven colliding winds of massive star binary systems. Although this is a completely different energy regime, binary systems are of great interest for asymmetric PNe as well. The setup allows us simulations using any arbitrary geometry.

  20. 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.

  1. 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.

  2. 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.

  3. 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]).

  4. 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.

  5. Using Hubble Space Telescope Images to Test Theoretical Models of Planetary Nebulae

    NASA Astrophysics Data System (ADS)

    Braxton, Kelsey M.; Balick, B.; Jacob, R.; Steffen, M.; Schonberner, D.

    2012-05-01

    Classical ionization models that predict the ionization structure of planetary nebulae generally assume constant gas density (or a central void and constant density) in the shell. More recently, Steffen, Jacob, Schoenberner (2005, A&A, 441, 573) have computed fully consistent one-dimensional radiation hydrodynamic ionization models (RHI models) with realistic stellar winds and evolving central stars. Their numerical results offer concrete predictions concerning the projected three-dimensional shapes of simple round and elliptical PNe. A first glance at their models shows them to be a superior way of modeling ionization structures in realistic PNe. We present high-spatial resolution and carefully flux calibrated images of PNe selected in Halpha, [OIII], and [NII] as well as the ratios [OIII]/Halpha and [NII]/Halpha in order to test the predictions of the RHI models. These were obtained uniformly and at the same epoch using the WFPC2 camera on the Hubble Space Telescope. Some of the targets are ionization bounded and others are density bounded. In the future these images will be compared to the models in detail. At this point we note many of the common features--some of them unexpected--that the models must explain.

  6. 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.

  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. 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).

  9. 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.

  10. 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.

  11. 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

  12. 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.

  13. 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.

  14. A pilot search for mm-RRLs in pre-Planetary Nebulae

    NASA Astrophysics Data System (ADS)

    Sánchez Contreras, C.; Báez-Rubio, A.; Alcolea, J.; Bujarrabal, V.; Martín-Pintado, J.

    2017-03-01

    We carried out pilot search for radio recombination line (RRL) emission at millimeter wavelengths in a small sample of pre-Planetary Nebulae (pPNe) and young PNe (yPNe) with emerging central ionized winds. RRLs at mm-wavelengths are excellent probes of the dense inner (<150 au) regions of these objects, where the yet unknown agents for PN-shaping operate, and which are usually heavily obscured at shorter wavelengths by optically thick circumstellar dust shells. We detect mm-RRLs in three objects: CRL 618, MWC 922, and M 2-9. We present the results from detailed line + continuum non-LTE 3D radiative transfer models for these targets, which enables constraning the structure, kinematics, and physical conditions (electron temperature and density) of their ionized cores. Amongst other parameters, we derive mass-loss rates of M_{pAGB} ≈ 10^{-6} - 10^{-7} M_{⊙} yr^{-1}, which are significantly higher than the values adopted by stellar evolution models currently in use.

  15. Polyatomic Molecules in Planetary Nebulae: A Survey of HCN and HCO+

    NASA Astrophysics Data System (ADS)

    Schmidt, Deborah Rose; Ziurys, Lucy

    2015-08-01

    It has been thought that most of the molecular material from the AGB phase of stellar evolution would be photodissociated by intense ultraviolet radiation from the remnant star as it evolves in the subsequent planetary nebula (PN) stage. However, recent detections of polyatomic species in certain PNe such as the Helix Nebula and M2-48 have indicated that the chemistry of these objects is more complicated than previously anticipated. A more complete evaluation of the molecular content of PNe is vital to our understanding of their environments, as well as their material contribution to the interstellar medium (ISM). In order to address this question, we have conducted a search for HCN and HCO+ in seventeen PNe previously detected in CO. Observations of the J=1→0 and J=3→2 transitions of HCN and HCO+ have been carried out using the 12 m telescope and the Sub-Millimeter Telescope (SMT) of the Arizona Radio Observatory (ARO). Both molecules were detected in eleven sources, or ~65% of the sample. Column densities of HCN and HCO+ were determines in the PNe, and, in those sources where both the J=1→0 and J=3→2 transitions of either molecule were detected, H2 densities. Assuming a kinetic temperature of 20 K, column densities were determined to be ~2.7 x 1012 to 8.0 x 1013 cm-2 for HCN, and between 7.5 x 1010 and 2.1 x 1013 cm-2 for HCO+. Corresponding fractional abundance, with respect to H2, ranged from 2.5 x 10-9 to 9.3 x 10-7 for HCN and 2.2 x 10-9 to 7.5 x 10-7 for HCO+. No apparent decrease in abundance of either molecule with nebular age was found, in contrast to the predictions of chemical models. These molecules are more effectively shielded from incoming radiation than previously thought, and in part reflect survival from the AGB stage. However, there may be an ongoing production mechanism for HCO+ in PNe based on CO+. The abundances are consistent with molecular dispersal into diffuse clouds. Overall, the results of this work suggest that polyatomic

  16. 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

  17. 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

  18. 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.

  19. From Miras to planetary nebulae: Which path for stellar evolution?; Proceedings of the International Colloquium, Universite de Montpellier II, France, Sept. 4-7, 1989

    NASA Astrophysics Data System (ADS)

    Mennessier, M. O.; Omont, A.

    This book considers stellar evolution of Mira variables to planetary nebulae. Topics discussed include pulsation and shock waves; mass loss; circumstellar dust; maser emission and OH/IR stars; C stars; and post-AGB evolution to planetary nebulae, protoplanetary nebulae, and prewhite dwarfs and binaries. Papers are presented on pulsations of model Mira variables, the environment of Miras from interferometry, the physics of mass loss from AGB stars, the mixing length and the mass loss rate, dust formation and stellar wind, dust formation in circumstellar shells of Mira variables, the evolution of water masers on the AGB, and phase lags from OH/IR stars. Attention is also given to the variability of carbon stars, transfer reactions as neutron sources for the s-process, planetary nebulae as post-AGB objects, the kinematic structure of NGC 7139, the post-AGB evolution of low-mass stars, OH/IR stars as the progenitors of planetary nebulae, atmospheric parameters for pre-WD, and a new protoplanetary nebula.

  20. 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

  1. Chemical Abundances of Planetary Nebulae in the Substructures of M31

    NASA Astrophysics Data System (ADS)

    Fang, Xuan; García-Benito, Rubén; Guerrero, Martín A.; Liu, Xiaowei; Yuan, Haibo; Zhang, Yong; Zhang, Bing

    2015-12-01

    We present deep spectroscopy of planetary nebulae (PNe) that are associated with the substructures of the Andromeda Galaxy (M31). The spectra were obtained with the Optical System for Imaging and low-intermediate-Resolution Integrated Spectroscopy spectrograph on the 10.4 m Gran Telescopio Canarias. Seven targets were selected for the observations, three in the Northern Spur and four associated with the Giant Stream. The most distant target in our sample, with a rectified galactocentric distance ≥slant 100 kpc, was the first PN discovered in the outer streams of M31. The [O iii] λ4363 auroral line is well detected in the spectra of all targets, enabling electron temperature determination. Ionic abundances are derived based on the [O iii] temperatures, and elemental abundances of helium, nitrogen, oxygen, neon, sulfur, and argon are estimated. The relatively low N/O and He/H ratios, as well as abundance ratios of α-elements, indicate that our target PNe might belong to populations as old as ∼2 Gyr. Our PN sample, including the current seven and the previous three observed by Fang et al., have rather homogeneous oxygen abundances. The study of abundances and the spatial and kinematical properties of our sample leads to the tempting conclusion that their progenitors might belong to the same stellar population, which hints at a possibility that the Northern Spur and the Giant Stream have the same origin. This may be explained by the stellar orbit proposed by Merrett et al. Judging from the position and kinematics, we emphasize that M32 might be responsible for the two substructures. Deep spectroscopy of PNe in M32 will help to assess this hypothesis. Based on observations made with the Gran Telescopio Canarias, installed at the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias, in the island of La Palma. These observations are associated with program No. GTC55-14B.

  2. 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.

  3. Total number of planetary nebulae in different galaxies and the PN distance scale.

    NASA Astrophysics Data System (ADS)

    Peimbert, M.

    1990-12-01

    RESUMEN A partir de una muestra de quince galaxias se encuentra que la tasa de natalidad de nebulosas planetarias por unidad de luminosidad, , disminuye al aumentar la luminosidad y al aumentar (B - V)0. Se discuten posibles explicaciones para estos resultados. Se estima el valor de para la Galaxia y a partir de el se encuentra que el numero total de nebulosas planetarias en nuestra galaxia con R < 0.64 pc- es de 7200 j 1800. El valor galactico de implica que la mayorfa de las estrellas de masa intermedia pasa por la etapa de nebulosa planetaria. El valor galactico de , la tasa de mortalidad estelar por unidad de luminosidad y la tasa de natalidad de enanas blancas favorecen escalas de distancias largas para nebulosas planetarias, como la de Cudworth (1974) y la de Mallik y Peimbert (1988). ABSTRACT From a sample of fifteen galaxies it is found that the birth rate of PN per unit luminosity, , decreases with increasing luminosity and with increasing (B - V)0 possible reasons for these relationships are discussed. The value for the Galaxy is estimated and, from it, a total number of PN of 7200 # 1800 wid R < 0.64 pc is obtained. The galactic value implies that most of the intermediate mass stars go through the PN stage. The galactic value, the stellar death rate per unit luminosity and the white dwarf birth rate are in favor of long distance scales to PN like those of Cudworth (1974) and Mallik and (1988). Key wonis: NEBULAE.PLANETARY - STARS-EVOLUTION - STARS-SThLIAR STA. S

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. The Virgo cD galaxy M87 and its environment as mapped by Planetary Nebulae

    NASA Astrophysics Data System (ADS)

    Longobardi, Alessia

    2015-08-01

    Cosmological simulations predict the evolution of galaxy halos in cluster environments. Because of their low surface brightness, 1% of the night sky or lower, it is difficult to measure their spatial distribution and line-of-sight motions of the associated stars. Planetary nebulas (PNs) are very good tracers of their parent stellar populations, and we can use them to investigate these extended halos as consequence of their relatively strong [OIII] emission line. We have used PNs to study the outer halo of M87, the BCG at the center of the Virgo cluster. From the deepest and most extended narrow band survey done with Supruime Cam on Subaru, we carry out the spectroscopic follow up with FLMES at the VLT of more than 300 emission line objects in the halo of M87 out to ~150 kpc in radius. We confirm 254 PNs associated with the M87 halo and 44 with the intracluster light in the Virgo core. We show that the galaxy halo overlaps with the Virgo intracluster light (ICL) at all distance. Halo and ICL are dynamically distinct components, have different density profiles and parent stellar populations. The latter result shows that the halo of M87 is redder and more metal rich than the ICL population. Because of the excellent spectra resolution of our data, we identify a chevron structure in the projected phase space and identify the substructure in light associated to this dynamical sub-component. This accretion event account for a third of the light of the halo at 90 kpc distance from the center. It shows that at these distances the M87 halo is significantly lumpy and still growing by accretion of satellites.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. HUBBLE SPACE TELESCOPE SNAPSHOT SEARCH FOR PLANETARY NEBULAE IN GLOBULAR CLUSTERS OF THE LOCAL GROUP

    SciTech Connect

    Bond, Howard E.

    2015-04-15

    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.

  16. 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.

  17. 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.

  18. XSHOOTER spectroscopy of the enigmatic planetary nebula Lin49 in the Small Magellanic Cloud

    NASA Astrophysics Data System (ADS)

    Otsuka, Masaaki; Kemper, F.; Leal-Ferreira, M. L.; Aleman, I.; Bernard-Salas, J.; Cami, J.; Ochsendorf, B. B.; Peeters, E.; Scicluna, P.

    2016-10-01

    We performed a detailed spectroscopic analysis of the fullerene C60-containing planetary nebula (PN) Lin49 in the Small Magellanic Cloud (SMC) using XSHOOTER at the European Southern Observatory Very Large Telescope and the Spitzer/Infrared Spectrograph instruments. We derived nebular abundances for nine elements. We used TLUSTY to derive photospheric parameters for the central star. Lin49 is C-rich and metal-deficient PN (Z ˜ 0.0006). The nebular abundances are in good agreement with asymptotic giant branch nucleosynthesis models for stars with initial mass 1.25 M⊙ and metallicity Z = 0.001. Using the TLUSTY synthetic spectrum of the central star to define the heating and ionizing source, we constructed the photoionization model with CLOUDY that matches the observed spectral energy distribution (SED) and the line fluxes in the UV to far-IR wavelength ranges simultaneously. We could not fit the ˜1-5 μm SED using a model with 0.005-0.1-μm-sized graphite grains and a constant hydrogen density shell owing to the prominent near-IR excess, while at other wavelengths the model fits the observed values reasonably well. We argue that the near-IR excess might indicate either (1) the presence of very small particles in the form of small carbon clusters, small graphite sheets, or fullerene precursors, or (2) the presence of a high-density structure surrounding the central star. We found that SMC C60 PNe show a near-IR excess component to lesser or greater degree. This suggests that these C60 PNe might maintain a structure nearby their central star.

  19. XMM-Newton Detection of Hot Gas in Two Evolved Elliptical Planetary Nebulae: the Eskimo Nebula and the Ghost of Jupiter

    NASA Astrophysics Data System (ADS)

    Guerrero, M. A.; Chu, Y.-H.; Gruendl, R. A.; Meixner, M.

    2004-12-01

    Planetary nebulae (PNe) consist of the stellar material ejected by low- and intermediate-mass stars (1-8 M⊙) at the end of the asymptotic giant branch phase (AGB). As such a star evolves off the AGB phase, the copious mass-loss strips off the stellar envelope and exposes the hot stellar core that ionizes the nebular material. The central stars of PNe present fast stellar winds with terminal velocities 1000-4000 km s-1, while fast collimated outflows with velocities up to 1000 km s-1 are also observed in PNe. The interactions of the fast stellar wind and/or collimated outflows with nebular material can give rise to diffuse X-ray emission from PNe. Diffuse X-ray emission has been detected only in young PNe previously. To investigate the evolution of hot gas in PN interiors, we obtained XMM-Newton observations of NGC 2392 (the Eskimo Nebula) and NGC 3242 (the Ghost of Jupiter), two evolved elliptical PNe. Diffuse X-ray emission is detected in both nebulae. In both cases, the hot gas is confined within the innermost shell, the X-ray spectrum can be described by a thin plasma emission model with temperature ˜2×106 K, and the X-ray luminosity is ˜1×1031 ergs s-1. Furthermore, the X-ray spectrum of NGC 3242 shows evidence of enhanced nitrogen abundance, while the X-ray morphology of NGC 2392 hints a possible association with its fast collimated outflows.

  20. History of the mass ejection in K4-37: from the AGB to the evolved planetary nebula phase

    NASA Astrophysics Data System (ADS)

    Miranda, L. F.; Guillén, P. F.; Olguín, L.; Vázquez, R.

    2017-04-01

    We present narrow-band, broad-band and Wide-field Infrared Survey Explorer (WISE) archive images, and high- and intermediate-resolution long-slit spectra of K4-37, a planetary nebula that has never been analysed in detail. Although K4-37 appears bipolar, the morphokinematical analysis discloses the existence of three distinct axes and additional particular directions in the object, indicating that K4-37 is a multi-axis planetary nebula that has probably been shaped by several bipolar outflows at different directions. A 4-6 M⊙ main-sequence progenitor is estimated from the derived high nebular He and N abundances, and very high N/O abundance ratio (∼2.32). The general properties are compatible with K4-37 being a highly evolved planetary nebula located at ∼14 kpc. The WISE image at 22 μm reveals K4-37 to be surrounded by a large (∼13 × 8 pc2) elliptical detached shell probably related to material ejected from the asymptotic giant branch (AGB) progenitor. The observed elliptical morphology suggests deformation of an originally spherical AGB shell by the interstellar medium magnetic field or by the influence of a companion. We compare K4-37 and NGC 6309 and found remarkable similarities in their physical structure but noticeably different chemical abundances that indicate very different progenitor mass. This strongly suggests that, irrespective of the initial mass, their (presumably binary) central stars have shared a very similar mass ejection history.

  1. Spatial Analysis of Spectra from Galactic Planetary Nebulae and Extragalactic H II Regions: Testing for Abundance Variations

    NASA Astrophysics Data System (ADS)

    Miller, Timothy R.

    2017-01-01

    Presented here is a spatial analysis of spectra for seven planetary nebulae (NGC 2440, NGC 3242, NGC 5315, NGC 5882, NGC 7662, IC 2165, and IC 3568) as well as H II regions from six nearly face-on, spiral galaxies (NGC 2403, NGC 3310, NGC 4321, NGC 5194, NGC 5236, and NGC 5457). The two main goals of the study were (1) to investigate whether or not each planetary nebula (PN) is chemically homogeneous; and (2) to search for evidence of azimuthal abundance gradients in the disks of the galaxies. Each of these test the validity of assumptions commonly made for these two object types, i.e., (1) Ejecta from asymptotic giant branch stars are well mixed and (2) elements returned to the interstellar medium of a spiral galaxy are “instantaneously” distributed around the disk for a fixed distance from the center.The PN homogeneity problem was addressed by spatially dividing each long-slit HST/STIS spectrum into many smaller regions across each object and calculating the abundances of each region. The major result is that the ejecta are indeed homogeneous in each planetary nebula for the elements probed. A secondary goal was to constrain the temperature and luminosity of each PN central star, which was accomplished by modeling each object using the photoionization code CLOUDY.The spectra for the galaxies are from the VIRUS-P spectrograph, an integral field unit consisting of 246 fibers arranged in a square, with the observations centered on or near the nuclear bulge, covering a full 360 degrees around each galaxy and encompassing numerous H II regions located near the bulge. Additional goals for each galaxy included obtaining radial abundance gradients and accurate carbon and neon abundances for high metallicity H II regions.

  2. Suzaku Reveals He-burning Products in the X-ray Emitting Planetary Nebula BD +30deg 3639

    NASA Technical Reports Server (NTRS)

    Murashima, M.; Kokubun, M.; Makishima, K.; Kotoku, J.; Murakami, H.; Matsushita, K.; Hayashida, K.; Hamaguchi, K.; Matsumoto, H.

    2004-01-01

    BD +30deg 3639, the brightest planetary nebula at X-ray energies, was observed with Suzaku, an X-ray observatory launched on 2005 July 10. Using the X-ray Imaging Spectrometer, the K-lines from C VI, O VII, and O VIII were resolved for the first time, and C/O, N/O, and Ne/O abundance ratios determined. The C/O abundance ratio exceeds the solar value by nearly two orders of magnitude, and that of Ne/O by at least a factor of 5. These results indicate that the X-rays are emitted mainly by helium shell-burning products.

  3. 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

  4. 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

  5. Molecules in the atmosphere and circumstellar shell of proto-planetary nebula IRAS22272+5435

    NASA Astrophysics Data System (ADS)

    Zacs, L.; Laure, A.; Sperauskas, J.

    2011-05-01

    IRAS22272+5435 is a typical proto-planetary nebula (PPN) associated in the optical with a carbon-rich star HD235858 which shows a significant s-process enhancement. The star is surrounded by the detached circumstellar envelope (CSE), a result of an earlier mass loss. The best-fit model for the dust shell of IRAS22272+5435 consists of the central star surrounded by two separate sets of dust shells representing a PPN shell and a post-AGB wind shell located in the inner cavity of the PPN shell. A presence of hot dust grains in the inner cavity of the PPN shell and occasional mass ejections driven possibly by pulsations with the period of around 131 days was suspected for this object. The spectrum of IRAS22272+5435 originates at various depths throughout different layers in the atmosphere of HD235858 significantly affected by pulsations and in the CSE. A large number of narrow molecular lines originated in the CSE are present in the optical spectrum of IRAS22272+5435, blueshifted relative to the photospheric lines. The CSE lines of C_2 (1,0), (2,0), (3,0), (4,0) Phillips system and CN (1,0), (2,0), (3,0), (4,0) Red System were identified. Time series of high resolution spectra shows significant changes in the intensity of C_2 and CN photospheric features. The molecular photospheric features are stronger than should be for standard photosphere of G5 supergiant applicable for HD235858, therefore, the temperature of environment where formed the most of molecules is much lower than the effective temperature of 5500 K. The maximal expansion velocity and the maximal C_2 abundance was observed for HD235858 on October 2006 when the photosphere of HD235858 passed the maximal expansion velocity according to the CORAVEL measurements. The lines of CN Red system in general varies in step with C_2, however, the Doppler shift relative to the systemic velocity is lower. Thus, the photospheric molecular features are formed apparently in the cool outflow at different high scale. The

  6. 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.

  7. THE NATURE OF DUST IN COMPACT GALACTIC PLANETARY NEBULAE FROM SPITZER SPECTRA

    SciTech Connect

    Stanghellini, Letizia; Garcia-Hernandez, D. A.; Manchado, Arturo; Davies, James E.; Shaw, Richard A.; Villaver, Eva; Perea-Calderon, Jose V. E-mail: agarcia@iac.es E-mail: Pedro.Garcia-Lario@sciops.esa.int E-mail: shaw@noao.edu E-mail: Jose.Perea@sciops.esa.int

    2012-07-10

    We present the Spitzer/Infrared Spectrograph (IRS) spectra of 157 compact Galactic planetary nebulae (PNe). These young PNe provide insight on the effects of dust in early post-asymptotic giant branch evolution, before much of the dust is altered or destroyed by the hardening stellar radiation field. Most of the selected targets have PN-type IRS spectra, while a few turned out to be misclassified stars. We inspected the group properties of the PN spectra and classified them based on the different dust classes (featureless or F, carbon-rich dust or CRD, oxygen-rich dust or ORD, mixed-chemistry dust or MCD) and subclasses (aromatic and aliphatic, and crystalline and amorphous). All PNe are characterized by dust continuum and more than 80% of the sample shows solid-state features above the continuum, in contrast with the Magellanic Cloud sample where only {approx}40% of the entire sample displays solid-state features; this is an indication of the strong link between dust properties and metallicity. The Galactic PNe that show solid-state features are almost equally divided among the CRD, ORD, and MCD. We analyzed dust properties together with other PN properties and found that (1) there is an enhancement of MCD PNe toward the Galactic center, in agreement with studies of Galactic bulge PNe; (2) CRD PNe could be seen as defining an evolutionary sequence, contrary to the ORD and MCD PNe, which are scattered in all evolutionary diagrams; (3) carbon-rich and oxygen-rich grains retain different equilibrium temperatures, as expected from models; and (4) ORD PNe are highly asymmetric, i.e., bipolar or bipolar core, and CRD PNe highly symmetric, i.e., round or elliptical; point symmetry is statistically more common in MCD than in other dust class PNe. By comparing the sample of this paper to that of Magellanic Cloud PNe, we find that the latter sample does not include MCD PNe, and the other dust classes are differently populated, with continuity of the fraction of F, CRD, ORD

  8. REBIRTH OF X-RAY EMISSION FROM THE BORN-AGAIN PLANETARY NEBULA A30

    SciTech Connect

    Guerrero, M. A.; Ruiz, N.; Toala, J. A.; Chu, Y.-H.; Gruendl, R. A.; Schoenberner, D.; Steffen, M.; Blair, W. P.

    2012-08-20

    The planetary nebula A30 is believed to have undergone a very late thermal pulse resulting in the ejection of knots of hydrogen-poor material. Using multi-epoch Hubble Space Telescope images, we have detected the angular expansion of these knots and derived an age of 850{sup +280}{sub -150} yr. To investigate the spectral and spatial properties of the soft X-ray emission detected by ROSAT, we have obtained Chandra and XMM-Newton deep observations of A30. The X-ray emission from A30 can be separated into 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. To help us assess the role of the current stellar wind in powering this X-ray emission, we have determined the stellar parameters and wind properties of the central star of A30 using a non-LTE model fit to its optical and UV spectra. The spatial distribution and spectral properties of the diffuse X-ray emission are highly suggestive that it is generated by the post-born-again and present fast stellar winds interacting with the hydrogen-poor ejecta of the born-again event. This emission can be attributed to shock-heated plasma, as the hydrogen-poor knots are ablated by the stellar winds, under which circumstances the efficient mass loading of the present fast stellar wind raises its density and damps its velocity to produce the observed diffuse soft X-rays. Charge transfer reactions between the ions of the stellar winds and material of the born-again ejecta have also been considered as a possible mechanism for the production of diffuse X-ray emission, and upper limits on the expected X-ray production by this mechanism have been derived. The origin of the X-ray emission from the central star of A30 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.

  9. 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.

  10. 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

  11. 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

  12. Compact Galactic Planetary Nebulae: An HST/WFC3 Morphological Catalog, and a Study of Their Role in the Galaxy

    NASA Astrophysics Data System (ADS)

    Stanghellini, Letizia; Shaw, Richard A.; Villaver, Eva

    2016-10-01

    We present the images of a Hubble Space Telescope (HST/WFC3) snapshot program of angularly compact Galactic planetary nebulae (PNe), acquired with the aim of studying their size, evolutionary status, and morphology. PNe that are smaller than ˜4″ are underrepresented in most morphological studies, and today they are less well studied than their immediate evolutionary predecessors, the pre-planetary nebulae. The images have been acquired in the light of [O iii]λ5007, which is commonly used to classify the PN morphology, in the UV continuum with the aim of detecting the central star unambiguously, and in the I-band to detect a cool stellar companion, if present. The sample of 51 confirmed PNe exhibits nearly the full range of primary morphological classes, with the distribution more heavily weighted toward bipolar PNe, but with the total of aspherical PNe almost identical to that of the general Galactic sample. A large range of microstructures is evident in our sample as well, with many nebulae displaying attached shells, halos, ansae, and internal structure in the form of arcs, rings, and spirals. Various aspherical structures in a few PNe, including detached arcs, suggest an interaction with the ISM. We studied the observed sample of compact Galactic PNe in the context of the general Galactic PN population, and explore whether their physical size, spatial distribution, reddening, radial metallicity gradient, and possible progenitors are peculiar within the population of Galactic PNe. We found that these compact Galactic PNe, which have been selected based on apparent dimensions, constitute a diverse Galactic PN population that is relatively uniformly distributed across the Galactic disk, including the outskirts of our Galaxy. This unique sample will be used in the future to probe the old Galactic disk population.

  13. 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

  14. 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.

  15. 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.

  16. Near-Infrared Imaging of 3 Bipolar Proto-Planetary Nebulae with HST/NICMOS - Hen401, Roberts 22, & the Boomerang Nebula

    NASA Astrophysics Data System (ADS)

    Sahai, R.; Dayal, A.; Kwok, S.; Su, K. Y. L.; Hrivnak, B. J.

    1998-12-01

    As part of a comprehensive study of the origins of aspherical structure in protoplanetary (PPN) and planetary nebulae (PN), we report here high-resolution H (F160W) and K (F222M) images of 3 bipolar PPN, Roberts 22, Hen 401, and the Boomerang Nebula, obtained with NICMOS/HST. All 3 objects have substantial cold, dense molecular envelopes seen in mm-wave CO lines. Amongst these, the Boomerang Nebula is specially noteworthy for harboring the coldest ( ~ 1K) gas in the Universe (Sahai & Nyman 1997, ApJ, 487, L1). The Hubble images reveal a rich and complex morphological structure of the circumstellar material for each of these objects. The morphology of our PN at H and K-band is found to be very similar to that seen at optical wavelengths (0.6mu m) with WFPC2, supporting our view that we are seeing scattered light from dust at all 3 wavelengths in these images. Although all 3 PPN are bipolar, their morphologies differ substantially in detail. The bipolar lobes in Hen 401 resemble very long, thin-walled cylinders, separated by a darker waist. The lobes in Roberts 22 are more squat, and characterised by a remarkable degree of point-symmetry. The waist region is significantly more clumpy than in Hen 401, presumably due to disintegration by fast collimated outflows (Sahai et al 1999, AJ, in press). Two bright compact clumps are seen in the vicinity of the waist, which are redder than the surrounding nebulosity. The bipolar lobes in the Boomerang (which extend far beyond the NICMOS 20'' field-of-view) have a ``figure-8'' morphology, and show the presence of partial shells and filaments embedded within a diffuse component. Roberts 22 and Hen 401 were also observed in the narrow-band F212N and F215N filter to isolate the H_2 v=0, S(1) 2.1mu m line emission, which typically traces regions of shocked gas in PPN. The H_2 emission is found to be similar to the distribution of scattered light in the bright lobes, consistent with the hypothesis that the lobes are overdense shocked

  17. 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

  18. 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.

  19. 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

  20. The Planetary Nebula System and Dynamics of NGC 5128. III. Kinematics and Halo Mass Distributions

    NASA Astrophysics Data System (ADS)

    Hui, Xiaohui; Ford, Holland C.; Freeman, Kenneth C.; Dopita, Michael A.

    1995-08-01

    We present a study of the halo dynamics and mass distributions of the nearby giant elliptical galaxy NGC 5128 using planetary nebulae (PNs) as test particles. Radial velocities of 433 PNs were obtained with multifiber spectrographs on both the Anglo-Australian Telescope (AAT) and the Cerro Tololo Inter-American Observatory (CTIO) 4 m telescope. The velocities were measured from the [O III] λ5007 emission line with a typical 1 σ error of ±4 km s-1 and ±30 km s-1 for the AAT and the CTIO data, respectively. These PNs cover the entire galaxy to a radius of 10 kpc and extend along the photometric major axis out to 20 kpc. The PN velocity field shows the distinctive characteristics of a triaxial potential: the galaxy's rotation axis is offset from its photometric minor axis by 39°±10°. the rotation axis and the line of maximum rotation are likely not orthogonal. We also find that the ordered motions of the stars become more important with increasing radius compared to their random motions. The rotation reaches approximately 100 km s-1 and 50 km s-1 along the photometric major and minor axes, giving a local V/σ ratio of about 1.0 and 0.5, respectively. The aximuthal variation of the velocity dispersion appears to be modulated by rotation, i.e., it reaches a maximum where the largest rotation is observed and drops to a minimum at zero rotation. The amplitude of this modulation is about 20km s-1, compared to a mean dispersion velocity of 110 km s-1. The kinematics of the globular clusters depend on the metallicity Taking [Fe/H] = -1.0 as the dividing point, the metal-poor clusters do not show any significant rotation. However, the metal-rich clusters show both major and minor axis rotation, and the amplitudes of the rotation are similar to that of the PNs. The stellar velocity dispersion measured from absorption-line spectra together with an Hα rotation curve of the dust lane suggest that the stellar orbits are isotropic and the mass-to-light ratio (M/LB) is 3

  1. The long-period binary central stars of the planetary nebulae NGC 1514 and LoTr 5

    NASA Astrophysics Data System (ADS)

    Jones, D.; Van Winckel, H.; Aller, A.; Exter, K.; De Marco, O.

    2017-04-01

    The importance of long-period binaries for the formation and evolution of planetary nebulae is still rather poorly understood, which in part is due to the lack of central star systems that are known to comprise such long-period binaries. Here, we report on the latest results from the on-going Mercator-HERMES survey for variability in the central stars of planetary nebulae. We present a study of the central stars of NGC 1514, BD+30°623, the spectrum of which shows features associated with a hot nebular progenitor as well as a possible A-type companion. Cross-correlation of high-resolution HERMES spectra against synthetic spectra shows the system to be a highly eccentric (e 0.5) double-lined binary with a period of 3300 days. Previous studies indicated that the cool component might be a horizontal branch star of mass 0.55 M⊙, but the observed radial velocity amplitudes rule out such a low mass. If we assume that the nebular symmetry axis and binary orbital plane are perpendicular, then the data are more consistent with a post-main-sequence star ascending towards the giant branch. We also present the continued monitoring of the central star of LoTr 5, HD 112313, which has now completed one full cycle, allowing the orbital period (P 2700 days) and eccentricity (e 0.3) to be derived. To date, the orbital periods of BD+30°623 and HD 112313 are the longest to have been measured spectroscopically in the central stars of planetary nebulae. Furthermore, these systems, along with BD+33°2642, comprise the only spectroscopic wide-binary central stars currently known. Based on observations made with the Mercator Telescope, operated on the island of La Palma by the Flemish Community, at the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias.The radial velocity data for both objects are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc

  2. 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.

  3. Luminosities and masses for three central stars of planetary nebulae in the Magellanic Clouds from ultraviolet spectroscopy with the IUE

    NASA Technical Reports Server (NTRS)

    Stecher, T. P.; Savedoff, M. P.; Maran, S. P.; Gull, T. R.; Aller, L. H.

    1982-01-01

    Physical parameters of the central stars of the planetary nebulae (PN) P40, N2, and N5 are determined from UV observations by the IUE spacecraft and emission line-data. The observations took place on May 23 and 26, 1981. Derived properties, such as the H-beta, color excess, nebular hydrogen emission, helium emission, and stellar continuum emission, the stellar radius, surface gravity, Zanstra temperature, luminosity, absolute bolometric magnitude, apparent visual magnitude, mass, and Zanstra parameter for the three PN central stars are presented. All the masses were over one solar mass, suggesting a specific PN nuclei mass. The finding was corroborated by all luminosities exceeding the Eddington luminosity for a 0.6 solar mass star, which has previously been calculated for the white dwarf core of a PN.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. PHR 1315-6555: a bipolar planetary nebula in the compact Hyades-age open cluster ESO 96-SC04

    NASA Astrophysics Data System (ADS)

    Parker, Quentin A.; Frew, David J.; Miszalski, Brent; Kovacevic, Anna V.; Frinchaboy, Peter M.; Dobbie, Paul D.; Köppen, Joachim

    2011-05-01

    We present a detailed study of a bipolar, possible Type I planetary nebula (PN), PHR 1315-6555 (PN G305.3-03.1), which was discovered as part of the Macquarie/AAO/Strasbourg Hα planetary nebula project (MASH), and that we considered at the time was an excellent candidate for membership of the distant, compact, intermediate-age open cluster, ESO 96-SC04. The strong evidence for this association is presented here, making this the only known example of a PN physically associated with a Galactic open cluster. Cluster membership is extremely important as it allows for very precise estimates of the fundamental properties of the PN as the cluster is at a known distance. The PN was discovered by one of us (QAP) during systematic MASH searches for new Galactic PNe of the AAO United Kingdom Schmidt Telescope (UKST) Hα survey and had been missed in earlier broad-band surveys, including specific CCD studies of the host cluster. We present original discovery images and Cerro Tololo Inter-American Observatory (CTIO) 4-m MOSAIC-II camera follow-up narrow-band images that reveal its bipolar morphology. We also present (i) low-resolution optical spectra that spectroscopically confirm the PN, (ii) accurate radial velocities of PN and cluster stars from high-resolution spectroscopy which show they are consistent and (iii) a reliable, independent distance estimate to the PN using a robust PN distance indicator which agrees with the published cluster distance to within the errors. We also provide preliminary estimates of basic PN properties and abundance estimates from deeper spectra that show it to be of possible Type I chemistry. This is also consistent with its estimated turn-off mass. Taken together, these findings present a powerful case for clear physical association between the PN and host cluster. Results for this association will be of considerable interest to specialists across differing astrophysical disciplines, including PNe, white dwarfs and open clusters.

  10. VARIABILITY IN PROTO-PLANETARY NEBULAE. III. LIGHT CURVE STUDIES OF MAGELLANIC CLOUD CARBON-RICH OBJECTS

    SciTech Connect

    Hrivnak, Bruce J.; Lu, Wenxian; Volk, Kevin; Szczerba, Ryszard; Hajduk, Marcin; Soszyński, Igor E-mail: wen.lu@valpo.edu

    2015-05-20

    We have investigated the light variability in a sample of 22 carbon-rich post-AGB stars in the LMC and SMC, based primarily on photometric data from the Optical Gravitational Lensing Experiment survey. All are found to vary. Dominant periods are found in eight of them; these periods range from 49 to 157 days, and most of these stars have F spectral types. These eight are found to be similar to the Milky Way Galaxy (MWG) carbon-rich proto-planetary nebulae (PPNs) in several ways: (a) they are in the same period range of ∼38 to ∼160 days, (b) they have similar spectral types, (c) they are (all but one) redder when fainter, (d) they have multiple periods, closely spaced in time, with an average ratio of secondary to primary period of ∼1.0, and as an ensemble, (e) they show a trend of decreasing period with increasing temperature, and (f) they show a trend of decreasing amplitude with decreasing period. However, they possibly differ in that the decreasing trend of period with temperature may be slightly offset from that of the MWG. These eight are classified as PPNs. The other 14 all show evidence of variability on shorter timescales. They are likely hotter PPNs or young planetary nebulae. However, in the MWG the numbers of PPNs peak in the F−G spectral types, while it appears that in the LMC they peak at a hotter B spectral type. One of the periodic ones shows a small, R Coronae Borealis type light curve drop.

  11. 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

  12. ETHOS 1: a high-latitude planetary nebula with jets forged by a post-common-envelope binary central star

    NASA Astrophysics Data System (ADS)

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

    2011-05-01

    We report on the discovery of ETHOS 1 (PN G068.1+11.0), the first spectroscopically confirmed planetary nebula (PN) from a survey of the SuperCOSMOS Science Archive for high-latitude PNe. ETHOS 1 stands out as one of the few PNe to have both polar outflows (jets) travelling at 120 ± 10 km s-1 and a close binary central star. The light curve observed with the Mercator Telescope reveals an orbital period of 0.535 d and an extremely large amplitude (0.816 mag) due to irradiation of the companion by a very hot pre-white dwarf. ETHOS 1 further strengthens the long-suspected link between binary central stars of PNe (CSPN) and jets. The Isaac Newton Telescope/Intermediate Dispersion Spectrograph and Very Large Telescope (VLT) FORS spectroscopy of the CSPN reveals weak N III, C III and C IV emission lines seen in other close binary CSPN and suggests that many CSPN with these weak emission lines are misclassified close binaries. We present VLT FORS imaging and Manchester Echelle Spectrometer long-slit observations from which a kinematic model of the nebula is built. An unusual combination of bipolar outflows and a spherical nebula conspires to produce an X-shaped appearance. The kinematic age of the jets (1750 ± 250 yr kpc-1) is found to be more than that of the inner nebula (900 ± 100 yr kpc-1), consistent with previous studies of similar PNe. Emission-line ratios of the jets are found to be consistent with that of reverse-shock models for fast low-ionization emitting regions (FLIERs) in PNe. Further large-scale surveys for close binary CSPN will be required to securely establish whether FLIERs are launched by close binaries. Based on observations made with the Flemish Mercator Telescope and Isaac Newton Telescope of the Observatorio del Roque de Los Muchachos and the VLT at the Paranal Observatory under programs 083.D-0654(A) and 085.D-0629(A).

  13. 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.

  14. 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

  15. ON THE NONTHERMAL κ-DISTRIBUTED ELECTRONS IN PLANETARY NEBULAE AND H ii REGIONS: THE κ INDEX AND ITS CORRELATIONS WITH OTHER NEBULAR PROPERTIES

    SciTech Connect

    Zhang, Yong; Zhang, Bing; Liu, Xiao-Wei

    2016-01-20

    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.

  16. 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.

  17. Discovery of oxygen in the PG 1159 degenerate stars - A direct evolutionary link to O VI planetary nebula nuclei and confirmation of pulsation theory

    NASA Technical Reports Server (NTRS)

    Sion, E. M.; Liebert, J.; Starrfield, S. G.

    1985-01-01

    The discovery of strong O VI absorption/emission lines in five members of the PG 1159 degenerate stars is reported. It is shown that the optical spectra are dominated by C IV, O VI, and He II, with no detectable N lines. It is confirmed that the planetary nebula-central star, K1-16, which is found to be a pulsating star by Grauer and Bond (1984), is a member of the spectroscopic group. The detection of strong oxygen features in the photospheres of the objects provides support of the prediction of Starrfield et al. (1984). The properties of the PG 1159 stars are compared with the so-called O VI central stars of planetary nebulae and both groups of stars are found to have similar spectral features, temperatures, and luminosities. The implications of the O VI/PG 1159 evolutionary link are assessed.

  18. Discovery of oxygen in the PG 1159 degenerate stars - A direct evolutionary link to O VI planetary nebula nuclei and confirmation of pulsation theory

    NASA Astrophysics Data System (ADS)

    Sion, E. M.; Liebert, J.; Starrfield, S. G.

    1985-05-01

    The discovery of strong O VI absorption/emission lines in five members of the PG 1159 degenerate stars is reported. It is shown that the optical spectra are dominated by C IV, O VI, and He II, with no detectable N lines. It is confirmed that the planetary nebula-central star, K1-16, which is found to be a pulsating star by Grauer and Bond (1984), is a member of the spectroscopic group. The detection of strong oxygen features in the photospheres of the objects provides support of the prediction of Starrfield et al. (1984). The properties of the PG 1159 stars are compared with the so-called O VI central stars of planetary nebulae and both groups of stars are found to have similar spectral features, temperatures, and luminosities. The implications of the O VI/PG 1159 evolutionary link are assessed.

  19. 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.

  20. DISCOVERY OF RUBIDIUM, CADMIUM, AND GERMANIUM EMISSION LINES IN THE NEAR-INFRARED SPECTRA OF PLANETARY NEBULAE

    SciTech Connect

    Sterling, N. C.; Dinerstein, Harriet L.; Kaplan, Kyle F.; Bautista, Manuel A. E-mail: harriet@astro.as.utexas.edu E-mail: manuel.bautista@wmich.edu

    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 Rb{sup 3+}/H{sup +} 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{sub ⊙}, [Fe/H] = −0.37) demonstrates the potential of using PN compositions to test s-process nucleosynthesis models.

  1. 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.

  2. 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.

  3. Kinematic Structure of H2 and [Fe II] in the Bipolar Planetary Nebula M2-9

    NASA Astrophysics Data System (ADS)

    Smith, Nathan; Balick, Bruce; Gehrz, Robert D.

    2005-08-01

    We present new high-dispersion, long-slit, infrared (IR) spectra of the double-shell bipolar planetary nebula M2-9 in the emission lines [Fe II] λ16435 and H2v=1-0 S(1) λ21218. H2 spectra reveal for the first time the kinematic structure of the outer shell in M2-9. Kinematics of the inner shell, traced by [Fe II], resemble those of optical forbidden lines like [N II] λ6583, although we note subtle differences. [Fe II] and H2 shells have expansion speeds roughly proportional to distance from the star (``Hubble'' flows) and share the same dynamical age of 1200-2000 yr, depending on the distance to M2-9. Thus, the inner ionized lobes and outer molecular lobes, as well as the molecular torus and ``outer loops'' measured by other observers, were all formed around the same time. Consequently, their nested structure likely arises from an excitation gradient rather than independent ejections. H2 and [Fe II] emission is distributed more uniformly than [N II], and IR lines are not dominated by the moving ionization pattern like visual-wavelength lines. We suggest that this is because IR lines of [Fe II] and H2 are excited by relatively isotropic far-UV radiation (Balmer continuum), whereas optical lines respond to a directed rotating beam of Lyman continuum. Finally, we highlight intriguing similarities between M2-9 and the Homunculus of η Car, despite the different central engines powering the two nebulae.

  4. Faint-source-star planetary microlensing: the discovery of the cold gas-giant planet OGLE-2014-BLG-0676Lb

    NASA Astrophysics Data System (ADS)

    Rattenbury, N. J.; Bennett, D. P.; Sumi, T.; Koshimoto, N.; Bond, I. A.; Udalski, A.; Shvartzvald, Y.; Maoz, D.; Jørgensen, U. G.; Dominik, M.; Street, R. A.; Tsapras, Y.; Abe, F.; Asakura, Y.; Barry, R.; Bhattacharya, A.; Donachie, M.; Evans, P.; Freeman, M.; Fukui, A.; Hirao, Y.; Itow, Y.; Li, M. C. A.; Ling, C. H.; Masuda, K.; Matsubara, Y.; Muraki, Y.; Nagakane, M.; Ohnishi, K.; Oyokawa, H.; Saito, To.; Sharan, A.; Sullivan, D. J.; Suzuki, D.; Tristram, P. J.; Yonehara, A.; Poleski, R.; Skowron, J.; Mróz, P.; Szymański, M. K.; Soszyński, I.; Pietrukowicz, P.; Kozłowski, S.; Ulaczyk, K.; Wyrzykowski, Ł.; Friedmann, M.; Kaspi, S.; Alsubai, K.; Browne, P.; Andersen, J. M.; Bozza, V.; Calchi Novati, S.; Damerdji, Y.; Diehl, C.; Dreizler, S.; Elyiv, A.; Giannini, E.; Hardis, S.; Harpsøe, K.; Hinse, T. C.; Liebig, C.; Hundertmark, M.; Juncher, D.; Kains, N.; Kerins, E.; Korhonen, H.; Mancini, L.; Martin, R.; Mathiasen, M.; Rabus, M.; Rahvar, S.; Scarpetta, G.; Skottfelt, J.; Snodgrass, C.; Surdej, J.; Taylor, J.; Tregloan-Reed, J.; Vilela, C.; Wambsganss, J.; Williams, A.; D'Ago, G.; Bachelet, E.; Bramich, D. M.; Figuera Jaimes, R.; Horne, K.; Menzies, J.; Schmidt, R.; Steele, I. A.

    2017-04-01

    We report the discovery of a planet - OGLE-2014-BLG-0676Lb- via gravitational microlensing. Observations for the lensing event were made by the following groups: Microlensing Observations in Astrophysics; Optical Gravitational Lensing Experiment; Wise Observatory; RoboNET/Las Cumbres Observatory Global Telescope; Microlensing Network for the Detection of Small Terrestrial Exoplanets; and μ-FUN. All analyses of the light-curve data favour a lens system comprising a planetary mass orbiting a host star. The most-favoured binary lens model has a mass ratio between the two lens masses of (4.78 ± 0.13) × 10-3. Subject to some important assumptions, a Bayesian probability density analysis suggests the lens system comprises a 3.09_{-1.12}^{+1.02} MJ planet orbiting a 0.62_{-0.22}^{+0.20} M⊙ host star at a deprojected orbital separation of 4.40_{-1.46}^{+2.16} au. The distance to the lens system is 2.22_{-0.83}^{+0.96} kpc. Planet OGLE-2014-BLG-0676Lb provides additional data to the growing number of cool planets discovered using gravitational microlensing against which planetary formation theories may be tested. Most of the light in the baseline of this event is expected to come from the lens and thus high-resolution imaging observations could confirm our planetary model interpretation.

  5. Ionization Structure in the 30 Doradus Nebula as seen with Hubble Space Telescope Wide Field Planetary Camera 2

    NASA Astrophysics Data System (ADS)

    Scowen, P. A.; Hester, J. J.; Sankrit, R.; Gallagher, J. S.; Ballester, G. E.; Burrows, C. J.; Clarke, J. T.; Crisp, D.; Evans, R. W.; Griffiths, R. E.; Hoessel, J. G.; Holtzman, J. A.; Krist, J.; Mould, J. R.; Stapelfeldt, K. R.; Trauger, J. T.; Watson, A. M.; Westphal, J. A.

    1998-07-01

    Using the Hubble Space Telescope (HST) and Wide Field Planetary Camera 2, we have imaged the central 20 pc of the giant H ii region 30 Doradus Nebula in three different emission lines. The images allow us to study the nebula with a physical resolution that is within a factor of 2 of that of typical ground-based observations of Galactic H ii regions. We present a gallery of interesting objects within the region studied. These include a tube blown by the wind of a high-velocity star and a discrete H ii region around an isolated B star. This small isolated H ii region appears to be in the midst of the champagne flow phase of its evolution. Most of the emission within 30 Dor is confined to a thin zone located between the hot interior of the nebula and surrounding dense molecular material. This zone appears to be directly analogous to the photoionized photoevaporative flows that dominate emission from small, nearby H ii regions. For example, a column of material protruding from the cavity wall to the south of the main cluster is found to be a direct analog to elephant trunks in M16. Surface brightness profiles across this structure are very similar to surface brightness profiles taken at ground-based resolution across the head of the largest column in M16. The dynamical effects of the photoevaporative flow can be seen as well. An arcuate feature located above this column and a similar feature surrounding a second nearby column are interpreted as shocks in which the photoevaporative flow stagnates against the high-temperature gas that fills the majority of the nebula. The ram pressure in the photoevaporative flow, derived from thermal pressure at the surface of the column, is found to balance with the pressure in the interior of the nebula derived from previous X-ray observations. By analogy with the comparison of ground-based and HST images of M16, we infer that the same sharply stratified structure seen in HST images of M16 almost certainly underlies the observed

  6. 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

  7. 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

  8. 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

  9. AN EXTREME HIGH-VELOCITY BIPOLAR OUTFLOW IN THE PRE-PLANETARY NEBULA IRAS 08005-2356

    SciTech Connect

    Sahai, R.; Patel, N. A.

    2015-09-01

    We report interferometric mapping of the bipolar pre-planetary nebula IRAS 08005-2356 (I 08005) with an angular resolution of ∼1″–5″, using the Submillimeter Array, in the {sup 12}CO J = 2–1, 3–2, {sup 13}CO J = 2–1, and SiO J = 5–4 (v = 0) lines. Single-dish observations, using the SMT 10 m, were made in these lines as well as in the CO J = 4–3 and SiO J = 6–5 (v = 0) lines. The line profiles are very broad, showing the presence of a massive (>0.1 M{sub ⊙}), extreme high velocity outflow (V ∼ 200 km s{sup −1}) directed along the nebular symmetry axis derived from the Hubble Space Telescope imaging of this object. The outflow's scalar momentum far exceeds that available from radiation pressure of the central post-AGB star, and it may be launched from an accretion disk around a main-sequence companion. We provide indirect evidence for such a disk from its previously published, broad Hα emission profile, which we propose results from Lyβ emission generated in the disk followed by Raman-scattering in the innermost regions of a fast, neutral wind.

  10. Chemical Abundances in the Extremely Carbon-rich and Xenon-rich Halo Planetary Nebula H4-1

    NASA Astrophysics Data System (ADS)

    Otsuka, Masaaki; Tajitsu, Akito

    2013-12-01

    We performed detailed chemical abundance analysis of the extremely metal-poor ([Ar/H] ~ -2) halo planetary nebula (PN) H4-1 based on the multi-wavelength spectra from Subaru/HDS, GALEX, SDSS, and Spitzer/IRS and determined the abundances of 10 elements. The C and O abundances were derived from collisionally excited lines (CELs) and are almost consistent with abundances from recombination lines (RLs). We demonstrated that the large discrepancy in the C abundance between CEL and RL in H4-1 can be solved using the temperature fluctuation model. We reported the first detection of the [Xe III] λ5846 line in H4-1 and determination of its elemental abundance ([Xe/H] > +0.48). H4-1 is the most Xe-rich PN among the Xe-detected PNe. The observed abundances are close to the theoretical prediction by a 2.0 M ⊙ single star model with an initially element rich ([r/Fe] = +2.0 dex) rapid neutron-capture process (r-process). The observed Xe abundance would be a product of the r-process in primordial supernovae. The [C/O]-[Ba/(Eu or Xe)] diagram suggests that the progenitor of H4-1 shares the evolution with carbon-enhanced metal-poor (CEMP)-r/s and CEMP-no stars. The progenitor of H4-1 is presumably a binary formed in an r-process-rich environment.

  11. Polycyclic aromatic hydrocarbons and molecular hydrogen in oxygen-rich planetary nebulae: the case of NGC 6720.

    PubMed

    Cox, N L J; Pilleri, P; Berné, O; Cernicharo, J; Joblin, C

    2016-02-11

    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.

  12. Analysis of Co-spatial UV-optical HST/STIS Spectra of Planetary Nebula NGC 3242

    NASA Astrophysics Data System (ADS)

    Miller, Timothy R.; Henry, Richard B. C.; Balick, Bruce; Kwitter, Karen B.; Dufour, Reginald J.; Shaw, Richard A.; Corradi, Romano L. M.

    2016-10-01

    This project sought to consider two important aspects of the planetary nebula NGC 3242 using new long-slit HST/STIS spectra. First, we investigated whether this object is chemically homogeneous by spatially dividing the slit into different regions and calculating the abundances of each region. The major result is that the elements of He, C, O, and Ne are chemically homogeneous within uncertainties across the regions probed, implying that the stellar outflow was well-mixed. Second, we constrained the stellar properties using photoionization models computed by CLOUDY and tested the effects of three different density profiles on these parameters. The three profiles tested were a constant density profile, a Gaussian density profile, and a Gaussian with a power-law density profile. The temperature and luminosity were not affected significantly by the choice of density structure. The values for the stellar temperature and luminosity from our best-fit model are {89.7}-4.7+7.3 kK and log(L/L ⊙) = {3.36}-0.22+0.28, respectively. Comparing to evolutionary models on an HR diagram, this corresponds to an initial and final mass of {0.95}-0.09+0.35{M}⊙ and {0.56}-0.01+0.01{M}⊙ , respectively. Based on observations 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, Incorporated, under NASA contract NAS5-26555.

  13. 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.

  14. The close binary central star of the planetary nebula Abell 41 - A helium-rich subdwarf primary

    NASA Astrophysics Data System (ADS)

    Green, R. F.; Liebert, J.; Wesemael, F.

    1984-05-01

    He II, He I, and H absorption features were detected in spectroscopy with 2 A resolution of the Abell 41 planetary nebula central star, which was recently reported by Grauer and Bond to be a close binary with a 2 hour 43 minute period. This subdwarf O spectrum has been analyzed with a grid of hot, high-gravity, LTE atmosphere models. T(eff) = 50,000 + or 5000 K, log g = 6 + or - 1, n(He)/n(H) = 10 exp -1.0 + or - 1. This temperature is a factor of 1.4-2.9 lower than the range used by Grauer and Bond, and the required secondary star heating is considerably reduced. Nevertheless, close agreement is found with their estimates for the distance, reddening, and the systemic parameters for the binary star. Their interpretation of Abell 41 as a precataclysmic variable object remains valid for a cool main-sequence or hotter evolved secondary star. The object should be a promising target for high-resolution (coude/echelle) follow-up spectroscopy.

  15. 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.

  16. VizieR Online Data Catalog: Kn 26, a new quadrupolar planetary nebula (Guerrero+, 2013)

    NASA Astrophysics Data System (ADS)

    Guerrero, M. A.; Miranda, L. F.; Ramos-Larios, G.; Vazquez, R.

    2013-03-01

    Narrow-band Hα, [NII] λ6583, and [OIII] λ5007 images of Kn 26 were acquired on June 21, 2009 using ALFOSC (Andalucia Faint Object Spectrograph and Camera) at the 2.56m Nordic Optical Telescope (NOT) of the Observatorio de Roque de los Muchachos (ORM, La Palma, Spain). Narrow-band H2 2.1218um, Brγ 2.1658um, and K continuum at 2.270um images of Kn 26 were obtained on June 27, 2010 using LIRIS at the Cassegrain focus of the 4.2m William Herschel Telescope (WHT) at the ORM. Intermediate-resolution long-slit spectra of Kn 26 were obtained on October 5, 2011 using the ALBIREO spectrograph at the 1.5m telescope of the Observatorio de Sierra Nevada (OSN), Granada, Spain. Long-slit high-dispersion spectroscopy on the Hα and [NII] λ6583 lines of Kn 26 has been acquired on June 13, 2010 using the Manchester Echelle Spectrometer (MES) mounted on the 2.1m (f/7.5) telescope at the Observatorio Astronomico Nacional de San Pedro Martir (OAN-SPM, Mexico). (2 data files).

  17. Integral field spectroscopy of planetary nebulae: mapping the line diagnostics and hydrogen-poor zones with VLT FLAMES

    NASA Astrophysics Data System (ADS)

    Tsamis, Y. G.; Walsh, J. R.; Péquignot, D.; Barlow, M. J.; Danziger, I. J.; Liu, X.-W.

    2008-05-01

    Results from the first dedicated study of Galactic planetary nebulae (PNe) by means of optical integral field spectroscopy with the Very Large Telescope Fibre Large Array Multi Element Spectrograph Argus integral field unit are presented. Three typical Galactic disc PNe have been mapped with the 11.5 × 7.2-arcsec2 Argus array: 2D spectral maps of the main shell of NGC5882 and of large areas of NGC 6153 and NGC 7009 with 297 spatial pixels per target were obtained at subarcsec resolutions. A corresponding number of 297 spectra per target were obtained in the 396.4-507.8nm range. Spatially resolved maps of emission lines and of nebular physical properties such as electron temperatures, densities and ionic abundances were produced. The abundances of helium and of doubly ionized carbon and oxygen, relative to hydrogen, were derived from optical recombination lines (ORLs), while those of O2+ were also derived from the classic collisionally excited lines (CELs). The occurrence of the abundance discrepancy problem, pertaining to oxygen, was investigated by mapping the ratio of ORL/CEL abundances for O2+ [the abundance discrepancy factor (ADF)] across the face of the PNe. The ADF varies between targets and also with position within the targets, attaining values of ~40 in the case of NGC 6153 and ~30 in the case of NGC 7009. Correlations of the ADF with geometric distance from the central star and plasma surface brightness (for NGC 6153), as well as with [OIII] electron temperature, plasma ionization state and other physical properties of the targets are established. Very small values of the temperature fluctuation parameter in the plane of the sky, t2A(O2+), are found in all cases. It is argued that these results provide further evidence for the existence in run-of-the-mill PNe of a distinct nebular component consisting of hydrogen-deficient, super-metal-rich plasma. The zones containing this posited component appear as undulations in the CII and OII ORL abundance

  18. 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 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.

  19. Masses of the Planetary Nebula Central Stars in the Galactic Globular Cluster System from HST Imaging and Spectroscopy

    NASA Astrophysics Data System (ADS)

    Jacoby, George H.; De Marco, Orsola; Davies, James; Lotarevich, I.; Bond, Howard E.; Harrington, J. Patrick; Lanz, Thierry

    2017-02-01

    The globular cluster (GC) system of our Galaxy contains four planetary nebulae (PNe): K 648 (or Ps 1) in M15, IRAS 18333-2357 in M22, JaFu 1 in Pal 6, and JaFu 2 in NGC 6441. Because single-star evolution at the low stellar mass of present-epoch GCs was considered incapable of producing visible PNe, their origin presented a puzzle. We imaged the PN JaFu 1 with the Hubble Space Telescope (HST) to obtain photometry of its central star (CS) and high-resolution morphological information. We imaged IRAS 18333-2357 with better depth and resolution, and we analyzed its archival HST spectra to constrain its CS temperature and luminosity. All PNe in Galactic GCs now have quality HST data, allowing us to improve CS mass estimates. We find reasonably consistent masses between 0.53 and 0.58 M ⊙ for all four objects, though estimates vary when adopting different stellar evolutionary calculations. The CS mass of IRAS 18333-2357, though, depends strongly on its temperature, which remains elusive due to reddening uncertainties. For all four objects, we consider their CS and nebula masses, their morphologies, and other incongruities to assess the likelihood that these objects formed from binary stars. Although generally limited by uncertainties (∼0.02 M ⊙) in post-AGB tracks and core mass versus luminosity relations, the high-mass CS in K 648 indicates a binary origin. The CS of JaFu 1 exhibits compact, bright [O iii] and Hα emission, like EGB 6, suggesting a binary companion or disk. Evidence is weaker for a binary origin of JaFu 2. Based, in part, on observations made with the NASA/ESA Hubble Space Telescope, obtained [from the Data Archive] 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. These observations are associated with program GO-11558.

  20. MORPHO-KINEMATIC ANALYSIS OF THE POINT-SYMMETRIC, BIPOLAR PLANETARY NEBULAE Hb 5 AND K 3-17, A PATHWAY TO POLY-POLARITY

    SciTech Connect

    Lopez, J. A.; Garcia-Diaz, Ma. T.; Steffen, W.; Riesgo, H.; Richer, M. G. E-mail: tere@astrosen.unam.mx E-mail: hriesgo@astrosen.unam.mx

    2012-05-10

    The kinematics of the bipolar planetary nebulae Hb 5 and K 3-17 are investigated in detail by means of a comprehensive set of spatially resolved high spectral resolution, long-slit spectra. Both objects share particularly interesting characteristics, such as a complex filamentary, rosette-type nucleus, axial point-symmetry, and very fast bipolar outflows. The kinematic information of Hb 5 is combined with Hubble Space Telescope imagery to construct a detailed three-dimensional model of the nebula using the code SHAPE. The model shows that the large-scale lobes are growing in a non-homologous way. The filamentary loops in the core are proven to actually be secondary lobes emerging from what appears to be a randomly punctured, dense, gaseous core and the material that forms the point-symmetric structure flows within the lobes with a distinct kinematic pattern and its interaction with the lobes has had a shaping effect on them. Hb 5 and K 3-17 may represent a class of fast evolving planetary nebulae that will develop poly-polar characteristics once the nebular core evolves and expands.

  1. The binary fraction of planetary nebula central stars - II. A larger sample and improved technique for the infrared excess search

    NASA Astrophysics Data System (ADS)

    Douchin, Dimitri; De Marco, Orsola; Frew, D. J.; Jacoby, G. H.; Jasniewicz, G.; Fitzgerald, M.; Passy, Jean-Claude; Harmer, D.; Hillwig, Todd; Moe, Maxwell

    2015-04-01

    There is no conclusive explanation of why ˜80 per cent of planetary nebulae (PNe) are non-spherical. In the Binary Hypothesis, a binary interaction is a preferred channel to form a non-spherical PN. A fundamental step to corroborate or disprove the Binary Hypothesis is to estimate the binary fraction of central stars of PNe (CSPNe) and compare it with a prediction based on the binary fraction of the progenitor, main-sequence population. In this paper, the second in a series, we search for spatially unresolved I- and J-band flux excess in an extended sample of 34 CSPN by a refined measurement technique with a better quantification of the uncertainties. The detection rate of I- (J-)band flux excess is 32 ± 16 per cent (50 ± 24 per cent). This result is very close to what was obtained in Paper I with a smaller sample. We account conservatively for unobserved cool companions down to brown dwarf luminosities, increasing these fractions to 40 ± 20 per cent (62 ± 30 per cent). This step is very sensitive to the adopted brightness limit of our survey. Accounting for visual companions increases the binary fraction to 46 ± 23 per cent (71 ± 34 per cent). These figures are lower than in Paper I. The error bars are better quantified, but still unacceptably large. Taken at face value, the current CSPN binary fraction is in line with the main-sequence progenitor population binary fraction. However, including white dwarfs companions could increase this fraction by as much as 13 (21) per cent points.

  2. Chemical abundances in the extremely carbon-rich and xenon-rich halo planetary nebula H4-1

    SciTech Connect

    Otsuka, Masaaki; Tajitsu, Akito E-mail: tajitsu@subaru.naoj.org

    2013-12-01

    We performed detailed chemical abundance analysis of the extremely metal-poor ([Ar/H] ∼ –2) halo planetary nebula (PN) H4-1 based on the multi-wavelength spectra from Subaru/HDS, GALEX, SDSS, and Spitzer/IRS and determined the abundances of 10 elements. The C and O abundances were derived from collisionally excited lines (CELs) and are almost consistent with abundances from recombination lines (RLs). We demonstrated that the large discrepancy in the C abundance between CEL and RL in H4-1 can be solved using the temperature fluctuation model. We reported the first detection of the [Xe III] λ5846 line in H4-1 and determination of its elemental abundance ([Xe/H] > +0.48). H4-1 is the most Xe-rich PN among the Xe-detected PNe. The observed abundances are close to the theoretical prediction by a 2.0 M {sub ☉} single star model with an initially element rich ([r/Fe] = +2.0 dex) rapid neutron-capture process (r-process). The observed Xe abundance would be a product of the r-process in primordial supernovae. The [C/O]-[Ba/(Eu or Xe)] diagram suggests that the progenitor of H4-1 shares the evolution with carbon-enhanced metal-poor (CEMP)-r/s and CEMP-no stars. The progenitor of H4-1 is presumably a binary formed in an r-process-rich environment.

  3. Galactic planetary nebulae with precise nebular abundances as a tool to understand the evolution of asymptotic giant branch stars

    NASA Astrophysics Data System (ADS)

    García-Hernández, D. A.; Ventura, P.; Delgado-Inglada, G.; Dell'Agli, F.; Di Criscienzo, M.; Yagüe, A.

    2016-09-01

    We present nucleosynthesis predictions (HeCNOCl) from asymptotic giant branch (AGB) models, with diffusive overshooting from all the convective borders, in the metallicity range Z⊙/4 < Z < 2 Z⊙. They are compared to recent precise nebular abundances in a sample of Galactic planetary nebulae (PNe) that is divided among double-dust chemistry (DC) and oxygen-dust chemistry (OC) according to the infrared dust features. Unlike the similar subsample of Galactic carbon-dust chemistry PNe recently analysed by us, here the individual abundance errors, the higher metallicity spread, and the uncertain dust types/subtypes in some PNe do not allow a clear determination of the AGB progenitor masses (and formation epochs) for both PNe samples; the comparison is thus more focused on a object-by-object basis. The lowest metallicity OC PNe evolve from low-mass (˜1 M⊙) O-rich AGBs, while the higher metallicity ones (all with uncertain dust classifications) display a chemical pattern similar to the DC PNe. In agreement with recent literature, the DC PNe mostly descend from high-mass (M ≥ 3.5 M⊙) solar/supersolar metallicity AGBs that experience hot bottom burning (HBB), but other formation channels in low-mass AGBs like extra mixing, stellar rotation, binary interaction, or He pre-enrichment cannot be disregarded until more accurate C/O ratios would be obtained. Two objects among the DC PNe show the imprint of advanced CNO processing and deep second dredge-up, suggesting progenitors masses close to the limit to evolve as core collapse supernovae (above 6M⊙). Their actual C/O ratio, if confirmed, indicate contamination from the third dredge-up, rejecting the hypothesis that the chemical composition of such high-metallicity massive AGBs is modified exclusively by HBB.

  4. Formation and X-ray emission from hot bubbles in planetary nebulae - II. Hot bubble X-ray emission

    NASA Astrophysics Data System (ADS)

    Toalá, J. A.; Arthur, S. J.

    2016-12-01

    We present a study of the X-ray emission from numerical simulations of hot bubbles in planetary nebulae (PNe). High-resolution, two-dimensional, radiation-hydrodynamical simulations of the formation and evolution of hot bubbles in PNe, with and without thermal conduction, are used to calculate the X-ray emission and study its time-dependence and relationship to the changing stellar parameters. Instabilities in the wind-wind interaction zone produce clumps and filaments in the swept-up shell of nebular material. Turbulent mixing and thermal conduction at the corrugated interface can produce quantities of intermediate temperature and density gas between the hot, shocked wind bubble, and the swept-up photoionized nebular material, which can emit in soft, diffuse X-rays. We use the CHIANTI software to compute synthetic spectra for the models and calculate their luminosities. We find that models both with conduction and those without can produce the X-ray temperatures and luminosities that are in the ranges reported in observations, although the models including thermal conduction are an order of magnitude more luminous than those without. Our results show that at early times the diffuse X-ray emission should be dominated by the contribution from the hot, shocked stellar wind, whereas at later times the nebular gas will dominate the spectrum. We analyse the effect of sampling on the resultant spectra and conclude that a minimum of 200 counts is required to reliably reproduce the spectral shape. Likewise, heavily smoothed surface-brightness profiles obtained from low-count detections of PNe do not provide a reliable description of the spatial distribution of the X-ray-emitting gas.

  5. First results from the faint object camera - High-resolution observations of the central object R136 in the 30 Doradus nebula

    NASA Technical Reports Server (NTRS)

    Weigelt, G.; Albrecht, R.; Barbieri, C.; Blades, J. C.; Boksenberg, A.; Crane, P.; Deharveng, J. M.; Disney, M. J.; Jakobsen, P.; Kamperman, T. M.

    1991-01-01

    R136 is the luminous central object of the giant H II region 30 Doradus in the LMC. The first high-resolution observations of R136 with the Faint Object Camera on board the Hubble Space Telescope are reported. The physical nature of the brightest component R136a has been a matter of some controversy over the last few years. The UV images obtained show that R136a is a very compact star cluster consisting of more than eight stars within 0.7 arcsec diameter. From these high-resolution images a mass upper limit can be derived for the most luminous stars observed in R136.

  6. Clown Face Nebula (NGC 2392)

    NASA Astrophysics Data System (ADS)

    Murdin, P.

    2000-11-01

    A planetary nebula, also known as the Eskimo Nebula, in the constellation Gemini, position RA 07 h 29.2 m, dec. +20° 55'. It is bluish, 13'' in diameter, and of ninth magnitude, with a tenth-magnitude central star. The blue-green nebula's hazy outer regions are thought to resemble an Eskimo's hood or clown's ruff....

  7. A search for planetary Nebulae with the Sloan digital sky survey: the outer regions of M31

    SciTech Connect

    Kniazev, Alexei Y.; Grebel, Eva K.; Martínez-Delgado, David; Zucker, Daniel B.; Rix, Hans-Walter; Snedden, Stephanie A.

    2014-01-01

    We have developed a method to identify planetary nebula (PN) candidates in imaging data of the Sloan Digital Sky Survey (SDSS). This method exploits the SDSS's five-band sampling of emission lines in PN spectra, which results in a color signature distinct from that of other sources. Selection criteria based on this signature can be applied to nearby galaxies in which PNe appear as point sources. We applied these criteria to the whole area of M31 as scanned by the SDSS, selecting 167 PN candidates that are located in the outer regions of M31. The spectra of 80 selected candidates were then observed with the 2.2 m telescope at Calar Alto Observatory. These observations and cross-checks with literature data show that our method has a selection rate efficiency of about 90%, but the efficiency is different for the different groups of PN candidates. In the outer regions of M31, PNe trace different well-known morphological features like the Northern Spur, the NGC 205 Loop, the G1 Clump, etc. In general, the distribution of PNe in the outer region 8 < R < 20 kpc along the minor axis shows the {sup e}xtended disk{sup —}a rotationally supported low surface brightness structure with an exponential scale length of 3.21 ± 0.14 kpc and a total mass of ∼10{sup 10} M {sub ☉}, which is equivalent to the mass of M33. We report the discovery of three PN candidates with projected locations in the center of Andromeda NE, a very low surface brightness giant stellar structure in the outer halo of M31. Two of the PNe were spectroscopically confirmed as genuine PNe. These two PNe are located at projected distances along the major axis of ∼48 Kpc and ∼41 Kpc from the center of M31 and are the most distant PNe in M31 found up to now. With the new PN data at hand we see the obvious kinematic connection between the continuation of the Giant Stream and the Northern Spur. We suggest that 20%-30% of the stars in the Northern Spur area may belong to the Giant Stream. In our data we also

  8. Candidates for Intracluster Planetary Nebulae in the Virgo Cluster Based on the Suprime-Cam Narrow-Band Imaging in [O III] and Hα

    NASA Astrophysics Data System (ADS)

    Okamura, Sadanori; Yasuda, Naoki; Arnaboldi, Magda; Freeman, Kenneth C.; Ando, Hiroyasu; Doi, Mamoru; Furusawa, Hisanori; Gerhard, Ortwin; Hamabe, Masaru; Kimura, Masahiko; Kajino, Toshitaka; Komiyama, Yutaka; Miyazaki, Satoshi; Nakata, Fumiaki; Napolitano, Nicola R.; Ouchi, Masami; Pannella, Maurilio; Sekiguchi, Maki; Shimasaku, Kazuhiro; Yagi, Masafumi

    2002-12-01

    We have identified 38 candidates of intracluster planetary nebulae (ICPNe) in a 34' × 27' field in the core of the Virgo cluster based on Suprime-Cam imaging through two narrow-band filters centered at redshifted wavelengths of the [O III] λ=5007Å and the Hα λ=6563Å lines. Broad-band images in the V and R bands are used to check for any emissions in the adjacent continuum. We describe the method briefly and present a list of the intracluster planetary nebula candidates, together with their finding charts. The ICPN candidates show a highly inhomogeneous distribution, which may suggest an association with the M 86-M 84 subcluster. The fraction of diffuse intracluster light with respect to the total light in galaxies is estimated to be about 10%, leading to an estimate of about 20% for the baryon fraction. A spectroscopic follow up and a wider survey are critical to reveal the nature of the intracluster stellar population.

  9. THE FORMATION OF FULLERENES: CLUES FROM NEW C{sub 60}, C{sub 70}, AND (POSSIBLE) PLANAR C{sub 24} DETECTIONS IN MAGELLANIC CLOUD PLANETARY NEBULAE

    SciTech Connect

    GarcIa-Hernandez, D. A.; Iglesias-Groth, S.; Acosta-Pulido, J. A.; Manchado, A.; Garcia-Lario, P.; Stanghellini, L.; Shaw, R. A.; Villaver, E.; Cataldo, F. E-mail: amt@iac.es E-mail: Pedro.Garcia-Lario@sciops.esa.int E-mail: letizia@noao.edu E-mail: franco.cataldo@fastwebnet.it

    2011-08-20

    We present 10 new Spitzer detections of fullerenes in Magellanic Cloud Planetary Nebulae, including the first extragalactic detections of the C{sub 70} molecule. These new fullerene detections together with the most recent laboratory data permit us to report an accurate determination of the C{sub 60} and C{sub 70} abundances in space. Also, we report evidence for the possible detection of planar C{sub 24} in some of our fullerene sources, as indicated by the detection of very unusual emission features coincident with the strongest transitions of this molecule at {approx}6.6, 9.8, and 20 {mu}m. The infrared spectra display a complex mix of aliphatic and aromatic species such as hydrogenated amorphous carbon grains (HACs), polycyclic aromatic hydrocarbon clusters, fullerenes, and small dehydrogenated carbon clusters (possible planar C{sub 24}). The coexistence of such a variety of molecular species supports the idea that fullerenes are formed from the decomposition of HACs. We propose that fullerenes are formed from the destruction of HACs, possibly as a consequence of shocks driven by the fast stellar winds, which can sometimes be very strong in transition sources and young planetary nebulae (PNe). This is supported by the fact that many of our fullerene-detected PNe show altered [Ne III]/[Ne II] ratios suggestive of shocks as well as P-Cygni profiles in their UV lines indicative of recently enhanced mass loss.

  10. Binary Central Stars of Planetary Nebulae Discovered Through Photometric Variability. V. The Central Stars of HaTr 7 and ESO 330-9

    NASA Astrophysics Data System (ADS)

    Hillwig, Todd C.; Frew, David J.; Reindl, Nicole; Rotter, Hannah; Webb, Andrew; Margheim, Steve

    2017-01-01

    We find the central stars (CSs) of the planetary nebulae (PNe) HaTr 7 and ESO 330-9 to be close-binary systems. Both have orbital periods of less than half a day and contain an irradiated cool companion to the hot CS. We provide light curves, spectra, radial velocity curves, orbital periods, and binary modeling results for both systems. The binary modeling leads to system parameters, or ranges of allowed parameters for each system. We find that for the CS of HaTr 7 we need to use limb-darkening values for the cool companion that are different than the expected values for an isolated star. We also fit the CS spectrum to determine {log}g and temperature values independent of the binary modeling. For ESO 330-9 we find that based on our binary modeling, the hot CS is most likely a post-red giant branch (RGB) star with a mass of around 0.4 {M}ȯ . We discuss our derived stellar and nebular parameters in the broader context of close-binary CSs and their surrounding planetary nebulae (PNe). We also discuss the present status of known or suspected post-RGB stars in PNe.

  11. Fainting (Syncope)

    MedlinePlus

    ... Adults Making Your Wishes Known Home & Community Home › Aging & Health A to Z › Fainting (Syncope) Font size A A A Print Share Glossary Basic Facts & Information Causes & Symptoms Diagnosis & Tests Care & Treatment Lifestyle & Management Other Resources Caregiving How ...

  12. Butterfly Nebula

    NASA Technical Reports Server (NTRS)

    1997-01-01

    The Hubble Space Telescope's Wide Field and Planetary Camera 2 (WFPC2) is back at work, capturing this image of the 'butterfly wing'- shaped nebula, NGC 2346. The nebula is about 2,000 light-years away from Earth in the direction of the constellation Monoceros. It represents the spectacular 'last gasp' of a binary star system at the nebula's center. The image was taken on March 6, 1997 as part of the recommissioning of the Hubble Space Telescope's previously installed scientific instruments following the successful servicing of the HST by NASA shuttle astronauts in February. WFPC2 was installed in HST during the servicing mission in 1993. At the center of the nebula lies a pair of stars that are so close together that they orbit around each other every 16 days. This is so close that, even with Hubble, the pair of stars cannot be resolved into its two components. One component of this binary is the hot core of a star that has ejected most of its outer layers, producing the surrounding nebula. Astronomers believe that this star, when it evolved and expanded to become a red giant, actually swallowed its companion star in an act of stellar cannibalism. The resulting interaction led to a spiraling together of the two stars, culminating in ejection of the outer layers of the red giant. Most of the outer layers were ejected into a dense disk, which can still be seen in the Hubble image, surrounding the central star. Later the hot star developed a fast stellar wind. This wind, blowing out into the surrounding disk, has inflated the large, wispy hourglass-shaped wings perpendicular to the disk. These wings produce the butterfly appearance when seen in projection. The total diameter of the nebula is about one-third of a light-year, or 2 trillion miles.

  13. Two compact planetary nebulae of moderate excitation - NGC 6565 (3-4.5 deg) and NGC 6644 (8-7.2 deg)

    NASA Technical Reports Server (NTRS)

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

    1988-01-01

    Data obtained with an image-tube scanner at the 3-m Shane telescope are combined with IUE data to obtain plasma diagnostics and chemical compositions for two planetary nebulae of moderately high excitation. Theoretical nebular models were calculated using stellar fluxes given by Husfeld et al. (1984) for T(asterisk) = 85,000 K, log g = 4.72, and elemental abundances were obtained by fitting theoretical to observed line intensities and also by using the model to determine ionization correction factors to be applied to observed ionic concentrations. Although C appears to be about 1.5 times as abundant in NGC 6644 as in NGC 6565, N, O, Ne, S, Cl, and Ar are depleted by factors ranging from 2 to 6 in NGC 6644 as compared to NGC 6565. The high-velocity object, NGC 6644, was evidently made from a less metal-rich mixture than the sun.

  14. Terminal velocity of wind, mass loss, and absorption lines of the central star of the planetary nebula 75 + 35. 1 deg

    SciTech Connect

    Feibelman, W.A.; Bruhweiler, F.C. Catholic Univ. of America, Washington, DC )

    1989-12-01

    The high-galactic latitude planetary nebula 75 + 35.1 deg was observed in the high-dispersion mode of the International Ultraviolet Explorer (IUE) satellite in the wavelength range 1150-1950 A. The N V resonance doublet at 1240 A and O V subordinate line at 1371 A exhibit strong stellar P Cygni profiles with absorption extending to -2150 km/s and -1000 km/s, respectively. Application of the first moment method implies a mass-loss rate of M = (1-3) x 10 to the -8th solar mass/yr. The high ionization of the wind lines and the presence of strong Fe VI and Fe V lines in the stellar photosphere support that this object is quite hot. A Teff of 75,000 + or - 10,000 K was adopted, although Tc = 94,000 K was found previously from low-resolution IUE data. 18 refs.

  15. Terminal velocity of wind, mass loss, and absorption lines of the central star of the planetary nebula 75 + 35.1 deg

    NASA Technical Reports Server (NTRS)

    Feibelman, Walter A.; Bruhweiler, Frederick C.

    1989-01-01

    The high-galactic latitude planetary nebula 75 + 35.1 deg was observed in the high-dispersion mode of the International Ultraviolet Explorer (IUE) satellite in the wavelength range 1150-1950 A. The N V resonance doublet at 1240 A and O V subordinate line at 1371 A exhibit strong stellar P Cygni profiles with absorption extending to -2150 km/s and -1000 km/s, respectively. Application of the first moment method implies a mass-loss rate of M = (1-3) x 10 to the -8th solar mass/yr. The high ionization of the wind lines and the presence of strong Fe VI and Fe V lines in the stellar photosphere support that this object is quite hot. A Teff of 75,000 + or - 10,000 K was adopted, although Tc = 94,000 K was found previously from low-resolution IUE data.

  16. STUDIES OF VARIABILITY IN PROTO-PLANETARY NEBULAE. II. LIGHT AND VELOCITY CURVE ANALYSES OF IRAS 22272+5435 AND 22223+4327

    SciTech Connect

    Hrivnak, Bruce J.; Lu, Wenxian; Sperauskas, Julius; Zacs, Laimons; Van Winckel, Hans; Bohlender, David E-mail: wen.lu@valpo.edu E-mail: Hans.VanWinckel@ster.kuleuven.be E-mail: zacs@latnet.lv

    2013-04-01

    We have carried out a detailed observational study of the light, color, and velocity variations of two bright, carbon-rich proto-planetary nebulae, IRAS 22223+4327 and 22272+5435. The light curves are based upon our observations from 1994 to 2011, together with published data by Arkhipova and collaborators. They each display four significant periods, with primary periods for IRAS 22223+4327 and 22272+5435 being 90 and 132 days, respectively. For each of them, the ratio of secondary to primary period is 0.95, a value much different from that found in Cepheids, but which may be characteristic of post-asymptotic giant branch (AGB) stars. Fewer significant periods are found in the smaller radial velocity data sets, but they agree with those of the light curves. The color curves generally mimic the light curves, with the objects reddest when faintest. A comparison in seasons when there exist contemporaneous light, color, and velocity curves reveals that the light and color curves are in phase, while the radial velocity curves are {approx}0.25 P out of phase with the light curves. Thus they differ from what is seen in Cepheids, in which the radial velocity curve is 0.50 P out of phase with the light curve. Comparison of the observed periods and amplitudes with those of post-AGB pulsation models shows poor agreement, especially for the periods, which are much longer than predicted. These observational data, particularly the contemporaneous light, color, and velocity curves, provide an excellent benchmark for new pulsation models of cool stars in the post-AGB, proto-planetary nebula phase.

  17. The chemical composition of TS 01, the most oxygen-deficient planetary nebula. AGB nucleosynthesis in a metal-poor binary star

    NASA Astrophysics Data System (ADS)

    Stasińska, G.; Morisset, C.; Tovmassian, G.; Rauch, T.; Richer, M. G.; Peña, M.; Szczerba, R.; Decressin, T.; Charbonnel, C.; Yungelson, L.; Napiwotzki, R.; Simón-Díaz, S.; Jamet, L.

    2010-02-01

    The planetary nebula TS 01 (also called PN G 135.9+55.9 or SBS 1150+599A) with its record-holding low oxygen abundance and its double degenerate close binary core (period 3.9 h) is an exceptional object located in the Galactic halo. We have secured observational data in a complete wavelength range to pin down the abundances of half a dozen elements in the nebula. The abundances are obtained via detailed photoionization modelling which takes into account all the observational constraints (including geometry and aperture effects) using the pseudo-3D photoionization code Cloudy_3D. The spectral energy distribution of the ionizing radiation is taken from appropriate model atmospheres. Incidentally we find from the new observational constraints that both stellar components contribute to the ionization: the “cool” one provides the bulk of hydrogen ionization, while the “hot” one is responsible for the presence of the most highly charged ions, which explains why previous attempts to model the nebula experienced difficulties. The nebular abundances of C, N, O, and Ne are found to be 1/3.5, 1/4.2, 1/70, and 1/11 of the solar value respectively, with uncertainties of a factor 2. Thus the extreme O deficiency of this object is confirmed. The abundances of S and Ar are less than 1/30 of solar. The abundance of He relative to H is 0.089 ± 0.009. Standard models of stellar evolution and nucleosynthesis cannot explain the abundance pattern observed in the nebula. To obtain an extreme oxygen deficiency in a star whose progenitor has an initial mass of about 1 M⊙ requires an additional mixing process, which can be induced by stellar rotation and/or by the presence of the close companion. We have computed a stellar model with an initial mass of 1 M⊙, appropriate metallicity, and initial rotation of 100 km s-1, and find that rotation greatly improves the agreement between the predicted and observed abundances. Based on observations obtained at the Canada

  18. THE ABUNDANCES OF LIGHT NEUTRON-CAPTURE ELEMENTS IN PLANETARY NEBULAE. III. THE IMPACT OF NEW ATOMIC DATA ON NEBULAR SELENIUM AND KRYPTON ABUNDANCE DETERMINATIONS

    SciTech Connect

    Sterling, N. C.; Porter, R. L.; Dinerstein, Harriet L. E-mail: ryanlporter@gmail.com

    2015-06-22

    The detection of neutron(n)-capture elements in several planetary nebulae (PNe) has provided a new means of investigating s-process nucleosynthesis in low-mass stars. However, a lack of atomic data has inhibited accurate trans-iron element abundance determinations in astrophysical nebulae. Recently, photoionization (PI) and recombination data were determined for Se and Kr, the two most widely detected n-capture elements in nebular spectra. We have incorporated these new data into the photoionization code Cloudy. To test the atomic data, numerical models were computed for 15 PNe that exhibit emission lines from multiple Kr ions. We found systematic discrepancies between the predicted and observed emission lines that are most likely caused by inaccurate PI and recombination data. These discrepancies were removed by adjusting the Kr{sup +}–Kr{sup 3+} PI cross sections within their cited uncertainties and the dielectronic recombination rate coefficients by slightly larger amounts. From grids of models spanning the physical conditions encountered in PNe, we derive new, broadly applicable ionization correction factor (ICF) formulae for calculating Se and Kr elemental abundances. The ICFs were applied to our previous survey of near-infrared [Kr iii] and [Se iv] emission lines in 120 PNe. The revised Se and Kr abundances are 0.1–0.3 dex lower than former estimates, with average values of [Se/(O, Ar)] = 0.12 ± 0.27 and [Kr/(O, Ar)] = 0.82 ± 0.29, but correlations previously found between their abundances and other nebular and stellar properties are unaffected. We also find a tendency for high-velocity PNe that can be associated with the Galactic thick disk to exhibit larger s-process enrichments than low-velocity PNe belonging to the thin-disk population.

  19. Very Large Telescope deep echelle spectroscopy of Galactic planetary nebulae NGC 6153, M 1-42 and Hf 2-2

    NASA Astrophysics Data System (ADS)

    McNabb, I. A.; Fang, X.; Liu, X.-W.

    2016-09-01

    We present deep spectroscopy of three Galactic planetary nebulae (PNe) with large abundance discrepancy factors: NGC 6153, M 1-42 and Hf 2-2. The spectra were obtained with Very Large Telescope/Ultraviolet and Visual Echelle Spectrograph and cover the whole optical range (3040-11 000 Å) with a spectral resolution of ˜20 000. For all three PNe, several hundred emission lines were detected and identified, with more than 70 per cent of them as permitted lines. Most of these permitted lines are excited by recombination. Numerous weak optical recombination lines (ORLs) of O II, C II, N II and Ne II were detected in the spectra and accurate fluxes measured. Line flux tables were compiled and ready for use by the community of nebular astrophysics. These ORLs were critically analysed using the effective recombination coefficients recently calculated for the optical recombination spectrum of N II and O II under the physical conditions of photoionized gaseous nebulae. Plasma diagnostics based on the heavy element ORLs were carried out using the new atomic data. Elemental abundances derived from the ORLs were systematically higher than those derived from the collisionally excited lines (CELs) by a factor of ˜11, 22 and 80 for NGC 6153, M 1-42 and Hf 2-2, respectively. The electron temperatures derived from the heavy element ORLs are systematically lower than those derived from the CELs. These ORL versus CEL abundance and temperature discrepancies, previously observed in the three PNe through deep spectroscopy with medium to low spectral resolution, are thus confirmed by our analysis of the deep echelle spectra using the new atomic data.

  20. Predicting the fate of binary red giants using the observed sequence E star population: binary planetary nebula nuclei and post-RGB stars

    NASA Astrophysics Data System (ADS)

    Nie, J. D.; Wood, P. R.; Nicholls, C. P.

    2012-07-01

    Sequence E variables are close binary red giants that show ellipsoidal light variations. They are likely the immediate precursors of planetary nebulae (PNe) with close binary central stars as well as other binary post-asymptotic giant branch (post-AGB) and binary post-red giant branch (post-RGB) stars. We have made a Monte Carlo simulation to determine the fraction of red giant binaries that go through a common envelope event leading to the production of a close binary system or a merged star. The novel aspect of this simulation is that we use the observed frequency of sequence E binaries in the Large Magellanic Cloud (LMC) to normalize our calculations. This normalization allows us to produce predictions that are relatively independent of model assumptions. In our standard model, and assuming that the relative numbers of PNe of various types are proportional to their birth rates, we find that in the LMC today the fraction of PNe with close binary central stars is 7-9 per cent, the fraction of PNe with intermediate period binary central stars having separations capable of influencing the nebula shape (orbital periods less than 500 yr) is 23-27 per cent, the fraction of PNe containing wide binaries that are unable to influence the nebula shape (orbital period greater than 500 yr) is 46-55 per cent, the fraction of PNe derived from single stars is 3-19 per cent, and 5-6 per cent of PNe are produced by previously merged stars. We also predict that the birth rate of post-RGB stars is ˜4 per cent of the total PN birth rate, equivalent to ˜50 per cent of the production rate of PNe with close binary central stars. These post-RGB stars most likely appear initially as luminous low-mass helium white dwarf binaries. The average lifetime of sequence E ellipsoidal variability with amplitude more than 0.02 mag is predicted to be ˜0.95 Myr. We use our model and the observed number of red giant stars in the top one magnitude of the RGB in the LMC to predict the number of PNe in

  1. Ant nebula

    NASA Technical Reports Server (NTRS)

    1999-01-01

    A new Hubble Space Telescope image of a celestial object called the Ant Nebula may shed new light on the future demise of our Sun. The image is available at http://www.jpl.nasa.gov/pictures/wfpc .

    The nebula, imaged on July 20, 1997, and June 30, 1998, by Hubble's Wide Field and Planetary Camera 2, was observed by Drs. Raghvendra Sahai and John Trauger of NASA's Jet Propulsion Laboratory, Pasadena, Calif.; Bruce Balick of the University of Washington in Seattle; and Vincent Icke of Leiden University in the Netherlands. JPL designed and built the camera.

    The Ant Nebula, whose technical name is Mz3, resembles the head and thorax of an ant when observed with ground-based telescopes. The new Hubble image, with 10 times the resolution revealing 100 times more detail, shows the 'ant's' body as a pair of fiery lobes protruding from a dying, Sun- like star. The Ant Nebula is located between 3,000 and 6,000 light years from Earth in the southern constellation Norma.

    The image challenges old ideas about what happens to dying stars. This observation, along with other pictures of various remnants of dying stars called planetary nebulae, shows that our Sun's fate will probably be much more interesting, complex and dramatic than astronomers previously believed.

    Although the ejection of gas from the dying star in the Ant Nebula is violent, it does not show the chaos one might expect from an ordinary explosion, but instead shows symmetrical patterns. One possibility is that the central star has a closely orbiting companion whose gravitational tidal forces shape the outflowing gas. A second possibility is that as the dying star spins, its strong magnetic fields are wound up into complex shapes like spaghetti in an eggbeater. Electrically charged winds, much like those in our Sun's solar wind but millions of times denser and moving at speeds up to 1,000 kilometers per second (more than 600 miles per second) from the star, follow the twisted field lines on their way

  2. Astrometry With the Hubble Space Telescope: Trigonometric Parallaxes of Planetary Nebula Nuclei NGC 6853, NGC 7293, ABELL 31, and DeHt 5

    NASA Technical Reports Server (NTRS)

    Benedict, G. F.; McArthur, Barbara E.; Napiwotzki, Ralf; Harrison, Thomas E.; Harris, Hugh C.; Nelan, Edmund; Bond, Howard E; Patterson, Richard J.; Ciardullo, Robin

    2009-01-01

    We present absolute parallaxes and relative proper motions for the central stars of the planetary nebulae NGC 6853 (The Dumbbell), NGC 7293 (The Helix), Abell 31, and DeHt 5. This paper details our reduction and analysis using DeHt 5 as an example. We obtain these planetary nebula nuclei (PNNi) parallaxes with astrometric data from Fine Guidance Sensors FGS 1r and FGS 3, white-light interferometers on the Hubble Space Telescope. Proper motions, spectral classifications and VJHKT2M and DDO51 photometry of the stars comprising the astrometric reference frames provide spectrophotometric estimates of reference star absolute parallaxes. Introducing these into our model as observations with error, we determine absolute parallaxes for each PNN. Weighted averaging with previous independent parallax measurements yields an average parallax precision, sigma (sub pi)/ pi = 5%. Derived distances are: d(sub NGC6853) = 405(exp +28 sub -25) pc, d(sub NGC7293) = 216(exp +14 sub -12) pc, d(sub Abell31) = 621(exp +91 sub -70) pc, and d(sub DeHt5) = 345(exp +19 sub -17) pc. These PNNi distances are all smaller than previously derived from spectroscopic analyses of the central stars. To obtain absolute magnitudes from these distances requires estimates of interstellar extinction. We average extinction measurements culled from the literature, from reddening based on PNNi intrinsic colors derived from model SEDs, and an assumption that each PNN experiences the same rate of extinction as a function of distance as do the reference stars nearest (in angular separation) to each central star. We also apply Lutz-Kelker bias corrections. The absolute magnitudes and effective temperatures permit estimates of PNNi radii through both the Stefan-Boltzmann relation and Eddington fluxes. Comparing absolute magnitudes with post-AGB models provides mass estimates. Masses cluster around 0.57 solar Mass, close to the peak of the white dwarf mass distribution. Adding a few more PNNi with well

  3. Astrometry with the Hubble Space Telescope: Trigonometric Parallaxes of Planetary Nebula Nuclei NGC 6853, NGC 7293, Abell 31, and DeHt 5

    NASA Astrophysics Data System (ADS)

    Benedict, G. Fritz; McArthur, Barbara E.; Napiwotzki, Ralf; Harrison, Thomas E.; Harris, Hugh C.; Nelan, Edmund; Bond, Howard E.; Patterson, Richard J.; Ciardullo, Robin

    2009-12-01

    We present absolute parallaxes and relative proper motions for the central stars of the planetary nebulae NGC 6853 (The Dumbbell), NGC 7293 (The Helix), Abell 31, and DeHt 5. This paper details our reduction and analysis using DeHt 5 as an example. We obtain these planetary nebula nuclei (PNNi) parallaxes with astrometric data from Fine Guidance Sensors FGS 1r and FGS 3, white-light interferometers on the Hubble Space Telescope. Proper motions, spectral classifications and VJHKT2M and DDO51 photometry of the stars comprising the astrometric reference frames provide spectrophotometric estimates of reference star absolute parallaxes. Introducing these into our model as observations with error, we determine absolute parallaxes for each PNN. Weighted averaging with previous independent parallax measurements yields an average parallax precision, σπ/π = 5%. Derived distances are: d NGC 6853 = 405+28 -25 pc, d NGC 7293 = 216+14 -12 pc, d Abell 31 = 621+91 -70 pc, and d DeHt 5 = 345+19 -17 pc. These PNNi distances are all smaller than previously derived from spectroscopic analyses of the central stars. To obtain absolute magnitudes from these distances requires estimates of interstellar extinction. We average extinction measurements culled from the literature, from reddening based on PNNi intrinsic colors derived from model SEDs, and an assumption that each PNN experiences the same rate of extinction as a function of distance as do the reference stars nearest (in angular separation) to each central star. We also apply Lutz-Kelker bias corrections. The absolute magnitudes and effective temperatures permit estimates of PNNi radii through both the Stefan-Boltzmann relation and Eddington fluxes. Comparing absolute magnitudes with post-AGB models provides mass estimates. Masses cluster around 0.57 M_{⊙}, close to the peak of the white dwarf mass distribution. Adding a few more PNNi with well-determined distances and masses, we compare all the PNNi with cooler white dwarfs

  4. FAR-INFRARED IMAGING OF POST-ASYMPTOTIC GIANT BRANCH STARS AND (PROTO)-PLANETARY NEBULAE WITH THE AKARI FAR-INFRARED SURVEYOR

    SciTech Connect

    Cox, N. L. J.; Garcia-Hernandez, D. A.; Manchado, A.

    2011-04-15

    By tracing the distribution of cool dust in the extended envelopes of post-asymptotic giant branch stars and (proto)-planetary nebulae ((P)PNe), we aim to recover, or constrain, the mass-loss history experienced by these stars in their recent past. The Far-Infrared Surveyor (FIS) instrument on board the AKARI satellite was used to obtain far-infrared maps for a selected sample of post-AGB stars and (P)PNe. We derived flux densities (aperture photometry) for 13 post-AGB stars and (P)PNe at four far-infrared wavelengths (65, 90, 140, and 160 {mu}m). Radial (azimuthally averaged) profiles are used to investigate the presence of extended emission from cool dust. No (detached) extended emission is detected for any target in our sample at levels significant with respect to background and cirrus emission. Only IRAS 21046+4739 reveals tentative excess emission between 30'' and 130''. Estimates of the total dust and gas mass from the obtained maps indicate that the envelope masses of these stars should be large in order to be detected with the AKARI FIS. Imaging with higher sensitivity and higher spatial resolution is needed to detect and resolve, if present, any cool compact or extended emission associated with these evolved stars.

  5. H I free-bound emission of planetary nebulae with large abundance discrepancies: Two-component models versus κ-distributed electrons

    SciTech Connect

    Zhang, Yong; Liu, Xiao-Wei; Zhang, Bing

    2014-01-01

    The 'abundance discrepancy' problem in the study of planetary nebulae (PNe), viz., the problem concerning systematically higher heavy-element abundances derived from optical recombination lines relative to those from collisionally excited lines, has been under discussion for decades, but no consensus on its solution has yet been reached. In this paper, we investigate the hydrogen free-bound emission near the Balmer jump region of four PNe that are among those with the largest abundance discrepancies, aiming to examine two recently proposed solutions to this problem: two-component models and κ electron energy distributions. We find that the Balmer jump intensities and the spectrum slopes cannot be simultaneously matched by the theoretical calculations based upon single Maxwell-Boltzmann electron-energy distributions, whereas the fitting can be equally improved by introducing κ electron energy distributions or an additional Maxwell-Boltzmann component. We show that although H I free-bound emission alone cannot distinguish between the two scenarios, it can provide important constraints on the electron energy distributions, especially for cold and low-κ plasmas.

  6. A KINEMATIC DISTANCE STUDY OF THE PLANETARY NEBULAE-SUPERNOVA REMNANT-H II REGION COMPLEX AT G35.6–0.5

    SciTech Connect

    Zhu, H.; Tian, W. W.; Su, H. Q.; Torres, D. F.; Pedaletti, G. E-mail: tww@bao.ac.cn

    2013-10-01

    Two possible planetary nebulae (PN G035.5–00.4 and IRAS 18551+0159), one newly re-identified supernova remnant (SNR G35.6–0.4), and one H II region (G35.6–0.5) form a line-of-sight-overlapping complex known as G35.6–0.5. We analyze 21 cm H I absorption spectra toward the complex to constrain the kinematic distances of these objects. PN G035.5–00.4 has a distance from 3.8 ± 0.4 kpc to 5.4 ± 0.7 kpc. IRAS 18551+0159 is at 4.3 ± 0.5 kpc. We discuss the distance for SNR 35.6–0.4, for which the previous estimate was 10.5 kpc, and find a plausible distance of 3.6 ± 0.4 kpc. The new distance of SNR G35.6–0.4 and the derived mass for the ∼55 km s{sup –1} CO molecular cloud can accommodate an association with HESS J1858+020. We also conclude that SNR G35.6–0.4 is unlikely to be associated with PSR J1857+0210 or PSR J1857+0212, which are projected onto the SNR area.

  7. SERENDIPITOUS DETECTION OF X-RAY EMISSION FROM THE HOT BORN-AGAIN CENTRAL STAR OF THE PLANETARY NEBULA K 1-16

    SciTech Connect

    Montez, Rodolfo Jr.; Kastner, Joel H. E-mail: jhk@cis.rit.edu

    2013-03-20

    We report the serendipitous detection of point-like X-ray emission from the hot, PG1159-type central star of the planetary nebula (CSPN) K 1-16 by the XMM-Newton and Chandra X-Ray Observatories. The CSPN lies superimposed on a galaxy cluster that includes an X-ray-bright quasar, but we have successfully isolated the CSPN X-ray emission from the strong diffuse background contributed by the quasar and intracluster gas. We have modeled the XMM-Newton and Chandra X-ray data, taking advantage of the contrasting detection efficiencies of the two observatories to better constrain the low-energy spectral response of Chandra's Advanced CCD Imaging Spectrometer. We find that the CSPN X-ray spectrum is well characterized by the combination of a non-local thermodynamic equilibrium model atmosphere with T{sub *} {approx} 135 kK and a carbon-rich, optically thin thermal plasma with T{sub X} {approx} 1 MK. These results for X-ray emission from the K 1-16 CSPN, combined with those obtained for other PG1159-type objects, lend support to the 'born-again' scenario for Wolf-Rayet and PG1159 CSPNe, wherein a late helium shell flash dredges up carbon-rich intershell material and ejects this material into the circumstellar environment.

  8. Serendipitous Detection of X-Ray Emission from the Hot Born-again Central Star of the Planetary Nebula K 1-16

    NASA Astrophysics Data System (ADS)

    Montez, Rodolfo, Jr.; Kastner, Joel H.

    2013-03-01

    We report the serendipitous detection of point-like X-ray emission from the hot, PG1159-type central star of the planetary nebula (CSPN) K 1-16 by the XMM-Newton and Chandra X-Ray Observatories. The CSPN lies superimposed on a galaxy cluster that includes an X-ray-bright quasar, but we have successfully isolated the CSPN X-ray emission from the strong diffuse background contributed by the quasar and intracluster gas. We have modeled the XMM-Newton and Chandra X-ray data, taking advantage of the contrasting detection efficiencies of the two observatories to better constrain the low-energy spectral response of Chandra's Advanced CCD Imaging Spectrometer. We find that the CSPN X-ray spectrum is well characterized by the combination of a non-local thermodynamic equilibrium model atmosphere with T sstarf ~ 135 kK and a carbon-rich, optically thin thermal plasma with T X ~ 1 MK. These results for X-ray emission from the K 1-16 CSPN, combined with those obtained for other PG1159-type objects, lend support to the "born-again" scenario for Wolf-Rayet and PG1159 CSPNe, wherein a late helium shell flash dredges up carbon-rich intershell material and ejects this material into the circumstellar environment.

  9. ALMA Observations of the Water Fountain Pre-Planetary Nebula IRAS 16342-3814: High-Velocity Bipolar Jets and an Expanding Torus.

    PubMed

    Sahai, R; Vlemmings, W H T; Gledhill, T; Sánchez Contreras, C; Lagadec, E; Nyman, L-Å; Quintana-Lacaci, G

    2017-01-20

    We have mapped (12)CO J=3-2 and other molecular lines from the "water-fountain" bipolar pre-planetary nebula (PPN) IRAS 16342-3814 with [Formula: see text] resolution using ALMA. We find (i) two very high-speed knotty, jet-like molecular outflows, (ii) a central high-density (> few × 10(6) cm(-3)), expanding torus of diameter 1300 AU, and (iii) the circumstellar envelope of the progenitor AGB, generated by a sudden, very large increase in the mass-loss rate to > 3.5 × 10(-4)M⊙ yr(-1) in the past ~455 yr. Strong continuum emission at 0.89 mm from a central source (690 mJy), if due to thermally-emitting dust, implies a substantial mass (0.017 M⊙) of very large (~mm-sized) grains. The measured expansion ages of the above structural components imply that the torus (age~160 yr) and the younger high-velocity outflow (age~110 yr) were formed soon after the sharp increase in the AGB mass-loss rate. Assuming a binary model for the jets in IRAS 16342, the high momentum rate for the dominant jet-outflow in IRAS 16342 implies a high minimum accretion rate, ruling out standard Bondi-Hoyle-Lyttleton wind accretion and wind Roche lobe overflow (RLOF) models with white-dwarf or main-sequence companions. Most likely, enhanced RLOF from the primary or accretion modes operating within common envelope evolution are needed.

  10. Neutron-capture element abundances in the planetary nebula NGC 5315 from deep high-resolution optical and near-IR spectrophotometry

    NASA Astrophysics Data System (ADS)

    Madonna, S.; García-Rojas, J.; Sterling, N. C.; Luridiana, V.

    2017-03-01

    We have done a spectroscopical analysis of the type I planetary nebula (PN) NGC 5315, through high-resolution (R ˜ 40000) optical spectroscopy with UVES at the 8.2m Very Large Telescope, and medium-resolution (R ˜ 4800) near-IR spectroscopy with FIRE at the 6.5m Magellan Baade telescope, covering a wide spectral range from 0.31 μm to 2.50μm. The main aim of this work is to investigate the slow neutron(n)-capture process (the s-process) in the Asymptotic Giant Branch (AGB) star progenitor of a type I PNe. We detected and identified about 700 features, including lines from the n-capture elements Kr, Se, and possibly Br and Xe. We compute physical conditions using line ratios of common ions. Ionic abundances are computed for the species with available atomic data. We calculate total abundances using recent ionization correction factors (ICFs) or by summing ionic abundances. Our results for common elements are in good agreement with previous works on the same object. We do not find a substantial s-process enrichment in NGC 5315, which is typical for type I PNe.

  11. Resolving shocked and UV excited components of H2 emission in planetary nebulae with high-resolution near-infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Kaplan, Kyle; Dinerstein, Harriet L.; Jaffe, Daniel Thomas

    2016-06-01

    Planetary nebulae (PNe) form when low and intermediate-mass stars eject their outer layers into the ISM at the end of the AGB phase. Many PNe exhibit near-infrared (NIR) emission from molecular hydrogen (H2). This NIR emission arises from radiative decay out of excited rotation-vibration (rovibrational) states. The rovibrational states can be populated by excitation to higher electronic states through absorption of a far-UV photon followed by a radiative cascade to the electronic ground state, or by collisions (e.g., in a hot gas). The two processes populate the rovibrational levels of H2 differently, so the observed emergent emission spectrum provides an effective probe of the mechanisms that excite the H2. Many PNe display line intensity ratios that are intermediate between these two processes (Otsuka et al. 2013). With the advantages of the high spectral resolution (R~40000), broad wavelength coverage (1.45-2.45 μm), and high spatial resolution of the Immersion GRating Infrared Spectrometer (IGRINS, Park et al. 2014), we are able to differentiate components in position-velocity space: we see a slowly expanding UV-excited H2 shell in the PN M 1-11 and two faster moving “bullets” of thermalized H2 that we interpret as shocked gas from a bipolar outflow. We also present observations of several other PNe that exhibit similar morphologies of thermalized and UV-excited H2 components.

  12. Cospatial Longslit UV-Optical Spectra of Ten Galactic Planetary Nebulae with HST STIS: Description of observations, global emission-line measurements, and empirical CNO abundances

    NASA Astrophysics Data System (ADS)

    Dufour, R. J.; Kwitter, K. B.; Shaw, R. A.; Balick, B.; Henry, R. B. C.; Miller, T. R.; Corradi, R. L. M.

    2015-01-01

    This poster describes details of HST Cycle 19 (program GO 12600), which was awarded 32 orbits of observing time with STIS to obtain the first cospatial UV-optical spectra of 10 Galactic planetary nebulae (PNe). The observational goal was to measure the UV emission lines of carbon and nitrogen with unprecedented S/N and wavelength and spatial resolution along the disk of each object over a wavelength range 1150-10270 Ang . The PNe were chosen such that each possessed a near-solar metallicity but the group together spanned a broad range in N/O. This poster concentrates on describing the observations, emission-line measurements integrated along the entire slit lengths, ionic abundances, and estimated total elemental abundances using empirical ionization correction factors and the ELSA code. Related posters by co-authors in this session concentrate on analyzing CNO abundances, progenitor masses and nebular properties of the best-observed targets using photoionization modeling of the global emission-line measurements [Henry et al.] or detailed analyses of spatial variations in electron temperatures, densities, and abundances along the sub arcsecond resolution slits [Miller et al. & Shaw et al.]. We gratefully acknowledge AURA/STScI for the GO 12600 program support, both observational and financial.

  13. ALMA Observations of the Water Fountain Pre-planetary Nebula IRAS 16342-3814: High-velocity Bipolar Jets and an Expanding Torus

    NASA Astrophysics Data System (ADS)

    Sahai, R.; Vlemmings, W. H. T.; Gledhill, T.; Sánchez Contreras, C.; Lagadec, E.; Nyman, L.-Å; Quintana-Lacaci, G.

    2017-01-01

    We have mapped 12CO J = 3–2 and other molecular lines from the “water fountain” bipolar pre-planetary nebula (PPN) IRAS 16342-3814 with ∼0.″35 resolution using Atacama Large Millimeter/submillimeter Array. We find (i) two very high-speed knotty, jet-like molecular outflows; (ii) a central high-density (> {few}× {10}6 cm‑3), expanding torus of diameter 1300 au; and (iii) the circumstellar envelope of the progenitor AGB, generated by a sudden, very large increase in the mass-loss rate to > 3.5× {10}-4 M⊙ yr‑1 in the past ∼455 years. Strong continuum emission at 0.89 mm from a central source (690 mJy), if due to thermally emitting dust, implies a substantial mass (0.017 M⊙) of very large (∼millimeter-sized) grains. The measured expansion ages of the above structural components imply that the torus (age ∼160 years) and the younger high-velocity outflow (age ∼110 years) were formed soon after the sharp increase in the AGB mass-loss rate. Assuming a binary model for the jets in IRAS 16342, the high momentum rate for the dominant jet-outflow in IRAS 16342 implies a high minimum accretion rate, ruling out standard Bondi–Hoyle–Lyttleton wind accretion and wind Roche-lobe overflow (RLOF) models with white-dwarf or main-sequence companions. Most likely, enhanced RLOF from the primary or accretion modes operating within common-envelope evolution are needed.

  14. BINARY CENTRAL STARS OF PLANETARY NEBULAE DISCOVERED THROUGH PHOTOMETRIC VARIABILITY. II. MODELING THE CENTRAL STARS OF NGC 6026 AND NGC 6337

    SciTech Connect

    Hillwig, Todd C.; Bond, Howard E.; Afsar, Melike; De Marco, Orsola

    2010-08-15

    Close-binary central stars of planetary nebulae (CSPNe) provide an opportunity to explore the evolution of PNe, their shaping, and the evolution of binary systems undergoing a common-envelope phase. Here, we present the results of time-resolved photometry of the binary central stars (CSs) of the PNe NGC 6026 and NGC 6337 as well as time-resolved spectroscopy of the CS of NGC 6026. The results of a period analysis give an orbital period of 0.528086(4) days for NGC 6026 and a photometric period of 0.1734742(5) days for NGC 6337. In the case of NGC 6337, it appears that the photometric period reflects the orbital period and that the variability is the result of the irradiated hemisphere of a cool companion. The inclination of the thin PN ring is nearly face-on. Our modeled inclination range for the close central binary includes nearly face-on alignments and provides evidence for a direct binary-nebular shaping connection. For NGC 6026, however, the radial-velocity curve shows that the orbital period is twice the photometric period. In this case, the photometric variability is due to an ellipsoidal effect in which the CS nearly fills its Roche lobe and the companion is most likely a hot white dwarf. NGC 6026 then is the third PN with a confirmed central binary where the companion is compact. Based on the data and modeling using a Wilson-Devinney code, we discuss the physical parameters of the two systems and how they relate to the known sample of close-binary CSs, which comprise 15%-20% of all PNe.

  15. The Dust Properties of Hot R Coronae Borealis Stars and a Wolf-Rayet Central Star of a Planetary Nebula: In Search of the Missing Link

    NASA Technical Reports Server (NTRS)

    Clayton, Geoffrey C.; De Marco, O.; Whitney, B. A.; Babler, B.; Gallagher, J. S.; Nordhaus, J.; Speck, A. K.; Wolff, M. J.; Freeman, W. R.; Camp, K. A.; Lawson, W. A.; Roman-Duval, J.; Misselt, K. A.; Meade, M.; Sonneborn, G.; Matsuura, M.; Meixner, M.

    2012-01-01

    We present new Spitzer IIRS spectra of two hot R Coronae Borealis (RCB) stars, one in the Galaxy,V348 Sgr, and one lying in the Large Magellanic Cloud, HV 2671. These two objects constitute a link between the RCB stars and the [WCL] class of central stars of planetary nebula (CSPNe) that has little or no hydrogen in their atmospheres such as CPD -560 8032. HV 2671 and V348 Sgr are members of a rare subclass that has significantly higher effective temperatures than most RCB stars, but sharing the traits of hydrogen deficiency and dust formation that define the cooler RCB stars. The [WC] CSPNe star, CPD -560 8032, displays evidence for dual-dust chemistry showing both PAHs and crystalline silicates in its mid-IR spectrum. HV 2671 shows strong PAH emission but shows no sign of having crystalline silicates. The spectrum of V348 Sgr is very different from those of CPD -56deg 8032 and HV 2671. The PAH emission seen strongly in the other two stars is only weakly present. Instead, the spectrum is dominated by a broad emission centered at about 8.5 microns. This feature is not identified with either PAHs or silicates. Several other novae and post-asymptotic giant branch stars show similar features in their IR spectra. The mid-IR spectrum of CPD -56deg 8032 shows emission features associated with C60 . The other two stars do not show evidence for C60. The nature of the dust around these stars does not help us in establishing further links that may indicate a common origin.

  16. ALMA Observations of the Water Fountain Pre-Planetary Nebula IRAS 16342-3814: High-Velocity Bipolar Jets and an Expanding Torus

    PubMed Central

    Sahai, R.; Vlemmings, W.H.T.; Gledhill, T.; Sánchez Contreras, C.; Lagadec, E.; Nyman, L-Å; Quintana-Lacaci, G.

    2017-01-01

    We have mapped 12CO J=3–2 and other molecular lines from the “water-fountain” bipolar pre-planetary nebula (PPN) IRAS 16342-3814 with ∼0⋅″35 resolution using ALMA. We find (i) two very high-speed knotty, jet-like molecular outflows, (ii) a central high-density (> few × 106 cm−3), expanding torus of diameter 1300 AU, and (iii) the circumstellar envelope of the progenitor AGB, generated by a sudden, very large increase in the mass-loss rate to > 3.5 × 10−4 M⊙ yr−1 in the past ~455 yr. Strong continuum emission at 0.89 mm from a central source (690 mJy), if due to thermally-emitting dust, implies a substantial mass (0.017 M⊙) of very large (~mm-sized) grains. The measured expansion ages of the above structural components imply that the torus (age~160 yr) and the younger high-velocity outflow (age~110 yr) were formed soon after the sharp increase in the AGB mass-loss rate. Assuming a binary model for the jets in IRAS 16342, the high momentum rate for the dominant jet-outflow in IRAS 16342 implies a high minimum accretion rate, ruling out standard Bondi-Hoyle-Lyttleton wind accretion and wind Roche lobe overflow (RLOF) models with white-dwarf or main-sequence companions. Most likely, enhanced RLOF from the primary or accretion modes operating within common envelope evolution are needed. PMID:28191303

  17. 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.

  18. Atomic data from the Iron Project. XLIV. Transition probabilities and line ratios for Fe VI with fluorescent excitation in planetary nebulae

    NASA Astrophysics Data System (ADS)

    Chen, Guo Xin; Pradhan, Anil K.

    2000-11-01

    Relativistic atomic structure calculations for electric dipole (E1), electric quadrupole (E2) and magnetic dipole (M1) transition probabilities among the first 80 fine-structure levels of Fe VI, dominated by configurations 3d3, 3d24s, and 3d24p, are carried out using the Breit-Pauli version of the code SUPERSTRUCTURE. Experimental energies are used to improve the accuracy of these transition probabilities. Employing the 80-level collision-radiative (CR) model with these dipole and forbidden transition probabilities, and Iron Project R-matrix collisional data, we present a number of [Fe VI] line ratios applicable to spectral diagnostics of photoionized H II regions. It is shown that continuum fluorescent excitation needs to be considered in CR models in order to interpret the observed line ratios of optical [Fe VI] lines in planetary nebulae NGC 6741, IC 351, and NGC 7662. The analysis leads to parametrization of line ratios as function of, and as constraints on, the electron density and temperature, as well as the effective radiation temperature of the central source and a geometrical dilution factor. The spectral diagnostics may also help ascertain observational uncertainties. The method may be generally applicable to other objects with intensive background radiation fields, such as novae and active galactic nuclei. The extensive new Iron Project radiative and collisional calculations enable a consistent analysis of many line ratios for the complex iron ions. The complete tables of transition probabilities are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/Abstract.html.

  19. Deep high spectral resolution spectroscopy and chemical composition of ionized nebulae

    NASA Astrophysics Data System (ADS)

    Esteban, C.; García-Rojas, J.; Mesa-Delgado, A.; Toribio San Cipriano, L.

    2014-01-01

    High spectral resolution spectroscopy has proved to be very useful for the advancement of chemical abundances studies in photoionized nebulae, such as H II regions and planetary nebulae (PNe). Classical analyses make use of the intensity of bright collisionally excited lines (CELs), which have a strong dependence on the electron temperature and density. By using high resolution spectrophotometric data, our group has led the determination of chemical abundances of some heavy element ions, mainly O++, O+, and C++ from faint recombination lines (RLs), allowing us to deblend them from other nearby emission lines or sky features. The importance of these lines is that their emissivity depends weakly on the temperature and density structure of the gas. The unresolved issue in this field is that recombination lines of heavy element ions give abundances that are about 2-3 times higher than those derived from CELs - in H II regions - for the same ion, and can even be a factor of 70 times higher in some PNe. This uncertainty puts into doubt the validity of face values of metallicity that we use as representative not only for ionized nebulae in the Local Universe, but also for star-forming dwarf and spiral galaxies at different redshifts. Additionally, high-resolution data can allow us to detect and deblend faint lines of neutron capture element ions in PNe. This information would introduce further restrictions to evolution models of AGBs and would help to quantify the chemical enrichment in s-elements produced by low and intermediate mass stars. The availability of an échelle spectrograph at the E-ELT will be of paramount interest to: (a) extend the studies of heavy-element recombination lines to low metallicity objects, (b) to extend abundance determinations of s-elements to planetary nebulae in the extragalactic domain and to bright Galactic and extragalactic H II regions.

  20. Faint detection of exoplanets in microlensing surveys

    SciTech Connect

    Brown, Robert A.

    2014-06-20

    We propose a new approach to discovering faint microlensing signals below traditional thresholds, and for estimating the binary-lens mass ratio and the apparent separation from such signals. The events found will be helpful in accurately estimating the true distribution of planetary semimajor axes, which is an important goal of space microlensing surveys.

  1. Chemical Abundances and Dust in the Halo Planetary Nebula K648 in M15: Its Origin and Evolution Based on an Analysis of Multiwavelength Data

    NASA Astrophysics Data System (ADS)

    Otsuka, Masaaki; Hyung, Siek; Tajitsu, Akito

    2015-04-01

    We report on an investigation of the extremely metal-poor and C-rich planetary nebula (PN) K648 in M15 using the UV to far-infrared data obtained using Subaru, the Hubble Space Telescope, the Far Ultraviolet Spectroscopic Explorer, Spitzer, and Herschel. We determined the nebular abundances of 10 elements. The enhancement of F ([F/H] = +0.96) is comparable to that of the halo PN BoBn1. The central stellar abundances of seven elements are determined. The stellar C/O ratio is similar to the nebular C/O ratios from recombination lines and from collisionally excited lines (CELs) within error, and the stellar Ne/O ratio is also close to the nebular CEL Ne/O ratio. We found evidence of carbonaceous dust grains and molecules including Class B 6-9 and 11.3 μm polycyclic aromatic hydrocarbons and the broad 11 μm feature. The profiles of these bands are similar to those of the C-rich halo PNe H4-1 and BoBn1. Based on the theoretical model, we determined the physical conditions of the gas and dust and their masses, i.e., 0.048 and 4.95 × 10-7 {{M}⊙ }, respectively. The observed chemical abundances and gas mass are in good agreement with an asymptotic giant branch nucleosynthesis model prediction for stars with an initial 1.25 {{M}⊙ } plus a 2.0 × 10-3 {{M}⊙ } partial mixing zone (PMZ) and stars with an initial mass of 1.5 {{M}⊙ } without a PMZ. The core mass of the central star is approximately 0.61-0.63 {{M}⊙ }. K648 is therefore likely to have evolved from a progenitor that experienced coalescence or tidal disruption during the early stages of evolution, and became a ˜1.25-1.5 {{M}⊙ } blue straggler.

  2. On the Complexity of H2 Excitation Near Hot Stars: High Spectral and Spatial Resolution Observations of Compact Planetary Nebulae with IGRINS

    NASA Astrophysics Data System (ADS)

    Dinerstein, Harriet L.; Kaplan, Kyle F.; Jaffe, Daniel T.

    2015-08-01

    Near-infrared emission lines of vibrationally-excited H2 were first detected in planetary nebulae (PNe) four decades ago. In some environments, e.g. outflows from low-mass young stellar objects, such emission is generally attributed to shock heating. The situation is more complicated for PNe, which host more than one potential agent of excitation. Shocks are indeed present within PNe, due to interactions among expanding layers of different velocities. On the other hand, the UV radiation field of the central star can populate excited vibrational levels of the ground electronic state via an indirect process, initiated by transitions to excited electronic states upon absorption of non-H-ionizing UV photons (the H2 Lyman-Werner bands), followed by radiative decay. When not modified by other processes, this produces a highly distinctive “pure fluorescent” H2 spectrum (Black & van Dishoeck 1987, ApJ, 322, 412). Such emission was first identified in a PN, Hb 12, by Dinerstein et al. 1988 (ApJ, 327, L27). Later surveys (e.g. Hora et al. 1999, ApJS, 124, 195; Likkel & Dinerstein et al. 2006, AJ, 131, 1515) found that some PNe display thermal (collisionally-dominated) spectra, a few are fluorescent, and others show intermediate line ratios. It is not always easy to distinguish whether the latter is due to a superposition of radiative and shock components (Davis et al. 2003, MNRAS, 344, 262), or to thermalization of initially radiatively excited molecules due to high density, a hard radiation field, and/or advective effects (e.g. Henney et al. 2007, ApJ, 671, 137). We present new observations of H2 in PNe obtained with the high-spectral resolution (R = 40,000), broad spectral grasp IGRINS spectrometer (Park & Jaffe et al. 2014, Proc SPIE, 9147). This instrument reveals small-scale structures in position-velocity space that differ in excitation and emergent line ratios. For example, the compact PN M 1-11 contains both a fluorescent shell of H2 and higher-velocity compact

  3. CO-SPATIAL LONG-SLIT UV/OPTICAL SPECTRA OF TEN GALACTIC PLANETARY NEBULAE WITH HST/STIS. II. NEBULAR MODELS, CENTRAL STAR PROPERTIES, AND He+CNO SYNTHESIS

    SciTech Connect

    Henry, R. B. C.; Miller, T. R.; Balick, B.; Dufour, R. J.; Kwitter, K. B.; Shaw, R. A.; Buell, J. F.; Corradi, R. L. M.

    2015-11-10

    The goal of the present study is twofold. First, we employ new HST/STIS spectra and photoionization modeling techniques to determine the progenitor masses of eight planetary nebulae (IC 2165, IC 3568, NGC 2440, NGC 3242, NGC 5315, NGC 5882, NGC 7662, and PB 6). Second, for the first time we are able to compare each object’s observed nebular abundances of helium, carbon, and nitrogen with abundance predictions of these same elements by a stellar model that is consistent with each object’s progenitor mass. Important results include the following: (1) the mass range of our objects’ central stars matches well with the mass distribution of other central stars of planetary nebulae and white dwarfs; (2) He/H is above solar in all of our objects, in most cases likely due to the predicted effects of first dredge-up; (3) most of our objects show negligible C enrichment, probably because their low masses preclude third dredge-up; (4) C/O versus O/H for our objects appears to be inversely correlated, which is perhaps consistent with the conclusion of theorists that the extent of atmospheric carbon enrichment from first dredge-up is sensitive to a parameter whose value increases as metallicity declines; (5) stellar model predictions of nebular C and N enrichment are consistent with observed abundances for progenitor star masses ≤1.5 M{sub ⊙}. Finally, we present the first published photoionization models of NGC 5315 and NGC 5882.

  4. The Twin Jet Nebula

    NASA Technical Reports Server (NTRS)

    1997-01-01

    M2-9 is a striking example of a 'butterfly' or a bipolar planetary nebula. Another more revealing name might be the 'Twin Jet Nebula.' If the nebula is sliced across the star, each side of it appears much like a pair of exhausts from jet engines. Indeed, because of the nebula's shape and the measured velocity of the gas, in excess of 200 miles per second, astronomers believe that the description as a super-super-sonic jet exhaust is quite apt. This is much the same process that takes place in a jet engine: The burning and expanding gases are deflected by the engine walls through a nozzle to form long, collimated jets of hot air at high speeds. M2-9 is 2,100 light-years away in the constellation Ophiucus. The observation was taken Aug. 2, 1997 by the Hubble telescope's Wide Field and Planetary Camera 2. In this image, neutral oxygen is shown in red, once-ionized nitrogen in green, and twice-ionized oxygen in blue.

  5. The Orion nebula star cluster

    NASA Technical Reports Server (NTRS)

    Panek, R. J.

    1982-01-01

    Photography through filters which suppress nebular light reveal a clustering of faint red stars centered on the Trapezium, this evidences a distinct cluster within the larger OB1 association. Stars within about 20 ft of trapezium comprise the Orion Nebula star cluster are considered. Topics discussed re: (1) extinction by dust grains; (2) photometric peculiarities; (3) spectroscopic peculiarities; (4) young variables; (5) the distribution and motion of gas within the cluster.

  6. Modelling the structure and kinematics of the Firework nebula: The nature of the GK Persei nova shell and its jet-like feature

    NASA Astrophysics Data System (ADS)

    Harvey, E.; Redman, M. P.; Boumis, P.; Akras, S.

    2016-10-01

    Aims: The shaping mechanisms of old nova remnants are probes for several important and unexplained processes, such as dust formation and the structure of evolved star nebulae. To gain a more complete understanding of the dynamics of the GK Per (1901) remnant, an examination of symmetry of the nova shell is explored, followed by a kinematical analysis of the previously detected jet-like feature in the context of the surrounding fossil planetary nebula. Methods: Faint-object high-resolution echelle spectroscopic observations and imaging were undertaken covering the knots which comprise the nova shell and the surrounding nebulosity. New imaging from the Aristarchos telescope in Greece and long-slit spectra from the Manchester Echelle Spectrometer instrument at the San Pedro Mártir observatory in Mexico were obtained, supplemented with archival observations from several other optical telescopes. Position-velocity arrays are produced of the shell, and also individual knots, and are then used for morpho-kinematic modelling with the shape code. The overall structure of the old knotty nova shell of GK Per and the planetary nebula in which it is embedded is then analysed. Results: Evidence is found for the interaction of knots with each other and with a wind component, most likely the periodic fast wind emanating from the central binary system. We find that a cylindrical shell with a lower velocity polar structure gives the best model fit to the spectroscopy and imaging. We show in this work that the previously seen jet-like feature is of low velocity. Conclusions: The individual knots have irregular tail shapes; we propose here that they emanate from episodic winds from ongoing dwarf nova outbursts by the central system. The nova shell is cylindrical, not spherical, and the symmetry axis relates to the inclination of the central binary system. Furthermore, the cylinder axis is aligned with the long axis of the bipolar planetary nebula in which it is embedded. Thus, the

  7. A Starfish Preplanetary Nebula: IRAS 19024+0044

    NASA Technical Reports Server (NTRS)

    Sahai, Raghvendra; Sanchez Contreras, Carmen; Morris, Mark

    2005-01-01

    Using the Hubble Space Telescope, we have imaged the OH/IR star IRAS 19024+0044 (I19024) at 0.6, 0.8, 1.1, and 1.6 micrometers, as part of our surveys of candidate preplanetary nebulae. The images show a multipolar nebula of size approximately equal to 3.'7 2.'3, with at least six elongated lobes emanating from the center of the nebula. Two of the lobes show limb-brightened tips having point-symmetric structure with respect to the expected location of the central star. The central region shows two dark bands southwest and northeast of a central shallow maximum that may be either two inclined dusty toroidal structures or the dense parts of a single wide, inhomogeneous, toroid. Avery faint, surface brightness-limited, diffuse halo surrounds the lobes. Long-slit/echelle optical spectroscopy obtained at the Mount Palomar and Keck observatories shows a spatially compact source of H(alpha) emission; the H(alpha) line shows a strong, narrow, central core with very broad (+/-1000 km/sec), weak wings, and a narrower blueshifted absorption feature signifying the presence of an approximately 100 km/sec(exp -1) outflow. The spectrum is characterized by a strong, relatively featureless, continuum and lacks the strong forbidden emission lines characteristic of planetary nebulae, confirming that IRAS 19024 is a preplanetary nebula; the spectral type for the central star, although uncertain, is most likely early G. Interferometric observations of the CO J = 1 -0 line emission with the Owens Valley Radio Interferometer show a marginally resolved molecular envelope (size 5.'5 x 4.'4) with an expansion velocity of 13 km/sec (exp -1), resulting from the asymptotic giant branch (AGB) progenitor's dense, slow wind. We derive a kinematic distance of 3.5 kpc to I19024, based on its radial velocity. The bolometric flux is 7:3 x 10(exp -9) erg s(exp -1) cm(exp -2), and the luminosity 2850 L. The relatively low luminosity of I19024, in comparison with stellar evolutionary models, indicates

  8. The Cat's Eye Nebula

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This NASA Hubble Space Telescope image shows one of the most complex planetary nebulae ever seen, NGC 6543, nicknamed the 'Cat's Eye Nebula.' Hubble reveals surprisingly intricate structures including concentric gas shells, jets of high-speed gas and unusual shock-induced knots of gas. Estimated to be 1,000 years old, the nebula is a visual 'fossil record' of the dynamics and late evolution of a dying star. A preliminary interpretation suggests that the star might be a double-star system. The suspected companion star also might be responsible for a pair of high-speed jets of gas that lie at right angles to this equatorial ring. If the companion were pulling in material from a neighboring star, jets escaping along the companion's rotation axis could be produced. These jets would explain several puzzling features along the periphery of the gas lobes. Like a stream of water hitting a sand pile, the jets compress gas ahead of them, creating the 'curlicue' features and bright arcs near the outer edge of the lobes. The twin jets are now pointing in different directions than these features. This suggests the jets are wobbling, or precessing, and turning on and off episodically. This color picture, taken with the Wide Field Planetary Camera-2, is a composite of three images taken at different wavelengths. (red, hydrogen-alpha; blue, neutral oxygen, 6300 angstroms; green, ionized nitrogen, 6584 angstroms). The image was taken on September 18, 1994. NGC 6543 is 3,000 light- years away in the northern constellation Draco. The term planetary nebula is a misnomer; dying stars create these cocoons when they lose outer layers of gas. The process has nothing to do with planet formation, which is predicted to happen early in a star's life.

  9. The "Water-Fountain Nebula" IRAS 16342-3814: Hubble Space Telescope/Very Large Array Study of a Bipolar Protoplanetary Nebula

    NASA Technical Reports Server (NTRS)

    Sahal, Raghvendra; teLintelHekkert, Peter; Morris, Mark; Zijlstra, Albert; Likkel, Lauren

    1999-01-01

    We present Hubble Space Telescope (HST) Wide-Field Planetary Camera 2 images and VLA OH maser emission-line maps of the cold infrared object IRAS 16342-3814, believed to be a protoplanetary nebula. The HST images show an asymmetrical bipolar nebula, with the lobes separated by a dark equatorial waist. The two bright lobes and the dark waist are simply interpreted as bubble-like reflection nebulae illuminated by starlight escaping through polar holes in a dense, flattened, optically thick cocoon of dust, which completely obscures the central star. A faint halo can be seen surrounding each of the lobes. The bubbles are likely to have been created by a fast outflow (evidenced by H2O emission) plowing into a surrounding dense, more slowly expanding, circumstellar envelope of the progenitor asymptotic giant-branch (AGB) star (evidenced by the halo). The IRAS fluxes indicate a circumstellar mass of about 0.7 solar mass (D/2 kpc) and an AGB mass-loss rate of about 10(exp -4) solar mass/yr (V(sub exp)/15 km/s)(D/2 kpc)(sup 2) (assuming a gas-to-dust ratio of 200). OH features with the largest redshifted and blueshifted velocities are concentrated around the bright eastern and western polar lobes, respectively, whereas intermediate-velocity features generally occur at low latitudes, in the dark waist region. We critically examine evidence for the post-AGB classification of IRAS 16342-3814.

  10. Fainting: First Aid

    MedlinePlus

    ... brain is momentarily inadequate, causing you to lose consciousness. This loss of consciousness is usually brief. Fainting can have no medical ... be a serious disorder. Therefore, treat loss of consciousness as a medical emergency until the signs and ...

  11. Dizziness and Fainting Spells

    MedlinePlus

    ... or Animals Genitals and Urinary Tract Glands & Growth Head Neck & Nervous System Heart Infections Learning Disabilities Obesity Orthopedic ... Vaccine Preventable Diseases Healthy Children > Health Issues > Conditions > Head Neck & Nervous System > Dizziness and Fainting Spells Health Issues ...

  12. THE 'SPIROGRAPH' NEBULA

    NASA Technical Reports Server (NTRS)

    2002-01-01

    THE 'SPIROGRAPH' NEBULA Glowing like a multi-faceted jewel, the planetary nebula IC 418 lies about 2,000 light-years from Earth in the direction of the constellation Lepus. This photograph is one of the latest from NASA's Hubble Space Telescope, obtained with the Wide Field Planetary Camera 2. A planetary nebula represents the final stage in the evolution of a star similar to our Sun. The star at the center of IC 418 was a red giant a few thousand years ago, but then ejected its outer layers into space to form the nebula, which has now expanded to a diameter of about 0.1 light-year. The stellar remnant at the center is the hot core of the red giant, from which ultraviolet radiation floods out into the surrounding gas, causing it to fluoresce. Over the next several thousand years, the nebula will gradually disperse into space, and then the star will cool and fade away for billions of years as a white dwarf. Our own Sun is expected to undergo a similar fate, but fortunately this will not occur until some 5 billion years from now. The Hubble image of IC 418 is shown in a false-color representation, based on Wide Field Planetary Camera 2 exposures taken in February and September, 1999 through filters that isolate light from various chemical elements. Red shows emission from ionized nitrogen (the coolest gas in the nebula, located furthest from the hot nucleus), green shows emission from hydrogen, and blue traces the emission from ionized oxygen (the hottest gas, closest to the central star). The remarkable textures seen