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Sample records for ii post-lbv wolf-rayet

  1. Ionizing stellar population in the disc of NGC 3310 - II. The Wolf-Rayet population

    NASA Astrophysics Data System (ADS)

    Miralles-Caballero, D.; Rosales-Ortega, F. F.; Díaz, A. I.; Otí-Floranes, H.; Pérez-Montero, E.; Sánchez, S. F.

    2014-12-01

    We use integral field spectroscopy to study in detail the Wolf-Rayet (WR) population in NGC 3310, spatially resolving 18 star-forming knots with typical sizes of 200-300 pc in the disc of the galaxy hosting a substantial population of WRs. The detected emission in the so-called blue bump is attributed mainly to late-type nitrogen WRs (WNL), ranging from a few dozens to several hundreds of stars per region. Our estimated WNL/(WNL+O) ratio is comparable to reported empirical relations once the extinction-corrected emission is further corrected by the presence of dust grains inside the nebula that absorb a non-negligible fraction of UV photons. Comparisons of observables with stellar population models show disagreement by factors larger than 2-3. However, if the effects of interacting binaries and/or photon leakage are taken into account, observations and predictions tend to converge. We estimate the binary fraction of the H II regions hosting WRs to be significant in order to recover the observed X-ray flux, hence proving that the binary channel can be critical when predicting observables. We also explore the connection of the environment with the current hypothesis that WRs can be progenitors to long-duration gamma-ray bursts (GRBs). Galaxy interactions, which can trigger strong episodes of star formation in the central regions, may be a plausible environment where WRs may act as progenitors of GRBs. Finally, even though the chemical abundance is generally homogeneous, we also find weak evidence for rapid N pollution by WR stellar winds at scales of ˜200 pc.

  2. Wolf-Rayet stars in the Small Magellanic Cloud. II. Analysis of the binaries

    NASA Astrophysics Data System (ADS)

    Shenar, T.; Hainich, R.; Todt, H.; Sander, A.; Hamann, W.-R.; Moffat, A. F. J.; Eldridge, J. J.; Pablo, H.; Oskinova, L. M.; Richardson, N. D.

    2016-06-01

    Context. Massive Wolf-Rayet (WR) stars are evolved massive stars (Mi ≳ 20 M⊙) characterized by strong mass-loss. Hypothetically, they can form either as single stars or as mass donors in close binaries. About 40% of all known WR stars are confirmed binaries, raising the question as to the impact of binarity on the WR population. Studying WR binaries is crucial in this context, and furthermore enable one to reliably derive the elusive masses of their components, making them indispensable for the study of massive stars. Aims: By performing a spectral analysis of all multiple WR systems in the Small Magellanic Cloud (SMC), we obtain the full set of stellar parameters for each individual component. Mass-luminosity relations are tested, and the importance of the binary evolution channel is assessed. Methods: The spectral analysis is performed with the Potsdam Wolf-Rayet (PoWR) model atmosphere code by superimposing model spectra that correspond to each component. Evolutionary channels are constrained using the Binary Population and Spectral Synthesis (BPASS) evolution tool. Results: Significant hydrogen mass fractions (0.1

  3. Optical spectrophotometry of Wolf-Rayet galaxies

    NASA Technical Reports Server (NTRS)

    Vacca, William D.; Conti, Peter S.

    1992-01-01

    We have obtained long-slit optical spectra of 10 Wolf-Rayet galaxies and four other starburst galaxies. Using the nebular emission lines we have determined the electron temperatures, electron densities, extinctions, oxygen abundances, mass of ionized hydrogen, and numbers of ionizing photons due to hot stars in these galaxies. The various forbidden line ratios clearly indicate a stellar origin for the emission-line spectrum. From the flux of the broad He II 4686 A emission feature we have estimated the number of Wolf-Rayet stars present. We have accounted for the contribution of these stars to the total ionizing flux and have calculated the ratio of the number of these stars to the number of O stars. Wolf-Rayet galaxies are among the youngest examples of the starburst phenomenon, which we observed at a propitious moment.

  4. Wolf-Rayet Stars

    NASA Astrophysics Data System (ADS)

    Hamann, Wolf-Rainer; Sander, Andreas; Todt, Helge

    Nearly 150 years ago, the French astronomers Charles Wolf and Georges Rayet described stars with very conspicuous spectra that are dominated by bright and broad emission lines. Meanwhile termed Wolf-Rayet Stars after their discoverers, those objects turned out to represent important stages in the life of massive stars. As the first conference in a long time that was specifically dedicated to Wolf-Rayet stars, an international workshop was held in Potsdam, Germany, from 1.-5. June 2015. About 100 participants, comprising most of the leading experts in the field as well as as many young scientists, gathered for one week of extensive scientific exchange and discussions. Considerable progress has been reported throughout, e.g. on finding such stars, modeling and analyzing their spectra, understanding their evolutionary context, and studying their circumstellar nebulae. While some major questions regarding Wolf-Rayet stars still remain open 150 years after their discovery, it is clear today that these objects are not just interesting stars as such, but also keystones in the evolution of galaxies. These proceedings summarize the talks and posters presented at the Potsdam Wolf-Rayet workshop. Moreover, they also include the questions, comments, and discussions emerging after each talk, thereby giving a rare overview not only about the research, but also about the current debates and unknowns in the field. The Scientific Organizing Committee (SOC) included Alceste Bonanos (Athens), Paul Crowther (Sheffield), John Eldridge (Auckland), Wolf-Rainer Hamann (Potsdam, Chair), John Hillier (Pittsburgh), Claus Leitherer (Baltimore), Philip Massey (Flagstaff), George Meynet (Geneva), Tony Moffat (Montreal), Nicole St-Louis (Montreal), and Dany Vanbeveren (Brussels).

  5. The Wolf-Rayet star population in the most massive giant H II regions of M33

    NASA Technical Reports Server (NTRS)

    Drissen, Laurent; Moffat, Anthony F. J.; Shara, Michael M.

    1990-01-01

    Narrow-band images of NGC 604, NGC 595, and NGC 592, the most massive giant H II regions (GHRs) in M33 have been obtained, in order to study their Wolf-Rayet content. These images reveal the presence of nine candidates in NGC 604 (seven WN, two WC), 10 in NGC 595 (nine WN, one WC), and two in NGC 592 (two WN). Precise positions and estimated magnitudes are given for the candidates, half of which have so far been confirmed spectroscopically as genuine W-R stars. The flux in the emission lines of all candidates is comparable to that of normal Galactic W-R stars of similar subtype. A few of the putative superluminous W-R stars are shown to be close visual double or multiple stars; their newly estimated luminosities are now more compatible with those of normal W-R stars. NGC 595 seems to be overabundant in W-R stars for its mass compared to other GHRs, while NGC 604 is normal. Factors influencing the W-R/O number ratio in GHRs are discussed: metallicity and age appear to be the most important.

  6. Wolf-Rayet phenomena

    NASA Technical Reports Server (NTRS)

    Conti, P. S.

    1982-01-01

    The properties of stars showing Wolf-Rayet phenomena are outlined along with the direction of future work. Emphasis is placed on the characteristics of W-R spectra. Specifically the following topics are covered: the absolute visual magnitudes; the heterogeneity of WN spectra; the existence of transition type spectra and compositions the mass loss rates; and the existence of very luminous and possibly very massive W-R stars. Also, a brief overview of current understanding of the theoretical aspects of stellar evolution and stellar winds and the various scenarios that have been proposed to understand W-R spectra are included.

  7. X-ray emission from the Wolf-Rayet bubble NGC 6888 - II. XMM-Newton EPIC observations

    NASA Astrophysics Data System (ADS)

    Toalá, J. A.; Guerrero, M. A.; Chu, Y.-H.; Arthur, S. J.; Tafoya, D.; Gruendl, R. A.

    2016-03-01

    We present deep XMM-Newton European Photon Imaging Camera observations of the Wolf-Rayet (WR) bubble NGC 6888 around the star WR 136. The complete X-ray mapping of the nebula confirms the distribution of the hot gas in three maxima spatially associated with the caps and north-west blowout hinted at by previous Chandra observations. The global X-ray emission is well described by a two-temperature optically thin plasma model (T1 = 1.4 × 106 K, T2 = 8.2 × 106 K) with a luminosity of LX = 7.8 × 1033 erg s-1 in the 0.3-1.5 keV energy range. The rms electron density of the X-ray-emitting gas is estimated to be ne = 0.4 cm-3. The high-quality observations presented here reveal spectral variations within different regions in NGC 6888, which allowed us for the first time to detect temperature and/or nitrogen abundance inhomogeneities in the hot gas inside a WR nebula. One possible explanation for such spectral variations is that the mixing of material from the outer nebula into the hot bubble is less efficient around the caps than in other nebular regions.

  8. The Wolf-Rayet stars

    NASA Astrophysics Data System (ADS)

    Sahade, J.

    1981-12-01

    Aspects of the problems of the Wolf-Rayet stars related to their chemical composition, their evolutionary status, and their apparent dichotomy in two spectral sequences are discussed. Dogmas concerning WR stars are critically discussed, including the belief that WR stars lack hydrogen, that they are helium stars evolved from massive close binaries, and the existence of a second WR stage in which the star is a short-period single-lined binary. The relationship of WR stars with planetary nebulae is addressed, as is the membership of these stars in clusters and associations. The division of WR stars into WN and WC sequences is considered, questioning the reasonability of accounting for WR line formation in terms of abundance differences.

  9. O stars and Wolf-Rayet stars

    NASA Technical Reports Server (NTRS)

    Conti, Peter S.; Underhill, Anne B.; Jordan, Stuart (Editor); Thomas, Richard (Editor)

    1988-01-01

    Basic information is given about O and Wolf-Rayet stars indicating how these stars are defined and what their chief observable properties are. Part 2 of the volume discussed four related themes pertaining to the hottest and most luminous stars. Presented are: an observational overview of the spectroscopic classification and extrinsic properties of O and Wolf-Rayet stars; the intrinsic parameters of luminosity, effective temperature, mass, and composition of the stars, and a discussion of their viability; stellar wind properties; and the related issues concerning the efforts of stellar radiation and wind on the immediate interstellar environment are presented.

  10. Photoelectric spectrophotometry of Wolf-Rayet stars

    NASA Technical Reports Server (NTRS)

    Bahng, J. D. R.

    1974-01-01

    Photoelectric spectrum scans of five southern Wolf-Rayet stars in the spectral range lambda lambda 4600-4720 were analyzed to study the variability of brightness and of emission line strengths. No variations of any kind in short time scale were found. However, in WC stars night-to-night variations of three to four percent were detected in the emission line strengths.

  11. The Tarantula Massive Binary Monitoring. II. First SB2 orbital and spectroscopic analysis for the Wolf-Rayet binary R145

    NASA Astrophysics Data System (ADS)

    Shenar, T.; Richardson, N. D.; Sablowski, D. P.; Hainich, R.; Sana, H.; Moffat, A. F. J.; Todt, H.; Hamann, W.-R.; Oskinova, L. M.; Sander, A.; Tramper, F.; Langer, N.; Bonanos, A. Z.; de Mink, S. E.; Gräfener, G.; Crowther, P. A.; Vink, J. S.; Almeida, L. A.; de Koter, A.; Barbá, R.; Herrero, A.; Ulaczyk, K.

    2017-02-01

    We present the first SB2 orbital solution and disentanglement of the massive Wolf-Rayet binary R145 (P = 159 d) located in the Large Magellanic Cloud. The primary was claimed to have a stellar mass greater than 300 M⊙, making it a candidate for being the most massive star known to date. While the primary is a known late-type, H-rich Wolf-Rayet star (WN6h), the secondary has so far not been unambiguously detected. Using moderate-resolution spectra, we are able to derive accurate radial velocities for both components. By performing simultaneous orbital and polarimetric analyses, we derive the complete set of orbital parameters, including the inclination. The spectra are disentangled and spectroscopically analyzed, and an analysis of the wind-wind collision zone is conducted. The disentangled spectra and our models are consistent with a WN6h type for the primary and suggest that the secondary is an O3.5 If*/WN7 type star. We derive a high eccentricity of e = 0.78 and minimum masses of M1sin3i ≈ M2sin3i = 13 ± 2 M⊙, with q = M2/M1 = 1.01 ± 0.07. An analysis of emission excess stemming from a wind-wind collision yields an inclination similar to that obtained from polarimetry (i = 39 ± 6°). Our analysis thus implies and , excluding M1 > 300 M⊙. A detailed comparison with evolution tracks calculated for single and binary stars together with the high eccentricity suggests that the components of the system underwent quasi-homogeneous evolution and avoided mass-transfer. This scenario would suggest current masses of ≈ 80 M⊙ and initial masses of Mi,1 ≈ 105 and Mi,2 ≈ 90 M⊙, consistent with the upper limits of our derived orbital masses, and would imply an age of ≈ 2.2 Myr. A copy of the disentangled spectra, as either FITS files or tables are available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/598/A85

  12. A NEAR-INFRARED SURVEY OF THE INNER GALACTIC PLANE FOR WOLF-RAYET STARS. II. GOING FAINTER: 71 MORE NEW W-R STARS

    SciTech Connect

    Shara, Michael M.; Faherty, Jacqueline K.; Zurek, David; Moffat, Anthony F. J.; Doyon, Rene; Gerke, Jill; Artigau, Etienne; Drissen, Laurent E-mail: jfaherty@amnh.org E-mail: moffat@astro.umontreal.ca E-mail: gerke@astronomy.ohio-state.edu E-mail: ldrissen@phy.ulaval.ca

    2012-06-15

    We are continuing a J, K and narrowband imaging survey of 300 deg{sup 2} of the plane of the Galaxy, searching for new Wolf-Rayet (W-R) stars. Our survey spans 150 Degree-Sign in Galactic longitude and reaches 1 Degree-Sign above and below the Galactic plane. The survey has a useful limiting magnitude of K = 15 over most of the observed Galactic plane, and K = 14 (due to severe crowding) within a few degrees of the Galactic center. Thousands of emission-line candidates have been detected. In spectrographic follow-ups of 146 relatively bright W-R star candidates, we have re-examined 11 previously known WC and WN stars and discovered 71 new W-R stars, 17 of type WN and 54 of type WC. Our latest image analysis pipeline now picks out W-R stars with a 57% success rate. Star subtype assignments have been confirmed with the K-band spectra and distances approximated using the method of spectroscopic parallax. Some of the new W-R stars are among the most distant known in our Galaxy. The distribution of these new W-R stars is beginning to trace the locations of massive stars along the distant spiral arms of the Milky Way.

  13. Wolf-Rayet Bubbles. I. Analytic Solutions

    NASA Astrophysics Data System (ADS)

    Garcia-Segura, Guillermo; Mac Low, Mordecai-Mark

    1995-12-01

    Stellar wind bubble dynamics are sensitive to the stellar wind velocity and mass-loss history. Observations of ring nebulae can thus strongly constrain theories of stellar winds and massive stellar evolution. Furthermore, ring nebulae are often observed around Wolf-Rayet stars likely to soon become supernovae, so their influence on the circumstellar medium is vital to understanding young supernova remnants such as Cas A. To interpret the observations, the connection between the input wind and the observed gas distribution must be described. This is our goal in this series of papers. In this paper, we present analytic solutions for the dynamics of bubbles expanding into media with power-law density distributions such as r-2. We apply the solutions to Wolf-Rayet bubbles expanding into red supergiant winds. A semianalytic method is used to model aspherical bubbles resulting from nonspherical red supergiant winds. Applying this method, we find, for the case of steady winds, that bubbles expand at nearly constant velocity in each direction, keeping their shapes. We can then make the approximation that the bubbles have constant-eccentricity ellipsoidal shapes to derive a fully analytic dynamical model. From this we derive solutions for the diffuse X-ray luminosities from steady winds, using the assumption of classical conductive evaporation. Useful relationships between observables are also given. The solutions are compared to observations of the Wolf-Rayet ring nebula NGC 6888. We find that with either the assumption of energy conservation or momentum conservation, the dynamics of this nebula cannot be explained if the reported wind kinetic energy of the central star WR 136 is used. The nebular kinematics require an order of magnitude less effective mechanical luminosity from WR 136, demanding a lower mass-loss rate, a lower wind velocity, or both.

  14. Models of Wolf-Rayet stars

    NASA Technical Reports Server (NTRS)

    Langer, Norbert

    1990-01-01

    The current status of knowledge about formation, structure and evolution of Wolf-Rayet stars is reviewed, with emphasis on a discussion of corresponding stellar models. The relevance of the LBV-scenario for WR star formation is outlined. Hydrogenless WR stars are shown to closely follow simple relations for the dependence of luminosity, radius, and surface temperature as a function of their mass. The use of these relations for simplified WR evolution calculations is demonstrated. Surface abundance predictions for the different WR types are discussed, with special emphasis to the WN + WC spectral type. Details are presented concerning the WR phase of a recent 60 solar mass evolutionary calculation, which was computed with the same input physics which reproduced the progenitor evolution of SN 1987 A in a 20 solar mass case, and which may be a representative case concerning WR stars in many respects.

  15. DISCOVERY OF A WOLF-RAYET STAR THROUGH DETECTION OF ITS PHOTOMETRIC VARIABILITY

    SciTech Connect

    Littlefield, Colin; Garnavich, Peter; McClelland, Colin; Rettig, Terrence; Marion, G. H.; Vinko, Jozsef; Wheeler, J. Craig

    2012-06-15

    We report the serendipitous discovery of a heavily reddened Wolf-Rayet star that we name WR 142b. While photometrically monitoring a cataclysmic variable, we detected weak variability in a nearby field star. Low-resolution spectroscopy revealed a strong emission line at 7100 A, suggesting an unusual object and prompting further study. A spectrum taken with the Hobby-Eberly Telescope confirms strong He II emission and an N IV 7112 A line consistent with a nitrogen-rich Wolf-Rayet star of spectral class WN6. Analysis of the He II line strengths reveals no detectable hydrogen in WR 142b. A blue-sensitive spectrum obtained with the Large Binocular Telescope shows no evidence for a hot companion star. The continuum shape and emission line ratios imply a reddening of E(B - V) = 2.2-2.6 mag. We estimate that the distance to WR 142b is 1.4 {+-} 0.3 kpc.

  16. The Multiplicity of Wolf-Rayet Stars

    NASA Technical Reports Server (NTRS)

    Wallace, Debra J.

    2004-01-01

    The most massive stars drastically reconfigure their surroundings via their strong stellar winds and powerful ionizing radiation. With this mass fueling their large luminosities, these stars are frequently used as standard candles in distance determination, and as tracers of stellar evolution in different regions and epochs. In their dieing burst, some of the once massive stars will enter a Wolf-Rayet (WR) phase lasting approx.10% of the stellar lifetime. This phase is particularly useful for study because these stars have strong spectroscopic signatures that allow them to be easily identified at great distances. But how accurate are these identifications? Increasingly, the relatively nearby stars we once assumed to be single are revealing themselves to be binary or multiple. New techniques, such as high-resolution imaging and interferometry, are changing our knowledge of these objects. I will discuss recent results in the literature and how this affects the binary distribution of WR stars. I will also discuss the implications of binary vs. single star evolution on evolution through the WR phase. Finally, I will discuss the implications of these revised numbers on both massive stellar evolution itself, and the impact that this has on the role of WR stars as calibrators.

  17. Wolf-Rayet stars with relativistic companions

    NASA Astrophysics Data System (ADS)

    Tutukov, A. V.; Fedorova, A. V.; Cherepashchuk, A. M.

    2013-09-01

    The evolution of close binary systems containing Wolf-Rayet (WR) stars and black holes (BHs) is analyzed numerically. Both the stellar wind from the donor star itself and the induced stellar wind due to irradiation of the donor with hard radiation arising during accretion onto the relativistic component are considered. The mass and angular momentum losses due to the stellar wind are also taken into account at phases when the WR star fills its Roche lobe. It is shown that, if a WR star with a mass higher than ˜10 M ⊙ fills its Roche lobe in an initial evolutionary phase, the donor star will eventually lose contact with the Roche lobe as the binary loses mass and angular momentum via the stellar wind, suggesting that the semi-detached binary will become detached. The star will remain a bright X-ray source, since the stellar wind that is captured by the black hole ensures a near-Eddington accretion rate. If the initial mass of the helium donor is below ˜5 M ⊙, the donor may only temporarily detach from its Roche lobe. Induced stellar wind plays a significant role in the evolution of binaries containing helium donors with initial masses of ˜2 M ⊙. We compute the evolution of three observed WR-BH binaries: Cyg X-3, IC 10 X-1, and NGC 300 X-1, as well as the evolution of the SS 433 binary system, which is a progenitor of such systems, under the assumption that this binary will avoid a common-envelope stage in its further evolution, as it does in its current evolutionary phase.

  18. Diagnostics of the unstable envelopes of Wolf-Rayet stars

    NASA Astrophysics Data System (ADS)

    Grassitelli, L.; Chené, A.-N.; Sanyal, D.; Langer, N.; St-Louis, N.; Bestenlehner, J. M.; Fossati, L.

    2016-05-01

    Context. The envelopes of stars near the Eddington limit are prone to various instabilities. A high Eddington factor in connection with the iron opacity peak leads to convective instability, and a corresponding envelope inflation may induce pulsational instability. Here, we investigate the occurrence and consequences of both instabilities in models of Wolf-Rayet stars. Aims: We determine the convective velocities in the sub-surface convective zones to estimate the amplitude of the turbulent velocity at the base of the wind that potentially leads to the formation of small-scale wind structures, as observed in several Wolf-Rayet stars. We also investigate the effect of stellar wind mass loss on the pulsations of our stellar models. Methods: We approximated solar metallicity Wolf-Rayet stars in the range 2-17 M⊙ by models of mass-losing helium stars, computed with the Bonn stellar evolution code. We characterized the properties of convection in the envelope of these stars adopting the standard mixing length theory. Results: Our results show the occurrence of sub-surface convective regions in all studied models. Small (≈1 km s-1) surface velocity amplitudes are predicted for models with masses below ≈10 M⊙. For models with M ≳ 10 M⊙, the surface velocity amplitudes are of the order of 10 km s-1. Moreover we find the occurrence of pulsations for stars in the mass range 9-14 M⊙, while mass loss appears to stabilize the more massive Wolf-Rayet stars. We confront our results with observationally derived line variabilities of 17 WN stars, of which we analysed eight here for the first time. The data suggest variability to occur for stars above 10 M⊙, which is increasing linearly with mass above this value, in agreement with our results. We further find our models in the mass range 9-14M⊙ to be unstable to radial pulsations, and predict local magnetic fields of the order of hundreds of gauss in Wolf-Rayet stars more massive than ≈10 M⊙. Conclusions: Our

  19. A new ejecta shell surrounding a Wolf-Rayet star in the LMC

    NASA Technical Reports Server (NTRS)

    Garnett, Donald R.; Chu, You-Hua

    1994-01-01

    We have obtained CCD spectra of newly discovered shell-like nebulae around the WN4 star Breysacher 13 and the WN1 star Breysacher 2 in the Large Magellanic Cloud (LMC). The shell around Br 13 shows definite signs of enrichment in both nitrogen and helium, having much stronger (N II) and He I emission lines than are seen in typical LMC H II regions. From the measured electron temperature of about 17,000 K in the shell, we derive He/H and N/O abundance ratios which are factors of 2 and more than 10 higher, respectively, than the average LMC interstellar values. The derived oxygen abundance in the Br 13 shell is down by a factor of 8 compared to the local LMC interstellar medium (ISM); however, the derived electron temperature is affected by the presence of an incomplete shock arising from the interaction of the stellar wind with photoionized material. This uncertainty does not affect the basic conclusion that the Br 13 shell is enriched by processed material from the Wolf-Rayet star. In contrast, the shell around Br 2 shows no clear evidence of enrichment. The nebular spectrum is characterized by extremely strong (O III) and He II emission and very weak (N II). We derive normal He, O, and N abundances from our spectrum. This object therefore appears to be simply a wind-blown structure associated with a relatively dense cloud near the Wolf-Rayet star, although the very high-ionization state of the gas is unusual for a nebula associated with a Wolf-Rayet star.

  20. The Masses of Black Holes with Wolf-Rayet Companions

    NASA Astrophysics Data System (ADS)

    Laycock, Silas; Steiner, James F.; Maccarone, Thomas J.; Christodoulou, Dimitris M.; Binder, Breanna A.; Yang, Jun; Cappallo, Rigel

    2016-04-01

    Black Holes with Wolf-Rayet companions represent a channel for forming the most massive stellar BHs. The recent, stunning LIGO detection of the gravitational wave signature from a merging stellar BH binary points to the importance of understanding the progenitor systems formation and evolution. The BH+WR binary IC 10 X-1 holds important clues to the puzzle, by helping establish the upper observed BH mass and pointing to an association between maximum possible BH mass and low metallicity environments. However, securing dynamical mass determiniations for WR+BH binaries appears to be complicated by interaction between the radiation field of the BH and the stellar wind. This causes a substantial change to our understanding of IC 10 X-1, and by extension to the mass distribution of BH binaries. A high precision ephemeris derived from a decade of Chandra/XMM X-ray timing observations, when combined with the optical RV curve, reveals a surprizing simultenaity of mid X-ray eclipse and the maximum blueshift velocity of He II emission lines. The optical emission lines appear to originate in a shielded sector of the WR star's stellar wind which escapes total X-ray ionization by the compact object. Unravelling this projection effect is necessary to obtain the system's true mass function. Complementary Chandra, XMM and NuStar datasets offer new insights into the mass and spin of the BH, and the structure of the photo-ionized wind. We will discuss possible routes toward the mass function in BH+WR binaries via multi-wavelength observations, and the additional leverage provided by further constraining the orbital period derivative.

  1. Searching for Hidden Wolf-Rayet Stars in the Galaxy 15 New Wolf-Rayet Stars

    NASA Astrophysics Data System (ADS)

    Hadfield, Lucy J.; van Dyk, S. D.; Morris, P. W.; Smith, J. D.; Marston, A. P.

    2006-12-01

    Hot, massive stars play a vital role in the working of the `cosmic cauldron', living life in the fast lane and ending their evolution via some of the most powerful events in the universe. Wolf-Rayet (WR) stars are the evolved descendants of the most massive stars. Believed to represent the bare He-core of their massive star precursor, their spectra are dominated by impressive emission features. This and the short duration of this evolutionary phase make WR stars excellent tracers of recent star formation in the nearby Universe as well as vital tests for stellar evolutionary models. Our Galaxy provides an excellent laboratory for studying massive stars as we can resolve objects on small scales and so hope to achieve sample completeness. To date 300 WR stars have been observed in our Galaxy but with studies predicting that the Milk Way should host 1000-2500 WR stars, it would appear that a large number of stars are still waiting to be discovered. Here we report the discovery of 15 (11 WN and 4 WC) WR stars found as part of near-mid infrared broad-band study of the Galactic WR population.

  2. Multiple Shells Around Wolf-Rayet Stars: Space Based Astrometric Observing

    NASA Technical Reports Server (NTRS)

    Marston, Anthony P.

    1995-01-01

    The completion of a complementary optical emission-line survey of the nebulae associated with Wolf-Rayet stars in the southern sky is reported, along with the completion of a survey the large-scale environments of Wolf-Rayet stars using IRAS Skyflux data. HIRES IRAS maps in the four IRAS wavebands for appoximately half of all galactic Wolf-Rayet stars are created.

  3. Le Phénomène Wolf-Rayet au Sein des Etoiles chaudes de Populations I et II: Histoire des Vents stellaires et Impact sur la Structure nébulaire circumstellaire

    NASA Astrophysics Data System (ADS)

    Grosdidier, Yves

    2000-12-01

    Les spectres des étoiles Wolf-Rayet pop. I (WR) présentent de larges raies en émission dues à des vents stellaires chauds en expansion rapide (vitesse terminale de l'ordre de 1000 km/s). Le modèle standard des étoiles WR reproduit qualitativement le profil général et l'intensité des raies observées. Mais la spectroscopie intensive à moyenne résolution de ces étoiles révèle l'existence de variations stochastiques dans les raies (sous-pics mobiles en accélération échelles de temps: environ 10-100 min.). Ces variations ne sont pas comprises dans le cadre du modèle standard et suggèrent une fragmentation intrinsèque des vents. Cette thèse de doctorat présente une étude de la variabilité des raies spectrales en émission des étoiles WR pop. II; la question de l'impact d'un vent WR fragmenté sur le milieu circumstellaire est aussi étudiée: 1) à partir du suivi spectroscopique intensif des raies CIIIl5696 et CIVl5801/12, nous analysons quantitativement (via le calcul des Spectres de Variance Temporelle) les vents issus de 5 étoiles centrales de nébuleuses planétaires (NP) galactiques présentant le phénomène WR; 2) nous étudions l'impact de la fragmentation des vents issus de deux étoiles WR pop. I sur le milieu circumstellaire via: i) l'imagerie IR (NICMOS2/HST) de WR 137, et ii) l'imagerie H-alpha (WFPC2/HST) et l'interférométrie Fabry-Perot H-alpha (SIS-CFHT) de la nébuleuse M 1-67 (étoile centrale: WR 124). Les principaux résultats sont les suivants: VENTS WR POP. II: (1) Nous démontrons la variabilité spectroscopique intrinsèque des vents issus des noyaux de NP HD 826 ([WC 8]), BD +30 3639 ([WC 9]) et LSS 3169 ([WC 9]), observés durant respectivement 22, 15 et 1 nuits, et rapportons des indications de variabilité pour les noyaux [WC 9] HD 167362 et He 2-142. Les variabilités de HD 826 et BD +30 3639 apparaissent parfois plus soutenues (``bursts'' qui se maintiennent durant plusieurs nuits); (2) La cinématique des sous

  4. X-ray Emission from Wolf-Rayet Nebulae

    NASA Astrophysics Data System (ADS)

    Toalá, J. A.; Guerrero, M. A.; Chu, Y.-H.; Gruendl, R. A.; Arthur, S. J.; Smith, R. C.; Snowden, S. L.

    2013-05-01

    We present the analysis of the hot plasma detected with XMM-Newton and Chandra X-ray observations toward the only two Wolf-Rayet bubbles so far detected: S 308 and NGC 6888. Both nebulae present spectra dominated by soft temperature plasmas of ˜10^{6} K with luminosities of L_{{X}}˜10^{33}-10^{34} erg s^{-1}, but with different X-ray-emitting plasma distribution. In the case of S 308 it presents a limb-brightened morphology, while in the case of NGC 6888, it shows three maxima localized at the Northeast and Southwest caps and another one extending toward the Northwest.

  5. ELEVEN NEW HEAVILY REDDENED FIELD WOLF-RAYET STARS

    SciTech Connect

    Smith, J. D. T.; Cushing, Michael; Barletta, Anthony; McCarthy, Don; Kulesa, Craig; Van Dyk, Schuyler D.

    2012-12-01

    We report the results of a medium-narrowband 2 {mu}m line survey covering 5.8 deg{sup 2} near the Galactic plane. We confirm 11 new field Wolf-Rayet stars along three lines of sight probing the inner Galaxy, demonstrating the capability to uncover distant and highly reddened populations of Galactic wind-borne emission-line stars suffering extinction as high as A{sub V} {approx} 40 and as distant as 9 kpc down to modest magnitude limits of K{sub s} {approx} 12.5. All stars are of subtype WC7-8, with median distance d = 6 kpc and median extinction A{sub K{sub s}} = 2.5. Over the fields surveyed, the density of Wolf-Rayet stars to limiting magnitude K{sub s} {approx} 12.5 was found to be 1.9 deg{sup -2}. We compare this to models which predict their distribution within the Galaxy and find that, even neglecting survey and subtype incompleteness, they consistently underpredict the number of newly discovered stars along the surveyed lines of sight.

  6. Colliding stellar winds in the eclipsing Wolf-Rayet binary V444 Cygni

    NASA Technical Reports Server (NTRS)

    Brown, Douglas N.; Shore, Steven N.

    1988-01-01

    High resolution spectra of V444 Cygni have been obtained using the International Ultraviolet Explorer Satellite. These spectra span both eclipses and include one observation at third quadrature. Together with seven archival spectra, they provide reasonably complete phase coverage for the system. The variations in the P Cygni profiles of the He(II) and N(IV) lines, imply the existence of a low density region in the WR wind. This region occupies a relatively narrow range of orbital phase coinciding with the highest terminal velocities observed in C IV. These data are interpreted to be evidence of an interaction region separating the winds of the O-star and Wolf-Rayet star.

  7. Photometry, polarimetry, spectroscopy, and spectropolarimetry of the enigmatic Wolf-Rayet star EZ Canis Majoris

    NASA Technical Reports Server (NTRS)

    Robert, Carmelle; Moffat, Anthony F. J.; Drissen, Laurent; Lamontagne, Robert; Seggewiss, Wilhelm; Niemela, Virpi S.; Cerruti, Miguel A.; Barrett, Paul; Bailey, Jeremy; Garcia, Jorge

    1992-01-01

    New observations of the peculiar Wolf-Rayet star EZ Canis Majoris collected since 1987 are presented, and photometric, polarimetric, spectroscopic, and spectropolarimetric data are discussed. Linear polarization data are well fitted with an eccentric binary model where an additional free parameter is included to allow for epoch-dependent changes of the geometrical electron distribution in the W-R envelope. This yields a set of basic parameters, including an eccentricity e = 0.39 +/- 0.02 and an orbital inclination i = 114 deg +/- 3 deg. The spectroscopic data show global profile variations for all three observed strong emission lines He II 5412 A, C IV 5807 A, and He I 5876 A. Radial velocities of the lines vary with the 3.766-day period. Radially expanding inhomogeneities are superposed on the line profiles and variable polarization in the lines is observed.

  8. Stagnant Shells in the Vicinity of the Dusty Wolf-Rayet-O/B Binary WR 112

    NASA Astrophysics Data System (ADS)

    Lau, Ryan M.; Hankins, Matthew; Schoedel, R.; Sanchez-Bermudez, Joel; Moffat, Anthony F. J.; Ressler, Michael E.

    2017-01-01

    We present high spatial resolution mid-infrared images of the nebula around the late-type carbon-rich Wolf-Rayet (WC)-O/B binary system WR 112 taken by the recently upgraded VLT spectrometer and imager for the mid-infrared (VISIR) with the PAH1, NeII_2, and Q3 filters. The observations reveal a morphology resembling a series of arc-like filaments and broken shells. Dust temperatures and masses are derived for each of the identified filamentary structures, which exhibit temperatures ranging from 179 ± 8 K at the exterior W2 filament to 355 ± 37 K in the central 3''. The total dust mass summed over all the features is 2.6 ± 0.4 × 10-5 M⊙. A multi-epoch analysis of previous mid-IR photometry of WR 112 over the past ~20 yr reveals no significant variability in the observed dust temperature and mass. The morphology of the mid-IR dust emission from WR 112 also exhibits no significant expansion between archival imaging data taken in 2007 May 7, which disputes the current interpretation of the nebula as a high expansion velocity (~1200 km s-1) "pinwheel"-shaped outflow driven by the colliding winds of the central WC-O/B system. An upper limit of <120 km s-1 is derived for the expansion velocity assuming a distance of 4.15 kpc. The upper limit on the average mass-loss rate from the central 3'' of WR 112 is estimated to be < 8 × 10-6 M⊙ yr-1. Based on these constraints, we suggest that the WR 112 nebula formed in the slow, dense outflow during a previous red supergiant (RSG) phase of the central Wolf-Rayet star.

  9. Determinación de abundancia de Hidrógeno en cuatro estrellas Wolf-Rayet

    NASA Astrophysics Data System (ADS)

    Gamen, R. C.; Niemela, V. S.

    Medium resolution optical CCD spectra of four stars with WN type emission lines, have been obtained with the Cassegrain REOSC spectrograph attached to the 2.15 m telescope at CASLEO (San Juan, Argentina), during March 1999. The spectra cover the wavelength range λλ3800 -- 5500Å. From these spectra we have determined the contribution of Hydrogen, detected by oscillation in the Pickering decrement of HeII emission lines, for 4 galactic Wolf-Rayet stars, namely WR 10 = HD 65865, WR 29 = LSS 1964, WR 54 = LSS 3111 and WR 58 = LSS 3162. Our results agree with those previously published by Smith et al. in 1966 (MNRAS, 281, 163).

  10. Nongrayness Effects in Wolf-Rayet Wind Momentum Deposition

    NASA Astrophysics Data System (ADS)

    Onifer, A. J.; Gayley, K. G.

    2004-05-01

    Wolf-Rayet winds are characterized by their large momentum fluxes and optically thick winds. A simple analytic approach that helps to understand the most critical processes is the effecively gray approximation, but this has not been generalized to more realistic nongray opacities. We have developed a simplified theory for describing the interaction of the stellar flux with nongray wind opacity. We replace the detailed line list with a set of statistical parameters that are sensitive to the line strengths as well as the wavelength distribution of lines. We determine these statistical parameters for several real line lists, exploring the effects of temperature and density changes on the efficiency of momentum driving relative to gray opacity. We wish to acknowledge NSF grant AST-0098155.

  11. SN 1985f - Death of a Wolf-Rayet star

    NASA Technical Reports Server (NTRS)

    Begelman, M. C.; Sarazin, C. L.

    1986-01-01

    The optical spectrum of SN 1985f has been analyzed, and the supernova ejecta is shown to contain approximately 5 or more solar masses of oxygen and very little hydrogen. It is suggested that the explosion resulted from the pair instability supernova of a WO Wolf-Rayet star of about 50 solar masses, and that the optical luminosity of the supernova is powered by the radioactive decay of Co-56 synthesized in the explosion. As calculated from the rate of the optical emission decay, the explosion occurred about 350 days before its discovery in February, 1985. It is believed that some of the oxygen-rich supernova remnants may also have been produced by explosions of WO stars.

  12. A search for Wolf-Rayet stars in active star forming regions of low mass galaxies - GR8, NGC 2366, IC 2574, and NGC 1569

    NASA Astrophysics Data System (ADS)

    Drissen, Laurent; Roy, Jean-Rene; Moffat, Anthony F. J.

    1993-10-01

    We report the detection, via narrow-band 4686 A filter imagery, of possible new Wolf-Rayet stars in the most massive giant H II regions of the irregular galaxies NGC 2366 and IC 2574. One stellar knot in the post-starburst galaxy NGC 1569 also appears to contain a weak excess of light at 4686 A. A similar search yielded negative results in the very low mass galaxy GR8. The strongest 4686 A excess is located close to the secondary eastern knot in the core of NGC 2366-I (NGC 2363). If this excess is of stellar origin, about five Wolf-Rayet stars of the luminous late-type can account for the excess emission. Nebular emission wraps around this cluster in the form of a shell. The putative Wolf-Rayet stars appear to be close to the center of the large expanding H II bubble discovered by Roy et al. (1991). A possible nebular origin of the 4686 A excess is also discussed.

  13. Triggered Star Formation Surrounding Wolf-Rayet Star HD 211853

    NASA Astrophysics Data System (ADS)

    Liu, Tie; Wu, Yuefang; Zhang, Huawei; Qin, Sheng-Li

    2012-05-01

    The environment surrounding Wolf-Rayet (W-R) star HD 211853 is studied in molecular, infrared, as well as radio, and H I emission. The molecular ring consists of well-separated cores, which have a volume density of 103 cm-3 and kinematic temperature ~20 K. Most of the cores are under gravitational collapse due to external pressure from the surrounding ionized gas. From the spectral energy distribution modeling toward the young stellar objects, the sequential star formation is revealed on a large scale in space spreading from the W-R star to the molecular ring. A small-scale sequential star formation is revealed toward core "A," which harbors a very young star cluster. Triggered star formations are thus suggested. The presence of the photodissociation region, the fragmentation of the molecular ring, the collapse of the cores, and the large-scale sequential star formation indicate that the "collect and collapse" process functions in this region. The star-forming activities in core "A" seem to be affected by the "radiation-driven implosion" process.

  14. Helium stars: towards an understanding of Wolf-Rayet evolution

    NASA Astrophysics Data System (ADS)

    McClelland, L. A. S.; Eldridge, J. J.

    2016-06-01

    Wolf-Rayet (WR) stars are massive stars that have lost most or all of their hydrogen via powerful stellar winds. Recent observations have indicated that hydrogen-free WR stars have cooler temperatures than those predicted by current evolutionary models. To investigate how varying mass-loss rate affects WR evolution, we have created a grid of pure helium star models. We compare our results with Galactic and Large Magellanic Cloud WR observations and show that the temperature ranges of observed WR stars can be reproduced by varying the mass-loss rate, which effectively determines the size of the helium envelope around the core. We also find that WN and WO stars arise from more massive stars, whereas WC stars come from lower masses. This contradicts the standard Conti scenario by which WN and WC stars evolve in an age sequence. We also predict the magnitudes of our models at core-collapse and compare with observations of nearby progenitors of Type Ib/c supernovae. We confirm the findings of previous studies that suggest WR stars are the progenitors of core-collapse supernovae; the progenitors would remain unobserved except in the cases where the progenitor is a low-mass helium giant, as is the case of iPTF13bvn.

  15. The IUE spectrum of the Wolf-Rayet system HD 193077.

    NASA Astrophysics Data System (ADS)

    Koenigsberger, G.

    1990-12-01

    The results of a detailed line-identification study of the IUE(1100-1900 A) spectrum of the Wolf-Rayet star HD 193077 (WR 138) is presented. The emission line spectrum is shown to be dominated by Fe V+Fe VI lines below 1500 A. The interstellar-line spectrum contains a large variety of atomic and ionic species, ranging from C I to Si IV and C IV, and CO. Interstellar features displaced by approximately -45 km s-1 are associated with the strong lines arising from the ionized species. The measurable photospheric absorption line spectrum contains lines primarily from Fe V, Fe IV, N IV, N III, C III, Ni IV, Si III, Si II, with an increase in full widhts at continuun intensity (FWCI) with decreasing ionization potential. This progression ranges from values of FWCI of 250 km s-1 for the highest ionization lines, through 800 km s-1 for the lowest ionization lines in the UV to approximately 1500 km s-1 for hydrogen, and is consistent with a rapidly rotating star. It is pointed out that the photospheric lines originating in the polar region will suffer from limb darkening effects which makes them weaker than would be observed in a non-rotating star of equivalent temperature and gravity, thus providing evidence, though not conclusive, that the emission-line and the photospheric-line spectra arise in the same star.

  16. Wolf-Rayet stars as starting points or as endpoints of the evolution of massive stars?

    NASA Technical Reports Server (NTRS)

    Lamers, H. J. G. L. M.; Maeder, A.; Schmutz, W.; Cassinelli, J. P.

    1991-01-01

    The paper investigates the evidence for the two interpretations of Wolf-Rayet stars suggested in the literature: (1) massive premain-sequence stars with disks and (2) massive stars which have lost most of their H-rich layers in a stellar wind is investigated. The abundance determinations which are done in two different ways and which lead to different conclusions are discussed. The composition is solar, which would suggest interpretation (1), or the CNO abundances are strongly anomalous, which would suggest interpretation (2). Results from evolutionary calculations, stellar statistics, the existence of Ofpe/WN9 transition stars and W-R stars with evolved companions show overwhelming evidence that W-R stars are not premain-sequence stars but that they are in a late stage of evolution. Moreover, the fact that W-R stars are usually in clear regions of space, whereas massive premain-sequence stars are embedded in ultracompact H II regions also shows that W-R stars are not young premain-sequence stars.

  17. A Study of Massive Stars Evolving toward the Wolf-Rayet Stage

    NASA Astrophysics Data System (ADS)

    Maryeva, O. V.; Klochkova, V. G.; Chentsov, E. L.; Polcaro, V. F.; Rossi, C.; Viotti, R. F.

    2017-02-01

    We present the results of our study of two massive stars, V1302 Aql (IRC+10420) and GR 290 (M33/V532, Romano's Star), with different initial masses but now approaching the region of Wolf-Rayet stars on the Hertzsprung-Russell diagram, one from the yellow hypergiants side and the other from the Luminous Blue Variables side.

  18. Inhomogeneites dans le Vent des Etoiles Wolf-Rayet

    NASA Astrophysics Data System (ADS)

    Robert, Carmelle

    1992-01-01

    Des mesures spectroscopiques effectuees avec un haut rapport signal sur bruit et une bonne resolution ont demontre l'existence de regions perturbees en mouvement dans le vent d'etoiles Wolf-Rayet (WR). L'echantillon d'objets etudies ici comprend 9 etoiles WR couvrant differents sous-types WN et WC. De nombreuses petites structures variables superposees au profil des raies d'emission formees dans le vent stellaire signalent la presence des perturbations. L'etude des variations globales des raies et l'examen des micro-structures individuelles ont permis de decrire plusieurs caracteristiques des perturbations. Entre autres, on observe des correlations significatives entre le niveau de variabilite des raies et certains parametres des etoiles qui confirment que le phenomene de variabilite est intrinseque au vent stellaire. En comparant les changements des vitesses radiales et des largeurs equivalentes des differentes raies d'une meme etoile, on conclut que les regions perturbees ont une etendue finie par rapport a l'enveloppe des etoiles. On peut facilement suivre les structures individuelles sur une periode de temps couvrant ~eq8 heures (et peut etre meme 24 heures) avant qu'elles ne disparaissent. Durant ce temps les structures se deplacent en s'eloignant du centre de la raie. A partir des differents comportements notes lors de l'analyse des variations globales et lors de l'examen des structures individuelles, on propose de representer les perturbations par un modele d'inhomogeneites discretes en expansion dans le vent. On suppose simplement que les inhomogeneites emettent comme le vent global (et absorbent aussi si le vent global montre un profil P Cyg). La superposition du graphique de l'acceleration radiale moyenne des inhomogeneites de WR140 en fonction de leur vitesse radiale et du modele theorique d'inhomogeneites qui suivent la loi generale de vitesse donne un taux d'acceleration lent, avec beta >= 3 pour les inhomogeneites de cette etoile. On obtient, entre

  19. The Post-LBV Supernova 2001em

    NASA Astrophysics Data System (ADS)

    Van Dyk, Schuyler D.; Chornock, R.; Filippenko, A. V.; Foley, R. J.; Lewin, W. H. G.; Li, W.; Panagia, N.; Pooley, D.; Stockdale, C. J.; Weiler, K. W.

    2009-12-01

    The supernova (SN) 2001em in UGC 11794 was classified early as Type Ib/c, i.e., as one arising from a hydrogen-stripped star. As part of a radio survey with the Very Large Array of SNe Ib/c at late times (Stockdale et al. 2003, BAAS, 35, 1346), SN 2001em was detected as a highly luminous radio source ˜2 years after explosion. The SN was also subsequently discovered with Chandra to be a very luminous X-ray source. The properties of both the radio and X-ray emission are more characteristic of the Type II-narrow (IIn) SNe, where the SN shock is interacting with dense, massive circumstellar matter, resulting in bright radio synchrotron emission and thermal bremsstrahlung from the interaction region. In fact, SN 2001em has shown to have spectroscopically transformed to a SN IIn. The premise that this might indicate an off-axis gamma-ray burst has been presented (Granot & Ramirez-Ruiz 2004, ApJ, 609, L9) and later, rather convincingly, refuted (e.g., Schinzel et al. 2009, ApJ, 691, 1380). Chugai & Chevalier (2006, ApJ, 641, 1051) have interpreted the spectral transformation and radio/X-ray emission as the SN shock overtaking the detached hydrogen envelope of the progenitor star, which was shed in a superwind episode many years prior to explosion. Chevalier (2007, RMxAC, 30, 41) has further pointed to the required mass-loss rate in the event being equivalent to what would occur in the eruption of a luminous blue variable (LBV). The optical (ground-based and HST) and radio/X-ray data, together with mid-infrared Spitzer observations, tend to support this scenario of a very massive star that experienced a powerful LBV outburst prior to explosion. Such an event may not be unique, with possible parallels in the cases of SNe 2005bf and 2006jc, and may provide valuable new information about massive stellar evolution.

  20. Short-lived radionuclide production by non-exploding Wolf-Rayet stars.

    NASA Astrophysics Data System (ADS)

    Arnould, M.; Paulus, G.; Meynet, G.

    1997-05-01

    This paper presents an extension and update of previous calculations of the production by non-exploding Wolf-Rayet stars of radionuclides that could be responsible for certain isotopic anomalies discovered in meteoritic inclusions, or in meteoritic grains of probable circumstellar origin. Quantitative predictions of the time dependence of the radionuclide composition of the wind of Wolf-Rayet stars with initial masses in the wide 25<=M_i_<=120Msun_ range and for metallicities 0.001<=Z<=0.04 are obtained from a set of revised stellar evolution models. Special emphasis is put on the radionuclides with half-lives between about 10^5^ and 10^8^yr that could be produced by neutron captures during central helium burning and ejected during the WC-WO evolutionary phases. We stress that the radionuclide yield predictions are much more secure for Wolf-Rayet stars than for any other potential source of these species that has been contemplated up to now. This relates directly to the simplicity of these stars compared to highly difficult to model objects like Asymptotic Giant Branch stars, novae or supernovae. Our abundance predictions are confronted with existing observational data, or are hoped to help unravelling cases of potential interest for further laboratory quest when observations are lacking. The case of ^26^Al, of special interest for γ-ray line astronomy as well as for cosmochemistry, is also briefly revisited. In contrast to the other considered radionuclides, ^26^Al is produced during hydrogen burning, and is ejected at the WN evolutionary phase of the Wolf-Rayet stars. Our computed yields are also used as the basis for a qualitative discussion of the astrophysical plausibility of the contamination of the protosolar nebula with the radionuclides loading the Wolf-Rayet winds. Our calculations indicate that ^26^Al, ^41^Ca and ^107^Pd can be produced at a level compatible with the observations from a large variety of Wolf-Rayet stars with different masses and initial

  1. Spectrum and light curve of a supernova shock breakout through a thick Wolf-Rayet wind

    SciTech Connect

    Svirski, Gilad; Nakar, Ehud

    2014-06-20

    Wolf-Rayet stars are known to eject winds. Thus, when a Wolf-Rayet star explodes as a supernova, a fast (≳ 40, 000 km s{sup –1}) shock is expected to be driven through a wind. We study the signal expected from a fast supernova shock propagating through an optically thick wind and find that the electrons behind the shock driven into the wind are efficiently cooled by inverse Compton over soft photons that were deposited by the radiation-mediated shock that crossed the star. Therefore, the bolometric luminosity is comparable to the kinetic energy flux through the shock, and the spectrum is found to be a power law, whose slope and frequency range depend on the number flux of soft photons available for cooling. Wolf-Rayet supernovae that explode through a thick wind have a high flux of soft photons, producing a flat spectrum, νF {sub ν} = Const, in the X-ray range of 0.1 ≲ T ≲ 50 keV. As the shock expands into an optically thin wind, the soft photons are no longer able to cool the shock that plows through the wind, and the bulk of the emission takes the form of a standard core-collapse supernova (without a wind). However, a small fraction of the soft photons is upscattered by the shocked wind and produces a transient unique X-ray signature.

  2. THE PROPAGATION OF NEUTRINO-DRIVEN JETS IN WOLF-RAYET STARS

    SciTech Connect

    Nagakura, Hiroki

    2013-02-20

    We numerically investigate the jet propagation through a rotating collapsing Wolf-Rayet star with detailed central engine physics constructed based on the neutrino-driven collapsar model. The collapsing star determines the evolution of the mass accretion rate, black hole mass, and spin, all of which are important ingredients for determining the jet luminosity. We reveal that neutrino-driven jets in rapidly spinning Wolf-Rayet stars are capable of breaking out from the stellar envelope, while those propagating in slower rotating progenitors fail to break out due to insufficient kinetic power. For progenitor models with successful jet breakouts, the kinetic energy accumulated in the cocoon could be as large as {approx}10{sup 51} erg and might significantly contribute to the luminosity of the afterglow emission or to the kinetic energy of the accompanying supernova if nickel production takes place. We further analyze the post-breakout phase using a simple analytical prescription and conclude that the relativistic jet component could produce events with an isotropic luminosity L {sub p(iso)} {approx} 10{sup 52} erg s{sup -1} and isotropic energy E {sub j(iso)} {approx} 10{sup 54} erg. Our findings support the idea of rapidly rotating Wolf-Rayet stars as plausible progenitors of GRBs, while slowly rotational ones could be responsible for low-luminosity or failed GRBs.

  3. Momentum deposition on Wolf-Rayet winds: Nonisotropic diffusion with effective gray opacity

    NASA Technical Reports Server (NTRS)

    Gayley, Kenneth G.; Owocki, Stanley P.; Cranmer, Steven R.

    1995-01-01

    We derive the velocity and mass-loss rate of a steady state Wolf-Rayet (WR) wind, using a nonisotropic diffusion approximation applied to the transfer between strongly overlapping spectral lines. Following the approach of Friend & Castor (1983), the line list is assumed to approximate a statistically parameterized Poisson distribution in frequency, so that photon transport is controlled by an angle-dependent, effectively gray opacity. We show the nonisotropic diffusion approximation yields good agreement with more accurate numerical treatments of the radiative transfer, while providing analytic insight into wind driving by multiple scattering. We illustrate, in particular, that multiple radiative momentum deposition does not require that potons be repeatedly reflected across substantial distances within the spherical envelope, but indeed is greatest when photons undergo a nearly local diffusion, e.g., through scattering by many lines closely spaced in frequency. Our results reiterate the view that the so-called 'momentum problem' of Wolf-Rayet winds is better characterized as an 'opacity problem' of simply identfying enough lines. One way of increasing the number of thick lines in Wolf-Rayet winds is to transfer opacity from saturated to unsaturated lines, yielding a steeper opacity distribution than that found in OB winds. We discuss the implications of this perspective for extending our approach to W-R wind models that incorporate a more fundamental treatment of the ionization and excitation processes that determine the line opacity. In particular, we argue that developing statistical descriptions of the lines to allow an improved effective opacity for the line ensemble would offer several advantages for deriving such more fundamental W-R wind models.

  4. Momentum deposition on Wolf-Rayet winds: Nonisotropic diffusion with effective gray opacity

    NASA Astrophysics Data System (ADS)

    Gayley, Kenneth G.; Owocki, Stanley P.; Cranmer, Steven R.

    1995-03-01

    We derive the velocity and mass-loss rate of a steady state Wolf-Rayet (WR) wind, using a nonisotropic diffusion approximation applied to the transfer between strongly overlapping spectral lines. Following the approach of Friend & Castor (1983), the line list is assumed to approximate a statistically parameterized Poisson distribution in frequency, so that photon transport is controlled by an angle-dependent, effectively gray opacity. We show the nonisotropic diffusion approximation yields good agreement with more accurate numerical treatments of the radiative transfer, while providing analytic insight into wind driving by multiple scattering. We illustrate, in particular, that multiple radiative momentum deposition does not require that photons be repeatedly reflected across substantial distances within the spherical envelope, but indeed is greatest when photons undergo a nearly local diffusion, e.g., through scattering by many lines closely spaced in frequency. Our results reiterate the view that the so-called 'momentum problem' of Wolf-Rayet winds is better characterized as an 'opacity problem' of simply identifying enough lines. One way of increasing the number of thick lines in Wolf-Rayet winds is to transfer opacity from saturated to unsaturated lines, yielding a steeper opacity distribution than that found in OB winds. We discuss the implications of this perspective for extending our approach to W-R wind models that incorporate a more fundamental treatment of the ionization and excitation processes that determine the line opacity. In particular, we argue that developing statistical descriptions of the lines to allow an improved effective opacity for the line ensemble would offer several advantages for deriving such more fundamental W-R wind models.

  5. A deep survey for Galactic Wolf-Rayet stars. I - Motivation, search technique, and first results

    NASA Technical Reports Server (NTRS)

    Shara, Michael M.; Smith, Lindsey F.; Potter, Michael; Moffat, Anthony F. J.

    1991-01-01

    Results are presented from a survey of large areas of the southern Milky Way for Wolf-Rayet (WR) stars to 17-18th magnitude, carried out using direct narrowband and broadband Schmidt plates. Thirteen new WR stars were detected in an about 40-deg-sq region in Carina, where 24 WR stars were already known; the new stars were found to be significantly redder, fainter, and farther away than the known stars. Of the new WR stars, 11 are of subtype WN, and two are WC, compared to the 17 WN and seven WC stars among the previously known WR stars in the same area.

  6. The vast population of Wolf-Rayet and red supergiant stars in M101. I. Motivation and first results

    SciTech Connect

    Shara, Michael M.; Bibby, Joanne L.; Zurek, David; Crowther, Paul A.; Moffat, Anthony F. J.; Drissen, Laurent

    2013-12-01

    Assembling a catalog of at least 10,000 Wolf-Rayet (W-R) stars is an essential step in proving (or disproving) that these stars are the progenitors of Type Ib and Type Ic supernovae. To this end, we have used the Hubble Space Telescope (HST) to carry out a deep, He II optical narrowband imaging survey of the ScI spiral galaxy M101. Almost the entire galaxy was imaged with the unprecedented depth and resolution that only the HST affords. Differenced with archival broadband images, the narrowband images allow us to detect much of the W-R star population of M101. We describe the extent of the survey and our images, as well as our data reduction procedures. A detailed broadband-narrowband imaging study of a field east of the center of M101, containing the giant star-forming region NGC 5462, demonstrates our completeness limits, how we find W-R candidates, their properties and spatial distribution, and how we rule out most contaminants. We use the broadband images to locate luminous red supergiant (RSG) candidates. The spatial distributions of the W-R and RSG stars near NGC 5462 are strikingly different. W-R stars dominate the complex core, while RSGs dominate the complex halo. Future papers in this series will describe and catalog more than a thousand W-R and RSG candidates that are detectable in our images, as well as spectra of many of those candidates.

  7. DISCOVERY OF TWIN WOLF-RAYET STARS POWERING DOUBLE RING NEBULAE

    SciTech Connect

    Mauerhan, Jon C.; Wachter, Stefanie; Van Dyk, Schuyler D.; Hoard, D. W.; Morris, Patrick W.

    2010-11-20

    We have spectroscopically discovered a pair of twin, nitrogen-type, hydrogen-rich, Wolf-Rayet stars (WN8-9h) that are both surrounded by circular, mid-infrared-bright nebulae detected with the Spitzer Space Telescope and MIPS instrument. The emission is probably dominated by a thermal continuum from cool dust, but also may contain contributions from atomic line emission. There is no counterpart at shorter Spitzer/IRAC wavelengths, indicating a lack of emission from warm dust. The two nebulae are probably wind-swept stellar ejecta released by the central stars during a prior evolutionary phase. The nebulae partially overlap on the sky and we speculate on the possibility that they are in the early stage of a collision. Two other evolved massive stars have also been identified within the area subtended by the nebulae, including a carbon-type Wolf-Rayet star (WC8) and an O7-8 III-I star, the latter of which appears to be embedded in one of the larger WN8-9h nebulae. The derived distances to these stars imply that they are coeval members of an association lying 4.9 {+-} 1.2 kpc from Earth, near the intersection of the Galaxy's Long Bar and the Scutum-Centaurus spiral arm. This new association represents an unprecedented display of complex interactions between multiple stellar winds, outflows, and the radiation fields of evolved massive stars.

  8. Discovery of Twin Wolf-Rayet Stars Powering Double Ring Nebulae

    NASA Astrophysics Data System (ADS)

    Mauerhan, Jon C.; Wachter, Stefanie; Morris, Patrick W.; Van Dyk, Schuyler D.; Hoard, D. W.

    2010-11-01

    We have spectroscopically discovered a pair of twin, nitrogen-type, hydrogen-rich, Wolf-Rayet stars (WN8-9h) that are both surrounded by circular, mid-infrared-bright nebulae detected with the Spitzer Space Telescope and MIPS instrument. The emission is probably dominated by a thermal continuum from cool dust, but also may contain contributions from atomic line emission. There is no counterpart at shorter Spitzer/IRAC wavelengths, indicating a lack of emission from warm dust. The two nebulae are probably wind-swept stellar ejecta released by the central stars during a prior evolutionary phase. The nebulae partially overlap on the sky and we speculate on the possibility that they are in the early stage of a collision. Two other evolved massive stars have also been identified within the area subtended by the nebulae, including a carbon-type Wolf-Rayet star (WC8) and an O7-8 III-I star, the latter of which appears to be embedded in one of the larger WN8-9h nebulae. The derived distances to these stars imply that they are coeval members of an association lying 4.9 ± 1.2 kpc from Earth, near the intersection of the Galaxy's Long Bar and the Scutum-Centaurus spiral arm. This new association represents an unprecedented display of complex interactions between multiple stellar winds, outflows, and the radiation fields of evolved massive stars.

  9. SN 2008D: A WOLF-RAYET EXPLOSION THROUGH A THICK WIND

    SciTech Connect

    Svirski, Gilad; Nakar, Ehud

    2014-06-10

    Supernova (SN) 2008D/XRT 080109 is considered to be the only direct detection of a shock breakout from a regular SN to date. While a breakout interpretation was favored by several papers, inconsistencies remain between the observations and current SN shock breakout theory. Most notably, the duration of the luminous X-ray pulse is considerably longer than expected for a spherical breakout through the surface of a type Ibc SN progenitor, and the X-ray radiation features, mainly its flat spectrum and its luminosity evolution, are enigmatic. We apply a recently developed theoretical model for the observed radiation from a Wolf-Rayet SN exploding through a thick wind and show that it naturally explains all of the observed features of SN 2008D X-ray emission, including the energetics, the spectrum, and the detailed luminosity evolution. We find that the inferred progenitor and SN parameters are typical for an exploding Wolf-Rayet. A comparison of the wind density found at the breakout radius and the density at much larger radii, as inferred by late radio observations, suggests an enhanced mass-loss rate taking effect about 10 days prior to the SN explosion. This finding joins accumulating evidence for a possible late phase in the stellar evolution of massive stars, involving vigorous mass loss a short time before the SN explosion.

  10. Multiwavelength observations of NaSt1 (WR 122): equatorial mass loss and X-rays from an interacting Wolf-Rayet binary

    NASA Astrophysics Data System (ADS)

    Mauerhan, Jon; Smith, Nathan; Van Dyk, Schuyler D.; Morzinski, Katie M.; Close, Laird M.; Hinz, Philip M.; Males, Jared R.; Rodigas, Timothy J.

    2015-07-01

    NaSt1 (aka Wolf-Rayet 122) is a peculiar emission-line star embedded in an extended nebula of [N II] emission with a compact dusty core. The object was previously characterized as a Wolf-Rayet (WR) star cloaked in an opaque nebula of CNO-processed material, perhaps analogous to η Car and its Homunculus nebula, albeit with a hotter central source. To discern the morphology of the [N II] nebula we performed narrow-band imaging using the Hubble Space Telescope and Wide-field Camera 3. The images reveal that the nebula has a disc-like geometry tilted ≈12° from edge-on, composed of a bright central ellipsoid surrounded by a larger clumpy ring. Ground-based spectroscopy reveals radial velocity structure (±10 km s-1) near the outer portions of the nebula's major axis, which is likely to be the imprint of outflowing gas. Near-infrared adaptive-optics imaging with Magellan AO has resolved a compact ellipsoid of Ks-band emission aligned with the larger [N II] nebula, which we suspect is the result of scattered He I line emission (λ2.06 μm). Observations with the Chandra X-ray Observatory have revealed an X-ray point source at the core of the nebula that is heavily absorbed at energies <1 keV and has properties consistent with WR stars and colliding-wind binaries. We suggest that NaSt1 is a WR binary embedded in an equatorial outflow that formed as the result of non-conservative mass transfer. NaSt1 thus appears to be a rare and important example of a stripped-envelope WR forming through binary interaction, caught in the brief Roche lobe overflow phase.

  11. The close binary frequency of Wolf-Rayet stars as a function of metallicity in M31 and M33

    SciTech Connect

    Neugent, Kathryn F.; Massey, Philip E-mail: phil.massey@lowell.edu

    2014-07-01

    Massive star evolutionary models generally predict the correct ratio of WC-type and WN-type Wolf-Rayet stars at low metallicities, but underestimate the ratio at higher (solar and above) metallicities. One possible explanation for this failure is perhaps single-star models are not sufficient and Roche-lobe overflow in close binaries is necessary to produce the 'extra' WC stars at higher metallicities. However, this would require the frequency of close massive binaries to be metallicity dependent. Here we test this hypothesis by searching for close Wolf-Rayet binaries in the high metallicity environments of M31 and the center of M33 as well as in the lower metallicity environments of the middle and outer regions of M33. After identifying ∼100 Wolf-Rayet binaries based on radial velocity variations, we conclude that the close binary frequency of Wolf-Rayets is not metallicity dependent and thus other factors must be responsible for the overabundance of WC stars at high metallicities. However, our initial identifications and observations of these close binaries have already been put to good use as we are currently observing additional epochs for eventual orbit and mass determinations.

  12. Estrellas Wolf-Rayet y el medio interestelar: huellas de una fuerte interacción

    NASA Astrophysics Data System (ADS)

    Cichowolski, S.; Arnal, E. M.

    Se presentan resultados observacionales de un estudio de la distribución de hidrógeno neutro en los alrededores de estrellas Wolf-Rayet (WR) galácticas. Los datos de la línea de 21 cm provienen de observaciones de resolución angular intermedia (9') tomadas con el radiotelescopio de Effelsberg. La muestra está compuesta por cuatro WR de la serie del nitrógeno (WN): WR130, WR131, WR155, WR156 y tres WR de la serie del carbono (WC): WR154, WR117 y WR126. Este análisis ha permitido detectar cavidades y envolturas de HI en expansión presumiblemente vinculadas a dichas estrellas.

  13. The Results of the 2013 Pro-Am Wolf-Rayet Campaign

    NASA Astrophysics Data System (ADS)

    Aldoretta, E. J.; St-Louis, N.; Richardson, N. D.; Moffat, A. F. J.; Eversberg, T.; Hill, G. M.; World-Wide WR Pro-Am Campaign Team

    Professional and amateur astronomers around the world contributed to a 4-month long campaign in 2013, mainly in spectroscopy but also in photometry, interferometry and polarimetry, to observe the first 3 Wolf-Rayet stars discovered: WR 134 (WN6b), WR 135 (WC8) and WR 137 (WC7pd+O9). Each of these stars are interesting in their own way, showing a variety of stellar wind structures. The spectroscopic data from this campaign were reduced and analyzed for WR 134 in order to better understand its behavior and long-term periodicity in the context of CIRs in the wind. We will be presenting the results of these spectroscopic data, which include the confirmation of the CIR variability and a time-coherency of ˜ 40 days (half-life of ˜ 20 days).

  14. Spectrophotometry of Wolf-Rayet stars - Intrinsic colors and absolute magnitudes

    NASA Technical Reports Server (NTRS)

    Torres-Dodgen, Ana V.; Massey, Philip

    1988-01-01

    Absolute spectrophotometry of about 10-A resolution in the range 3400-7300 A have been obtained for southern Wolf-Rayet stars, and line-free magnitudes and colors have been constructed. The emission-line contamination in the narrow-band ubvr systems of Westerlund (1966) and Smith (1968) is shown to be small for most WN stars, but to be quite significant for WC stars. It is suggested that the more severe differences in intrinsic color from star to star of the same spectral subtype noted at shorter wavelengths are due to differences in atmospheric extent. True continuum absolute visual magnitudes and intrinsic colors are obtained for the LMC WR stars. The most visually luminous WN6-WN7 stars are found to be located in the core of the 30 Doradus region.

  15. Effects of Nongray Opacity on Radiatively Driven Wolf-Rayet Winds

    NASA Astrophysics Data System (ADS)

    Onifer, A. J.; Gayley, K. G.

    2002-05-01

    Wolf-Rayet winds are characterized by their large momentum fluxes, and simulations of radiation driving have been increasingly successful in modeling these winds. Simple analytic approaches that help understand the most critical processes for copious momentum deposition already exist in the effectively gray approximation, but these have not been extended to more realistic nongray opacities. With this in mind, we have developed a simplified theory for describing the interaction of the stellar flux with nongray wind opacity. We replace the detailed line list with a set of statistical parameters that are sensitive not only to the strength but also the wavelength distribution of lines, incorporating as a free parameter the rate of photon frequency redistribution. We label the resulting flux-weighted opacity the statistical Sobolev- Rosseland (SSR) mean, and explore how changing these various statistical parameters affects the flux/opacity interaction. We wish to acknowledge NSF grant AST-0098155

  16. Searching for a magnetic field in Wolf-Rayet stars using FORS 2 spectropolarimetry

    NASA Astrophysics Data System (ADS)

    Hubrig, S.; Scholz, K.; Hamann, W.-R.; Schöller, M.; Ignace, R.; Ilyin, I.; Gayley, K. G.; Oskinova, L. M.

    2016-05-01

    To investigate if magnetic fields are present in Wolf-Rayet stars, we selected a few stars in the Galaxy and one in the Large Magellanic Cloud (LMC). We acquired low-resolution spectropolarimetric observations with the European Southern Observatory FORS 2 (FOcal Reducer low dispersion Spectrograph) instrument during two different observing runs. During the first run in visitor mode, we observed the LMC Wolf-Rayet star BAT99 7 and the stars WR 6, WR 7, WR 18, and WR 23 in our Galaxy. The second run in service mode was focused on monitoring the star WR 6. Linear polarization was recorded immediately after the observations of circular polarization. During our visitor observing run, the magnetic field for the cyclically variable star WR 6 was measured at a significance level of 3.3σ ( = 258 ± 78 G). Among the other targets, the highest value for the longitudinal magnetic field, = 327 ± 141 G, was measured in the LMC star BAT99 7. Spectropolarimetric monitoring of the star WR 6 revealed a sinusoidal nature of the variations with the known rotation period of 3.77 d, significantly adding to the confidence in the detection. The presence of the rotation-modulated magnetic variability is also indicated in our frequency periodogram. The reported field magnitude suffers from significant systematic uncertainties at the factor of 2 level, in addition to the quoted statistical uncertainties, owing to the theoretical approach used to characterize it. Linear polarization measurements showed no line effect in the stars, apart from WR 6. BAT99 7, WR 7, and WR 23 do not show variability of the linear polarization over two nights.

  17. An IRAS-Based Search for New Dusty Late-Type WC Wolf-Rayet Stars

    NASA Technical Reports Server (NTRS)

    Cohen, Martin

    1995-01-01

    I have examined all Infrared Astronomical Satellite (IRAS) data relevant to the 173 Galactic Wolf-Rayet (W-R) stars in an updated catalog, including the 13 stars newly discovered by Shara and coworkers. Using the W-R coordinates in these lists, I have examined the IRAS Point Source Catalog (PSC), the Faint Source Catalog, and the Faint Source Reject Catalog, and have generated one-dimensional spatial profiles, 'ADDSCANs', and two-dimensional full-resolution images, 'FRESCOS'. The goal was to assemble the best set of observed IRAS color indices for different W-R types, in particular for known dusty late-type WC Wolf-Rayet (WCL) objects. I have also unsuccessfully sought differences in IRAS colors and absolute magnitudes between single and binary W-R stars. The color indices for the entire ensemble of W-R stars define zones in the IRAS color-color ([12] - [25], [25] - [60])-plane. By searching the PSC for otherwise unassociated sources that satisfy these colors, I have identified potential new W-R candidates, perhaps too faint to have been recognized in previous optical searches. I have extracted these candidates' IRAS low-resolution spectrometer (LRS) data and compared the spectra with the highly characteristic LRS shape for known dusty WCL stars. The 13 surviving candidates must now be ex amined by optical spectroscopy. This work represents a much more rigorous and exhaustive version of the LRS study that identified IRAS 17380 - 3031 (WR98a) as the first new W-R (WC9) star discovered by IPAS. This search should have detected dusty WCL stars to a distance of 7.0 kpc from the Sun, for l is greater than 30 degrees, and to 2.9 kpc even in the innermost galaxy. For free-free-dominated W-R stars the corresponding distances are 2.5 and 1.0 kpc, respectively.

  18. An IRAS-based search for new Dusty Late-Type WC Wolf-Rayet stars

    NASA Technical Reports Server (NTRS)

    Cohen, Martin

    1995-01-01

    I have examined all Infrared Astronomical Satellite (IRAS) data relevant to the 173 Galactic Wolf-Rayet (W-R) stars in an updated catalog, including the 13 stars newly discovered by Shara and coworkers. Using the W-R coordinates in these lists, I have examined the IRAS Point Source Catalog (PSC), the Faint Source Catalog, and the Faint Source Reject Catalog, and have generated one-dimensional spatial profiles ('ADDSCANs') and two-dimensional full-resolution images ('FRESCOs'). The goal was to assemble the best set of observed IRAS color indices for different W-R types, in particular for known dusty late-type WC Wolf-Rayet (WCL) objects. I have also unsuccessfully sought differences in IRAS colors and absolute magnitudes between single and binary W-R stars. The color indices for the entire ensemble of W-R stars define zones in the IRAS color-color plane. By searching the PSC for otherwise unassociated sources that satisfy these colors, I have identified potential new W-R candidates, perhaps too faint to have been recognized in previous optical searches. I have extracted these candidates' IRAS low-resolution spectrometer (LRS) data and compared the spectra with the highly characteristic LRS shape for known dusty WCL stars. The 13 surviving candidates must now be examined by optical spectroscopy. This work represents a much more rigorous and exhaustive version of the LRS study that identified IRAS 17380 - 3031 (WR98a) as the first new W-R (WC9) star discovered by IRAS. This search should have detected dusty WCL stars to a distance of 7.0 kpc from the Sun, for the absolute value of l greater than 30 deg, and to 2.9 kpc even in the innermost Galaxy. For free-free-dominated W-R stars the corresponding distances are 2.5 and 1.0 kpc, respectively.

  19. Variable dust formation by the colliding-wind Wolf-Rayet system HD 36402 in the Large Magellanic Cloud

    NASA Astrophysics Data System (ADS)

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

    2013-05-01

    Infrared photometry of the probable triple WC4(+O?)+O8I: Wolf-Rayet system HD 36402 (= BAT99-38) in the Large Magellanic Cloud shows emission characteristic of heated dust. The dust emission is variable on a time-scale of years, with a period near 4.7 yr, possibly associated with orbital motion of the O8 supergiant and the inner P ≃ 3.03-d WC4+O binary. The phase of maximum dust emission is close to that of the X-ray minimum, consistent with both processes being tied to colliding wind effects in an elliptical binary orbit. It is evident that Wolf-Rayet dust formation occurs also in metal-poor environments.

  20. Wolf-Rayet stars in the Small Magellanic Cloud. I. Analysis of the single WN stars

    NASA Astrophysics Data System (ADS)

    Hainich, R.; Pasemann, D.; Todt, H.; Shenar, T.; Sander, A.; Hamann, W.-R.

    2015-09-01

    Context. Wolf-Rayet (WR) stars have a severe impact on their environments owing to their strong ionizing radiation fields and powerful stellar winds. Since these winds are considered to be driven by radiation pressure, it is theoretically expected that the degree of the wind mass-loss depends on the initial metallicity of WR stars. Aims: Following our comprehensive studies of WR stars in the Milky Way, M 31, and the LMC, we derive stellar parameters and mass-loss rates for all seven putatively single WN stars known in the SMC. Based on these data, we discuss the impact of a low-metallicity environment on the mass loss and evolution of WR stars. Methods: The quantitative analysis of the WN stars is performed with the Potsdam Wolf-Rayet (PoWR) model atmosphere code. The physical properties of our program stars are obtained from fitting synthetic spectra to multi-band observations. Results: In all SMC WN stars, a considerable surface hydrogen abundance is detectable. The majority of these objects have stellar temperatures exceeding 75 kK, while their luminosities range from 105.5 to 106.1L⊙. The WN stars in the SMC exhibit on average lower mass-loss rates and weaker winds than their counterparts in the Milky Way, M 31, and the LMC. Conclusions: By comparing the mass-loss rates derived for WN stars in different Local Group galaxies, we conclude that a clear dependence of the wind mass-loss on the initial metallicity is evident, supporting the current paradigm that WR winds are driven by radiation. A metallicity effect on the evolution of massive stars is obvious from the HRD positions of the SMC WN stars at high temperatures and high luminosities. Standard evolution tracks are not able to reproduce these parameters and the observed surface hydrogen abundances. Homogeneous evolution might provide a better explanation for their evolutionary past. Appendices are available in electronic form at http://www.aanda.org

  1. Ultraviolet observations of clusters of Wolf-Rayet stars in the SBm3 galaxy NGC 4214 and Ultraviolet and optical observations of LINER's

    NASA Technical Reports Server (NTRS)

    Filippenko, Alexei V.

    1992-01-01

    The purpose of the grant was to obtain and analyze IUE (UV) and ground-based (optical) spectra of the central bar of NGC 4214, which contains several bright H II regions, in order to further explore the properties of the Wolf-Rayet stars in this galaxy. Several spatially distinct regions, with widely different equivalent widths of optical Wolf-Rayet lines, could be sampled by the large IUE entrance aperture. By using newly developed extraction techniques, the spectra of these H II regions could be isolated, and differences in their stellar populations would be systematically studied. Data were obtained with IUE in late February and early March, 1992. Some of the shifts were successful, but a few were not -- apparently the blind offset from the nearby star did not work equally well in all cases. Thus, the signal-to-noise ratio is somewhat lower than we had hoped. This necessitated a more careful extraction of the spectra of individual H II regions from the two-dimensional spectra. (A program that models the point spread function in the spatial direction was used to deblend the distinct H II regions.) The IUE data are currently being analyzed in conjunction with ground-based optical spectra. There appear to be obvious variations in the stellar population over angular scales of only a few arc seconds. The second part of the research performed under this grant was a continuation of a project that uses IUE (UV) and ground-based (optical) spectra to infer the physical conditions in Low-Ionization Nuclear Emission-Line Regions (LINER's). We have obtained spectra of a few key objects that cover a representative range in LINER continuum and emission-line properties. The overall goals are to (1) separate the emission into spatially distinct components, (2) establish whether the observed nuclear ultraviolet continua indicate sufficient photoionizing fluxes to account for the emission lines, (3) determine whether the nuclear emission can be explained by hot stars alone, (4

  2. 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.

  3. Project Runaway: Calibrating the Spectroscopic Distance Scale Using Runaway O and Wolf-Rayet Stars

    NASA Astrophysics Data System (ADS)

    Hartkopf, William I.; Mason, B. D.

    2009-05-01

    Well-determined O star masses are notoriously difficult to obtain, due to such factors as broad spectral lines, larger and less-reliable average distances, high multiplicity rates, crowded fields, and surrounding nebulosity. Some of these difficulties are reduced for the subset of O stars known as runaways, however. They have escaped some of the nebulosity and crowding, and the event leading to their ejection virtually guarantees that these objects are either single stars or extremely hard spectroscopic binaries. The goal of this project is to increase the sample of known runaway stars, using updated proper motions from the soon-to-be-released UCAC3 catalog, as well as published radial velocities and data from recent duplicity surveys of massive stars using AO and speckle interferometry. Input files include the Galactic O Star Catalog of Maiz-Apellaniz et al. (2004 ApJSS 151, 103) as well as the Seventh Catalogue of Galactic Wolf-Rayet Stars and its more recent Annex (van der Hucht 2001 NewAR 45, 135; 2006 A&A 458, 453). The new runaway star sample will form the basis for a list of SIM targets aimed at improving the distances of Galactic O and WR stars, calibrating the spectroscopic distance scale and leading to more accurate mass estimates for these massive stars.

  4. A Global Assessment of Wolf-Rayet Binaries in the Magellanic Clouds

    NASA Astrophysics Data System (ADS)

    Moffat, A. F. J.

    2008-08-01

    In the Galaxy, comprehensive empirical studies of advanced massive-star evolution via Wolf-Rayet (WR) stars have been hampered by huge disparities in apparent brightness and interstellar extinction, and by uncertainties in the distances. These problems all but disappear in the Magellanic Clouds (MCs), where one can also systematically probe the effects of lower initial metallicity (Z). Over two decades ago I began, partly involving Virpi Niemela, a vast optical spectroscopic program to examine all of the (then about 100) known MC WR stars for binarity and use them to extract information on general properties of WR stars. Now in 2006 the last step of this project is being wrapped up by the third doctoral student [Olivier Schnurr working on the WNL stars, after Peter Bartzakos (WC) in 1998 and Cédric Foellmi (WNE) in 2002] to embark on this project, now including the 144 known MC WR stars, as defined by the catalogues of Breysacher et al. for the LMC and Massey et al. for the SMC. Here we will summarize the highlights of this work. These include (1) a normal binary WR frequency in both MCs as in the Galaxy, (2) the increased presence of H in WNE stars, even binaries, as one goes to lower Z, (3) colliding winds, and (4) very massive WNLha stars. I will end with some suggestions for future work.

  5. Wolf-Rayet, Yellow and Red Supergiant in the single massive stars perspective

    NASA Astrophysics Data System (ADS)

    Georgy, Cyril; Hirschi, R.; Ekstrom, S.; Meynet, G.

    2013-06-01

    Rotation and mass loss are the key ingredients determining the fate of single massive stars. In recent years, a large effort has been made to compute whole grids of stellar models at different metallicities, including or not the effects of rotation, with the Geneva evolution code. In this talk, I will focus on the evolved stages of massive star evolution (red and yellow supergiants, Wolf-Rayet stars), in the framework of these new grids of models. I will highlight the effects of rotation and mass loss on the post-main sequence evolution of massive stars at solar and lower metallicity. In particular, I will discuss their impact on the maximum mass for a star to end its life as a RSG (leading to a type IIP supernova), on the possibility for a star to finish as a YSG, and on the initial mass ranges leading to various WR star subtypes. I will then compare the results predicted by our code with observed populations of evolved massive stars, bringing constraints on our computations, as well as some indications on the binary star fraction needed to reproduce them.

  6. DISENTANGLING THE NATURE OF THE RADIO EMISSION IN WOLF-RAYET STARS

    SciTech Connect

    Montes, Gabriela; Perez-Torres, Miguel A.; Alberdi, Antonio; Gonzalez, Ricardo F. E-mail: torres@iaa.e E-mail: g.montes@astrosmo.unam.m

    2009-11-01

    We present quasi-simultaneous, multi-frequency Very Large Array observations at 4.8, 8.4, and 22.5 GHz of a sample of 13 Wolf-Rayet (WR) stars, aimed at disentangling the nature of their radio emission and the possible detection of a non-thermal behavior in close binary systems. We detected 12 stars from our sample, for which we derived spectral information and estimated their mass-loss rates. From our data, we identified four thermal sources (WR 89, 113, 138, and 141), and three sources with a composite spectrum (similar contribution of thermal and non-thermal emission; WR 8, 98, and 156). On the other hand, from the comparison with previous observations, we confirm the non-thermal spectrum of one (WR 105), and also found evidence of a composite spectrum for WR 79a, 98a, 104, and 133. Finally, we discuss the possible scenarios to explain the nature of the emission for the observed objects.

  7. Stationary hydrodynamic models of Wolf-Rayet stars with optically thick winds.

    NASA Astrophysics Data System (ADS)

    Heger, A.; Langer, N.

    1996-11-01

    We investigate the influence of a grey, optically thick wind on the surface and internal structure of Wolf-Rayet (WR) stars. We calculate hydrodynamic models of chemically homogeneous helium stars with stationary outflows, solving the full set of stellar structure equations from the stellar center up to well beyond the sonic point of the wind, including the line force originating from absorption lines in a parameterized way. For specific assumptions about mass loss rate and wind opacity above our outer boundary, we find that the iron opacity peak may lead to local super-Eddington luminosities at the sonic point. By varying the stellar wind parameters over the whole physically plausible range, we show that the radius of the sonic point of the wind flow is always very close to the hydrostatic stellar radius obtained in WR star models which ignore the wind. However, our models confirm the possibility of large values for observable WR radii and correspondingly small effective temperatures found in earlier models. We show further that the energy which is contained in a typical WR wind can not be neglected. The stellar luminosity may be reduced by several 10%, which has a pronounced effect on the mass-luminosity relation, i. e., the WR masses derived for a given luminosity may be considerably larger. Thereby, also the momentum problem of WR winds is considerably reduced, as well as the scatter in the ˙(M) vs. M diagram for observed hydrogen-free WN stars.

  8. International Ultraviolet Explorer Observations of Wolf-Rayet Binaries: Wind Structures. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Koenigsberger, G.

    1983-01-01

    Spectra of six WN + OB Wolf-Rayet systems obtained with the IUE are analyzed for phase-dependent variations. Periodic variability at emission-line frequencies is detected in V444 Cyg, HD 90657, HD 211853, HD 186943 and HD 94546 on low dispersion SWP images. No changes in the low dispersion spectra of HD 193077 are apparent. We find the variations in the UV to be similar in nature to those observed in optical spectra of various WR sources. That is, there is a strengthening of absorption components in P Cygni-type features at orbital phases in which the O-star is behind the WR wind. With the aid of a computer code which models this type of variations, and through a comparison with HD 193077, the dominant mechanism producing the variations is shown to be selective atmospheric eclipses of the O-star by the WR wind. Based on this interpretation, a straightforward technique is applied to the line of N IV 1718, by which an optical depth distribution in the WN winds of the form tau varies as r(-1) is derived for 16 r 66 solar radii. Phase-dependent variations in the width of the C IV 1550 absorption component in V444 Cyg, HD 90657 and HD 211853 are interpretated as wind-wind collision effects.

  9. Line profiles variations from atmospheric eclipses: Constraints on the wind structure in Wolf-Rayet stars

    NASA Technical Reports Server (NTRS)

    Auer, L. H.; Koenigsberger, G.

    1994-01-01

    Binary systems in which one of the components has a stellar wind may present a phenomenon known as 'wind' or 'atmospheric eclipse', in which that wind occults the luminous disk of the companion. The enhanced absorption profile, relative to the spectrum at uneclipsed orbital phases, can be be modeled to yield constraints on the spatial structure of the eclipsing wind. A new, very efficient approach to the radiative transfer problem, which makes no requirements with respect to monotonicity of the velocity gradient or size of that gradient, is presented. The technique recovers both the comoving frame calculation and the Sobolev approximation in the appropiate limits. Sample computer simulations of the line profile variations induced by wind eclipses are presented. It is shown that the location of the wind absorption features in frequency is a diagnostic tool for identifying the size of the wind acceleration region. Comparison of the model profile variations with the observed variations in the Wolf-Rayet (W-R)+6 binary system V444 Cyg illustrate how the method can be used to derive information on the structure of the wind of the W-R star constrain the size of the W-R core radius.

  10. An atlas of Copernicus ultraviolet spectra of Wolf-Rayet stars

    NASA Technical Reports Server (NTRS)

    Johnson, H. M.

    1978-01-01

    An atlas of Copernicus UV scans is presented, and line identifications are tabulated, for the Wolf-Rayet stars Gamma-2 Vel (WC 8 + O7), HD 50896 (= EZ CMa; WN 5), and HD 92740 (WN 7). The atlas covers the wavelength ranges from 946.8 to 3182 A for Gamma-2 Vel, from 1012 to 1294 A for HD 50896, and from 1051 to 1243 A for HD 92740. The wavelengths include corrections for components of satellite velocity, earth velocity, and stellar heliocentric velocity; each spectral feature is classified as interstellar, photospheric, emission, UV-displaced P Cygni line absorption, or P Cygni line emission. UV-edge velocities of the P Cygni profiles are estimated, P Cygni profile types are discussed, and the results are compared with Copernicus scans of OB stars exhibiting UV P Cygni profiles. It is noted that: (1) the line-strength ratio of molecular hydrogen to atomic species appears to be substantially greater in the scans of the WN stars than in the Gamma-2 Vel scans; (2) some of the P Cygni profiles in Gamma-2 Vel differ significantly from the corresponding profiles in OB stars; and (3) there may be a slight inverse correlation between ejection velocities and excitation potentials in Gamma-2 Vel.

  11. Using MOST to reveal the secrets of the mischievous Wolf-Rayet binary CV Ser

    NASA Astrophysics Data System (ADS)

    David-Uraz, Alexandre; Moffat, Anthony F. J.; Chené, André-Nicolas; Rowe, Jason F.; Lange, Nicholas; Guenther, David B.; Kuschnig, Rainer; Matthews, Jaymie M.; Rucinski, Slavek M.; Sasselov, Dimitar; Weiss, Werner W.

    2012-11-01

    The Wolf-Rayet (WR) binary CV Serpentis (= WR113, WC8d + O8-9IV) has been a source of mystery since it was shown that its atmospheric eclipses change with time over decades, in addition to its sporadic dust production. The first high-precision time-dependent photometric observations obtained with the Microvariability and Oscillations of STars (MOST) space telescope in 2009 show two consecutive eclipses over the 29-d orbit, with varying depths. A subsequent MOST run in 2010 showed a seemingly asymmetric eclipse profile. In order to help make sense of these observations, parallel optical spectroscopy was obtained from the Mont Megantic Observatory (2009, 2010) and from the Dominion Astrophysical Observatory (2009). Assuming these depth variations are entirely due to electron scattering in a β-law wind, an unprecedented 62 per cent increase in M⊙ is observed over one orbital period. Alternatively, no change in mass-loss rate would be required if a relatively small fraction of the carbon ions in the wind globally recombined and coaggulated to form carbon dust grains. However, it remains a mystery as to how this could occur. There also seems to be evidence for the presence of corotating interaction regions (CIR) in the WR wind: a CIR-like signature is found in the light curves, implying a potential rotation period for the WR star of 1.6 d. Finally, a new circular orbit is derived, along with constraints for the wind collision.

  12. {sup 26}Al AND THE FORMATION OF THE SOLAR SYSTEM FROM A MOLECULAR CLOUD CONTAMINATED BY WOLF-RAYET WINDS

    SciTech Connect

    Gaidos, Eric; Krot, Alexander N.; Williams, Jonathan P.; Raymond, Sean N. E-mail: sasha@higp.hawaii.edu E-mail: sean.raymond@colorado.edu

    2009-05-10

    In agreement with previous work, we show that the presence of the short-lived radionuclide (SLR) {sup 26}Al in the early solar system was unlikely (less than 2% a priori probability) to be the result of direct introduction of supernova (SN) ejecta into the gaseous disk during the Class II stage of protosolar evolution. We also show that Bondi-Hoyle accretion of any contaminated residual gas from the Sun's natal star cluster contributed negligible {sup 26}Al to the primordial solar system. Our calculations are consistent with the absence of the oxygen isotopic signature expected with any late introduction of SN ejecta into the protoplanetary disk. Instead, the presence of {sup 26}Al in the oldest solar system solids (calcium-aluminum-rich inclusions (CAIs)) and its apparent uniform distribution with the inferred canonical {sup 26}Al/{sup 27}Al ratio of (4.5-5) x 10{sup -5} support the inheritance of {sup 26}Al from the Sun's parent giant molecular cloud. We propose that this radionuclide originated in a prior generation of massive stars that formed in the same molecular cloud and contaminated that cloud by Wolf-Rayet winds. We calculated the Galactic distribution of {sup 26}Al/{sup 27}Al ratios that arise from such contamination using the established embedded cluster mass and stellar initial mass functions, published nucleosynthetic yields from the winds of massive stars, and by assuming rapid and uniform mixing into the cloud. Although our model predicts that the majority of stellar systems contain no {sup 26}Al from massive stars, and that the a priori probability that the {sup 26}Al/{sup 27}Al ratio will reach or exceed the canonical solar system value is only {approx}6%, the maximum in the distribution of nonzero values is close to the canonical {sup 26}Al/{sup 27}Al ratio. We find that the Sun most likely formed 4-5 million years (Myr) after the massive stars that were the source of {sup 26}Al. Furthermore, our model can explain the initial solar system

  13. First survey of Wolf-Rayet star populations over the full extension of nearby galaxies observed with CALIFA

    NASA Astrophysics Data System (ADS)

    Miralles-Caballero, D.; Díaz, A. I.; López-Sánchez, Á. R.; Rosales-Ortega, F. F.; Monreal-Ibero, A.; Pérez-Montero, E.; Kehrig, C.; García-Benito, R.; Sánchez, S. F.; Walcher, C. J.; Galbany, L.; Iglesias-Páramo, J.; Vílchez, J. M.; González Delgado, R. M.; van de Ven, G.; Barrera-Ballesteros, J.; Lyubenova, M.; Meidt, S.; Falcon-Barroso, J.; Mast, D.; Mendoza, M. A.; Califa Collaboration

    2016-08-01

    The search of extragalactic regions with conspicuous presence of Wolf-Rayet (WR) stars outside the Local Group is challenging task owing to the difficulty in detecting their faint spectral features. In this exploratory work, we develop a methodology to perform an automated search of WR signatures through a pixel-by-pixel analysis of integral field spectroscopy (IFS) data belonging to the Calar Alto Legacy Integral Field Area survey, CALIFA. This procedure has been applied to a sample of nearby galaxies spanning a wide range of physical, morphological, and environmental properties. This technique allowed us to build the first catalogue of regions rich in WR stars with spatially resolved information, and enabled us to study the properties of these complexes in a two-dimensional (2D) context. The detection technique is based on the identification of the blue WR bump (around He iiλ4686 Å, mainly associated with nitrogen-rich WR stars; WN) and the red WR bump (around C ivλ5808 Å, mainly associated with carbon-rich WR stars; WC) using a pixel-by-pixel analysis that maximizes the number of independent regions within a given galaxy. We identified 44 WR-rich regions with blue bumps distributed in 25 out of a total of 558 galaxies. The red WR bump was identified only in 5 of those regions. Most of the WR regions are located within one effective radius from the galaxy centre, and around one-third are located within ~1 kpc or less from the centre. We found that the majority of the galaxies hosting WR populations in our sample are involved in some kind of interaction process. Half of the host galaxies share some properties with gamma-ray burst (GRB) hosts where WR stars, such as potential candidates to the progenitors of GRBs, are found. We also compared the WR properties derived from the CALIFA data with stellar population synthesis models, and confirm that simple star models are generally not able to reproduce the observations. We conclude that other effects, such as

  14. X-RAY EMISSION FROM NITROGEN-TYPE WOLF-RAYET STARS

    SciTech Connect

    Skinner, Stephen L.; Sokal, Kimberly R.; Zhekov, Svetozar A.; Guedel, Manuel; Schmutz, Werner

    2010-03-15

    We summarize new X-ray detections of four nitrogen-type Wolf-Rayet (WR) stars obtained in a limited survey aimed at establishing the X-ray properties of WN stars across their full range of spectral subtypes. None of the detected stars is so far known to be a close binary. We report Chandra detections of WR 2 (WN2), WR 18 (WN4), and WR 134 (WN6), and an XMM-Newton detection of WR79a (WN9ha). These observations clearly demonstrate that both WNE and WNL stars are X-ray sources. We also discuss Chandra archive detections of the WN6h stars WR 20b, WR 24, and WR 136 and ROSAT non-detections of WR 16 (WN8h) and WR 78 (WN7h). The X-ray spectra of all WN detections show prominent emission lines and an admixture of cool (kT < 1 keV) and hot (kT > 2 keV) plasma. The hotter plasma is not predicted by radiative wind shock models and other as yet unidentified mechanisms are at work. Most stars show X-ray absorption in excess of that expected from visual extinction (A {sub V}), likely due to their strong winds or cold circumstellar gas. Existing data suggest a falloff in X-ray luminosity toward later WN7-9 subtypes, which have higher L {sub bol} but slower, denser winds than WN2-6 stars. This provides a clue that wind properties may be a more crucial factor in determining emergent X-ray emission levels than bolometric luminosity.

  15. Spatial distribution of Galactic Wolf-Rayet stars and implications for the global population

    NASA Astrophysics Data System (ADS)

    Rosslowe, C. K.; Crowther, P. A.

    2015-03-01

    We construct revised near-infrared absolute magnitude calibrations for 126 Galactic Wolf-Rayet (WR) stars at known distances, based in part upon recent large-scale spectroscopic surveys. Application to 246 WR stars located in the field permits us to map their Galactic distribution. As anticipated, WR stars generally lie in the thin disc (˜40 pc half-width at half-maximum) between Galactocentric radii 3.5-10 kpc, in accordance with other star formation tracers. We highlight 12 WR stars located at vertical distances of ≥300 pc from the mid-plane. Analysis of the radial variation in WR subtypes exposes a ubiquitously higher NWC/NWN ratio than predicted by stellar evolutionary models accounting for stellar rotation. Models for non-rotating stars or accounting for close binary evolution are more consistent with observations. We consolidate information acquired about the known WR content of the Milky Way to build a simple model of the complete population. We derive observable quantities over a range of wavelengths, allowing us to estimate a total number of 1900 ± 250 Galactic WR stars, implying an average duration of ˜ 0.4 Myr for the WR phase at the current Milky Way star formation rate. Of relevance to future spectroscopic surveys, we use this model WR population to predict follow-up spectroscopy to KS ≃ 17.5 mag will be necessary to identify 95 per cent of Galactic WR stars. We anticipate that ESA's Gaia mission will make few additional WR star discoveries via low-resolution spectroscopy, though will significantly refine existing distance determinations. Appendix A provides a complete inventory of 322 Galactic WR stars discovered since the VIIth catalogue (313 including Annex), including a revised nomenclature scheme.

  16. Characterizing Wolf-Rayet stars in the near- and mid-infrared

    SciTech Connect

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

    2014-05-01

    We present refined color-color selection criteria for identifying Wolf-Rayet (WR) stars using available mid-infrared (MIR) photometry from WISE in combination with near-infrared (NIR) photometry from the Two Micron All Sky Survey. Using a sample of spectrally classified objects, we find that WR stars are well distinguished from the field stellar population in the (W1 – W2) versus (J – K{sub s} ) color-color diagram, and further distinguished from other emission line objects such as planetary nebulae, Be, and cataclysmic variable stars using a combination of NIR and MIR color constraints. As proof of concept we applied the color constraints to a photometric sample in the Galactic plane, located WR star candidates, and present five new spectrally confirmed and classified WC (1) and WN (4) stars. Analysis of the 0.8-5.0 μm spectral data for a subset of known, bright WC and WN stars shows that emission lines (primarily He I) extend into the 3.0-5.0 μm spectral region, although their strength is greatly diminished compared to the 0.8-2.5 μm region. The WR population stands out relative to background field stars at NIR and MIR colors due to an excess continuum contribution, likely caused by free-free scattering in dense winds. Mean photometric properties of known WRs are presented and imply that reddened late-type WN and WC sources are easier to detect than earlier-type sources at larger Galactic radii. WISE W3 and W4 images of 10 WR stars show evidence of circumstellar shells linked to mass ejections from strong stellar winds.

  17. X-Ray Emission from the Wolf-Rayet Bubble S 308

    NASA Technical Reports Server (NTRS)

    Toala, J. A.; Guerrero, M. A.; Chu, Y.-H.; Gruendl, R. A.; Arthur, S. J.; Smith, R. C.; Snowden, S. L.

    2012-01-01

    The Wolf-Rayet (WR) bubble S 308 around the WR star HD 50896 is one of the only two WR bubbles known to possess X-ray emission. We present XMM-Newton observations of three fields of this WR bubble that, in conjunction with an existing observation of its Northwest quadrant (Chu et al. 2003), map most of the nebula. The X-ray emission from S 308 displays a limb-brightened morphology, with a 22' in size central cavity and a shell thickness of approx. 8'. This X-ray shell is confined by the optical shell of ionized material. The spectrum is dominated by the He-like triplets of N VI at approx.0.43 keV and O VII at approx.0.5 keV, and declines towards high energies, with a faint tail up to 1 keV. This spectrum can be described by a two-temperature optically thin plasma emission model (T1 approx.1.1 x 10(exp 6) K, T2 approx.13 x 10(exp 6) K), with a total X-ray luminosity approx.3 x 10(exp 33) erg/s at the assumed distance of 1.8 kpc. Qualitative comparison of the X-ray morphology of S 308 with the results of numerical simulations of wind-blown WR bubbles suggests a progenitor mass of 40 Stellar mass and an age in the WR phase approx.20,000 yrs. The X-ray luminosity predicted by simulatioms including the effects of heat conduction is in agreement with the observations, however, the simulated X-ray spectrum indicates generally hotter gas than is derived from the observations. We suggest that non-equilibrium ionization (NEI) may provide an explanation for this discrepancy.

  18. A modern search for Wolf-Rayet stars in the Magellanic Clouds: First results

    SciTech Connect

    Massey, Philip; Neugent, Kathryn F.; Morrell, Nidia; Hillier, D. John E-mail: kneugent@lowell.edu E-mail: hillier@pitt.edu

    2014-06-10

    Over the years, directed surveys and incidental spectroscopy have identified 12 Wolf-Rayet (WR) stars in the Small Magellanic Cloud (SMC) and 139 in the Large Magellanic Cloud (LMC), numbers which are often described as 'essentially complete'. Yet, new WRs are discovered in the LMC almost yearly. We have therefore initiated a new survey of both Magellanic Clouds using the same interference-filter imaging technique previously applied to M31 and M33. We report on our first observing season, in which we have successfully surveyed ∼15% of our intended area of the SMC and LMC. Spectroscopy has confirmed nine newly found WRs in the LMC (a 6% increase), including one of WO-type, only the third known in that galaxy and the second to be discovered recently. The other eight are WN3 stars that include an absorption component. In two, the absorption is likely from an O-type companion, but the other six are quite unusual. Five would be classified naively as 'WN3+O3 V', but such a pairing is unlikely given the rarity of O3 stars, the short duration of this phase (which is incommensurate with the evolution of a companion to a WN star), and because these stars are considerably fainter than O3 V stars. The sixth star may also fall into this category. CMFGEN modeling suggests these stars are hot, bolometrically luminous, and N-rich like other WN3 stars, but lack the strong winds that characterize WNs. Finally, we discuss two rare Of?p stars and four Of supergiants we found, and propose that the B[e] star HD 38489 may have a WN companion.

  19. The Nature of Newly Discovered Wolf-Rayet Stars in the LMC

    NASA Astrophysics Data System (ADS)

    Massey, Philip

    2014-10-01

    We have recently discovered five Wolf-Rayet (WR) stars in the LMC which might be naively classified as "WN3+O3 V." However, such a pairing is unlikely for a number of reasons: (a) O3 V stars are very rare, as they are the hottest and most luminous of the dwarfs; (b) the absolute visual magnitudes of our stars are quite faint (Mv=-3) compared to even an O3 V star by itself (Mv=-5.5); (c) these stars do not exhibit radial velocity variations, although our data on this are admittedly limited; and (d) such a pairing would be hard to understand from a stellar evolution point of view, since a massive star will evolve out of the O3 V phase in about a million years, while it takes several million years to form a WN star. We are forced to conclude that we have discoverd a new class of WRs. We have excellent optical spectra with Magellan, and our modeling of these data suggest a very high effective temperature (70,000 K), strongly enhanced nitrogen, and a very low mass-loss rate. However, these physical parameters are poorly constrained by the optical data alone, and we now seek UV spectra that will contain lines that will better determine the temperatures, and the important resonance lines that provide crucial diagnostics of the stellar winds. The results of this modeling will allow us to understand the nature of these objects, and where they fit in the evolution of massive stars. If they are the products of single star evolution, they indicate we have some fundamental misconceptions. If they are the products of binary evolution, how do we explain the absence of any companions? We can only address these questions by having reliable stellar parameters and abundances.

  20. The Wolf-Rayet Star Population of the Milky Way Galaxy

    NASA Astrophysics Data System (ADS)

    Kanarek, Graham

    Wolf-Rayet (WR) stars are a late stage in the evolution of massive stars (M ≥ 25 M), characterized by strong stellar winds ( M˙ 10-5 M/yr). Ionizing radiation from the central star heats the expanding outer envelope of material, leading to recombination emission lines of helium, carbon, nitrogen, oxygen, and/or hydrogen in the WR star spectrum. This outflow of material enriches the surrounding ISM, which is further enriched when the WR star likely explodes as a type Ib or Ic supernova. WR stars are also likely progenitors for long soft gamma-ray bursts, and they are excellent tracers of the present sites of massive star formation in our Galaxy. The current Galactic WR star catalog is very incomplete. I discuss three methods of selecting strong WR star candidates from crowded fields in the Galactic plane: image subtraction, narrowband (NB) color, and broadband (BB) color. Using these methods, an extensive near-infrared narrowband survey begun in 2005-2006, and extended by me, has yielded 28% of the known Galactic WR stars to date; I add 59 new WR stars to the total in this thesis. I then compare two recent models of the Galactic population of WR stars, discuss the implications with respect to how many WR stars remain to be found, and use these results to inform an analysis of the remaining 834 strong carbon-rich WC star candidates from the survey. I also provide a listing of these 834 WC star candidates throughout our Galaxy, and map them; a central result of this thesis. Finally, I present selection criteria which may be used to identify [WR] stars (central stars of planetary nebulae which display WR spectral features), and proof of concept observations which led to 7 new confirmed [WC] stars.

  1. The Prevalence and Impact of Wolf-Rayet Stars in Emerging Massive Star Clusters

    NASA Astrophysics Data System (ADS)

    Sokal, Kimberly R.; Johnson, Kelsey E.; Indebetouw, Rémy; Massey, Philip

    2016-08-01

    We investigate Wolf-Rayet (WR) stars as a source of feedback contributing to the removal of natal material in the early evolution of massive star clusters. Despite previous work suggesting that massive star clusters clear out their natal material before the massive stars evolve into the WR phase, WR stars have been detected in several emerging massive star clusters. These detections suggest that the timescale for clusters to emerge can be at least as long as the time required to produce WR stars (a few million years), and could also indicate that WR stars may be providing the tipping point in the combined feedback processes that drive a massive star cluster to emerge. We explore the potential overlap between the emerging phase and the WR phase with an observational survey to search for WR stars in emerging massive star clusters hosting WR stars. We select candidate emerging massive star clusters from known radio continuum sources with thermal emission and obtain optical spectra with the 4 m Mayall Telescope at Kitt Peak National Observatory and the 6.5 m MMT.4 We identify 21 sources with significantly detected WR signatures, which we term “emerging WR clusters.” WR features are detected in ˜50% of the radio-selected sample, and thus we find that WR stars are commonly present in currently emerging massive star clusters. The observed extinctions and ages suggest that clusters without WR detections remain embedded for longer periods of time, and may indicate that WR stars can aid, and therefore accelerate, the emergence process.

  2. SEARCH FOR A MAGNETIC FIELD VIA CIRCULAR POLARIZATION IN THE WOLF-RAYET STAR EZ CMa

    SciTech Connect

    De la Chevrotiere, A.; St-Louis, N.; Moffat, A. F. J.; Collaboration: MiMeS Collaboration

    2013-02-20

    We report on the first deep, direct search for a magnetic field via the circular polarization of Zeeman splitting in a Wolf-Rayet (W-R) star. Using the highly efficient ESPaDOnS spectropolarimeter at the Canada-France-Hawaii Telescope, we observed at three different epochs one of the best W-R candidates in the sky expected to harbor a magnetic field, the bright, highly variable WN4 star EZ CMa = WR6 = HD 50896. We looked for the characteristic circular polarization (Stokes V) pattern in strong emission lines that would arise as a consequence of a global, rotating magnetic field with a split monopole configuration. We also obtained nearly simultaneous linear polarization spectra (Stokes Q and U), which are dominated by electron scattering, most likely from a flattened wind with large-scale corotating structures. As the star rotates with a period of 3.766 days, our view of the wind changes, which in turn affects the value of the linear polarization in lines versus continuum at the {approx}0.2% level. Depending on the epoch of observation, our Stokes V data were affected by significant crosstalk from Stokes Q and U to V. We removed this spurious signal from the circular polarization data and experimented with various levels of spectral binning to increase the signal-to-noise ratio of our data. In the end, no magnetic field is unambiguously detected in EZ CMa. Assuming that the star is intrinsically magnetic and harbors a split monopole configuration, we find an upper limit of B {approx} 100 G for the intensity of its field in the line-forming regions of the stellar wind.

  3. Hα imaging survey of Wolf-Rayet galaxies: morphologies and star formation rates

    NASA Astrophysics Data System (ADS)

    Jaiswal, S.; Omar, A.

    2016-10-01

    The Hα and optical broad-band images of 25 nearby Wolf-Rayet (WR) galaxies are presented. The WR galaxies are known to have a recent (≤10 Myr) and massive star formation episode. The photometric Hα fluxes are estimated and corrected for extinction and line contamination in the filter pass-bands. The star formation rates (SFRs) are estimated using Hα images and from archival data in the far-ultraviolet (FUV), far-infrared (FIR) and 1.4-GHz radio continuum wavebands. A comparison of SFRs estimated from different wavebands is made after including similar data available in the literature for other WR galaxies. The Hα-based SFRs are found to be tightly correlated with SFRs estimated from the FUV data. The correlations also exist with SFR estimates based on the radio and FIR data. The WR galaxies also follow the radio-FIR correlation known for normal star-forming galaxies, although it is seen here that the majority of dwarf WR galaxies have a radio deficiency. An analysis using the ratio of non-thermal to thermal radio continuum and the ratio of the FUV to Hα SFRs indicates that WR galaxies have lower non-thermal radio emission compared to normal galaxies, most likely due to a lack of supernovae in the very young star formation episode in the WR galaxies. The morphologies of 16 galaxies in our sample are highly suggestive of an ongoing tidal interaction or a past merger in these galaxies. This survey strengthens the conclusions obtained from previous similar studies indicating the importance of tidal interactions in triggering star-formation in WR galaxies.

  4. A Wolf-Rayet-Like Progenitor of SN 2013cu from Spectral Observations of a Stellar Wind

    NASA Technical Reports Server (NTRS)

    Gal-Yam, Avishay; Arcavi, I.; Ofek, E. O.; Ben-Ami, S.; Cenko, S. B.; Kasliwal, M. M.; Cao, Y.; Yaron, O.; Tal, D.; Silverman, J. M.; Horesh, A.; Cia, A. De; Taddia, F.; Sollerman, J.; Perley, D.; Vreeswijk, P. M.; Kulkarni, S. R.; Nugent, P. E.; Filippenko, A. V.; Wheeler, J. C.

    2014-01-01

    The explosive fate of massive Wolf-Rayet stars (WRSs) is a key open question in stellar physics. An appealing option is that hydrogen- deficient WRSs are the progenitors of some hydrogen-poor supernova explosions of types IIb, Ib and Ic. A blue object, having luminosity and colours consistent with those of some WRSs, has recently been identified in pre-explosion images at the location of a supernova of type Ib, but has not yet been conclusively determined to have been the progenitor. Similar work has so far only resulted in non-detections. Comparison of early photometric observations of type Ic supernovae with theoretical models suggests that the progenitor stars had radii of less than 10(exp 12) centimetres, as expected for some WRSs. The signature of WRSs, their emission line spectra, cannot be probed by such studies. Here we report the detection of strong emission lines in a spectrum of type IIb supernova 2013cu (iPTF13ast) obtained approximately 15.5 hours after explosion (by 'flash spectroscopy', which captures the effects of the supernova explosion shock breakout flash on material surrounding the progenitor star).We identify Wolf-Rayet-like wind signatures, suggesting a progenitor of the WN(h) subclass (those WRSs with winds dominated by helium and nitrogen, with traces of hydrogen). The extent of this dense wind may indicate increased mass loss from the progenitor shortly before its explosion, consistent with recent theoretical predictions.

  5. An HST/WFPC2 Survey for Nearby Companions of Galactic Wolf-Rayet Stars

    NASA Astrophysics Data System (ADS)

    Wallace, D. J.

    2003-12-01

    Wolf-Rayet (WR) stars provide key insights about the final evolutionary phase of the most massive stars. I present here the results of a new, high angular resolution, imaging survey of 61 Galactic WR stars, which was designed to detect new companions, clusters, and/or associations surrounding these stars. High resolution observations are essential to provide a true census of the number and astrophysical parameters of massive stars, to understand the effects of nearby companions on their evolutionary paths, and to understand the effects of these companions on the stellar environment. The survey is based on images of each WR target made with the Planetary Camera of the Hubble Space Telescope WFPC2 instrument (usually through the F336W, F439W, and F555W filters, which are near counterparts of the Johnson UBV filters). I measured astrometric positions and photometric magnitudes on the HST synthetic system for all the stars found within 15 arcsec of each WR star. I present results on new companions for 23 (38%) of the 61 WR stars in the survey sample. Three WR stars (WR 86, WR 146, and WR 147) are resolved as close colliding-wind binary systems. Another three WR stars (WR 98a, WR 104, and WR 112) are dusty WC9 type stars in hierarchical multiple systems. Six WR stars are members of previously unrecognized stellar groups. Finally, for thirteen WR stars, I determine new stellar parameters based on an analysis of the color-color and color-magnitude diagrams of the nearby cluster/association main sequence stars. My WR sample breaks down into 57% cluster/association members, 33% field stars, and 10% runaways. This agrees reasonably well with the fractions determined by Mason et al. (1998) of 72%, 20%, and 8% for the same categories among the O stars. I find the same trend that the binary fraction decreases from cluster/association to field and to runaway groups in accordance with our expectation that many of the latter were originally binary members that were ejected by

  6. How Wolf-Rayet winds are driven by starlight and spectral lines

    NASA Astrophysics Data System (ADS)

    Onifer, Andrew Joseph, III

    Finding the cause of the enormous increase in the mass- loss rate of a Wolf-Rayet (W-R) star, as compared to its O star progenitor, has remained a challenge for many years. This thesis explores the hypothesis that line driving causes the large observed W-R mass-loss rates. Frequency redistribution can cause the photons to filter into gaps in the line spectrum, reducing the efficiency of line driving. Therefore, the role that frequency redistribution plays in lowering the predicted mass-loss rate is explored, both via simple two-domain idealizations of the line list and via a real W-R line list. A simple analytic theory, called the Statistical Sobolev Rosseland (SSR) theory, is developed that calculates the local efficiency of line driving in a completely redistributing wind. In the process a conceptual language is developed to explain the key issues in W-R wind line driving. The results are that with no redistribution, the reduction in radius, and corresponding increase in temperature, of an O star as it evolves into a W-R star causes roughly a six-fold increase in the mass-loss rate. However, with large amounts of redistribution, the efficiency of the wind drops greatly in the presence of spectral gaps. In the most extreme case of SSR, the mass- loss rate drops by a factor of up to an order of magnitude relative to the gray value. To avoid this it is necessary to fill the gaps in the spectrum, and the effect that ionization stratification has in filling the gaps globally over the wind is explored. It is found that with the current line list ionization changes can only fill the gaps sufficiently to cause about a factor of two increase over the SSR value. The conclusion is that in order for line driving to explain the mass-loss rates of W-R winds, more opacity needs to be discovered to fill the gaps, either locally, or globally over a realistic range of ionization strata.

  7. Source-plane reconstruction of the giant gravitational arc in A2667: A candidate Wolf-Rayet galaxy at z ∼ 1

    SciTech Connect

    Cao, Shuo; Zhu, Zong-Hong; Covone, Giovanni; Jullo, Eric; Richard, Johan; Izzo, Luca

    2015-01-01

    We present a new analysis of Hubble Space Telescope, Spitzer Space Telescope, and Very Large Telescope imaging and spectroscopic data of a bright lensed galaxy at z = 1.0334 in the lensing cluster A2667. Using this high-resolution imaging, we present an updated lens model that allows us to fully understand the lensing geometry and reconstruct the lensed galaxy in the source plane. This giant arc gives a unique opportunity to view the structure of a high-redshift disk galaxy. We find that the lensed galaxy of A2667 is a typical spiral galaxy with a morphology similar to the structure of its counterparts at higher redshift, z ∼ 2. The surface brightness of the reconstructed source galaxy in the z {sub 850} band reveals the central surface brightness I(0) = 20.28 ± 0.22 mag arcsec{sup –2} and a characteristic radius r{sub s} = 2.01 ± 0.16 kpc at redshift z ∼ 1. The morphological reconstruction in different bands shows obvious negative radial color gradients for this galaxy. Moreover, the redder central bulge tends to contain a metal-rich stellar population, rather than being heavily reddened by dust due to high and patchy obscuration. We analyze the VIMOS/integral field unit spectroscopic data and find that, in the given wavelength range (∼1800-3200 Å), the combined arc spectrum of the source galaxy is characterized by a strong continuum emission with strong UV absorption lines (Fe II and Mg II) and shows the features of a typical starburst Wolf-Rayet galaxy, NGC 5253. More specifically, we have measured the equivalent widths of Fe II and Mg II lines in the A2667 spectrum, and obtained similar values for the same wavelength interval of the NGC 5253 spectrum. Marginal evidence for [C III] 1909 emission at the edge of the grism range further confirms our expectation.

  8. The Wind-Wind Collision Region of the Wolf-Rayet Binary V444 Cygni: How Much Optical Line Emission Does It Produce?

    NASA Astrophysics Data System (ADS)

    Flores, Aaron; Auer, Lawrence H.; Koenigsberger, Gloria; Cardona, Octavio

    2001-12-01

    We model the emission-line profile variations that are expected to be produced by physical and wind eclipses in the Wolf-Rayet (W-R+O) binary system V444 Cyg. A comparison of the theoretical profiles with the He II 4686 Å line observed in V444 Cyg allows us to isolate the effects that are likely to be due to the wind-wind collision region in this particular line. We estimate that the wind-wind collision region contributes no more than ~12% of the equivalent width of the emission line, with smaller values during elongations, when part of the shock cone is being eclipsed by the O star. The upper limit implies a maximum contribution from the wind-wind collision region of ~1×1035 ergs s-1 to the total luminosity of He II 4686 Å line. Using the analytical solution of Cantó et al., we find that the bulk of this emission arises along the shock cone walls where the flow velocity is ~800 km s-1, at a distance of ~8 Rsolar from the O star's surface, and at θ=65°-75° from the line joining the centers of the two stars, with origin in the O star. The derived surface density of this region is σ=0.22 g cm-2, which, together with the He II 4686 Å luminosity, indicates that the thickness of the shock lies in the range 2-10×1010 cm and the total density is 1-6×1012 cm-3.

  9. The Wind-Wind Collision Region of the Wolf-Rayet Binary V444 Cyg: How much optical line emission does it produce ?

    NASA Astrophysics Data System (ADS)

    Flores, A.; Auer, L. H.; Koenigsberger, G.; Cardona, O.

    2001-12-01

    We model the emission line profile variations that are expected to be produced by physical and wind eclipses in the Wolf-Rayet (WR+O) binary system V444 Cyg. A comparison of the theoretical profiles with the He II 4686 Å line observed in V444 Cyg allows us to isolate the effects that are likely to be due to the wind-wind collision region, in this particular line. We estimate that the WWC region contributes no more than ~ 12% of the equivalent width of the emission line, with smaller values during elongations, when part of the shock cone is being eclipsed by the O-star. The upper limit implies a maximum contribution from the wind-wind collision region of ~ 1.*E35 ergs s-1 to the total luminosity of He II 4686 Å line. Using the analytical solution of Cantó et al. (1996), we find that the bulk of this emission seems to be arising along the shock cone walls where the flow velocity is ~ 800 km s-1, at a distance of ~ 8 {Rsun }\\> from the O-star's surface, and at Θ =60-70o from the line joining the centers of the two stars, with origin in the O-star. The derived surface density of this region is σ =0.22 gr cm-2, which together with the He II 4686 Å luminosity, indicates that the thickness of the shock lies in the range 2-10 x 1010 cm and the total density is 1-6 x 1012 cm-3.

  10. X-ray Observations of Binary and Single Wolf-Rayet Stars with XMM-Newton and Chandra

    NASA Technical Reports Server (NTRS)

    Skinner, Stephen; Gudel, Manuel; Schmutz, Werner; Zhekov, Svetozar

    2006-01-01

    We present an overview of recent X-ray observations of Wolf-Rayet (WR) stars with XMM-Newton and Chandra. These observations are aimed at determining the differences in X-ray properties between massive WR + OB binary systems and putatively single WR stars. A new XMM spectrum of the nearby WN8 + OB binary WR 147 shows hard absorbed X-ray emission (including the Fe Ka line complex), characteristic of colliding wind shock sources. In contrast, sensitive observations of four of the closest known single WC (carbon-rich) WR stars have yielded only nondetections. These results tentatively suggest that single WC stars are X-ray quiet. The presence of a companion may thus be an essential factor in elevating the X-ray emission of WC + OB stars to detectable levels.

  11. The Statistical Sobolev-Rosseland Mean and the Effects of Frequency Redistribution on Wolf-Rayet Wind Driving

    NASA Astrophysics Data System (ADS)

    Onifer, A. J.; Gayley, K. G.

    2003-06-01

    The optically thick character of Wolf-Rayet winds implies that stellar continuum photons are multiply scattered, as a result of both free electron opacity and overlapping wind-broadened spectral lines. This allows the wind to accumulate a substantial excess in momentum flux relative to the driving radiation field, as is observationally required. Nevertheless, sustaining such a high degree of multiple scattering requires not only a large optical depth spatially but also substantial spectral blanketing. The latter is difficult to maintain when redistribution during scattering allows radiative flux to shift preferentially into spectral regions with fewer lines, since then the channels carrying much of the flux are also the least well blanketed. This paper parameterizes the potential severity of this effect in simple terms, using a generalization of the Rosseland mean treated in the Sobolev approximation. We show that our approach provides an informative starting point for characterizing and conceptualizing nongray effects in optically thick supersonic flows.

  12. Mass loss from Wolf-Rayet stars - an analysis of radio and infrared observations of MR 111 /AS 422/

    NASA Astrophysics Data System (ADS)

    Felli, M.; Panagia, N.

    1982-11-01

    VLA radio observations at 1.3 cm of the Wolf-Rayet star MR 111 are reported. The collected fluxes over a frequency range from 1.65 micron to 6 cm are considered and separated into two components: a stellar blackbody and an extended envelope emission. The envelope emission is interpreted in terms of an ionized accelerated outflow due to mass loss. The parameters that define the outflow, i.e., the mass loss and the shape of the velocity curve, as well as the stellar photospheric radius, are derived from a best fit of the available data. MR 111 is found to be a WN-type star, with a radius of 25 solar radii losing mass at a rate of 0.000025 solar mass/yr with acceleration occurring in the inner part of the outflow.

  13. The Galactic hybrid Wolf-Rayet WN7o/CE + O7V((f)) binary system WR145

    NASA Astrophysics Data System (ADS)

    Muntean, V.; Moffat, A. F. J.; Chené, A. N.; de La Chevrotière, A.

    2009-11-01

    A spectroscopic study of the binary Wolf-Rayet (WR)+O system WR145 is performed, in order to determine the radial velocity orbits of the individual stars, the angle of orbital inclination and the stellar masses. The emission and absorption components are separated from the original spectra, allowing us to confirm the spectral classification WN7o/CE of the hybrid WR component and to derive a spectral classification O7V((f)) for the O star. A study of the wind-collision properties is performed. Fitting the radial velocity and full width at half-maximum of the excess emission with Lührs' model results in an inclination angle of i = 63°, leading to estimates of the stellar masses: MWR = 18Msolar and MO = 31Msolar. Both of these masses are compatible with those of other stars of similar types.

  14. Pinwheels in the sky, with dust: 3D modelling of the Wolf-Rayet 98a environment

    NASA Astrophysics Data System (ADS)

    Hendrix, Tom; Keppens, Rony; van Marle, Allard Jan; Camps, Peter; Baes, Maarten; Meliani, Zakaria

    2016-08-01

    The Wolf-Rayet 98a (WR 98a) system is a prime target for interferometric surveys, since its identification as a `rotating pinwheel nebulae', where infrared images display a spiral dust lane revolving with a 1.4 yr periodicity. WR 98a hosts a WC9+OB star, and the presence of dust is puzzling given the extreme luminosities of Wolf-Rayet stars. We present 3D hydrodynamic models for WR 98a, where dust creation and redistribution are self-consistently incorporated. Our grid-adaptive simulations resolve details in the wind collision region at scales below one percent of the orbital separation (˜4 au), while simulating up to 1300 au. We cover several orbital periods under conditions where the gas component alone behaves adiabatic, or is subject to effective radiative cooling. In the adiabatic case, mixing between stellar winds is effective in a well-defined spiral pattern, where optimal conditions for dust creation are met. When radiative cooling is incorporated, the interaction gets dominated by thermal instabilities along the wind collision region, and dust concentrates in clumps and filaments in a volume-filling fashion, so WR 98a must obey close to adiabatic evolutions to demonstrate the rotating pinwheel structure. We mimic Keck, ALMA or future E-ELT observations and confront photometric long-term monitoring. We predict an asymmetry in the dust distribution between leading and trailing edge of the spiral, show that ALMA and E-ELT would be able to detect fine-structure in the spiral indicative of Kelvin-Helmholtz development, and confirm the variation in photometry due to the orientation. Historic Keck images are reproduced, but their resolution is insufficient to detect the details we predict.

  15. An extensive spectroscopic time series of three Wolf-Rayet stars - I. The lifetime of large-scale structures in the wind of WR 134

    NASA Astrophysics Data System (ADS)

    Aldoretta, E. J.; St-Louis, N.; Richardson, N. D.; Moffat, A. F. J.; Eversberg, T.; Hill, G. M.; Shenar, T.; Artigau, É.; Gauza, B.; Knapen, J. H.; Kubát, J.; Kubátová, B.; Maltais-Tariant, R.; Muñoz, M.; Pablo, H.; Ramiaramanantsoa, T.; Richard-Laferrière, A.; Sablowski, D. P.; Simón-Díaz, S.; St-Jean, L.; Bolduan, F.; Dias, F. M.; Dubreuil, P.; Fuchs, D.; Garrel, T.; Grutzeck, G.; Hunger, T.; Küsters, D.; Langenbrink, M.; Leadbeater, R.; Li, D.; Lopez, A.; Mauclaire, B.; Moldenhawer, T.; Potter, M.; dos Santos, E. M.; Schanne, L.; Schmidt, J.; Sieske, H.; Strachan, J.; Stinner, E.; Stinner, P.; Stober, B.; Strandbaek, K.; Syder, T.; Verilhac, D.; Waldschläger, U.; Weiss, D.; Wendt, A.

    2016-08-01

    During the summer of 2013, a 4-month spectroscopic campaign took place to observe the variabilities in three Wolf-Rayet stars. The spectroscopic data have been analysed for WR 134 (WN6b), to better understand its behaviour and long-term periodicity, which we interpret as arising from corotating interaction regions (CIRs) in the wind. By analysing the variability of the He II λ5411 emission line, the previously identified period was refined to P = 2.255 ± 0.008 (s.d.) d. The coherency time of the variability, which we associate with the lifetime of the CIRs in the wind, was deduced to be 40 ± 6 d, or ˜18 cycles, by cross-correlating the variability patterns as a function of time. When comparing the phased observational grey-scale difference images with theoretical grey-scales previously calculated from models including CIRs in an optically thin stellar wind, we find that two CIRs were likely present. A separation in longitude of Δφ ≃ 90° was determined between the two CIRs and we suggest that the different maximum velocities that they reach indicate that they emerge from different latitudes. We have also been able to detect observational signatures of the CIRs in other spectral lines (C IV λλ5802,5812 and He I λ5876). Furthermore, a DAC was found to be present simultaneously with the CIR signatures detected in the He I λ5876 emission line which is consistent with the proposed geometry of the large-scale structures in the wind. Small-scale structures also show a presence in the wind, simultaneously with the larger scale structures, showing that they do in fact co-exist.

  16. RE-EXAMINING HIGH ABUNDANCE SLOAN DIGITAL SKY SURVEY MASS-METALLICITY OUTLIERS: HIGH N/O, EVOLVED WOLF-RAYET GALAXIES?

    SciTech Connect

    Berg, Danielle A.; Skillman, Evan D.; Marble, Andrew R. E-mail: skillman@astro.umn.edu

    2011-09-01

    We present new MMT spectroscopic observations of four dwarf galaxies representative of a larger sample observed by the Sloan Digital Sky Survey and identified by Peeples et al. as low-mass, high oxygen abundance outliers from the mass-metallicity relation. Peeples showed that these four objects (with metallicity estimates of 8.5 {<=} 12 + log(O/H) {<=} 8.8) have oxygen abundance offsets of 0.4-0.6 dex from the M{sub B} luminosity-metallicity relation. Our new observations extend the wavelength coverage to include the [O II] {lambda}{lambda}3726, 3729 doublet, which adds leverage in oxygen abundance estimates and allows measurements of N/O ratios. All four spectra are low excitation, with relatively high N/O ratios (N/O {approx}> 0.10), each of which tend to bias estimates based on strong emission lines toward high oxygen abundances. These spectra all fall in a regime where the 'standard' strong-line methods for metallicity determinations are not well calibrated either empirically or by photoionization modeling. By comparing our spectra directly to photoionization models, we estimate oxygen abundances in the range of 7.9 {<=} 12 + log (O/H) {<=} 8.4, consistent with the scatter of the mass-metallicity relation. We discuss the physical nature of these galaxies that leads to their unusual spectra (and previous classification as outliers), finding their low excitation, elevated N/O, and strong Balmer absorption are consistent with the properties expected from galaxies evolving past the 'Wolf-Rayet galaxy' phase. We compare our results to the 'main' sample of Peeples and conclude that they are outliers primarily due to enrichment of nitrogen relative to oxygen and not due to unusually high oxygen abundances for their masses or luminosities.

  17. Wolf-Rayet stars in M81: detection and characterization using GTC/OSIRIS spectra and HST/ACS images

    NASA Astrophysics Data System (ADS)

    Gómez-González, V. M. A.; Mayya, Y. D.; Rosa-González, D.

    2016-08-01

    We here report the properties of Wolf-Rayet (W-R) stars in 14 locations in the nearby spiral galaxy M81. These locations were found serendipitously while analysing the slit spectra of a sample of ˜150 star-forming complexes, taken using the long-slit and multiobject spectroscopic modes of the OSIRIS instrument at the 10.4-m Gran Telescopio Canarias. Colours and magnitudes of the identified point sources in the Hubble Space Telescope images compare well with those of individual W-R stars in the Milky Way. Using templates of individual W-R stars, we infer that the objects responsible for the observed W-R features are single stars in 12 locations, comprising of three WNLs, three WNEs, two WCEs and four transitional WN/C types. In diagrams involving bump luminosities and the width of the bumps, the W-R stars of the same sub-class group together, with the transitional stars occupying locations intermediate between the WNE and WCE groups, as expected from the evolutionary models. However, the observed number of 4 transitional stars out of our sample of 14 is statistically high as compared to the 4 per cent expected in stellar evolutionary models.

  18. Chemical self-enrichment of HII regions by the Wolf-Rayet phase of an 85 M⊙ star

    NASA Astrophysics Data System (ADS)

    Kröger, D.; Hensler, G.; Freyer, T.

    2006-04-01

    It is clear from stellar evolution and from observations of WR stars that massive stars are releasing metal-enriched gas through their stellar winds in the Wolf-Rayet phase. Although Hii region spectra serve as diagnostics to determine the present-day chemical composition of the interstellar medium, it is far from being understood to what extent the Hii gas is already contaminated by chemically processed stellar wind. Therefore, we analyzed our models of radiative and wind bubbles of an isolated 85 M⊙ star with solar metallicity (Kröger et al. 2006, A&A, in preparation) with respect to the chemical enrichment of the circumstellar Hii region. Plausibly, the hot stellar wind bubble (SWB) is enriched with 14N during the WN phase and even much higher with 12C and 16O during the WC phase of the star. During the short period that the 85 M⊙ star spends in the WC stage enriched SWB material mixes with warm Hii gas of solar abundances and thus enhances the metallicity in the Hii region. However, at the end of the stellar lifetime the mass ratios of the traced elements N and O in the warm ionized gas are insignificantly higher than solar, whereas an enrichment of 22% above solar is found for C. Important issues from the presented study comprise a steeper radial gradient of C than O and a decreasing effect of self-enrichment for metal-poor galaxies.

  19. The CHARA Array resolves the long-period Wolf-Rayet binaries WR 137 and WR 138

    NASA Astrophysics Data System (ADS)

    Richardson, Noel D.; Shenar, Tomer; Roy-Loubier, Olivier; Schaefer, Gail; Moffat, Anthony F. J.; St-Louis, Nicole; Gies, Douglas R.; Farrington, Chris; Hill, Grant M.; Williams, Peredur M.; Gordon, Kathryn; Pablo, Herbert; Ramiaramanantsoa, Tahina

    2016-10-01

    We report on interferometric observations with the CHARA Array of two classical Wolf-Rayet (WR) stars in suspected binary systems, namely WR 137 and WR 138. In both cases, we resolve the component stars to be separated by a few milliarcseconds. The data were collected in the H band, and provide a measure of the fractional flux for both stars in each system. We find that the WR star is the dominant H-band light source in both systems (fWR,137 = 0.59 ± 0.04; fWR,138 = 0.67 ± 0.01), which is confirmed through both comparisons with estimated fundamental parameters for WR stars and O dwarfs, as well as through spectral modelling of each system. Our spectral modelling also provides fundamental parameters for the stars and winds in these systems. The results on WR 138 provide evidence that it is a binary system which may have gone through a previous mass-transfer episode to create the WR star. The separation and position of the stars in the WR 137 system together with previous results from the IOTA interferometer provides evidence that the binary is seen nearly edge-on. The possible edge-on orbit of WR 137 aligns well with the dust production site imaged by the Hubble Space Telescope during a previous periastron passage, showing that the dust production may be concentrated in the orbital plane.

  20. Detached dust shell around Wolf-Rayet star WR60-6 in the young stellar cluster VVV CL036

    SciTech Connect

    Borissova, J.; Amigo, P.; Kurtev, R.; Kumar, M. S. N.; Chené, A.-N.; Minniti, D.

    2014-01-01

    The discovery of a detached dust shell around the Wolf-Rayet (WR) star WR60-6 in the young stellar cluster VVV CL036 is reported. This shell is uncovered through the Spitzer-MIPS 24 μm image, where it appears brightest, and it is invisible at shorter wavelengths. Using new APEX observations and other data available from the literature, we have estimated some of the shell parameters: the inner and outer radii of 0.15 and 0.90 pc, respectively; the overall systemic velocity of the molecular {sup 12}CO(3 → 2) emission of –45.7 ± 2.3 km s{sup –1}; an expansion velocity of the gas of 16.3 ± 1 km s{sup –1}; the dust temperature and opacity of 122 ± 12 K and 1.04, respectively; and an age of 2.8 × 10{sup 4} yr. The WR star displays some cyclic variability. The mass computed for the WR60-6 nebula indicates that the material was probably ejected during its previous stages of evolution. In addition, we have identified a bright spot very close to the shell, which can be associated with the Midcourse Space Experiment source G312.13+00.20.

  1. High-resolution X-Ray Spectroscopy Reveals the Special Nature of Wolf-Rayet Star Winds

    NASA Astrophysics Data System (ADS)

    Oskinova, L. M.; Gayley, K. G.; Hamann, W.-R.; Huenemoerder, D. P.; Ignace, R.; Pollock, A. M. T.

    2012-03-01

    We present the first high-resolution X-ray spectrum of a putatively single Wolf-Rayet (WR) star. 400 ks observations of WR 6 by the XMM-Newton telescope resulted in a superb quality high-resolution X-ray spectrum. Spectral analysis reveals that the X-rays originate far out in the stellar wind, more than 30 stellar radii from the photosphere, and thus outside the wind acceleration zone where the line-driving instability (LDI) could create shocks. The X-ray emitting plasma reaches temperatures up to 50 MK and is embedded within the unshocked, "cool" stellar wind as revealed by characteristic spectral signatures. We detect a fluorescent Fe line at ≈6.4 keV. The presence of fluorescence is consistent with a two-component medium, where the cool wind is permeated with the hot X-ray emitting plasma. The wind must have a very porous structure to allow the observed amount of X-rays to escape. We find that neither the LDI nor any alternative binary scenario can explain the data. We suggest a scenario where X-rays are produced when the fast wind rams into slow "sticky clumps" that resist acceleration. Our new data show that the X-rays in single WR star are generated by some special mechanism different from the one operating in the O-star winds.

  2. POPULATION I WOLF-RAYET RUNAWAY STARS: THE CASE OF WR124 AND ITS EXPANDING NEBULA M1-67

    SciTech Connect

    Marchenko, S. V.; Moffat, A. F. J.; Crowther, P. A. E-mail: moffat@astro.umontreal.c

    2010-11-20

    In 1997 and 2008 we used the WFPC2 camera on board the Hubble Space Telescope to obtain two sets of narrow-band H{alpha} images of the runaway Wolf-Rayet (WR) star WR 124 surrounded by its nebula M1-67. This two-epoch imaging provides an expansion parallax and thus a practically assumption-free geometric distance to the nebula, d = 3.35 {+-} 0.67 kpc. Combined with the global velocity distribution in the ejected nebula, this confirms the extreme runaway status of WR 124. WR stars embedded within such ejection nebulae at the point of core collapse would produce different supernova characteristics from those expected for stars surrounded by wind-filled cavities. In galaxies with extremely low ambient metallicity, Z {<=} 10{sup -3} Z {sub sun}, {gamma}-ray bursts originating from fast-moving runaway WR stars may produce afterglows which appear to be coming from regions with a relatively homogeneous circumburst medium.

  3. NEW CONSTRAINTS ON THE ORIGIN OF THE SHORT-TERM CYCLICAL VARIABILITY OF THE WOLF-RAYET STAR WR 46

    SciTech Connect

    Henault-Brunet, V.; St-Louis, N.; Marchenko, S. V.; Pollock, A. M. T.; Talavera, A.; Carpano, S. E-mail: stlouis@astro.umontreal.ca E-mail: andy.pollock@esa.int E-mail: scarpano@rssd.esa.int

    2011-07-01

    The Wolf-Rayet star WR 46 is known to exhibit a very complex variability pattern on relatively short timescales of a few hours. Periodic but intermittent radial velocity shifts of optical lines as well as multiple photometric periods have been found in the past. Non-radial pulsations, rapid rotational modulation, or the presence of a putative low-mass companion have been proposed to explain the short-term behavior. In an effort to unveil its true nature, we observed WR 46 with the Far Ultraviolet Spectroscopic Explorer (FUSE) over several short-term variability cycles. We found significant variations on a timescale of {approx}8 hr in the far-ultraviolet (FUV) continuum, in the blue edge of the absorption trough of the O VI {lambda}{lambda}1032, 1038 doublet P Cygni profile and in the S VI {lambda}{lambda}933, 944 P Cygni absorption profile. We complemented these observations with X-ray and UV light curves and an X-ray spectrum from archival X-ray Multi-Mirror Mission-Newton Space Telescope (XMM-Newton) data. The X-ray and UV light curves show variations on a timescale similar to the variability found in the FUV. We discuss our results in the context of the different scenarios suggested to explain the short-term variability of this object and reiterate that non-radial pulsations is the scenario most likely to occur.

  4. Modelling the thermal X-ray emission around the Galactic Centre from colliding Wolf-Rayet winds

    NASA Astrophysics Data System (ADS)

    Russell, Christopher M. P.; Wang, Q. Daniel; Cuadra, Jorge

    2017-02-01

    The Galactic Centre is a hotbed of astrophysical activity, with the injection of wind material from ˜30 massive Wolf-Rayet (WR) stars orbiting within 12 arcsec of the supermassive black hole (SMBH) playing an important role. Hydrodynamic simulations of such colliding and accreting winds produce a complex density and temperature structure of cold wind material shocking with the ambient medium, creating a large reservoir of hot, X-ray-emitting gas. This work aims to confront the 3 Ms of Chandra X-ray Visionary Program observations of this diffuse emission by computing the X-ray emission from these hydrodynamic simulations of the colliding WR winds, amid exploring a variety of SMBH feedback mechanisms. The major success of the model is that it reproduces the spectral shape from the 2-5 arcsec ring around the SMBH, where most of the stellar wind material that is ultimately captured by Sgr A* is shock-heated and thermalized. This naturally explains that the hot gas comes from colliding WR winds, and that the wind speeds of these stars are, in general, well constrained. The flux level of these spectra, as well as 12 × 12-arcsec2 images of 4-9 keV, shows that the X-ray flux is tied to the SMBH feedback strength; stronger feedback clears out more hot gas, thereby decreasing the thermal X-ray emission. The model in which Sgr A* produced an intermediate-strength outflow during the last few centuries best matches the observations to within about 10 per cent, showing that SMBH feedback is required to interpret the X-ray emission in this region.

  5. X-ray emission from the Wolf-Rayet bubble NGC 6888. I. Chandra ACIS-S observations

    SciTech Connect

    Toalá, J. A.; Guerrero, M. A.

    2014-02-01

    We analyze Chandra observations of the Wolf-Rayet (W-R) bubble NGC 6888. This W-R bubble presents similar spectral and morphological X-ray characteristics to those of S 308, the only other W-R bubble also showing X-ray emission. The observed spectrum is soft, peaking at the N VII line emission at 0.5 keV, with additional line emission at 0.7-0.9 keV and a weak tail of harder emission up to ∼1.5 keV. This spectrum can be described by a two-temperature optically thin plasma emission model (T {sub 1} ∼ 1.4 × 10{sup 6} K, T {sub 2} ∼ 7.4 × 10{sup 6} K). We confirm the results of previous X-ray observations that no noticeable temperature variations are detected in the nebula. The X-ray-emitting plasma is distributed in three apparent morphological components: two caps along the tips of the major axis and an extra contribution toward the northwest blowout not reported in previous analyses of the X-ray emission toward this W-R nebula. Using the plasma model fits of the Chandra ACIS spectra for the physical properties of the hot gas and the ROSAT PSPC image to account for the incomplete coverage of Chandra observations, we estimate a luminosity of L {sub X} = (7.7 ± 0.1) ×10{sup 33} erg s{sup –1} for NGC 6888 at a distance of 1.26 kpc. The average rms electron density of the X-ray-emitting gas is ≳ 0.4 cm{sup –3} for a total mass ≳ 1.2 M {sub ☉}.

  6. Searching for magnetic fields in 11 Wolf-Rayet stars: Analysis of circular polarization measurements from ESPaDOnS

    SciTech Connect

    De la Chevrotière, A.; St-Louis, N.; Moffat, A. F. J.; Collaboration: MiMeS Collaboration

    2014-02-01

    With recent detections of magnetic fields in some of their progenitor O stars, combined with known strong fields in their possible descendant neutron stars, it is natural to search for magnetic fields in Wolf-Rayet (WR) stars, despite the problems associated with the presence of winds enhanced by an order of magnitude over those of O stars. We continue our search among a sample of 11 bright WR stars following our introductory study in a previous paper of WR6 = EZ CMa using the spectropolarimeter ESPaDOnS at Canada-France-Hawaii Telescope, most of them in all four Stokes parameters. This sample includes six WN stars and five WC stars encompassing a range of spectral subclasses. Six are medium/long-period binaries and three show corotating interaction regions. We report no definite detections of a magnetic field in the winds in which the lines form (which is about the same distance from the center of the star as it is from the surface of the progenitor O star) for any of the eleven stars. Possible reasons and their implications are discussed. Nonetheless, the data show evidence supporting marginal detections for WR134, WR137, and WR138. According to the Bayesian analysis, the most probable field intensities are B {sub wind} ∼ 200, 130, and 80 G, respectively, with a 95.4% probability that the magnetic fields present in the observable parts of their stellar wind, if stronger, does not exceed B{sub wind}{sup max}∼1900 G, ∼1500 G, and ∼1500 G, respectively. In the case of non-detections, we report an average field strength upper limit of B{sub wind}{sup max}∼500 G.

  7. Modelling the thermal X-ray emission around the Galactic center from colliding Wolf-Rayet winds

    NASA Astrophysics Data System (ADS)

    Post Russell, Christopher Michael; Wang, Q. Daniel; Cuadra, Jorge

    2017-01-01

    The Galactic center is a hotbed of astrophysical activity, with the injection of wind material from ˜30 massive Wolf-Rayet (WR) stars orbiting within 12" of the super-massive black hole (SMBH) playing an important role. Hydrodynamic simulations of such colliding and accreting winds produce a complex density and temperature structure of cold wind material shocking with the ambient medium, creating a large reservoir of hot, X-ray-emitting gas. This work aims to confront the 3Ms of Chandra X-ray Visionary Program (XVP) observations of this diffuse emission by computing the X-ray emission from these hydrodynamic simulations of the colliding WR winds, amid exploring a variety of SMBH feedback mechanisms. The major success of the model is that it reproduces the spectral shape from the 2"-5" ring around the SMBH, where most of the stellar wind material that is ultimately captured by Sgr A* is shock-heated and thermalized. This naturally explains that the hot gas comes from colliding WR winds, and that the wind speeds of these stars are in general well constrained. The flux level of these spectra, as well as 12"x12" images of 4-9 keV, show the X-ray flux is tied to the SMBH feedback strength; stronger feedback clears out more hot gas, thereby decreasing the thermal X-ray emission. The model in which Sgr A* produced an intermediate-strength outflow during the last few centuries best matches the observations to within about 10%, showing SMBH feedback is required to interpret the X-ray emission in this region.

  8. REVEALING THE ASYMMETRY OF THE WIND OF THE VARIABLE WOLF-RAYET STAR WR1 (HD 4004) THROUGH SPECTROPOLARIZATION

    SciTech Connect

    St-Louis, N.

    2013-11-01

    In this paper, high quality spectropolarimetric observations of the Wolf-Rayet (WR) star WR1 (HD 4004) obtained with ESPaDOnS at the Canada-France-Hawaii Telescope are presented. All major emission lines present in the spectrum show depolarization in the relative Stokes parameters Q/I and U/I. From the behavior of the amount of line depolarization as a function of line strength, the intrinsic continuum light polarization of WR1 is estimated to be P/I = 0.443% ± 0.028% with an angle of θ = –26.°2. Although such a level of polarization could in principle be caused by a wind flattened by fast rotation, the scenario in which it is a consequence of the presence of corotating interaction regions (CIRs) in the wind is preferred. This is supported by previous photometric and spectroscopic observations showing periodic variations with a period of 16.9 days. This is now the third WR star thought to exhibit CIRs in its wind that is found to have line depolarization. Previous authors have found a strong correlation between line depolarization and the presence of an ejected nebula, which they interpret as a sign that the star has relatively recently reached the WR phase since the nebula are thought to dissipate very fast. In cases where the presence of CIRs in the wind is favored to explain the depolarization across spectral lines, the above-mentioned correlation may indicate that those massive stars have only very recently transited from the previous evolutionary phase to the WR phase.

  9. The X-ray light curve of the massive colliding wind Wolf-Rayet + O binary WR 21a

    NASA Astrophysics Data System (ADS)

    Gosset, Eric; Nazé, Yaël

    2016-05-01

    Our dedicated XMM-Newton monitoring, as well as archival Chandra and Swift datasets, were used to examine the behaviour of the WN5h+O3V binary WR 21a at high energies. For most of the orbit, the X-ray emission exhibits few variations. However, an increase in strength of the emission is seen before periastron, following a 1 /D relative trend, where D is the separation between both components. This increase is rapidly followed by a decline due to strong absorption as the Wolf-Rayet (WR) comes in front. The fitted local absorption value appears to be coherent with a mass-loss rate of about 1 × 10-5 M⊙ yr-1 for the WR component. However, absorption is not the only parameter affecting the X-ray emission at periastron as even the hard X-ray emission decreases, suggesting a possible collapse of the colliding wind region near to or onto the photosphere of the companion just before or at periastron. An eclipse may appear as another potential scenario, but it would be in apparent contradiction with several lines of evidence, notably the width of the dip in the X-ray light curve and the absence of variations in the UV light curve. Afterwards, the emission slowly recovers, with a strong hysteresis effect. The observed behaviour is compatible with predictions from general wind-wind collision models although the absorption increase is too shallow. Based on observations collected at ESO as well as with Swift, Chandra, and the ESA science mission XMM-Newton, an ESA Science Mission with instruments and contributions directly funded by ESA Member States and the USA (NASA).

  10. Modelling the thermal X-ray emission around the Galactic centre from colliding Wolf-Rayet winds

    NASA Astrophysics Data System (ADS)

    Russell, Christopher M. P.; Wang, Q. Daniel; Cuadra, Jorge

    2017-01-01

    The Galactic centre is a hotbed of astrophysical activity, with the injection of wind material from ~30 massive Wolf-Rayet (WR) stars orbiting within 12'' of the super-massive black hole (SMBH) playing an important role. Hydrodynamic simulations of such colliding and accreting winds produce a complex density and temperature structure of cold wind material shocking with the ambient medium, creating a large reservoir of hot, X-ray-emitting gas. This work aims to confront the 3Ms of Chandra X-ray Visionary Program (XVP) observations of this diffuse emission by computing the X-ray emission from these hydrodynamic simulations of the colliding WR winds, amid exploring a variety of SMBH feedback mechanisms. The major success of the model is that it reproduces the spectral shape from the 2''-5'' ring around the SMBH, where most of the stellar wind material that is ultimately captured by Sgr A* is shock-heated and thermalised. This naturally explains that the hot gas comes from colliding WR winds, and that the wind speeds of these stars are in general well constrained. The flux level of these spectra, as well as 12''×12'' images of 4-9 keV, show the X-ray flux is tied to the SMBH feedback strength; stronger feedback clears out more hot gas, thereby decreasing the thermal X-ray emission. The model in which Sgr A* produced an intermediate-strength outflow during the last few centuries best matches the observations to within about 10%, showing SMBH feedback is required to interpret the X-ray emission in this region.

  11. Sur la nature de la variabilite spectrale et photometrique periodique d'etoiles Wolf-Rayet apparemment isolees

    NASA Astrophysics Data System (ADS)

    Morel, Thierry

    Il est depuis longtemps suspecté que les étoiles Wolf-Rayet apparemment isolées présentant des variations périodiques dans le profil de leurs raies spectrales, en photométrie ou en polarimétrie sont associées à un compagnon dégénéré (étoile à neutron ou trou noir), et constituent ainsi une phase évolutive dont l'existence, bien que prédite par les modèles évolutifs des systèmes binaires massifs rapprochés, n'a pas encore été catégoriquement confirmée observationnellement. Cependant, de récentes études ayant trait à la variabilité spectrale des étoiles OB laissent émettre quelques doutes quant à la pertinence de ce modèle, en démontrant que des vents largement asphériques peuvent se développer dans les étoiles de type précoce. Le scénario alternatif serait donc de considérer que la variabilité périodique observée n'est pas due à la présence d'un compagnon dégénéré affectant la structure à grande échelle du vent de l'étoile Wolf-Rayet, mais est au contraire induite par la modulation par rotation d'un vent nettement anisotropique. Cet ouvrage présente les résultats d'un vaste programme d'observations spectroscopiques et photométriques (généralement simultanées) se proposant de lever l'ambiguïté sur la nature précise des étoiles Wolf-Rayet apparemment isolées dont la périodicité des variations est. soit depuis longtemps établie (WR 6), soit suspectée (WR 1, WR 134, WR 136). Notre étude a permis de confirmer l'existence d'une périodicité de 2.3 jours pour l'étoile WR 134. En outre, nous présentons des arguments mettant en doute l'éventuelle association de WR 6 et WR 134 avec un compagnon dégénéré. Alternativement, nous proposons que la variabilité périodique observée serait plutôt induite, à l'instar de nombreuses étoiles OB, par la rotation de structures azimutalement étendues dans le vent. Ce modèle est plus à même d'appréhender certains aspects de la variabilité, notamment la

  12. Searching for Magnetic Fields in 11 Wolf-Rayet Stars: Analysis of Circular Polarization Measurements from ESPaDOnS

    NASA Astrophysics Data System (ADS)

    de la Chevrotière, A.; St-Louis, N.; Moffat, A. F. J.; MiMeS Collaboration

    2014-02-01

    With recent detections of magnetic fields in some of their progenitor O stars, combined with known strong fields in their possible descendant neutron stars, it is natural to search for magnetic fields in Wolf-Rayet (WR) stars, despite the problems associated with the presence of winds enhanced by an order of magnitude over those of O stars. We continue our search among a sample of 11 bright WR stars following our introductory study in a previous paper of WR6 = EZ CMa using the spectropolarimeter ESPaDOnS at Canada-France-Hawaii Telescope, most of them in all four Stokes parameters. This sample includes six WN stars and five WC stars encompassing a range of spectral subclasses. Six are medium/long-period binaries and three show corotating interaction regions. We report no definite detections of a magnetic field in the winds in which the lines form (which is about the same distance from the center of the star as it is from the surface of the progenitor O star) for any of the eleven stars. Possible reasons and their implications are discussed. Nonetheless, the data show evidence supporting marginal detections for WR134, WR137, and WR138. According to the Bayesian analysis, the most probable field intensities are B wind ~ 200, 130, and 80 G, respectively, with a 95.4% probability that the magnetic fields present in the observable parts of their stellar wind, if stronger, does not exceed B_{{wind}}^{{max}}\\sim 1900 G, ~1500 G, and ~1500 G, respectively. In the case of non-detections, we report an average field strength upper limit of B_{{wind}}^{{max}}\\sim 500 G. Based on observations obtained at the Canada-France-Hawaii Telescope (CFHT), which is operated by the National Research Council of Canada, the Institut National des Sciences de l'Univers of the Centre National de la Recherche Scientifique of France, and the University of Hawaii. This research used the facilities of the Canadian Astronomy Data Centre operated by the National Research Council of Canada with the

  13. Integral field spectroscopy of M1-67. A Wolf-Rayet nebula with luminous blue variable nebula appearance

    NASA Astrophysics Data System (ADS)

    Fernández-Martín, A.; Vílchez, J. M.; Pérez-Montero, E.; Candian, A.; Sánchez, S. F.; Martín-Gordón, D.; Riera, A.

    2013-06-01

    Aims: This work aims to disentangle the morphological, kinematic, and chemical components of the nebula M1-67 to shed light on its process of formation around the central Wolf-Rayet (WR) star WR124. Methods: We have carried out integral field spectroscopy observations over two regions of M1-67, covering most of the nebula in the optical range. Maps of electron density, line ratios, and radial velocity were created to perform a detailed analysis of the two-dimensional structure. We studied the physical and chemical properties by means of integrated spectra selected over the whole nebula. Photoionization models were performed to confirm the empirical chemical results theoretically. In addition, we obtained and analysed infrared spectroscopic data and the MIPS 24 μm image of M1-67 from Spitzer. Results: We find that the ionized gas of M1-67 is condensed in knots aligned in a preferred axis along the NE-SW direction, like a bipolar structure. Both electron density and radial velocity decrease in this direction when moving away from the central star. From the derived electron temperature, Te ~ 8200 K, we have estimated chemical abundances, obtaining that nitrogen appears strongly enriched and oxygen depleted. From the last two results, we infer that this bipolarity is the consequence of an ejection of an evolved stage of WR124 with material processed in the CNO cycle. Furthermore, we find two regions placed outside of the bipolar structure with different spectral and chemical properties. The infrared study has revealed that the bipolar axis is composed of ionized gas with a low ionization degree that is well mixed with warm dust and of a spherical bubble surrounding the ejection at 24 μm. Taking the evolution of a 60 M⊙ star and the temporal scale of the bipolar ejection into account, we propose that the observed gas was ejected during an eruption in the luminous blue variable stage. The star has entered the WR phase recently without apparent signs of interaction

  14. The ionized gas at the centre of IC 10: a possible localized chemical pollution by Wolf-Rayet stars

    NASA Astrophysics Data System (ADS)

    López-Sánchez, Á. R.; Mesa-Delgado, A.; López-Martín, L.; Esteban, C.

    2011-03-01

    We present results from integral field spectroscopy with the Potsdam Multi-Aperture Spectrograph at the 3.5-m telescope at Calar Alto Observatory of the intense star-forming region [HL90] 111 at the centre of the starburst galaxy IC 10. We have obtained maps with a spatial sampling of 1 × 1 arcsec2= 3.9× 3.9 pc2 of different emission lines and analysed the extinction, physical conditions, nature of the ionization and chemical abundances of the ionized gas, as well determined locally the age of the most recent star formation event. By defining several apertures, we study the main integrated properties of some regions within [HL90] 111. Two contiguous spaxels show an unambiguous detection of the broad He IIλ4686 emission line, this feature seems to be produced by a single late-type WN star. We also report a probable N and He enrichment in the precise spaxels where the Wolf-Rayet (WR) features are detected. The enrichment pattern is roughly consistent with that expected for the pollution of the ejecta of a single or a very small number of WR stars. Furthermore, this chemical pollution is very localized (˜2 arcsec ˜7.8 pc) and it should be difficult to detect in star-forming galaxies beyond the Local Volume. We also discuss the use of the most common empirical calibrations to estimate the oxygen abundances of the ionized gas in nearby galaxies from 2D spectroscopic data. The ionization degree of the gas plays an important role when applying these empirical methods, as they tend to give lower oxygen abundances with increasing ionization degree. Based on observations collected at the Centro Astrónomico Hispano Alemán (CAHA) at Calar Alto, operated jointly by the Max-Plank Institut für Astronomie and the Instituto de Astrofísica de Andalucía (CSIC).Visiting Astronomer at the Instituto de Astrofísica de Canarias.

  15. Large-scale Periodic Variability of the Wind of the Wolf-Rayet Star WR 1 (HD 4004)

    NASA Astrophysics Data System (ADS)

    Chené, A.-N.; St-Louis, N.

    2010-06-01

    We present the results of an intensive photometric and spectroscopic monitoring campaign of the WN4 Wolf-Rayet (WR) star WR 1 = HD 4004. Our broadband V photometry covering a timespan of 91 days shows variability with a period of P = 16.9+0.6 -0.3 days. The same period is also found in our spectral data. The light curve is non-sinusoidal with hints of a gradual change in its shape as a function of time. The photometric variations nevertheless remain coherent over several cycles and we estimate that the coherence timescale of the light curve is of the order of 60 days. The spectroscopy shows large-scale line-profile variability which can be interpreted as excess emission peaks moving from one side of the profile to the other on a timescale of several days. Although we cannot unequivocally exclude the unlikely possibility that WR 1 is a binary, we propose that the nature of the variability we have found strongly suggests that it is due to the presence in the wind of the WR star of large-scale structures, most likely corotating interaction regions (CIRs), which are predicted to arise in inherently unstable radiatively driven winds when they are perturbed at their base. We also suggest that variability observed in WR 6, WR 134, and WR 137 is of the same nature. Finally, assuming that the period of CIRs is related to the rotational period, we estimate the rotation rate of the four stars for which sufficient monitoring has been carried out, i.e., v rot = 6.5, 40, 70, and 275 km s-1 for WR 1, WR 6, WR 134, and WR 137, respectively. Based on observations obtained at the Canada-France-Hawaii Telescope (CFHT) which is operated by the National Research Council of Canada, the Institut National des Sciences de l'Univers of the Centre National de Recherche Scientifique of France, and the University of Hawaii. Also based on observations obtained at the Observatoire du Mont Mégantic with is operated by the Centre de Recherche en Astrophysique du Québec and the Observatoire de

  16. 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'.

  17. Line formation in winds with enhanced equatorial mass-loss rates and its application to the Wolf-Rayet star HD 50896

    NASA Technical Reports Server (NTRS)

    Rumpl, W. M.

    1980-01-01

    A model having a spherically symmetric velocity distribution with a higher density at the equatorial region was developed to simulate the UV spectrum of the Wolf-Rayet star HD 50896. The spectrum showed P Cygni-shaped profiles whose emissions are stronger than expected in a spherically symmetric stellar wind. The model was studied varying the inclination angle of the star-wind system and the polar to equatorial density ratios; it was shown that HD 50896 could possess a nonspherically symmetric wind and that its symmetry axis is inclined between 60 and 90 deg. It is possible that the velocity distribution of the wind could include an inner constant velocity plateau beyond which the wind accelerates to its terminal velocity as indicated by infrared continuum investigations.

  18. In pursuit of gamma-ray burst progenitors: the identification of a sub-population of rotating Wolf-Rayet stars

    NASA Astrophysics Data System (ADS)

    Vink, J. S.; Gräfener, G.; Harries, T. J.

    2011-12-01

    Long-duration gamma-ray bursts (GRBs) involve the most powerful cosmic explosions since the Big Bang. Whilst it has been established that GRBs are related to the death throes of massive stars, the identification of their elusive progenitors has proved challenging. Theoretical modelling suggests that rotating Wolf-Rayet (WR) stars are the best candidates. Wolf-Rayet stars are thought to be in advanced core burning stages, just prior to explosion, but their strong stellar winds shroud their surfaces, preventing a direct measurement of their rotation. Fortunately, linear spectropolarimetry may be used to probe the flattening of their winds because of stellar spin. Spectropolarimetry surveys have shown that the vast majority of WR stars (80%) have spherically symmetric winds and are therefore rotating slowly, yet a small minority (of 20%) display a spectropolarimetric signature indicative of rotation. Here we find a highly significant correlation between WR objects that carry the signature of stellar rotation and the small subset of WR stars with ejecta nebulae that have only recently transitioned from a previous red sugergiant or luminous blue variable phase. As these youthful WR stars have yet to spin-down because of mass loss, they are the best candidate GRB progenitors identified to date. When we take recently published WR ejecta nebula numbers (of Stock & Barlow 2010, MNRAS, 409, 1429), we find that five out of the six line-effect WR stars are surrounded by ejecta nebulae. The statistics imply that the null hypothesis of no correlation between line-effect WR stars and ejecta nebulae can be rejected at the 0.0004% level. Given that four line-effect and WR ejecta nebula have spectroscopically been confirmed to contain nucleo-synthetic products, we argue that the correlation is both statistically significant and physically convincing. The implication is that we have identified a sub-population of WR stars that fulfils the necessary criteria for making GRBs. Finally

  19. Outflow-Induced Dynamical and Radiative Instability in Stellar Envelopes with an Application to Luminous Blue Variables and Wolf-Rayet Stars

    NASA Technical Reports Server (NTRS)

    Stothers, Richard B.; Hansen, James E. (Technical Monitor)

    2002-01-01

    Theoretical models of the remnants of massive stars in a very hot, post-red-supergiant phase display no obvious instability if standard assumptions are made. However, the brightest observed classical luminous blue variables (LBVs) may well belong to such a phase. A simple time-dependent theory of moving stellar envelopes is developed in order to treat deep hydrodynamical disturbances caused by surface mass loss and to test the moving envelopes for dynamical instability. In the case of steady-state outflow, the theory reduces to the equivalent of the Castor, Abbott, and Klein formulation for optically thick winds at distances well above the sonic point. The time-dependent version indicates that the brightest and hottest LBVs are both dynamically and radiatively unstable, as a result of the substantial lowering of the generalized Eddington luminosity limit by the mass-loss acceleration. It is suggested that dynamical instability, by triggering secular cycles of mass loss, is primarily what differentiates LBVs from the purely radiatively unstable Wolf-Rayet stars. Furthermore, when accurate main-sequence mass-loss rates are used to calculate the evolutionary tracks, the predicted surface hydrogen and nitrogen abundances of the blue remnants agree much better with observations of the brightest LBVs than before.

  20. A NEAR-INFRARED SURVEY OF THE INNER GALACTIC PLANE FOR WOLF-RAYET STARS. I. METHODS AND FIRST RESULTS: 41 NEW WR STARS

    SciTech Connect

    Shara, Michael M.; Gerke, Jill; Zurek, David; Moffat, Anthony F. J.; Doyon, Rene; Villar-Sbaffi, Alfredo; Stanonik, Kathryn; Artigau, Etienne; Drissen, Laurent E-mail: jgerke@amnh.org E-mail: moffat@astro.umontreal.ca E-mail: alfredovs@hotmail.com E-mail: eartigau@gemini.edu

    2009-08-15

    The discovery of new Wolf-Rayet (WR) stars in our Galaxy via large-scale narrowband optical surveys has been severely limited by dust extinction. Recent improvements in infrared technology have made narrowband-broadband imaging surveys viable again. We report a new J, K, and narrowband imaging survey of 300 deg{sup 2} of the plane of the Galaxy, spanning 150 degrees in Galactic longitude and reaching 1 degree above and below the Galactic plane. The survey has a useful limiting magnitude of K = 15 over most of the observed Galactic plane, and K = 14 within a few degrees of the Galactic center. Thousands of emission line candidates have been detected. In spectrographic follow-ups of 173 WR star candidates we have discovered 41 new WR stars, 15 of type WN and 26 of type WC. Star subtype assignments have been confirmed with K-band spectra, and distances approximated using the method of spectroscopic parallax. A few of the new WR stars are among the most distant known in our Galaxy. The distribution of these new WR stars is seen to follow that of previously known WR stars along the spiral arms of the Galaxy. Tentative radial velocities were also measured for most of the new WR stars.

  1. 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.

  2. SN 2015bh: NGC 2770's 4th supernova or a luminous blue variable on its way to a Wolf-Rayet star?

    NASA Astrophysics Data System (ADS)

    Thöne, C. C.; de Ugarte Postigo, A.; Leloudas, G.; Gall, C.; Cano, Z.; Maeda, K.; Schulze, S.; Campana, S.; Wiersema, K.; Groh, J.; de la Rosa, J.; Bauer, F. E.; Malesani, D.; Maund, J.; Morrell, N.; Beletsky, Y.

    2017-03-01

    Very massive stars in the final phases of their lives often show unpredictable outbursts that can mimic supernovae, so-called, "SN impostors", but the distinction is not always straightforward. Here we present observations of a luminous blue variable (LBV) in NGC 2770 in outburst over more than 20 yr that experienced a possible terminal explosion as type IIn SN in 2015, named SN 2015bh. This possible SN (or "main event") had a precursor peaking 40 days before maximum. The total energy release of the main event is 1.8 × 1049 erg, consistent with a <0.5 M⊙ shell plunging into a dense CSM. The emission lines show a single narrow P Cygni profile during the LBV phase and a double P Cygni profile post maximum suggesting an association of the second component with the possible SN. Since 1994 the star has been redder than an LBV in an S-Dor-like outburst. SN 2015bh lies within a spiral arm of NGC 2770 next to several small star-forming regions with a metallicity of 0.5 solar and a stellar population age of 7-10 Myr. SN 2015bh shares many similarities with SN 2009ip and may form a new class of objects that exhibit outbursts a few decades prior to a "hyper eruption" or final core-collapse. If the star survives this event it is undoubtedly altered, and we suggest that these "zombie stars" may evolve from an LBV to a Wolf-Rayet star over the timescale of only a few years. The final fate of these stars can only be determined with observations a decade or more after the SN-like event.

  3. A Search for X-Ray Evidence of a Compact Companion to the Unusual Wolf-Rayet Star HD 50896 (EZ CMa)

    NASA Technical Reports Server (NTRS)

    Skinner, Stephen L.; Itoh, Masayuki; Nagase, Fumiaki

    1998-01-01

    We analyze results of a approx.25 ksec ASCA X-ray observation of the unusual Wolf-Rayet star HD 50896 (= EZ CMa). This WN5 star shows optical and ultraviolet variability at a 3.766 day period, which has been interpreted as a possible signature of a compact companion. Our objective was to search for evidence of hard X-rays (greater than or equal to 5 keV) which could be present if the WN5 wind is accreting onto a compact object. The ASCA spectra are dominated by emission below 5 keV and show no significant emission in the harder 5-10 keV range. Weak emission lines are present, and the X-rays arise in an optically thin plasma which spans a range of temperatures from less than or equal to 0.4 keV up to at least approx. 2 keV. Excess X-ray absorption above the interstellar value is present, but the column density is no larger than N(sub H) approx. 10(exp 22)/sq cm. The absorption-corrected X-ray luminosity L(sub x)(0.5 - 10 keV) = 10(exp 32.85) erg/s gives L(sub x)/ L(sub bol) approx. 10(exp -6), a value that is typical of WN stars. No X-ray variability was detected. Our main conclusion is that the X-ray properties of HD 50896 are inconsistent with the behavior expected for wind accretion onto a neutron star or black hole companion. Alternative models based on wind shocks can explain most aspects of the X-ray behavior, and we argue that the hotter plasma near approx. 2 keV could be due to the WR wind shocking onto a normal (nondegenerate) companion.

  4. XMM-NEWTON OBSERVATIONS REVEAL VERY HIGH X-RAY LUMINOSITY FROM THE CARBON-RICH WOLF-RAYET STAR WR 48a

    SciTech Connect

    Zhekov, Svetozar A.; Gagne, Marc; Skinner, Stephen L. E-mail: mgagne@wcupa.edu

    2011-01-20

    We present XMM-Newton observations of the dusty Wolf-Rayet (W-R) star WR 48a. This is the first detection of this object in X-rays. The XMM-Newton EPIC spectra are heavily absorbed and the presence of numerous strong emission lines indicates a thermal origin of the WR 48a X-ray emission, with dominant temperature components at kT{sub cool} {approx} 1 keV and kT{sub hot} {approx} 3 keV, the hotter component dominating the observed flux. No significant X-ray variability was detected on timescales {<=}1 day. Although the distance to WR 48a is uncertain, if it is physically associated with Open clusters Danks 1 and 2 at d {approx}4 kpc, then the resultant X-ray luminosity L{sub X}{approx} 10{sup 35} erg s{sup -1} makes it the most X-ray luminous W-R star in the Galaxy detected so far, after the black hole candidate Cyg X-3. We assume the following scenarios as the most likely explanation for the X-ray properties of WR 48a: (1) colliding stellar winds in a wide WR+O binary system, or in a hierarchical triple system with non-degenerate stellar components and (2) accretion shocks from the WR 48a wind onto a close companion (possibly a neutron star). More specific information about WR 48a and its wind properties will be needed to distinguish between the above possibilities.

  5. The putative nebula of the Wolf-Rayet WR 60 star: a case of mistaken identity and reclassification as a new supernova remnant G310.5+0.8

    NASA Astrophysics Data System (ADS)

    Stupar, M.; Parker, Q. A.; Filipović, M. D.

    2011-04-01

    We present narrow band AAO/UKST H α images and medium and low resolution optical spectra of a nebula shell putatively associated with the Wolf-Rayet star WR 60. We also present the first identification of this shell in the radio regime at 843 MHz and at 4850 MHz from the Sydney University Molonglo Sky Survey (SUMSS), and from the Parkes-MIT-NRAO (PMN) survey respectively. This radio emission closely follows the optical emission. The optical spectra from the shell exhibits the typical shock excitation signatures sometimes seen in Wolf-Rayet stellar ejecta but also common to supernova remnants. A key finding however, is that the WR 60 star, is not, in fact, anywhere near the geometrical centre of the putative arcuate nebula ejecta as had been previously stated. This was due to an erroneous positional identification for the star in the literature which we now correct. This new identification calls into serious question any association of the nebula with WR 60 as such nebula are usually quite well centred on the WR stars themselves. We now propose that this fact combined with our new optical spectra, deeper H α imaging and newly identified radio structures actually imply that the WR 60 nebula should be reclassified as an unassociated new supernova remnant which we designate G310.5+0.8.

  6. Mesure du taux de rotation des etoiles Wolf-Rayet a partir de la variabilite periodique a grande echelle des vents stellaires

    NASA Astrophysics Data System (ADS)

    Chene, Andre-Nicolas

    The aim of this thesis is to determine the rotation rates of Wolf-Rayet (WR) stars. Since these stars have a very dense stellar winds, it is impossible to directly observe their photosphere. Consequently, it is also impossible to measure their rotation velocity directly from the widning of absorption photospheric line profiles. Therefore, we propose instead to determine the rotation period of WR stars from large-scale periodic wind variations an adopted stellar radius from the literature. The type of large-scale variability that is related to stellar rotation is due to the presence in some WR winds of density structures called Corotating Interaction Regions (CIR). CIRs are caused by perturbations at the base of the wind, which in turn could be caused e.g. by a magnetic field or by pulsations. These perturbations propagate through the wind while being carried around by rotation. This generates spiral-like structures in the density distribution that can lead to a characteristic, large-scale variability pattern in WR-wind emission lines. Since the density distribution changes periodically according to the stellar rotation, the period of the resulting large-scale spectral variability corresponds directly to the period of rotation. In this thesis, I present the results of a systematic search for large-scale spectroscopic variability in the brightest, apparently single WR stars. Such a variability was found in 10 WR stars among the 25 northern and 43 southern stars of our sample. In order to determine if all of these 10 stars are variable due to the presence of CIRs, one needs to carry out intensive monitoring and verify if the spectral variabilities is periodic. In the literature, two cases of WR stars presenting CIR-type variability have been established; WR 6 (P=3.77 days) and WR 134 (P=2.25 days). In this thesis, another case is found, WR 1, with a period of 16.89 days. Also in this thesis, another star showing large-scale spectroscopic variability has been monitored

  7. The rise and fall of the Type Ib supernova iPTF13bvn. Not a massive Wolf-Rayet star

    NASA Astrophysics Data System (ADS)

    Fremling, C.; Sollerman, J.; Taddia, F.; Ergon, M.; Valenti, S.; Arcavi, I.; Ben-Ami, S.; Cao, Y.; Cenko, S. B.; Filippenko, A. V.; Gal-Yam, A.; Howell, D. A.

    2014-05-01

    Context. We investigate iPTF13bvn, a core-collapse (CC) supernova (SN) in the nearby spiral galaxy NGC 5806. This object was discovered by the intermediate Palomar Transient Factory (iPTF) very close to the estimated explosion date and was classified as a stripped-envelope CC SN, likely of Type Ib. Furthermore, a possible progenitor detection in pre-explosion Hubble Space Telescope (HST) images was reported, making this the only SN Ib with such an identification. Based on the luminosity and color of the progenitor candidate, as well as on early-time spectra and photometry of the SN, it was argued that the progenitor candidate is consistent with a single, massive Wolf-Rayet (WR) star. Aims: We aim to confirm the progenitor detection, to robustly classify the SN using additional spectroscopy, and to investigate if our follow-up photometric and spectroscopic data on iPTF13bvn are consistent with a single-star WR progenitor scenario. Methods: We present a large set of observational data, consisting of multi-band light curves (UBVRI, g'r'i'z') and optical spectra. We perform standard spectral line analysis to track the evolution of the SN ejecta. We also construct a bolometric light curve and perform hydrodynamical calculations to model this light curve to constrain the synthesized radioactive nickel mass and the total ejecta mass of the SN. Late-time photometry is analyzed to constrain the amount of oxygen. Furthermore, image registration of pre- and post-explosion HST images is performed. Results: Our HST astrometry confirms the location of the progenitor candidate of iPTF13bvn, and follow-up spectra securely classify this as a SN Ib. We use our hydrodynamical model to fit the observed bolometric light curve, estimating the total ejecta mass to be 1.9 M⊙ and the radioactive nickel mass to be 0.05 M⊙. The model fit requires the nickel synthesized in the explosion to be highly mixed out in the ejecta. We also find that the late-time nebular r'-band luminosity is not

  8. The Rise and Fall of the Type Ib Supernova iPTF13bvn Not a Massive Wolf-Rayet Star

    NASA Technical Reports Server (NTRS)

    Fremling, C.; Sollerman, J.; Taddia, F.; Ergon, M.; Valenti, S.; Arcavi, I.; Ben-Ami, S.; Cao, Y.; Cenko, S. B.; Filippenko, A. V.; Gal-Yam, A.; Howell, D. A.

    2014-01-01

    Context. We investigate iPTF13bvn, a core-collapse (CC) supernova (SN) in the nearby spiral galaxy NGC 5806. This object was discovered by the intermediate Palomar Transient Factory (iPTF) very close to the estimated explosion date and was classified as a stripped-envelope CC SN, likely of Type Ib. Furthermore, a possible progenitor detection in pre-explosion Hubble Space Telescope (HST) images was reported, making this the only SN Ib with such an identification. Based on the luminosity and color of the progenitor candidate, as well as on early-time spectra and photometry of the SN, it was argued that the progenitor candidate is consistent with a single, massive Wolf-Rayet (WR) star. Aims. We aim to confirm the progenitor detection, to robustly classify the SN using additional spectroscopy, and to investigate if our follow-up photometric and spectroscopic data on iPTF13bvn are consistent with a single-star WR progenitor scenario. Methods. We present a large set of observational data, consisting of multi-band light curves (UBVRI, g'r'i'z') and optical spectra. We perform standard spectral line analysis to track the evolution of the SN ejecta. We also construct a bolometric light curve and perform hydrodynamical calculations to model this light curve to constrain the synthesized radioactive nickel mass and the total ejecta mass of the SN. Late-time photometry is analyzed to constrain the amount of oxygen. Furthermore, image registration of pre- and post-explosion HST images is performed. Results. Our HST astrometry confirms the location of the progenitor candidate of iPTF13bvn, and follow-up spectra securely classify this as a SN Ib. We use our hydrodynamical model to fit the observed bolometric light curve, estimating the total ejecta mass to be 1.9 solar mass and the radioactive nickel mass to be 0.05 solar mass. The model fit requires the nickel synthesized in the explosion to be highly mixed out in the ejecta. We also find that the late-time nebular r

  9. Relación física entre el cúmulo abierto Hogg 15 y la estrella Wolf-Rayet WR 47

    NASA Astrophysics Data System (ADS)

    Piatti, A. E.; Bica, E.; Santos, J. F. C., Jr.; Clariá, J. J.

    We revise the fundamental parameters of the faint open cluster Hogg 15, for which two recent colour-magnitude diagram (CMD) studies have obtained significantly different ages (Sagar et al. 2001, MNRAS, 327, 23; Piatti & Clariá 2001, A&A, 370, 931). In the present study, we combine a series of methods trying to constrain age, together with other fundamental parameters. We employ spatial extractions to construct the CMDs, and the cluster integrated spectrum to compare the latter with those of templates of known age. For Hogg 15 we derive an age of (20 ± 10) Myr, a reddening of (1.10 ± 0.05) mag, and a distance of (3.1 ± 0.5) kpc. We conclude that the estimation of an older age in the study of Piatti & Clariá can be accounted for in terms of main sequence/turnoff curvature being blurred in the CMDs, an effect mainly caused by field contamination. To clarify the issue of whether the Wolf-Rayet star HDE 311884 (WR 47), known to be a WN6 + O5V binary system, is associated or not with Hogg 15, we discuss its fundamental parameters, particularly its distance. Based on the WR 47 spectrum and available photometry, we assume that the underestimated distance implied by the Hipparcos parallax (216 pc) is affected by its binary character. By comparing the WR 47 spectrum with those of WR stars of a similar type, we conclude that WR 47 is not affected by a E(B-V) colour excess much higher than that associated with Hogg 15, namely E(B-V) = 1.10. On the basis of the WR 47's resulting distance of (5.2 ± 0.9) kpc, which largely surpasses that of the cluster, we conclude that WR 47 is not related to Hogg 15 from the point of view of origin, since the cluster and the star do not belong to the same formation event.

  10. FUSE Observations of the SMC 16 day Wolf-Rayet Binary Sanduleak 1 (WO4+O4): Atmospheric Eclipses and Colliding Stellar Winds

    NASA Astrophysics Data System (ADS)

    St-Louis, Nicole; Moffat, Anthony F. J.; Marchenko, Sergey; Pittard, Julian Mark

    2005-08-01

    In this paper we present the results of a FUSE monitoring campaign of the SMC WO4+O4 V Wolf-Rayet binary Sanduleak 1. Our 18 spectra obtained during a little more than one orbital cycle in 2000 October combined with four archival spectra show variability in the S VI, C III, C IV, and O VI P Cygni profiles, which we attribute to emission from the shock cone resulting from the collision between the two strong winds and to atmospheric eclipses of the O star continuum light by the W-R wind. All the lines vary in concert indicating that the cooling is such that even lines such as the OVI λλ1032, 1038 doublet form in the linear part of the cone. We have also applied both a simple geometrical model and profile fits, including emission from the normal wind, extra emission from the shock cone, and the atmospheric eclipse. Adopting an orbital inclination of ~40°, we deduce a total cone opening angle of ~80° and a streaming velocity for the gas along the shock cone of ~3000 km s-1. The luminosity ratio required to fit our spectra is LO/LW-R=3.5, and the stellar radii are 3.5 and 12 Rsolar, respectively, for the W-R and O stars. We also present radiative driving models for this binary system having two massive stars with strong winds and discuss radiative inhibition and braking effects. In particular, we address the coupling of the O star radiation with the W-R star wind. Finally, we present a PICA hydrodynamic colliding-wind model for Sand 1. We find an opening angle for the shock cone similar to that deduced from the line-profile fitting, but significantly longer cooling lengths along the shock cone. However, the model reveals some cold gas that is stripped off the O4 surface and mixed with the hotter WO4 material, thereby accelerating its cooling. This could very well explain why shorter cooling lengths are inferred from the profile fits. Based on observations made with the NASA-CNES-CSA Far Ultraviolet Spectroscopic Explorer. FUSE is operated for NASA by Johns Hopkins

  11. Discovery and Characterization of Luminous Blue Variables, Wolf-Rayet Stars, and Massive Supergiants and Their Shells Using Spitzer, WISE, and Herschel Data

    NASA Astrophysics Data System (ADS)

    Stringfellow, Guy

    The extensive WISE all-sky 12 and 22 micron survey data, the Herschel PACS and SPIRE imaging archive (including the GTO and OT Key Programs), as well as the Spitzer IRAC 8 and MIPS 24 micron imaging archival data (GO, GTO, and Legacy Surveys) are being mined for the discovery of new shell and ring-nebulae. Combined with 2MASS data, the progenitor stars are also being identified, and optical and near-IR spectroscopy obtained to confirm their spectral types. Origin of the nebulae arise from a variety of progenitors that include very massive stars, with the vast majority not having been previously identified. Representative classes for the progenitor stars are Luminous Blue Variables (LBVs), Wolf-Rayet (WR), B[e], OB, and Supergiant stars. The discovery potential for these rare massive evolved stars from the mid-IR imaging archives is greater than any other technique utilized over the past several decades, including extensive broadband infrared photometry-color determinations (Hadfield et al. 2007), and near-IR narrowband methods (Shara et al. 2009). The statistics being provided on this new, previously hidden population of evolved stars may very well enable evolutionary pathways to be better delineated, thereby identifying the physics operating in these extreme stars. The data being collected will more tightly define the evolutionary models that apply to these stars, and that enter into modeling and interpretation of extragalactic massive star formation regions (starbursts). Multi-wavelength color-color maps wil be constructed and used to analyze the dust distribution, the energetics of the nebulae and its interaction with the ISM, and identification of nearby star formation perhaps being triggered by the massive stars and the nebulae they produce. As demonstrated in a recent publication presenting the discovery and analysis of two new candidate LBVs found in the early WISE data release (Gvaramadze et al. 2012), much discovery potential yet resides within the

  12. A radial velocity survey for post-common-envelope Wolf-Rayet central stars of planetary nebulae: first results and discovery of the close binary nucleus of NGC 5189

    NASA Astrophysics Data System (ADS)

    Manick, Rajeev; Miszalski, Brent; McBride, Vanessa

    2015-04-01

    The formation of Wolf-Rayet central stars of planetary nebulae ([WR] CSPNe) whose spectroscopic appearance mimics massive WR stars remains poorly understood. Least understood is the nature and frequency of binary companions to [WR] CSPNe that may explain their H-deficiency. We have conducted a systematic radial velocity (RV) study of six [WR] CSPNe to search for post-common-envelope (post-CE) [WR] binaries. We used a cross-correlation method to construct the RV time series as successfully done for massive close binary WR stars. No significant RV variability was detected for the late-[WC] type nuclei of Hen 2-113, Hen 3-1333, PMR 2 and Hen 2-99. Significant, large-amplitude variability was found in the [WC4] nucleus of NGC 5315. In the [WO1] nucleus of NGC 5189, we discovered significant periodic variability that reveals a close binary with Porb = 4.04 ± 0.1 d. We measured a semi-amplitude of 62.3 ± 1.3 km s-1 that gives a companion mass of m2 ≥ 0.5 M⊙ or m2 = 0.84 M⊙ (assuming i = 45°). The most plausible companion type is a massive white dwarf (WD) as found in Fleming 1. The spectacular nebular morphology of NGC 5189 fits the pattern of recently discovered post-CE PNe extremely well with its dominant low-ionization structures (e.g. as in NGC 6326) and collimated outflows (e.g. as in Fleming 1). The long 4.04 d orbital period is either anomalous (e.g. NGC 2346) or it may indicate that there is a sizeable population of [WR] binaries with massive WD companions in relatively wide orbits, perhaps influenced by interactions with the strong [WR] wind.

  13. Spectrophotometry of Wolf-Rayet stars. I - Continuum energy distributions

    NASA Technical Reports Server (NTRS)

    Morris, Patrick W.; Brownsberger, Kenneth R.; Conti, Peter S.; Massey, Philip; Vacca, William D.

    1993-01-01

    All available low-resolution IUE spectra are assembled for Galactic, LMC, and SMC W-R stars and are merged with ground-based optical and NIR spectra in order to collate in a systematic fashion the shapes of these energy distributions over the wavelength range 0.1-1 micron. They can be consistently fitted by a power law of the form F(lambda) is approximately equal to lambda exp -alpha over the range 1500-9000 A to derive color excesses E(B-V) and spectral indices by removing the 2175-A interstellar absorption feature. The WN star color excesses derived are found to be in good agreement with those of Schmutz and Vacca (1991) and Koesterke et al. (1991). Significant heterogeneity in spectral index values was generally seen with any given subtype, but the groups consisting of the combined set of Galactic and LMC W-R stars, the separate WN and WC sequences, and the Galactic and LMC W-R stars all showed a striking and consistent Gaussian-like frequency distribution of values.

  14. The Unusual Wolf-Rayet Star EZ CMa

    NASA Technical Reports Server (NTRS)

    Skinner, Stephen L.

    2002-01-01

    The XMM-Newton observations were obtained on 29 - 30 October 2001 during the AO-1 Guest Observer program. Our X-ray analysis focused on data from the European Photon Imaging Camera (EPIC). The VLA observations were obtained during a 3.5 hour interval on 1999 Oct. 19 with the array in hybrid BnA configuration. Radio continuum data were acquired at five different frequencies 1.42 GHz (21 cm), 4.86 GHz (6 cm), 8.44 GHz (3.6 cm), 14.94 GHz (2 cm), and 22.46 GHz (1.3 cm). These radio data are unique since they provide an excellent snapshot picture of the dependence of the radio flux on frequency obtained over a short time interval and are thus immune to the variability effects which can distort results obtained from non-contemporaneous observations at different frequencies.

  15. TRIGGERING COLLAPSE OF THE PRESOLAR DENSE CLOUD CORE AND INJECTING SHORT-LIVED RADIOISOTOPES WITH A SHOCK WAVE. II. VARIED SHOCK WAVE AND CLOUD CORE PARAMETERS

    SciTech Connect

    Boss, Alan P.; Keiser, Sandra A. E-mail: keiser@dtm.ciw.edu

    2013-06-10

    A variety of stellar sources have been proposed for the origin of the short-lived radioisotopes that existed at the time of the formation of the earliest solar system solids, including Type II supernovae (SNe), asymptotic giant branch (AGB) and super-AGB stars, and Wolf-Rayet star winds. Our previous adaptive mesh hydrodynamics models with the FLASH2.5 code have shown which combinations of shock wave parameters are able to simultaneously trigger the gravitational collapse of a target dense cloud core and inject significant amounts of shock wave gas and dust, showing that thin SN shocks may be uniquely suited for the task. However, recent meteoritical studies have weakened the case for a direct SN injection to the presolar cloud, motivating us to re-examine a wider range of shock wave and cloud core parameters, including rotation, in order to better estimate the injection efficiencies for a variety of stellar sources. We find that SN shocks remain as the most promising stellar source, though planetary nebulae resulting from AGB star evolution cannot be conclusively ruled out. Wolf-Rayet (WR) star winds, however, are likely to lead to cloud core shredding, rather than to collapse. Injection efficiencies can be increased when the cloud is rotating about an axis aligned with the direction of the shock wave, by as much as a factor of {approx}10. The amount of gas and dust accreted from the post-shock wind can exceed that injected from the shock wave, with implications for the isotopic abundances expected for a SN source.

  16. Triggering Collapse of the Presolar Dense Cloud Core and Injecting Short-lived Radioisotopes with a Shock Wave. II. Varied Shock Wave and Cloud Core Parameters

    NASA Astrophysics Data System (ADS)

    Boss, Alan P.; Keiser, Sandra A.

    2013-06-01

    A variety of stellar sources have been proposed for the origin of the short-lived radioisotopes that existed at the time of the formation of the earliest solar system solids, including Type II supernovae (SNe), asymptotic giant branch (AGB) and super-AGB stars, and Wolf-Rayet star winds. Our previous adaptive mesh hydrodynamics models with the FLASH2.5 code have shown which combinations of shock wave parameters are able to simultaneously trigger the gravitational collapse of a target dense cloud core and inject significant amounts of shock wave gas and dust, showing that thin SN shocks may be uniquely suited for the task. However, recent meteoritical studies have weakened the case for a direct SN injection to the presolar cloud, motivating us to re-examine a wider range of shock wave and cloud core parameters, including rotation, in order to better estimate the injection efficiencies for a variety of stellar sources. We find that SN shocks remain as the most promising stellar source, though planetary nebulae resulting from AGB star evolution cannot be conclusively ruled out. Wolf-Rayet (WR) star winds, however, are likely to lead to cloud core shredding, rather than to collapse. Injection efficiencies can be increased when the cloud is rotating about an axis aligned with the direction of the shock wave, by as much as a factor of ~10. The amount of gas and dust accreted from the post-shock wind can exceed that injected from the shock wave, with implications for the isotopic abundances expected for a SN source.

  17. The Astronomical Zoo in MIPSGAL I and II

    NASA Astrophysics Data System (ADS)

    Kuchar, Thomas A.; Mizuno, D.; Shenoy, S.; Paladini, R.; Kraemer, K.; Price, S.; Marleau, F.; Padgett, D.; Indebetouw, R.; Ingalls, J.; Ali, B.; Berriman, B.; Boulanger, F.; Cutri, R.; Latter, W.; Miville-Deschenes, M.; Molinari, S.; Rebull, L.; Testi, L.; Shipman, R.; Martin, P.; Carey, S.; Noriega-Crespo, A.

    2006-12-01

    The view of the Galactic Plane at 24 µm is breathtaking. A great part of this beauty arises from the complexity of the Interstellar Medium shaped by endless energetic events driven by HII regions, supernova explosions, Wolf-Rayets, Luminous Blue Variables, and evolved and new born massive stars. A sample of these objects is presented in this poster, gathered from the Multiband Imaging Photometer for Spitzer (MIPS) Survey of the Galactic Plane I and II (MIPSGAL; see Carey et al. 2006, this meeting). The global color properties of these objects are derived by combining the data at 24 and 70um with that from the Galactic Legacy Infrared Mid-Plane Survey Extraordinaire (GLIMPSE), and following similar schemes as those used in the Spitzer Surveys of the Magellanic Clouds (Bolatto et al. 2006, astroph-0608561; Meixner et al. 2006, astroph-0606356). This work is based on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology under a contract with NASA. Support for this work was provided by NASA in part through an award issued by JPL/Caltech.

  18. An atlas of optical spectrophotometry of Wolf-Rayet carbon and oxygen stars

    NASA Technical Reports Server (NTRS)

    Torres, Ana V.; Massey, Philip

    1987-01-01

    The atlas contains a homogeneous set of optical spectrophotometric observations (3300-7300 A) at moderate resolution (about 10 A) of almost all WC and WO stars in the Galaxy, the LMC, and the SMC. The data are presented in the form of spectral tracings (in magnitude units) arranged by subtype, with no correction for interstellar reddening. A montage of prototype stars of each spectral class is also shown. Comprehensive line identifications are given for the optical lines of WC and WO spectra, with major contributions tabulated and unidentified lines noted.

  19. Stratification of the extended atmosphere of the Wolf-Rayet component of V444 Cygni

    NASA Technical Reports Server (NTRS)

    Eaton, J. A.; Cherepashchuk, A. M.; Khaliullin, Kh. F.

    1985-01-01

    Ultraviolet spectra covering both eclipses of V444 Cygni have been obtained. Longward of 1570 angstroms, the continuum brightness showed essentially the same variation seen in the optical (at 4244 angstroms). Striking atmospheric eclipses of up to 0.7 mag in depth were detected, however, in individual strong lines as well as over large ranges of the continuum shortward of 1500 angstroms. IUE data are used to estimate the degree of interstellar extinction and terminal expansion velocity of the system and to study the phase dependence of the continuum and line absorptions.

  20. Remarkable long-term changes in the small Magellanic Cloud Wolf-Rayet system HD 5980

    NASA Technical Reports Server (NTRS)

    Koenigsberger, G.; Moffat, A. F. J.; St-Louis, N.; Auer, L. H.; Drissen, L.; Seggewiss, W.

    1994-01-01

    In this paper we report the remarkable changes which occured in the Small Magellanic Cloud W-R system HD5980 = AB5 between 1978 and 1991. Within this timescale, there has been a systematic enhancement (by factors of 2-10 depending on the line) in the equivalent widths of all emission lines, and a change in the relative strengths of N III, N IV, and N V lines. Currently, the W-R spectrum is more typical of a WN6 star than a WN3 or WN4, as it was originally classified. The terminal speed of the wind has diminished by approximately 600 km/s, while the system has brightened in the visual by 0.45 mag. The UV (1850 A) continuum changed by less than 0.13 mag. The change from WN3 or WN4 to WN6 is unprecedented. The system appears to be composed at least three stars: two WNs in mutual 19.266 day orbit and an O-type supergiant. We propose that the changes observed in HD 5980 are related to an increase in wind density of one (or both?) of the W-R components, where the brighter WN6 component will dominate the W-R spectrum after the change, and we speculate that this modification of the wind structure is driven by tidal interaction induced by a possible current periastron passage of the third component in the system.

  1. Carbon and helium abundances in Wolf-Rayet WC stars determined from optical recombination lines

    NASA Technical Reports Server (NTRS)

    Torres, Ana V.

    1988-01-01

    Carbon to helium ratios and ionization fractions are derived for 74 WC stars in the Galaxy and the LMC from optically thin recombination lines at visual wavelengths. The range of C/He ratios is 0.13 to 0.79 by number, similar to the ratios calculated by Nugis (1975) and about 20 times greater than the ratios of Smith and Willis (1982). These ratios also agree with the abundances determined in the most recent evolutionary models of massive stars, which include mass loss, convective dredge-up, and new nuclear reaction rates. The range of values found for the C/He ratios implies that the convective cores of WC stars do not occupy a very large mass fraction. The C/He ratio differs within a subtype by a factor of three or less, but the mean tends to increase toward earlier subtypes, although the standard deviation from the mean is large enough to allow the interpretation that the C/He ratio is constant for all WC subtypes.

  2. The ionization state and possible ragged structured of the atmospheres of Wolf-Rayet stars

    NASA Astrophysics Data System (ADS)

    Antokhin, I. I.; Kholtygin, A. F.; Cherepashchuk, A. M.

    1988-06-01

    Calculations of the ionization structure of WR atmospheres are made in terms of Beal's model (1944), taking into account the outward decrease of matter density. It is found that the simultaneous existence of zones with various stages of ionization is possible only in a very narrow interval for the effective core temperature, which is inconsistent with observations. A qualitative model for the WR atmosphere is proposed, consisting of several thousand clots (clouds) of matter with possible dimensions of 1-2 solar radii and with densities of the order of ten times that of intercloud density. This model allows for the simultaneous existence of different stages of ionization in a wide range of effective temperatures. Observational evidence for this model would be the discovery of fast variability (on a time scale of 10 h) of WR emission line profiles with an amplitude of several percent.

  3. Ionization state and a possible cloudy structure of the atmospheres of Wolf-Rayet stars.

    NASA Astrophysics Data System (ADS)

    Antokhin, I. I.; Cherepashchuk, A. M.; Kholtygin, A. F.

    Calculations of the ionization structure of the WR atmosphere have been carried out in terms of Beals' model. It has been obtained that the simultaneous existence of zones with various ionization stages of matter is possible only in a very narrow interval for Teff. This confirms the qualitative model for the WR atmosphere consisting of some thousand dense clouds and low-dense intercloud matter.

  4. WR 110: A Single Wolf-Rayet Star with Corotating Interaction Regions in its Wind?

    NASA Astrophysics Data System (ADS)

    Chené, A.-N.; Moffat, A. F. J.; Cameron, C.; Fahed, R.; Gamen, R. C.; Lefèvre, L.; Rowe, J. F.; St-louis, N.; Muntean, V.; De La Chevrotière, A.; Guenther, D. B.; Kuschnig, R.; Matthews, J. M.; Rucinski, S. M.; Sasselov, D.; Weiss, W. W.

    2011-07-01

    A 30 day contiguous photometric run with the Microvariability and Oscillations of STars (MOST) satellite on the WN5-6b star WR 110 (HD 165688) reveals a fundamental periodicity of P = 4.08 ± 0.55 days along with a number of harmonics at periods P/n, with n ≈ 2, 3, 4, 5, and 6, and a few other possible stray periodicities and/or stochastic variability on timescales longer than about a day. Spectroscopic radial velocity studies fail to reveal any plausible companion with a period in this range. Therefore, we conjecture that the observed light-curve cusps of amplitude ~0.01 mag that recur at a 4.08 day timescale may arise in the inner parts, or at the base, of a corotating interaction region (CIR) seen in emission as it rotates around with the star at constant angular velocity. The hard X-ray component seen in WR 110 could then be a result of a high velocity component of the CIR shock interacting with the ambient wind at several stellar radii. Given that most hot, luminous stars showing CIRs have two CIR arms, it is possible that either the fundamental period is 8.2 days or, more likely in the case of WR 110, there is indeed a second weaker CIR arm for P = 4.08 days, that occurs ~two-thirds of a rotation period after the main CIR. If this interpretation is correct, WR 110 therefore joins the ranks with three other single WR stars, all WN, with confirmed CIR rotation periods (WR 1, WR 6, and WR 134), albeit with WR 110 having by far the lowest amplitude photometric modulation. This illustrates the power of being able to secure intense, continuous high-precision photometry from space-based platforms such as MOST. It also opens the door to revealing low-amplitude photometric variations in other WN stars, where previous attempts have failed. If all WN stars have CIRs at some level, this could be important for revealing sources of magnetism or pulsation in addition to rotation periods. Based on data from the MOST satellite, a Canadian Space Agency mission, jointly operated by Dynacon Inc., the University of Toronto Institute for Aerospace Studies and the University of British Columbia, with the assistance of the University of Vienna.

  5. Properties of the giant H II regions and bar in the nearby spiral galaxy NGC 5430

    NASA Astrophysics Data System (ADS)

    Brière, É.; Cantin, S.; Spekkens, K.

    2012-09-01

    In order to better understand the impact of the bar on the evolution of spiral galaxies, we measure the properties of giant H II regions and the bar in the SB(s)b galaxy NGC 5430. We use two complementary data sets, both obtained at the Observatoire du Mont-Mégantic: a hyperspectral data cube from the imaging Fourier transform spectrograph SpIOMM (Spectromètre-Imageur à transformée de Fourier de l-Observatoire du Mont-Mégantic) and high-resolution spectra across the bar from a long-slit spectrograph. We flux-calibrate SpIOMM spectra for the first time, and produce Hα and [N II]λ6584 Å intensity maps from which we identify 51 giant H II regions in the spiral arms and bar. We evaluate the type of activity, the oxygen abundance and the age of the young populations contained in these giant H II regions and in the bar. Thus, we confirm that NGC 5430 does not harbour a strong active galactic nucleus, and that its Wolf-Rayet knot shows a pure H II region nature. We find no variation in abundance or age between the bar and spiral arms, nor as a function of galactocentric radius. These results are consistent with the hypothesis that a chemical mixing mechanism is at work in the galaxy's disc to flatten the oxygen abundance gradient. Using the STARBURST99 model, we estimate the ages of the young populations, and again find no variations in age between the bar and the arms or as a function of radius. Instead, we find evidence for two galaxy-wide waves of star formation, about 7.1 and 10.5 Myr ago. While the bar in NGC 5430 is an obvious candidate to trigger these two episodes, it is not clear how the bar could induce widespread star formation on such a short time-scale.

  6. GR 290 (Romano’s Star). II. Light History and Evolutionary State

    NASA Astrophysics Data System (ADS)

    Polcaro, V. F.; Maryeva, O.; Nesci, R.; Calabresi, M.; Chieffi, A.; Galleti, S.; Gualandi, R.; Haver, R.; Mills, O. F.; Osborn, W. H.; Pasquali, A.; Rossi, C.; Vasilyeva, T.; Viotti, R. F.

    2016-06-01

    We have investigated the past light history of the luminous variable star GR 290 (M33/V532, Romano’s Star) in the M33 galaxy, and collected new spectrophotometric observations in order to analyze links between this object, the LBV category, and the Wolf-Rayet stars of the nitrogen sequence. We have built the historical light curve of GR 290 back to 1901, from old observations of the star found in several archival plates of M33. These old recordings together with published and new data on the star allowed us to infer that for at least half a century the star was in a low luminosity state, with B ≃ 18-19, most likely without brighter luminosity phases. After 1960, five large variability cycles of visual luminosity were recorded. The amplitude of the oscillations was seen increasing toward the 1992-1994 maximum, then decreasing during the last maxima. The recent light curve indicates that the photometric variations have been quite similar in all the bands and that the B - V color index has been constant within ±0.1m despite the 1.5m change of the visual luminosity. The spectrum of GR 290 at the large maximum of 1992-94 was equivalent to late-B-type, while, during 2002-2014, it varied between WN10h-11h near the visual maxima to WN8h-9h at the luminosity minima. We have detected, during this same period, a clear anti-correlation between the visual luminosity, the strength of the He ii 4686 Å emission line, the strength of the 4600-4700 Å lines’ blend, and the spectral type. From a model analysis of the spectra collected during the whole 2002-2014 period, we find that the Rosseland radius R2/3, changed between the minimum and maximum luminosity phases by a factor of three while Teff varied between about 33,000 and 23,000 K. We confirm that the bolometric luminosity of the star has not been constant, but has increased by a factor of ˜1.5 between minimum and maximum luminosity, in phase with the apparent luminosity variations. Presently, GR 290 falls in the H

  7. Color excesses, intrinsic colors, and absolute magnitudes of Galactic and Large Magellanic Cloud Wolf-Rayet stars

    NASA Technical Reports Server (NTRS)

    Vacca, William D.; Torres-Dodgen, Ana V.

    1990-01-01

    A new method of determining the color excesses of WR stars in the Galaxy and the LMC has been developed and is used to determine the excesses for 44 Galactic and 32 LMC WR stars. The excesses are combined with line-free, narrow-band spectrophotometry to derive intrinsic colors of the WR stars of nearly all spectral subtypes. No correlation of UV spectral index or intrinsic colors with spectral subtype is found for the samples of single WN or WC stars. There is evidence that early WN stars in the LMC have flatter UV continua and redder intrinsic colors than early WN stars in the Galaxy. No separation is found between the values derived for Galactic WC stars and those obtained for LMC WC stars. The intrinsic colors are compared with those calculated from model atmospheres of WR stars and generally good agreement is found. Absolute magnitudes are derived for WR stars in the LMC and for those Galactic WR stars located in clusters and associations for which there are reliable distance estimates.

  8. The Variability of the BRITE-est Wolf-Rayet star gamma Velorum. Photometric and Spectroscopic Evidence of Colliding Winds.

    NASA Astrophysics Data System (ADS)

    Richardson, Noel; St-Jean, Lucas; Moffat, Anthony F. J.; St. Louis, Nicole; Post Russell, Christopher Michael; Shenar, Tomer; Pablo, Herbert; Hill, Grant M.; Ramiaramanantsoa, Tahina; Hamaguchi, Kenji; Corcoran, Michael F.

    2017-01-01

    We report on the first results of an intensive photometric and spectroscopic campaign on the bright WC+O binary, gamma Velorum. The system was observed with two-color photometry with the BRITE-Constellation nanosatellites for six months, while we collected ~500 optical spectra in parallel from ground-based observatories. We report on the spectroscopic orbit and the evidence of colliding winds, both spectroscopically and photometrically. We find evidence of an inverse relationship between the orbital separation and the observed flux. Through a comparison with multiple spectra and the red/blue filter responses, we find that the flux excess seen photometrically is caused by the excess line emission at periastron. We have begun to quantify these variations and will compare them with smoothed-particle hydrodynamics simulations. We will further constrain these processes using XMM-Newton X-ray spectroscopy that will be obtained in late-2016 in parallel with further optical photometric and spectroscopic observations.

  9. A 2007 photometric study and UV spectral analysis of the Wolf-Rayet binary V444 Cyg

    NASA Astrophysics Data System (ADS)

    Eriş, F. Z.; Ekmekçi, F.

    2011-07-01

    Photometric and spectroscopic characteristics of the WN5+O6 binary system, V444 Cyg, were studied. The Wilson-Devinney (WD) analysis, using new BV observations carried out at the Ankara University Observatory, revealed the masses, radii, and temperatures of the components of the system as MWR=10.64 M⊙, MO=24.68 M⊙, RWR=7.19 R⊙, RO=6.85 R⊙, TWR=31 000 K, and TO=40 000 K , respectively. It was found that both components had a full spherical geometry, whereas the circumstellar envelope of the WR component had an asymmetric structure. The O-C analysis of the system revealed a period lengthening of 0.139±0.018 s yr-1, implying a mass loss rate of (6.76 ± 0.39) × 10-6 M⊙ yr-1 for the WR component. Moreover, 106 IUE-NEWSIPS spectra were obtained from NASA's IUE archive for line identification and determination of line profile variability with phase, wind velocities and variability in continuum fluxes. The integrated continuum flux level (between 1200-2000 \\rA) showed a mild and regular increase from orbital phase 0.00 up to 0.50 and then a decrease in the same way back to phase 0.00. This is evaluated as the O component making a constant and regular contribution to the system's UV light as the dominant source. The C IV line, originating in the circumstellar envelope, had the highest velocity while N IV line, originating in deeper layers of the envelope, had the lowest velocity. The average radial velocity calculated by using the C IV line (wind velocity) was found as 2326 km s-1. Tables 2 and 3 and Figs. 4 and 8 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr or via http:://cdsweb.u-strasbg.fr/AN/332/616

  10. Progenitors of supernova Ibc: a single Wolf-Rayet star as the possible progenitor of the SN Ib iPTF13bvn

    NASA Astrophysics Data System (ADS)

    Groh, Jose H.; Georgy, Cyril; Ekström, Sylvia

    2013-10-01

    Core-collapse supernova (SN) explosions mark the end of the tumultuous life of massive stars. Determining the nature of their progenitors is a crucial step towards understanding the properties of SNe. Until recently, no progenitor has been directly detected for SN of type Ibc, which are believed to come from massive stars that lose their hydrogen envelope through stellar winds and from binary systems where the companion has stripped the H envelope from the primary. Here we analyze recently reported observations of iPTF13bvn, which could possibly be the first detection of a SN Ib progenitor based on pre-explosion images. Very interestingly, the recently published Geneva models of single stars can reproduce the observed photometry of the progenitor candidate and its mass-loss rate, confirming a recently proposed scenario. We find that a single WR star with initial mass in the range 31-35 M⊙ fits the observed photometry of the progenitor of iPTF13bvn. The progenitor likely has a luminosity of log (L⋆/L⊙) ~ 5.55, surface temperature ~45 000 K, and mass of ~10.9 M⊙ at the time of explosion. Our non-rotating 32 M⊙ model overestimates the derived radius of the progenitor, although this could likely be reconciled with a fine-tuned model of a more massive (between 40 and 50 M⊙), hotter, and luminous progenitor. Our models indicate a very uncertain ejecta mass of ~8 M⊙, which is higher than the average of the SN Ib ejecta mass that is derived from the lightcurve (2-4 M⊙). This possibly high ejecta mass could produce detectable effects in the iPTF13bvn lightcurve and spectrum. If the candidate is indeed confirmed to be the progenitor, our results suggest that stars with relatively high initial masses (> 30 M⊙) can produce visible SN explosions at their deaths and do not collapse directly to a black hole.

  11. Erratum: ``X-Ray Emission from Colliding Wind Shocks in the Wolf-Rayet Binary WR 140'' (ApJ, 538, 808 [2000])

    NASA Astrophysics Data System (ADS)

    Zhekov, Svetozar A.; Skinner, Stephen L.

    2002-09-01

    There is a typographic error concerning the flux units in Table 3. Footnote e in Table 3 should read: ``Observed value (0.5-10 keV) followed in parentheses by intrinsic (unabsorbed) value. Units are 10-11 ergs cm-2 s-1.''

  12. 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.

  13. MOST: A Powerful Tool to Reveal the True Nature of the Mysterious Dust-Forming Wolf-Rayet Binary CV Ser

    NASA Astrophysics Data System (ADS)

    David-Uraz, A.; Moffat, A. F. J.; Chené, A.-N.; MOST Collaboration

    2012-12-01

    The WR + O binary CV Ser has been a source of mystery since it was shown that its atmospheric eclipses change with time over decades, in addition to its sporadic dust production. However, the first high-precision time-dependent photometric observations obtained with the MOST space telescope in 2009 show two consecutive eclipses over the 29 day orbit, with varying depths. A subsequent MOST run in 2010 showed a somewhat asymmetric eclipse profile. Parallel optical spectroscopy was obtained from the Observatoire du Mont-Mégantic (2009 and 2010) and from the Dominion Astrophysical Observatory (2009).

  14. Massive stars exploding in a He-rich circumstellar medium - II. The transitional case of SN 2005la

    NASA Astrophysics Data System (ADS)

    Pastorello, A.; Quimby, R. M.; Smartt, S. J.; Mattila, S.; Navasardyan, H.; Crockett, R. M.; Elias-Rosa, N.; Mondol, P.; Wheeler, J. C.; Young, D. R.

    2008-09-01

    We present photometric and spectroscopic data of the peculiar SN 2005la, an object which shows an optical light curve with some luminosity fluctuations and spectra with comparably strong narrow hydrogen and helium lines, probably of circumstellar nature. The increasing full width at half-maximum velocity of these lines is indicative of an acceleration of the circumstellar material. SN 2005la exhibits hybrid properties, sharing some similarities with both Type IIn supernovae and 2006jc-like (Type Ibn) events. We propose that the progenitor of SN 2005la was a very young Wolf-Rayet (WN-type) star which experienced mass ejection episodes shortly before core collapse.

  15. He II emitters in the VIMOS VLT Deep Survey: Population III star formation or peculiar stellar populations in galaxies at 2 < z < 4.6?

    NASA Astrophysics Data System (ADS)

    Cassata, P.; Le Fèvre, O.; Charlot, S.; Contini, T.; Cucciati, O.; Garilli, B.; Zamorani, G.; Adami, C.; Bardelli, S.; Le Brun, V.; Lemaux, B.; Maccagni, D.; Pollo, A.; Pozzetti, L.; Tresse, L.; Vergani, D.; Zanichelli, A.; Zucca, E.

    2013-08-01

    Aims: The aim of this work is to identify He II emitters at 2 < z < 4.6 and to constrain the source of the hard ionizing continuum that powers the He II emission. Methods: We assembled a sample of 277 galaxies with a highly reliable spectroscopic redshift at 2 < z < 4.6 from the VIMOS-VLT Deep Survey (VVDS) Deep and Ultra-Deep data, and we identified 39 He II λ1640 emitters. We studied their spectral properties, measuring the fluxes, equivalent widths (EW), and full width at half maximum (FWHM) for most relevant lines, including He II λ1640, Lyα line, Si II λ1527, and C IV λ1549. Results: About 10% of galaxies at z ~ 3 and iAB ≤ 24.75 show He II in emission, with rest frame equivalent widths EW0 ~ 1-7 Å, equally distributed between galaxies with Lyα in emission or in absorption. We find 11 (3.9% of the global population) reliable He II emitters with unresolved He II lines (FWHM0 < 1200 km s-1), 13 (4.6% of the global population) reliable emitters with broad He II emission (FWHM0 > 1200 km s-1), 3 active galactic nuclei (AGN), and an additional 12 possible He II emitters. The properties of the individual broad emitters are in agreement with expectations from a Wolf-Rayet (W-R) model. Instead, the properties of the narrow emitters are not compatible with this model, nor with predictions of gravitational cooling radiation produced by gas accretion, unless this is severely underestimated by current models by more than two orders of magnitude. Rather, we find that the EW of the narrow He II line emitters are in agreement with expectations for a Population III (PopIII) star formation, if the episode of star formation is continuous, and we calculate that a PopIII star formation rate (SFR) of 0.1-10 M⊙ yr-1 alone is enough to sustain the observed He II flux. Conclusions: We conclude that narrow He II emitters are powered either by the ionizing flux from a stellar population rare at z ~ 0 but much more common at z ~ 3, or by PopIII star formation. As proposed by

  16. A giant outburst two years before the core-collapse of a massive star.

    PubMed

    Pastorello, A; Smartt, S J; Mattila, S; Eldridge, J J; Young, D; Itagaki, K; Yamaoka, H; Navasardyan, H; Valenti, S; Patat, F; Agnoletto, I; Augusteijn, T; Benetti, S; Cappellaro, E; Boles, T; Bonnet-Bidaud, J-M; Botticella, M T; Bufano, F; Cao, C; Deng, J; Dennefeld, M; Elias-Rosa, N; Harutyunyan, A; Keenan, F P; Iijima, T; Lorenzi, V; Mazzali, P A; Meng, X; Nakano, S; Nielsen, T B; Smoker, J V; Stanishev, V; Turatto, M; Xu, D; Zampieri, L

    2007-06-14

    The death of massive stars produces a variety of supernovae, which are linked to the structure of the exploding stars. The detection of several precursor stars of type II supernovae has been reported (see, for example, ref. 3), but we do not yet have direct information on the progenitors of the hydrogen-deficient type Ib and Ic supernovae. Here we report that the peculiar type Ib supernova SN 2006jc is spatially coincident with a bright optical transient that occurred in 2004. Spectroscopic and photometric monitoring of the supernova leads us to suggest that the progenitor was a carbon-oxygen Wolf-Rayet star embedded within a helium-rich circumstellar medium. There are different possible explanations for this pre-explosion transient. It appears similar to the giant outbursts of luminous blue variable stars (LBVs) of 60-100 solar masses, but the progenitor of SN 2006jc was helium- and hydrogen-deficient (unlike LBVs). An LBV-like outburst of a Wolf-Rayet star could be invoked, but this would be the first observational evidence of such a phenomenon. Alternatively, a massive binary system composed of an LBV that erupted in 2004, and a Wolf-Rayet star exploding as SN 2006jc, could explain the observations.

  17. GRB 980425 host: [C II], [O I], and CO lines reveal recent enhancement of star formation due to atomic gas inflow

    NASA Astrophysics Data System (ADS)

    Michałowski, M. J.; Castro Cerón, J. M.; Wardlow, J. L.; Karska, A.; Messias, H.; van der Werf, P.; Hunt, L. K.; Baes, M.; Castro-Tirado, A. J.; Gentile, G.; Hjorth, J.; Le Floc'h, E.; Pérez-Martínez, R.; Nicuesa Guelbenzu, A.; Rasmussen, J.; Rizzo, J. R.; Rossi, A.; Sánchez-Portal, M.; Schady, P.; Sollerman, J.; Xu, D.

    2016-11-01

    Context. Accretion of gas from the intergalactic medium is required to fuel star formation in galaxies. We have recently suggested that this process can be studied using host galaxies of gamma-ray bursts (GRBs). Aims: Our aim is to test this possibility by studying in detail the properties of gas in the closest galaxy hosting a GRB (980425). Methods: We obtained the first ever far-infrared (FIR) line observations of a GRB host, namely Herschel/PACS resolved [C ii] 158 μm and [O i] 63 μm spectroscopy, and an APEX/SHeFI CO(2-1) line detection and ALMA CO(1-0) observations of the GRB 980425 host. Results: The GRB 980425 host has elevated [C ii]/FIR and [O i]/FIR ratios and higher values of star formation rates (SFR) derived from line ([C ii], [O i], Hα) than from continuum (UV, IR, radio) indicators. [C ii] emission exhibits a normal morphology, peaking at the galaxy centre, whereas [O i] is concentrated close to the GRB position and the nearby Wolf-Rayet region. The high [O i] flux indicates that there is high radiation field and high gas density at these positions, as derived from modelling of photo-dissociation regions. The [C ii]/CO luminosity ratio of the GRB 980425 host is close to the highest values found for local star-forming galaxies. Indeed, its CO-derived molecular gas mass is low given its SFR and metallicity, but the [C ii]-derived molecular gas mass is close to the expected value. Conclusions: The [O i] and H i concentrations and the high radiation field and density close to the GRB position are consistent with the hypothesis of a very recent (at most a few tens of Myr ago) inflow of atomic gas triggering star formation. In this scenario dust has not had time to build up (explaining high line-to-continuum ratios). Such a recent enhancement of star formation activity would indeed manifest itself in high SFRline/SFRcontinuum ratios because the line indicators are sensitive only to recent (≲10 Myr) activity, whereas the continuum indicators measure

  18. GEMINI 3D spectroscopy of BAL + IR + FeII QSOs - I. Decoupling the BAL, QSO, starburst, NLR, supergiant bubbles and galactic wind in Mrk 231

    NASA Astrophysics Data System (ADS)

    Lipari, S.; Sanchez, S. F.; Bergmann, M.; Terlevich, R.; Garcia-Lorenzo, B.; Punsly, B.; Mediavilla, E.; Taniguchi, Y.; Ajiki, M.; Zheng, W.; Acosta, J.; Jahnke, K.

    2009-02-01

    In this paper we present the first results of a study of BAL QSOs (at low and high redshift), based on very deep Gemini GMOS integral field spectroscopy. In particular, the results obtained for the nearest BAL IR-QSO Mrk 231 are presented. For the nuclear region of Mrk 231, the QSO and host galaxy components were modelled, using a new technique of decoupling 3D spectra. From this study, the following main results were found: (i) in the pure host galaxy spectrum an extreme nuclear starburst component was clearly observed, as a very strong increase in the flux, at the blue wavelengths; (ii) the BAL system I is observed in the spectrum of the host galaxy; (iii) in the clean/pure QSO emission spectrum, only broad lines were detected. 3D GMOS individual spectra (specially in the near-infrared CaII triplet) and maps confirm the presence of an extreme and young nuclear starburst (8 < age < 15 Myr), which was detected in a ring or toroid with a radius r = 0.3arcsec ~ 200 pc, around the core of the nucleus. The extreme continuum blue component was detected only to the south of the core of the nucleus. This area is coincident with the region where we previously suggested that the galactic wind is cleaning the nuclear dust. Very deep 3D spectra and maps clearly show that the BAL systems I and II - in the strong `absorption lines' NaIDλ5889-95 and CaII Kλ3933 - are extended (reaching ~1.4-1.6 arcsec ~ 1.2-1.3 kpc, from the nucleus) and clearly elongated at the position angle (PA) close to the radio jet PA, which suggest that the BAL systems I and II are `both' associated with the radio jet. The physical properties of the four expanding nuclear bubbles were analysed, using the GMOS 3D spectra and maps. In particular, we found strong multiple LINER/OF emission-line systems and Wolf-Rayet features in the main knots of the more external super bubble S1 (r = 3.0 kpc). The kinematics of these knots - and the internal bubbles - suggest that they are associated with an area of

  19. CARBON STARS WITH INFRARED SPECTRA IN GROUP P OF THE IRAS/LRS DATABASE

    SciTech Connect

    Chen, P. S.

    2012-10-01

    Sources with infrared spectra in Group P of the IRAS/LRS database all show polycyclic aromatic hydrocarbon features. They are often planetary nebulae, H II regions, reflection/dark nebulae, Wolf-Rayet stars, or external galaxies. However, we noted that some carbon stars are also included in this group. We searched for and investigated all infrared spectra in Group P of the IRAS/LRS database. Finally, we found 11 previously known carbon stars and identified 8 new candidate carbon stars in Group P. Infrared spectra of these stars may present the 11.2 {mu}m SiC emission features indicative of their carbon-rich properties.

  20. Sources of High-Energy Emission in the Green Pea Galaxies: New Constraints from Magellan Spectra

    NASA Astrophysics Data System (ADS)

    Carroll, Derek Alexander

    2016-01-01

    The recently discovered Green Pea galaxies display extreme starburst activity and may be some of the only possible Lyman continuum emitting galaxies at low redshift. Green Peas are characterized by their unusually high [O III]/[O II] ratios, similar to the ratios observed in high-redshift galaxies. In addition, the presence of the high-energy He II 4686 line shows that the Green Peas are highly ionized. However, the origin of the He II emission in the Green Peas, and many other starburst galaxies, is still an open question. We analyze IMACS and MagE spectra from the Magellan telescopes in order to evaluate the most probable cause of this He II emission. We also analyze other properties like dust content, temperature and density, and kinematic components. Our IMACS spectra show no Wolf-Rayet (WR) features. We set upper limits on the WR populations in our sample and conclude that Wolf-Rayet stars are not a likely candidate for the He II emission. With deeper MagE spectra we investigate energetic shocks as a possible source of the He II, and move one step closer to uncovering the origin of high-energy photons in these unique starbursts.

  1. Photometry of the 4686 A emission line of gamma(2) Velorum from the South Pole

    SciTech Connect

    Taylor, M. Florida Univ., Gainesville )

    1990-10-01

    An automated optical telescope located at the Amundsen-Scott South Pole station on Antarctica, has been used to obtain more than 78 h of photometry of the He II emission line (4686 A) of the spectroscopic binary gamma(2) Velorum. These data were obtained on seven different days during the 1987 austral winter; the longest continuous run spans 19 h. Two independent period search techniques have been used to search for periodic behavior in the strength of the He II emission line of this Wolf-Rayet star. They are: (1) power spectrum analysis and (2) a first-order sine function fit to the data using least squares. Various multiplicities of a period on the order of 1.3 h with amplitudes of a few percent are found in most of these data. According to recent theoretical models of Wolf-Rayet stars, fluctuations in the He II emission line may indicate vibrational instability in gamma(2) Vel. These pulsations may, in turn, give rise to shocks which propagate outward and which may provide the necessary conditions for periodic changes in the state of a given region of the atmosphere to occur. 15 refs.

  2. Photometry of the 4686 A emission line of gamma(2) Velorum from the South Pole

    NASA Technical Reports Server (NTRS)

    Taylor, Maryjane

    1990-01-01

    An automated optical telescope located at the Amundsen-Scott South Pole station on Antarctica, has been used to obtain more than 78 h of photometry of the He II emission line (4686 A) of the spectroscopic binary gamma(2) Velorum. These data were obtained on seven different days during the 1987 austral winter; the longest continuous run spans 19 h. Two independent period search techniques have been used to search for periodic behavior in the strength of the He II emission line of this Wolf-Rayet star. They are: (1) power spectrum analysis and (2) a first-order sine function fit to the data using least squares. Various multiplicities of a period on the order of 1.3 h with amplitudes of a few percent are found in most of these data. According to recent theoretical models of Wolf-Rayet stars, fluctuations in the He II emission line may indicate vibrational instability in gamma(2) Vel. These pulsations may, in turn, give rise to shocks which propagate outward and which may provide the necessary conditions for periodic changes in the state of a given region of the atmosphere to occur.

  3. Chemical evolution of fluorine in the bulge. High-resolution K-band spectra of giants in three fields

    NASA Astrophysics Data System (ADS)

    Jönsson, H.; Ryde, N.; Harper, G. M.; Cunha, K.; Schultheis, M.; Eriksson, K.; Kobayashi, C.; Smith, V. V.; Zoccali, M.

    2014-04-01

    Context. Possible main formation sites of fluorine in the Universe include asymptotic giant branch (AGB) stars, the ν-process in Type II supernova, and/or Wolf-Rayet stars. The importance of the Wolf-Rayet stars has theoretically been questioned and they are probably not needed in modeling the chemical evolution of fluorine in the solar neighborhood. It has, however, been suggested that Wolf-Rayet stars are indeed needed to explain the chemical evolution of fluorine in the bulge. The molecular spectral data, needed to determine the fluorine abundance, of the often used HF-molecule has not been presented in a complete and consistent way and has recently been debated in the literature. Aims: We intend to determine the trend of the fluorine-oxygen abundance ratio as a function of a metallicity indicator in the bulge to investigate the possible contribution from Wolf-Rayet stars. Additionally, we present here a consistent HF line list for the K- and L-bands including the often used 23 358.33 Å line. Methods: High-resolution near-infrared spectra of eight K giants were recorded using the spectrograph CRIRES mounted at the VLT. A standard setting was used that covered the HF molecular line at 23 358.33 Å. The fluorine abundances were determined using spectral fitting. We also re-analyzed five previously published bulge giants observed with the Phoenix spectrograph on Gemini using our new HF molecular data. Results: We find that the fluorine-oxygen abundance in the bulge probably cannot be explained with chemical evolution models that only include AGB stars and the ν-process in supernovae Type II, that is a significant amount of fluorine production in Wolf-Rayet stars is most likely needed to explain the fluorine abundance in the bulge. For the HF line data, we find that a possible reason for the inconsistencies in the literature, where two different excitation energies were used, is two different definitions of the zero-point energy for the HF molecule and therefore

  4. Nebular phase observations of the Type-Ib supernova iPTF13bvn favour a binary progenitor

    NASA Astrophysics Data System (ADS)

    Kuncarayakti, H.; Maeda, K.; Bersten, M. C.; Folatelli, G.; Morrell, N.; Hsiao, E. Y.; González-Gaitán, S.; Anderson, J. P.; Hamuy, M.; de Jaeger, T.; Gutiérrez, C. P.; Kawabata, K. S.

    2015-07-01

    Aims: We present and analyse late-time observations of the Type-Ib supernova with possible pre-supernova progenitor detection, iPTF13bvn, which were done ~300 days after the explosion. We discuss them in the context of constraints on the supernova's progenitor. Previous studies have proposed two possible natures for the progenitor of the supernova, i.e. a massive Wolf-Rayet star or a lower-mass star in a close binary system. Methods: Our observations show that the supernova has entered the nebular phase, with the spectrum dominated by Mg I]λλ4571, [O I]λλ6300, 6364, and [Ca II]λλ7291, 7324 emission lines. We measured the emission line fluxes to estimate the core oxygen mass and compared the [O I]/[Ca II] line ratio with other supernovae. Results.The core oxygen mass of the supernova progenitor was estimated to be ≲0.7 M⊙, which implies initial progenitor mass that does not exceed ~15-17 M⊙.Since the derived mass is too low for a single star to become a Wolf-Rayet star, this result lends more support to the binary nature of the progenitor star of iPTF13bvn. The comparison of [O I]/[Ca II] line ratio with other supernovae also shows that iPTF13bvn appears to be in close association with the lower mass progenitors of stripped-envelope and Type-II supernovae. Based on observations obtained at the Southern Astrophysical Research (SOAR) telescope, which is a joint project of the Ministério da Ciência, Tecnologia, e Inovação (MCTI) da República Federativa do Brasil, the US National Optical Astronomy Observatory (NOAO), the University of North Carolina at Chapel Hill (UNC), and Michigan State University (MSU); Chilean Telescope Time Allocation Committee proposal CN2014A-91.

  5. Catalog of far-ultraviolet objective-prism spectrophotometry: Skylab experiment S-019, ultraviolet steller astronomy

    NASA Technical Reports Server (NTRS)

    Henize, K. G.; Wray, J. D.; Parsons, S. B.; Benedict, G. F.

    1979-01-01

    Ultraviolet stellar spectra in the wavelength region from 1300 to 5000 A (130 to 500) were photographed during the three manned Skylab missions using a 15 cm aperture objective-prism telescope. The prismatic dispersion varied from 58 A mm/1 at 1400 A to 1600 A mm/1 at 3000 A. Approximately 1000 spectra representing 500 stars were measured and reduced to observed fluxes. About 100 stars show absorption lines of Si IV, C IV, or C II. Numerous line features are also recorded in supergiant stars, shell stars, A and F stars, and Wolf-Rayet stars. Most of the stars in the catalog are of spectral class B, with a number of O and A type stars and a sampling of WC, WN, F and C type stars. Spectrophotometric results are tabulated for these 500 stars.

  6. The trace of the CNO cycle in the ring nebula NGC 6888

    SciTech Connect

    Mesa-Delgado, A.; Esteban, C.; García-Rojas, J.; Reyes-Pérez, J.; Morisset, C.; Bresolin, F.

    2014-04-20

    We present new results on the chemical composition of the Galactic ring nebula NGC 6888 surrounding the WN6(h) star WR136. The data are based on deep spectroscopical observations taken with the High Dispersion Spectrograph at the 8.2 m Subaru Telescope. The spectra cover the optical range from 3700 to 7400 Å. The effect of the CNO cycle is well-identified in the abundances of He, N, and O, while elements not involved in the synthesis such as Ar, S, and Fe present values consistent with the solar vicinity and the ambient gas. The major achievement of this work is the first detection of the faint C II λ4267 recombination line in a Wolf-Rayet nebula. This allows us to estimate the C abundance in NGC 6888 and therefore investigate for the first time the trace of the CNO cycle in a ring nebula around a Wolf-Rayet star. Although the detection of the C II line has a low signal-to-noise ratio, the C abundance seems to be higher than the predictions of recent stellar evolution models of massive stars. The Ne abundance also shows a puzzling pattern with an abundance of about 0.5 dex lower than the solar vicinity, which may be related to the action of the NeNa cycle. Attending to the constraints imposed by the dynamical timescale and the He/H and N/O ratios of the nebula, the comparison with stellar evolution models indicates that the initial mass of the stellar progenitor of NGC 6888 is between 25 M {sub ☉} and 40 M {sub ☉}.

  7. The Trace of the CNO Cycle in the Ring Nebula NGC 6888

    NASA Astrophysics Data System (ADS)

    Mesa-Delgado, A.; Esteban, C.; García-Rojas, J.; Reyes-Pérez, J.; Morisset, C.; Bresolin, F.

    2014-04-01

    We present new results on the chemical composition of the Galactic ring nebula NGC 6888 surrounding the WN6(h) star WR136. The data are based on deep spectroscopical observations taken with the High Dispersion Spectrograph at the 8.2 m Subaru Telescope. The spectra cover the optical range from 3700 to 7400 Å. The effect of the CNO cycle is well-identified in the abundances of He, N, and O, while elements not involved in the synthesis such as Ar, S, and Fe present values consistent with the solar vicinity and the ambient gas. The major achievement of this work is the first detection of the faint C II λ4267 recombination line in a Wolf-Rayet nebula. This allows us to estimate the C abundance in NGC 6888 and therefore investigate for the first time the trace of the CNO cycle in a ring nebula around a Wolf-Rayet star. Although the detection of the C II line has a low signal-to-noise ratio, the C abundance seems to be higher than the predictions of recent stellar evolution models of massive stars. The Ne abundance also shows a puzzling pattern with an abundance of about 0.5 dex lower than the solar vicinity, which may be related to the action of the NeNa cycle. Attending to the constraints imposed by the dynamical timescale and the He/H and N/O ratios of the nebula, the comparison with stellar evolution models indicates that the initial mass of the stellar progenitor of NGC 6888 is between 25 M ⊙ and 40 M ⊙. Based on data collected at Subaru Telescope, which is operated by the National Astronomical Observatory of Japan.

  8. Photobilirubin II.

    PubMed Central

    Bonnett, R; Buckley, D G; Hamzetash, D; Hawkes, G E; Ioannou, S; Stoll, M S

    1984-01-01

    An improved preparation of photobilirubin II in ammoniacal methanol is described. Evidence is presented which distinguishes between the two structures proposed earlier for photobilirubin II in favour of the cycloheptadienyl structure. Nuclear-Overhauser-enhancement measurements with bilirubin IX alpha and photobilirubin II in dimethyl sulphoxide are complicated by the occurrence of negative and zero effects. The partition coefficient of photobilirubin II between chloroform and phosphate buffer (pH 7.4) is 0.67. PMID:6743241

  9. Photosystem II

    ScienceCinema

    James Barber

    2016-07-12

    James Barber, Ernst Chain Professor of Biochemistry at Imperial College, London, gives a BSA Distinguished Lecture titled, "The Structure and Function of Photosystem II: The Water-Splitting Enzyme of Photosynthesis."

  10. FAQs II

    ERIC Educational Resources Information Center

    Kezar, Adrianna; Frank, Vikki; Lester, Jaime; Yang, Hannah

    2008-01-01

    In their paper entitled "Why should postsecondary institutions consider partnering to offer (Individual Development Accounts (IDAs)?" the authors reviewed frequently asked questions they encountered from higher education professionals about IDAs, but as their research continued so did the questions. FAQ II has more in-depth questions and…

  11. SAGE II

    Atmospheric Science Data Center

    2016-02-16

    ... of stratospheric aerosols, ozone, nitrogen dioxide, water vapor and cloud occurrence by mapping vertical profiles and calculating ... (i.e. MLS and SAGE III versus HALOE) Fixed various bugs Details are in the  SAGE II V7.00 Release Notes .   ...

  12. Gamma II

    NASA Astrophysics Data System (ADS)

    Barker, Thurburn; Castelaz, M.; Cline, J.; Owen, L.; Boehme, J.; Rottler, L.; Whitworth, C.; Clavier, D.

    2011-05-01

    GAMMA II is the Guide Star Automatic Measuring MAchine relocated from STScI to the Astronomical Photographic Data Archive (APDA) at the Pisgah Astronomical Research Institute (PARI). GAMMA II is a multi-channel laser-scanning microdensitometer that was used to measure POSS and SERC plates to create the Guide Star Catalog and the Digital Sky Survey. The microdensitometer is designed with submicron accuracy in x and y measurements using a HP 5507 laser interferometer, 15 micron sampling, and the capability to measure plates as large as 0.5-m across. GAMMA II is a vital instrument for the success of digitizing the direct, objective prism, and spectra photographic plate collections in APDA for research. We plan several targeted projects. One is a collaboration with Drs. P.D. Hemenway and R. L. Duncombe who plan to scan 1000 plates of 34 minor planets to identify systematic errors in the Fundamental System of celestial coordinates. Another is a collaboration with Dr. R. Hudec (Astronomical Institute, Academy of Sciences of the Czech Republic) who is working within the Gaia Variability Unit CU7 to digitize objective prism spectra on the Henize plates and Burrell-Schmidt plates located in APDA. These low dispersion spectral plates provide optical counterparts of celestial high-energy sources and cataclysmic variables enabling the simulation of Gaia BP/RP outputs. The astronomical community is invited to explore the more than 140,000 plates from 20 observatories now archived in APDA, and use GAMMA II. The process of relocating GAMMA to APDA, re-commissioning, and starting up the production scan programs will be described. Also, we will present planned research and future upgrades to GAMMA II.

  13. PORT II

    NASA Technical Reports Server (NTRS)

    Muniz, Beau

    2009-01-01

    One unique project that the Prototype lab worked on was PORT I (Post-landing Orion Recovery Test). PORT is designed to test and develop the system and components needed to recover the Orion capsule once it splashes down in the ocean. PORT II is designated as a follow up to PORT I that will utilize a mock up pressure vessel that is spatially compar able to the final Orion capsule.

  14. PESTICINS II. I and II

    PubMed Central

    Brubaker, Robert R.; Surgalla, Michael J.

    1962-01-01

    Brubaker, Robert R. (Fort Detrick, Frederick, Md.) and Michael J. Surgalla. Pesticins. II. Production of pesticin I and II. J. Bacteriol. 84:539–545. 1962.—Pesticin I was separated from pesticin I inhibitor by ion-exchange chromatography of cell-free culture supernatant fluids and by acid precipitation of soluble preparations obtained from mechanically disrupted cells. The latter procedure resulted in formation of an insoluble pesticin I complex which, upon removal by centrifugation and subsequent dissolution in neutral buffer, exhibited a 100- to 1,000-fold increase in antibacterial activity over that originally observed. However, activity returned to the former level upon addition of the acid-soluble fraction, which contained pesticin I inhibitor. Since the presence of pesticin I inhibitor leads to serious errors in the determination of pesticin I, an assay medium containing ethylenediaminetetraacetic acid in excess Ca++ was developed; this medium eliminated the effect of the inhibitor. By use of the above medium, sufficient pesticin I was found to be contained within 500 nonirradiated cells to inhibit growth of a suitable indicator strain; at least 107 cells were required to effect a corresponding inhibition by pesticin II. Although both pesticins are located primarily within the cell during growth, pesticin I may arise extracellularly during storage of static cells. Slightly higher activity of pesticin I inhibitor was found in culture supernatant fluids than occurred in corresponding cell extracts of equal volume. The differences and similarities between pesticin I and some known bacteriocins are discussed. PMID:14016110

  15. Fluorine in the Solar Neighborhood: No Evidence for the Neutrino Process

    NASA Astrophysics Data System (ADS)

    Jönsson, H.; Ryde, N.; Spitoni, E.; Matteucci, F.; Cunha, K.; Smith, V.; Hinkle, K.; Schultheis, M.

    2017-01-01

    Asymptotic giant branch (AGB) stars are known to produce “cosmic” fluorine, but it is uncertain whether these stars are the main producers of fluorine in the solar neighborhood or if any of the other proposed formation sites, Type II supernovae (SNe II) and/or Wolf-Rayet (W-R) stars, are more important. Recent articles have proposed both AGB stars and SNe II as the dominant sources of fluorine in the solar neighborhood. In this paper we set out to determine the fluorine abundance in a sample of 49 nearby, bright K giants for which we previously have determined the stellar parameters, as well as alpha abundances homogeneously from optical high-resolution spectra. The fluorine abundance is determined from a 2.3 μm HF molecular line observed with the spectrometer Phoenix. We compare the fluorine abundances with those of alpha-elements mainly produced in SNe II and find that fluorine and the alpha-elements do not evolve in lockstep, ruling out SNe II as the dominating producers of fluorine in the solar neighborhood. Furthermore, we find a secondary behavior of fluorine with respect to oxygen, which is another evidence against the SNe II playing a large role in the production of fluorine in the solar neighborhood. This secondary behavior of fluorine will put new constraints on stellar models of the other two suggested production sites: AGB stars and W-R stars.

  16. OPTICAL SPECTROPHOTOMETRIC MONITORING OF THE EXTREME LUMINOUS BLUE VARIABLE STAR GR 290 (ROMANO's STAR) IN M 33

    SciTech Connect

    Polcaro, V. F.; Viotti, R. F.; Rossi, C.; Galleti, S.; Gualandi, R.; Norci, L.

    2011-01-15

    We study the long-term, S Dor-type variability and the present hot phase of the luminous blue variable (LBV) star GR 290 (Romano's Star) in M 33 in order to investigate possible links between the LBV and the late, nitrogen sequence Wolf-Rayet Stars (WNL) stages of very massive stars. We use intermediate-resolution spectra, obtained with the William Herschel Telescope (WHT) in 2008 December, when GR 290 was at minimum (V = {approx}18.6), as well as new low-resolution spectra and BVRI photometry obtained with the Loiano and Cima Ekar telescopes during 2007-2010. We identify more than 80 emission lines in the 3100-10000 A range covered by the WHT spectra, belonging to different species: the hydrogen Balmer and Paschen series, neutral and ionized helium, C III, N II-III, S IV, Si III-IV, and many forbidden lines of [N II], [O III], [S III], [A III], [Ne III], and [Fe III]. Many lines, especially the He I triplets, show a P Cygni profile with an a-e radial velocity difference of -300 to -500 km s{sup -1}. The shape of the 4630-4713 A emission blend and of other emission lines resembles that of WN9 stars; the blend deconvolution shows that the He II 4686 A has a strong broad component with FWHM {approx_equal} 1700 km s{sup -1}. During 2003-2010 the star underwent large spectral variations, best seen in the 4630-4686 A emission feature. Using the late-WN spectral types of Crowther and Smith, GR 290 apparently varied between the WN11 and WN8-9 spectral types; the hotter the star was the fainter its visual magnitude was. This spectrum-visual luminosity anticorrelation of GR 290 is reminiscent of the behavior of the best-studied LBVs, such as S Dor and AG Car. During the 2008 minimum, we found a significant decrease in bolometric luminosity, which could be attributed to absorption by newly formed circumstellar matter. We suggest that the broad 4686 A line and the optical continuum formed in a central Wolf-Rayet region, while the narrow emission line spectrum originated in an

  17. Search for OB stars running away from young star clusters. II. The NGC 6357 star-forming region

    NASA Astrophysics Data System (ADS)

    Gvaramadze, V. V.; Kniazev, A. Y.; Kroupa, P.; Oh, S.

    2011-11-01

    shells typical of luminous blue variable and late WN-type Wolf-Rayet stars.

  18. The Metal-Rich Universe

    NASA Astrophysics Data System (ADS)

    Israelian, Garik; Meynet, Georges

    2012-10-01

    Preface; Part I. Abundances in the Galaxy: Field Stars: 1. Metal-rich stars and stellar populations: A brief history and new results; 2. The metal-rich nature of stars with planets; 3. Solar chemical peculiarities; 4. Kinematics of metal-rich stars with and without planets; 5. Elemental abundance trends in the metal-rich thin and thick disks; 6. Metal-rich massive stars - how metal-rich are they?; 7. Hercules stream stars and the metal-rich thick disk; 8. Abundance survey of the galactic thick disk; Part II. Abundances in the Galaxy: Galactic Stars in Clusters, Bulges and Centre: 9. Galactic open clusters with super solar metallicities; 10. Old and very metal-rich open clusters in the BOCCE project; 11. Massive stars vs. nebular abundances in the Orion nebula; 12. Abundance surveys of metal-rich bulge stars; 13. Metal abundances in the galactic center; 14. Light elements in the galactic bulge; 15. Metallicity and ages of selected G-K giants; Part III. Observations - Abundances in Extragalactic Contexts: 16. Stellar abundances of early-type galaxies and galactic spheroids: Evidence for metal-rich stars; 17. Measuring chemical abundances in extragalactic metal-rich HII regions; 18. On the maximum oxygen abundance in metal-rich spiral galaxies; 19. Starbursts and their contribution to metal enrichment; 20. High metallicities at high redshifts; 21. Evolution of dust and elemental abundances in quasar DLAs and GRB afterglows as a function of cosmic time; 22. Dust, metals and diffuse interstellar bands in damped Lyman Alpha systems; 23. Tracing metallicities in the Universe with the James Webb Space Telescope; Part IV. Stellar Populations and Mass Functions: 24. The stellar initial mass function of metal-rich populations; 25. IMF effects on the metallicity and colour evolution of disk galaxies; 26. The metallicity of circumnuclear star forming regions; 27. The stellar population of bulges; 28. The metallicity distribution of the stars in elliptical galaxies; 29. Wolf-Rayet

  19. Fluorine Abundances in the Large Magellanic Cloud and ω Centauri: Evidence for Neutrino Nucleosynthesis?

    NASA Astrophysics Data System (ADS)

    Cunha, Katia; Smith, Verne V.; Lambert, David L.; Hinkle, Kenneth H.

    2003-09-01

    The behavior of fluorine with metallicity has not yet been probed in any stellar population. In this work, we present the first fluorine abundances measured outside of the Milky Way from a sample of red giants in the Large Magellanic Cloud (LMC), as well the Galactic globular cluster ω Centauri. The fluorine abundances are derived from vibration-rotation transitions of HF using infrared spectra obtained with the Phoenix spectrograph on the Gemini South 8.1 m telescope. It is found that the abundance ratio of F/O declines as the oxygen abundance decreases. The values of F/O are especially low in the two ω Cen giants; this very low value of F/O probably indicates that 19F synthesis in asymptotic giant branch (AGB) stars is not the dominant source of fluorine in stellar populations. The observed decline in F/O with lower O abundances is in qualitative agreement with what is expected if 19F is produced via H- and He-burning sequences in very massive stars, with this fluorine then ejected in high mass-loss rate Wolf-Rayet winds. A quantitative comparison of observations with this process awaits results from more detailed chemical evolution models incorporating the yields from Wolf-Rayet winds. Perhaps of more significance is the quantitative agreement between the Galactic and LMC results with predictions from models in which 19F is produced from neutrino nucleosynthesis during core collapse in supernovae of Type II. The very low values of F/O in ω Cen are also in agreement with neutrino nucleosynthesis models if the ``peculiar'' star formation history of ω Cen, with two to four distinct episodes of star formation, is considered. Based on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreeement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the Particle Physics and Astronomy Research Council (United Kingdom

  20. The Origin and Optical Depth of Ionizing Photons in the Green Pea Galaxies

    NASA Astrophysics Data System (ADS)

    Jaskot, A. E.; Oey, M. S.

    2014-09-01

    Our understanding of radiative feedback and star formation in galaxies at high redshift is hindered by the rarity of similar systems at low redshift. However, the recently identified Green Pea (GP) galaxies are similar to high-redshift galaxies in their morphologies and star formation rates and are vital tools for probing the generation and transmission of ionizing photons. The GPs contain massive star clusters that emit copious amounts of high-energy radiation, as indicated by intense [OIII] 5007 emission and HeII 4686 emission. We focus on six GP galaxies with high ratios of [O III] 5007,4959/[O II] 3727 ~10 or more. Such high ratios indicate gas with a high ionization parameter or a low optical depth. The GP line ratios and ages point to chemically homogeneous massive stars, Wolf-Rayet stars, or shock ionization as the most likely sources of the He II emission. Models including shock ionization suggest that the GPs may have low optical depths, consistent with a scenario in which ionizing photons escape along passageways created by recent supernovae. The GPs and similar galaxies can shed new light on cosmic reionization by revealing how ionizing photons propagate from massive star clusters to the intergalactic medium.

  1. A nonthermal superbubble in the irregular galaxy IC 10

    NASA Technical Reports Server (NTRS)

    Yang, Hui; Skillman, Evan D.

    1993-01-01

    We present synthesis radio continuum observations of the nearby irregular galaxy IC 10. These observations, at 6, 20, and 49 cm, allow us to measure the flux and spectral index of a number of resolved sources in IC 10. While most of these are easily identified as thermal emission from H II regions and a few are nonthermal background sources, one extended, nonthermal source appears to be a superbubble in IC 10. Its large size (about 250 pc) implies that it is most likely the product of several supernovae. Comparisons of these radio observations with Halpha, H I, and optical imaging observations reveal that the large nonthermal superbubble is associated with a region of star formation containing two of the most luminous H II regions and the most massive H I cloud in IC 10. We tentatively identify a stellar cluster with two Wolf-Rayet stars in the center of the superbubble. We propose that this superbubble in IC 10 represents a bridge between the giant H II regions and the H I shells and supershells observed in our Galaxy and external galaxies.

  2. HUBBLE SPACE TELESCOPE EMISSION-LINE GALAXIES AT z ∼ 2: THE MYSTERY OF NEON

    SciTech Connect

    Zeimann, Gregory R.; Ciardullo, Robin; Gebhardt, Henry; Gronwall, Caryl; Hagen, Alex; Trump, Jonathan R.; Bridge, Joanna S.; Luo, Bin; Schneider, Donald P.

    2015-01-01

    We use near-infrared grism spectroscopy from the Hubble Space Telescope to examine the strength of [Ne III] λ3869 relative to Hβ, [O II] λ3727, and [O III] λ5007 in 236 low-mass (7.5 ≲ log (M {sub *}/M {sub ☉}) ≲ 10.5) star-forming galaxies in the redshift range 1.90 < z < 2.35. By stacking the data by stellar mass, we show that the [Ne III]/[O II] ratios of the z ∼ 2 universe are marginally higher than those seen in a comparable set of local Sloan Digital Sky Survey galaxies, and that [Ne III]/[O III] is enhanced by ∼0.2 dex. We consider the possible explanations for this ∼4σ result, including higher oxygen depletion out of the gas phase, denser H II regions, higher production of {sup 22}Ne via Wolf-Rayet stars, and the existence of a larger population of X-ray obscured active galactic nuclei at z ∼ 2 compared to z ∼ 0. None of these simple scenarios, alone, are favored to explain the observed line ratios. We conclude by suggesting several avenues of future observations to further explore the mystery of enhanced [Ne III] emission.

  3. FLUORINE ABUNDANCES OF GALACTIC LOW-METALLICITY GIANTS

    SciTech Connect

    Li, H. N.; Zhao, G.; Ludwig, H.-G.; Caffau, E.; Christlieb, N. E-mail: gzhao@nao.cas.cn E-mail: ecaffau@lsw.uni-heidelberg.de

    2013-03-01

    With abundances and 2{sigma} upper limits of fluorine (F) in seven metal-poor field giants, nucleosynthesis of stellar F at low metallicity is discussed. The measurements are derived from the HF(1-0) R9 line at 23358 A using near-infrared K-band high-resolution spectra obtained with CRIRES at the Very Large Telescope. The sample reaches lower metallicities than previous studies on F of field giants, ranging from [Fe/H] = -1.56 down to -2.13. Effects of three-dimensional model atmospheres on the derived F and O abundances are quantitatively estimated and shown to be insignificant for the program stars. The observed F yield in the form of [F/O] is compared with two sets of Galactic chemical evolution models, which quantitatively demonstrate the contribution of Type II supernova (SN II) {nu}-process and asymptotic giant branch/Wolf-Rayet stars. It is found that at this low-metallicity region, models cannot well predict the observed distribution of [F/O], while the observations are better fit by models considering an SN II {nu}-process with a neutrino energy of E {sub {nu}} = 3 Multiplication-Sign 10{sup 53} erg. Our sample contains HD 110281, a retrograde orbiting low-{alpha} halo star, showing a similar F evolution as globular clusters. This supports the theory that such halo stars are possibly accreted from dwarf galaxy progenitors of globular clusters in the halo.

  4. High-resolution CCD spectra of stars in globular clusters. III - M4, M13, and M22

    NASA Technical Reports Server (NTRS)

    Wallerstein, George; Leep, E. Myckky; Oke, J. B.

    1987-01-01

    Spectra of 0.3 and 0.6 A resolution of stars in M4, M13 and M22 to derive abundances of various atomic species and the CN molecule. For M13, the usual Fe/H ratio and a surprisingly high aluminum abundance is found. The CN lines indicate a larger column density in the oxygen-rich star III-63 than in the oxygen-poor star II-67 by a factor of 10. It appears that II-67 is deficient in C, N, and O by about a factor 3 relative to iron for all three elements. For M4, Fe/H = -1.2 using solar f values derived via the Bell et al. (1976) model. This Fe abundance lies between earlier echelle values and photometric values. For two stars, CN data are obtained that can be understood if there was a slight excess of C/Fe and N/Fe prior to CN cycling and mixing. For M22, a large difference in CN is found between stars III-3 and IV-102. The origin of the CNO elements is discussed in terms of mass loss from an early generation of red giants and possibly Wolf-Rayet stars.

  5. Ovarian Cancer Stage II

    MedlinePlus

    ... Download Title: Ovarian Cancer Stage II Description: Three-panel drawing of stage IIA, IIB, and stage II primary peritoneal cancer; the first panel (stage IIA) shows cancer inside both ovaries that ...

  6. Factor II deficiency

    MedlinePlus

    ... if one or more of these factors are missing or are not functioning like they should. Factor II is one such coagulation factor. Factor II deficiency runs in families (inherited) and is very rare. Both parents must ...

  7. Workshop on Colliding Winds in Binary Stars to Honor Jorge Sahade

    NASA Astrophysics Data System (ADS)

    Niemela, Virpi; Morrell, Nidia; Pismis, Paris; Torres-Peimbert, Silvia

    1996-12-01

    Topics considered include: the beginning of the story; mass flow in and out of close binaries; winds of massive, main sequence close binaries; chromospheric activity, stellar winds and red stragglers; uv observations of mass transfer in algols; the circumstellar matter in pre-supernovae of type Ia; observations of colliding winds in O-type binaries; colliding winds in massive binaries involving Wolf-Rayet stars; episodic dust formation by Wolf-Rayet stars: smoke signals from colliding winds; x-ray emission from colliding wind binaries; colliding stellar winds: a new method of determining mass-loss rates via x-ray spectroscopy; sudden radiative braking in colliding hot-star winds; optical observations of colliding winds in gamma2 velorum; left overs for dinner; HD 5980: the Wolf-Rayet binary that became a luminous blue variable; the erupting Wolf-Rayet binary HD 5980 in the small magellanic cloud: spectral transition from B1.5Ia(+) to WN6 and the accompanying light curve; the elliptic orbit of the WR binary system CV serpentis; evidence for colliding winds in WR 146; is there wind-wind collision in WR 141 (HD 193928)?; search for interacting winds in the WN7 + O binary; line formation in CH Cyg: a symbiotic binary; period analysis of radial velocity of pleione; H(alpha) detection of colliding winds in O-type binaries; HD 5980 in the infrared; photometric and polarimetric observations of the Wolf-Rayet eclipsing binary HD 5980 in the small magellanic cloud, and analysis of linear polarization in two Wolf-Rayet binary systems.

  8. The emission-line regions in the nucleus of NGC 1313 probed with GMOS-IFU: a supergiant/hypergiant candidate and a kinematically cold nucleus

    NASA Astrophysics Data System (ADS)

    Menezes, R. B.; Steiner, J. E.

    2017-04-01

    NGC 1313 is a bulgeless nearby galaxy, classified as SB(s)d. Its proximity allows high spatial resolution observations. We performed the first detailed analysis of the emission-line properties in the nuclear region of NGC 1313, using an optical data cube obtained with the Gemini Multi-object Spectrograph. We detected four main emitting areas, three of them (regions 1, 2 and 3) having spectra typical of H II regions. Region 1 is located very close to the stellar nucleus and shows broad spectral features characteristic of Wolf-Rayet stars. Our analysis revealed the presence of one or two WC4-5 stars in this region, which is compatible with results obtained by previous studies. Region 4 shows spectral features (as a strong Hα emission line, with a broad component) typical of a massive emission-line star, such as a luminous blue variable, a B[e] supergiant or a B hypergiant. The radial velocity map of the ionized gas shows a pattern consistent with rotation. A significant drop in the values of the gas velocity dispersion was detected very close to region 1, which suggests that the young stars there were formed from this cold gas, possibly keeping low values of velocity dispersion. Therefore, although detailed measurements of the stellar kinematics were not possible (due to the weak stellar absorption spectrum of this galaxy), we predict that NGC 1313 may also show a drop in the values of the stellar velocity dispersion in its nuclear region.

  9. Far Ultraviolet Spectroscopic Explorer Measurements of Interstellar Fluorine

    NASA Astrophysics Data System (ADS)

    Federman, S. R.; Sheffer, Yaron; Lambert, David L.; Smith, V. V.

    2005-02-01

    The source of fluorine is not well understood, although core-collapse supernovae, Wolf-Rayet stars, and asymptotic giant branch stars have been suggested. A search for evidence of the ν-process during Type II supernovae is presented. Absorption from interstellar F I is seen in spectra of HD 208440 and HD 209339A acquired with the Far Ultraviolet Spectroscopic Explorer. In order to extract the column density for F I from the line at 954 Å, absorption from H2 has to be modeled and then removed. Our analysis indicates that for H2 column densities less than about 3×1020 cm-2, the amount of F I can be determined from λ954. For these two sight lines, there is no clear indication for enhanced F abundances resulting from the ν-process in a region shaped by past supernovae. Based on observations made with the NASA/CNES/CSA Far Ultraviolet Spectroscopic Explorer (FUSE), which is operated for NASA by the Johns Hopkins University under NASA contract NAS 5-32985.

  10. Probing a GRB Progenitor at a Redshift of z=2: A Comprehensive Observing Campaign of the Afterglow of GRB 030226l

    NASA Technical Reports Server (NTRS)

    Klose, S.; Greiner, J.; Rau, A.; Henden, A. A.; Hartmann, D. H.; Zeh, A.; Ries, C.; Masetti, N.; Malesani, D.; Guenther, E.

    2004-01-01

    We report results from a comprehensive optical/near-infrared follow-up observing campaign of the afterglow of GRB 030226, including VLT spectroscopy and polarimetry, supplemented by Chandra X-ray and BOOTES-1 rapid response observations. First observations at ESO started 0.2 days after the burst when the afterglow was at a magnitude of R approx. 19. The multi-color light curve of the afterglow, with a break around 1 day after the burst, is achromatic within the observational uncertainties even during episodes of short-term fluctuations. Close to the break time the degree of linear polarization of the afterglow light was less than 1.1%, consistent with low intrinsic polarization observed in other afterglows. VLT spectra show a foreground absorber of Mg II at a redshift z=1.042 and two absorption line systems at redshifts z=1.962+/-0.001 and at z=1.986+/-0.001, placing the lower limit for the redshift of the GRB close to 2. The kinematics and the composition of the absorbing clouds is very similar to those observed in the afterglow of GRB 021004, supporting the view that at least some GRBs are physically related to the explosion of a Wolf-Rayet star.

  11. Spitzer infrared spectrograph point source classification in the Small Magellanic Cloud

    NASA Astrophysics Data System (ADS)

    Ruffle, Paul M. E.; Kemper, F.; Jones, O. C.; Sloan, G. C.; Kraemer, K. E.; Woods, Paul M.; Boyer, M. L.; Srinivasan, S.; Antoniou, V.; Lagadec, E.; Matsuura, M.; McDonald, I.; Oliveira, J. M.; Sargent, B. A.; Sewiło, M.; Szczerba, R.; van Loon, J. Th.; Volk, K.; Zijlstra, A. A.

    2015-08-01

    The Magellanic Clouds are uniquely placed to study the stellar contribution to dust emission. Individual stars can be resolved in these systems even in the mid-infrared, and they are close enough to allow detection of infrared excess caused by dust. We have searched the Spitzer Space Telescope data archive for all Infrared Spectrograph (IRS) staring-mode observations of the Small Magellanic Cloud (SMC) and found that 209 Infrared Array Camera (IRAC) point sources within the footprint of the Surveying the Agents of Galaxy Evolution in the Small Magellanic Cloud (SAGE-SMC) Spitzer Legacy programme were targeted, within a total of 311 staring-mode observations. We classify these point sources using a decision tree method of object classification, based on infrared spectral features, continuum and spectral energy distribution shape, bolometric luminosity, cluster membership and variability information. We find 58 asymptotic giant branch (AGB) stars, 51 young stellar objects, 4 post-AGB objects, 22 red supergiants, 27 stars (of which 23 are dusty OB stars), 24 planetary nebulae (PNe), 10 Wolf-Rayet stars, 3 H II regions, 3 R Coronae Borealis stars, 1 Blue Supergiant and 6 other objects, including 2 foreground AGB stars. We use these classifications to evaluate the success of photometric classification methods reported in the literature.

  12. Failed Collapsar Jets to Explain Low Luminosity GRB Properties

    NASA Astrophysics Data System (ADS)

    Hamidani, Hamid; Umeda, Hideyuki; Takahashi, Koh

    Using the collapsar scenario for long GRBs [1], we present series of numerical simulations to investigate properties of expanding jets, driven by engines deploying the same total energy (1052 erg), differently. We include a wide range of engine durations (Tinj), from 0.1 to 100 s, as well as different initial opening angles (θ0) for the deployed energy. We employ an AMR 2D special relativistic hydrodynamical code, using a 25 solar mass Wolf-Rayet star as the progenitor [2]. We analyze the effect of the engine duration on the jet's hydrodynamic properties, and discuss the implications on GRB and SN emissions. Our results show that the expanding jet's hydrodynamical properties significantly differ, in particular outflow collimation and relativistic acceleration. The implication of this is that brief engines (with Tinj < Tbreakout, either due to a short Tinj or to a large θ0) represent excellent systems to explain the debated low-luminosity GRBs (llGRBs), displaying two of llGRBs peculiar features: i) the estimated llGRBs rate at least about 100 times higher than that of GRBs [3,4,5], and ii) potentially energetic SN emission [6]. We find that these two features only arise from brief engines. The conclusion is that brief engines dominate collapsars, at least at low redshift.

  13. International Ultraviolet Explorer (IUE) ultraviolet spectral atlas of selected astronomical objects

    NASA Technical Reports Server (NTRS)

    Wu, Chi-Chao; Reichert, Gail A.; Ake, Thomas B.; Boggess, Albert; Holm, Albert V.; Imhoff, Catherine L.; Kondo, Yoji; Mead, Jaylee M.; Shore, Steven N.

    1992-01-01

    The IUE Ultraviolet Spectral Atlas of Selected Astronomical Objects (or 'the Atlas'), is based on the data that were available in the IUE archive in 1986, and is intended to be a quick reference for the ultraviolet spectra of many categories of astronomical objects. It shows reflected sunlight from the Moon, planets, and asteroids, and also shows emission from comets. Comprehensive compilations of UV spectra for main sequence, subgiant, giant, bright giant, and supergiant stars are published elsewhere. This Atlas contains the spectra for objects occupying other areas of the Hertzsprung-Russell diagram: pre-main sequence stars, chemically peculiar stars, pulsating variables, subluminous stars, and Wolf-Rayet stars. This Atlas also presents phenomena such as the chromospheric and transition region emissions from late-type stars; composite spectra of stars, gas streams, accretion disks and gas envelopes of binary systems; the behavior of gas ejecta shortly after the outburst of novac and supernovac; and the H II regions, planetary nebulae, and supernova remnants. Population 2 stars, globular clusters, and luminous stars in the Magellanic Clouds, M31, and M33, are also included in this publication. Finally, the Atlas gives the ultraviolet spectra of galaxies of different Hubble types and of active galaxies.

  14. IGRINS on the DCT

    NASA Astrophysics Data System (ADS)

    Prato, Lisa A.

    2017-01-01

    Through an agreement with the University of Texas at Austin and the Korea Astronomy and Space Science Institute, the Immersion Grating Infrared Spectrograph (IGRINS) saw first light on the Lowell Observatory 4.3 m Discovery Channel Telescope (DCT) telescope on September 8, 2016. IGRINS, originally commissioned at the McDonald Observatory 2.7 m telescope, provides a spectral resolution of 45,000 and a simultaneous spectral grasp of 1.45 to 2.45 microns, recording all of the H and K bands with no gaps in wavelength coverage on two H2RG detectors in a single exposure. The instrument design minimizes optical surfaces, optimizing throughput, and has no moving parts, key for stability. IGRINS on the DCT attains a signal to noise of 100 per resolution element in one hour of integration time on a K=12 magnitude source, currently making it the most sensitive high-resolution spectrograph in the world at H and K. Science programs in the fourth quarter, 2016, include such diverse topics as abundance measurements in M dwarfs and population II stars, studies of ices and atmospheres in outer solar system bodies, measurement of fundamental properties of pre-main sequence stars, calibrating young star evolution, defining the substellar boundary at the youngest ages, outflow characteristics in Wolf-Rayet stars, finding the first generation of exoplanets, gas dynamics in planetary nebulae, and structure of the ISM in molecular clouds. In this talk I will report on initial results from selected programs.

  15. Optical observations of the fast declining Type Ib supernova iPTF13bvn

    NASA Astrophysics Data System (ADS)

    Srivastav, Shubham; Anupama, G. C.; Sahu, D. K.

    2014-12-01

    We present optical UBVRI photometry and medium resolution spectroscopy of the Type Ib supernova iPTF13bvn, spanning a phase of ˜-13 d to +71 d with respect to B-band maximum. The post-maximum decline rates indicate a fast decline with Δm15(B) = 1.82. Correcting for a Galactic extinction E(B - V)MW = 0.045 and host galaxy extinction of E(B - V)host = 0.17, the absolute V-band magnitude peaks at MV = -17.23 ± 0.20. The bolometric light curve indicates that ˜0.09 M⊙ of 56Ni was synthesized in the explosion. The earliest spectrum (-13 d) shows the presence of He I 5876 Å feature at a velocity of ˜15 000 km s-1, which falls rapidly by the time the SN approaches the epoch of B-band maximum. The photospheric velocity near maximum light, as indicated by the Fe II 5169 Å feature, is ˜9000 km s-1. The estimate for the 56Ni mass, together with the estimates for the ejected mass (Mej) and kinetic energy of the explosion (Ek) indicate that iPTF13bvn is a low-luminosity Type Ib supernova, with a lower than average ejected mass and kinetic energy. Our results suggest that the progenitor of iPTF13bvn is inconsistent with a single Wolf-Rayet star.

  16. Erratum: The 2.27 day period of WR-134 (HD 191765)

    NASA Technical Reports Server (NTRS)

    Mccandliss, Stephan R.; Bohannan, Bruce; Robert, Carmelle; Moffat, Anthony F. J.

    1994-01-01

    The original temporal analysis of a 12 night spectral timeseries of Wolf-Rayet (WR)-134 has been found to be flawed and a re-analysis shows that the line profile variations are indeed periodic. When combined with a 4 night timeseries taken 45 days earlier, a period near 2.27 d is found in periodograms of the He II lambda 5412 line centroid, rms line width, and line skew variations. When the emission line residuals are ordered as a function of phase, a sinuous feature appears to 'snake' about the line center with an amplitude of +/-500 km/s. This is approximately equal to 20 larger than the line centroid amplitude; the calculation of which is heavily weighted by static portions of the line profile. In addition to the 'snake,' emission residuals appear that move away from line center on unbound trajectories and are thought to result from the interaction of a periodic driver with the unstable flow of the radiation driven wind.

  17. Investigation of ultraviolet fluxes of normal and peculiar stars

    NASA Technical Reports Server (NTRS)

    Deutschman, W. A.; Schild, R. E.

    1974-01-01

    Data from Project Celescope, a program that photographed the ultraviolet sky, in order to study several problems in current astrophysics are analyzed. Two star clusters, the Pleiades and the Hyades, reveal differences between the two that we are unable to explain simply from their differences in chemical abundance, rotation, or reddening. Data for Orion show large scatter, which appears to be in the sense that the Orion stars are too faint for their ground-based photometry. Similarly, many supergiants in the association Sco OB1 are too faint in the ultraviolet, but the ultraviolet brightness appears to be only poorly correlated with spectral type. Ultraviolet Celescope data for several groups of peculiar stars have also been analyzed. The strong He I stars are too faint in the ultraviolet, possibly owing to enhancement of O II continuous opacity due to oxygen overabundance. The Be stars appear to have ultraviolet colors normal for their MK spectral types. The P Cygni stars are considerably fainter than main-sequence stars of comparable spectral type, probably owing, at least in part, to line blocking by resonance lines of multiply ionized light metals. The Wolf-Rayet stars have ultraviolet color temperatures of O stars.

  18. Erratum: The 2.27 day period of WR-134 (HD 191765)

    NASA Astrophysics Data System (ADS)

    McCandliss, Stephan R.; Bohannan, Bruce; Robert, Carmelle; Moffat, Anthony F. J.

    1994-11-01

    The original temporal analysis of a 12 night spectral timeseries of Wolf-Rayet (WR)-134 has been found to be flawed and a re-analysis shows that the line profile variations are indeed periodic. When combined with a 4 night timeseries taken 45 days earlier, a period near 2.27 d is found in periodograms of the He II lambda 5412 line centroid, rms line width, and line skew variations. When the emission line residuals are ordered as a function of phase, a sinuous feature appears to 'snake' about the line center with an amplitude of +/-500 km/s. This is approximately equal to 20 larger than the line centroid amplitude; the calculation of which is heavily weighted by static portions of the line profile. In addition to the 'snake,' emission residuals appear that move away from line center on unbound trajectories and are thought to result from the interaction of a periodic driver with the unstable flow of the radiation driven wind.

  19. IUE spectrophotometry of the hot helium-rich PG1159 DO degenerates

    NASA Astrophysics Data System (ADS)

    Sion, E. M.; Liebert, J.; Starrfield, S.; Wesemael, F.

    1984-12-01

    The PG1159 degenerates represent the hottest spectroscopic subgroup of DO stars. Their optical spectra are characterized by broad HeII (lambda 4686) absorption and several transitions of CIV, NIII and CIII. High resolution MMT scans reveal central emission reversals. The discovery of complex, non-radial pulsations in four members of the class underscores the need for accurate temperatures, gravities and abundances for these object. Low resolution IUE spectra of four PG1159 stars, PG1151-029, PG1424+535, PG1520+525 were obtained, as well as an additional image of PG1159-035 and an optical ultraviolet spectrum of PG2131+066. IUE (SWP) spectra suggest the presence of numerous metallic absorption features of CIV (lambda 1550), NV (lambda 1240) and a few unidentified features. The metal absorption lines and HEII (lambda 1640) have equivalent widths of a few angstroms. IUE/optical energy distributions are considered. Tentative identifications of CIV absorptions and possibly, weak OVI features in optical ultraviolet reticon spectra suggest a probable link to the subluminous Wolf-Rayet OV5 I planetary nuclei. The PG1159 DO degenerates are the hottest known (Te 100,000K), high gravity (log g 7 ) objects.

  20. FLUORINE IN THE SOLAR NEIGHBORHOOD: IS IT ALL PRODUCED IN ASYMPTOTIC GIANT BRANCH STARS?

    SciTech Connect

    Jönsson, H.; Ryde, N.; Harper, G. M.; Richter, M. J.; Hinkle, K. H.

    2014-07-10

    The origin of ''cosmic'' fluorine is uncertain, but there are three proposed production sites/mechanisms for the origin: asymptotic giant branch (AGB) stars, ν nucleosynthesis in Type II supernovae, and/or the winds of Wolf-Rayet stars. The relative importance of these production sites has not been established even for the solar neighborhood, leading to uncertainties in stellar evolution models of these stars as well as uncertainties in the chemical evolution models of stellar populations. We determine the fluorine and oxygen abundances in seven bright, nearby giants with well determined stellar parameters. We use the 2.3 μm vibrational-rotational HF line and explore a pure rotational HF line at 12.2 μm. The latter has never been used before for an abundance analysis. To be able to do this, we have calculated a line list for pure rotational HF lines. We find that the abundances derived from the two diagnostics agree. Our derived abundances are well reproduced by chemical evolution models including only fluorine production in AGB stars and, therefore, we draw the conclusion that this might be the main production site of fluorine in the solar neighborhood. Furthermore, we highlight the advantages of using the 12 μm HF lines to determine the possible contribution of the ν process to the fluorine budget at low metallicities where the difference between models including and excluding this process is dramatic.

  1. IPHAS and the symbiotic stars . II. New discoveries and a sample of the most common mimics

    NASA Astrophysics Data System (ADS)

    Corradi, R. L. M.; Valentini, M.; Munari, U.; Drew, J. E.; Rodríguez-Flores, E. R.; Viironen, K.; Greimel, R.; Santander-García, M.; Sabin, L.; Mampaso, A.; Parker, Q.; DePew, K.; Sale, S. E.; Unruh, Y. C.; Vink, J. S.; Rodríguez-Gil, P.; Barlow, M. J.; Lennon, D. J.; Groot, P. J.; Giammanco, C.; Zijlstra, A. A.; Walton, N. A.

    2010-01-01

    Context. Knowledge of the total population of symbiotic stars in the Galaxy is important for understanding basic aspects of stellar evolution in interacting binaries and the relevance of this class of objects in the formation of supernovae of type Ia. Aims: In a previous paper, we presented the selection criteria needed to search for symbiotic stars in IPHAS, the INT Hα survey of the Northern Galactic plane. IPHAS gives us the opportunity to make a systematic, complete search for symbiotic stars in a magnitude-limited volume. Methods: Follow-up spectroscopy at different telescopes worldwide of a sample of sixty two symbiotic star candidates is presented. Results: Seven out of nineteen S-type candidates observed spectroscopically are confirmed to be genuine symbiotic stars. The spectral type of their red giant components, as well as reddening and distance, were computed by modelling the spectra. Only one new D-type symbiotic system, out of forty-three candidates observed, was found. This was as expected (see discussion in our paper on the selection criteria). The object shows evidence for a high density outflow expanding at a speed ≥65 km s-1. Most of the other candidates are lightly reddened classical T Tauri stars and more highly reddened young stellar objects that may be either more massive young stars of HAeBe type or classical Be stars. In addition, a few notable objects have been found, such as three new Wolf-Rayet stars and two relatively high-luminosity evolved massive stars. We also found a helium-rich source, possibly a dense ejecta hiding a WR star, which is surrounded by a large ionized nebula. Conclusions: These spectroscopic data allow us to refine the selection criteria for symbiotic stars in the IPHAS survey and, more generally, to better understand the behaviour of different Hα emitters in the IPHAS and 2MASS colour-colour diagrams. Based on observations obtained at; the 2.6 m Nordic Optical Telescope operated by NOTSA; the 2.5 m INT and 4.2 m

  2. World War II Homefront.

    ERIC Educational Resources Information Center

    Garcia, Rachel

    2002-01-01

    Presents an annotated bibliography that provides Web sites focusing on the U.S. homefront during World War II. Covers various topics such as the homefront, Japanese Americans, women during World War II, posters, and African Americans. Includes lesson plan sources and a list of additional resources. (CMK)

  3. FIRE II Cirrus Info

    Atmospheric Science Data Center

    2014-03-18

    ... Page:  FIRE II Main Grouping:  Cirrus Description:  First ISCCP Regional Experiment (FIRE) ... stratocumulus systems, the radiative properties of these clouds and their interactions. Data Products:  Cirrus ...

  4. START II and beyond

    SciTech Connect

    Mendelsohn, J.

    1996-10-01

    The second Strategic Arms Reduction Treaty (START II), signed by President George Bush and Russian President Boris yeltsin in January 1993, was ratified by the US Senate in January 1996 by and overwhelming vote of 87-4. The treaty, which will slash the strategic arsenals of the United States and Russia to 3,000-3,500 warheads each, is now before the two houses of the Russian Parliament (the Duma and the Federation Council) awaiting ratification amidst confusion and criticism. The Yeltsin administration supports START II and spoke in favor of Russian ratification after the Senate acted on the treaty. The Russian foreign minister and the Russian military believed that START II should be ratified as soon as possible. During the recent presidential campaign and his subsequent illness, President Yeltsin has been virtually silent on the subject of START II and nuclear force reductions. Without a push from the Yeltsin administration, the tone among Duma members, has been sharply critical of START II. Voices across the Russian political spectrum have questioned the treaty and linked it to constraints on highly capable theater missile defense (TMD) systems and the continued viability of the ABM Treaty. And urged that START II ratification be held hostage until NATO abandons its plans to expand eastward. Although the START I and START II accords have generated the momentum, opportunity and expectation-both domestic and international-for additional nuclear arms reductions, the current impasse over ratification in the Duma has cast a shadow over the future of START II and raised questions about the chances for any follow-on (START III) agreement.

  5. Mod II engine development

    NASA Technical Reports Server (NTRS)

    Karl, David W.

    1987-01-01

    The Mod II engine, a four-cylinder, automotive Stirling engine utilizing the Siemens-Rinia double-acting concept, was assembled and became operational in January 1986. This paper describes the Mod II engine, its first assembly, and the subsequent development work done on engine components up to the point that engine performance characterization testing took place. Performance data for the engine are included.

  6. 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.

  7. Carnitine palmitoyltransferase II deficiency

    PubMed Central

    Roe, C R.; Yang, B-Z; Brunengraber, H; Roe, D S.; Wallace, M; Garritson, B K.

    2008-01-01

    Background: Carnitine palmitoyltransferase II (CPT II) deficiency is an important cause of recurrent rhabdomyolysis in children and adults. Current treatment includes dietary fat restriction, with increased carbohydrate intake and exercise restriction to avoid muscle pain and rhabdomyolysis. Methods: CPT II enzyme assay, DNA mutation analysis, quantitative analysis of acylcarnitines in blood and cultured fibroblasts, urinary organic acids, the standardized 36-item Short-Form Health Status survey (SF-36) version 2, and bioelectric impedance for body fat composition. Diet treatment with triheptanoin at 30% to 35% of total daily caloric intake was used for all patients. Results: Seven patients with CPT II deficiency were studied from 7 to 61 months on the triheptanoin (anaplerotic) diet. Five had previous episodes of rhabdomyolysis requiring hospitalizations and muscle pain on exertion prior to the diet (two younger patients had not had rhabdomyolysis). While on the diet, only two patients experienced mild muscle pain with exercise. During short periods of noncompliance, two patients experienced rhabdomyolysis with exercise. None experienced rhabdomyolysis or hospitalizations while on the diet. All patients returned to normal physical activities including strenuous sports. Exercise restriction was eliminated. Previously abnormal SF-36 physical composite scores returned to normal levels that persisted for the duration of the therapy in all five symptomatic patients. Conclusions: The triheptanoin diet seems to be an effective therapy for adult-onset carnitine palmitoyltransferase II deficiency. GLOSSARY ALT = alanine aminotransferase; AST = aspartate aminotransferase; ATP = adenosine triphosphate; BHP = β-hydroxypentanoate; BKP = β-ketopentanoate; BKP-CoA = β-ketopentanoyl–coenzyme A; BUN = blood urea nitrogen; CAC = citric acid cycle; CoA = coenzyme A; CPK = creatine phosphokinase; CPT II = carnitine palmitoyltransferase II; LDL = low-density lipoprotein; MCT

  8. RESOLVING IONIZATION AND METALLICITY ON PARSEC SCALES ACROSS MRK 71 WITH HST-WFC3

    SciTech Connect

    James, Bethan L.; Auger, Matthew; Aloisi, Alessandra; Calzetti, Daniela; Kewley, Lisa

    2016-01-01

    Blue compact dwarf (BCD) galaxies in the nearby universe provide a means for studying feedback mechanisms and star formation processes in low-metallicity environments in great detail. Owing to their vicinity, these local analogs to primordial young galaxies are well suited for high-resolution studies that are unfeasible for high-redshift galaxies. Here we present Hubble Space Telescope Wide Field Camera 3 observations of one such BCD, Mrk 71, one of the most powerful local starbursts known, in the light of [O ii], He ii, Hβ, [O iii], Hα, and [S ii]. At D ≃ 3.44 Mpc, this extensive suite of emission-line images enables us to explore the chemical and physical conditions of Mrk 71 on ∼2 pc scales. We use emission-line diagnostics to distinguish ionization mechanisms on a pixel-by-pixel basis and show that despite the previously reported hypersonic gas and superbubble blowout, the gas in Mrk 71 is photoionized, with no sign of shock-excited emission. He ii emission line images are used to identify up to six Wolf-Rayet stars, three of which lie on the edge of a blowout region. Using strong-line metallicity diagnostics, we present the first “metallicity image” of a galaxy, revealing chemical inhomogeneity on scales of <50 pc. We additionally demonstrate that while chemical structure can be lost at large scales, metallicity diagnostics can break down on spatial scales smaller than an H ii region. This study highlights not only the benefits of high-resolution spatially resolved observations in assessing the effects of feedback mechanisms but also the potential limitations when employing emission-line diagnostics; these results are particularly relevant as we enter the era of extremely large telescopes.

  9. Radiative properties of pair-instability supernova explosions

    NASA Astrophysics Data System (ADS)

    Dessart, Luc; Waldman, Roni; Livne, Eli; Hillier, D. John; Blondin, Stéphane

    2013-02-01

    We present non-local thermodynamic equilibrium time-dependent radiative transfer simulations of pair-instability supernovae (PISNe) stemming from red-supergiant (RSG), blue-supergiant and Wolf-Rayet star rotation-free progenitors born in the mass range 160-230 M⊙, at 10-4 Z⊙. Although subject to uncertainties in convection and stellar mass-loss rates, our initial conditions come from physically-consistent models that treat evolution from the main sequence, the onset of the pair-production instability, and the explosion phase. With our set of input models characterized by large 56Ni and ejecta masses, and large kinetic energies, we recover qualitatively the Type II-Plateau, II-peculiar and Ib/c light-curve morphologies, although they have larger peak bolometric luminosities (˜109 to 1010 L⊙) and a longer duration (˜200 d). We discuss the spectral properties for each model during the photospheric and nebular phases, including Balmer lines in II-P and II-pec at early times, the dominance of lines from intermediate-mass elements near the bolometric maximum, and the strengthening of metal line blanketing thereafter. Having similar He-core properties, all models exhibit similar post-peak spectra that are strongly blanketed by Fe ii and Fe i lines, characterized by red colours, and that arise from photospheres/ejecta with a temperature of ≲4000 K. Combined with the modest linewidths after the bolometric peak, these properties contrast with those of known superluminous SNe, suggesting that PISNe are yet to be discovered. Being reddish, PISNe will be difficult to observe at high redshift except when they stem from RSG explosions, in which case they could be used as metallicity probes and distance indicators.

  10. Resolving Ionization and Metallicity on Parsec Scales across Mrk 71 with HST-WFC3

    NASA Astrophysics Data System (ADS)

    James, Bethan L.; Auger, Matthew; Aloisi, Alessandra; Calzetti, Daniela; Kewley, Lisa

    2016-01-01

    Blue compact dwarf (BCD) galaxies in the nearby universe provide a means for studying feedback mechanisms and star formation processes in low-metallicity environments in great detail. Owing to their vicinity, these local analogs to primordial young galaxies are well suited for high-resolution studies that are unfeasible for high-redshift galaxies. Here we present Hubble Space Telescope Wide Field Camera 3 observations of one such BCD, Mrk 71, one of the most powerful local starbursts known, in the light of [O ii], He ii, Hβ, [O iii], Hα, and [S ii]. At D ≃ 3.44 Mpc, this extensive suite of emission-line images enables us to explore the chemical and physical conditions of Mrk 71 on ∼2 pc scales. We use emission-line diagnostics to distinguish ionization mechanisms on a pixel-by-pixel basis and show that despite the previously reported hypersonic gas and superbubble blowout, the gas in Mrk 71 is photoionized, with no sign of shock-excited emission. He ii emission line images are used to identify up to six Wolf-Rayet stars, three of which lie on the edge of a blowout region. Using strong-line metallicity diagnostics, we present the first “metallicity image” of a galaxy, revealing chemical inhomogeneity on scales of <50 pc. We additionally demonstrate that while chemical structure can be lost at large scales, metallicity diagnostics can break down on spatial scales smaller than an H ii region. This study highlights not only the benefits of high-resolution spatially resolved observations in assessing the effects of feedback mechanisms but also the potential limitations when employing emission-line diagnostics; these results are particularly relevant as we enter the era of extremely large telescopes.

  11. About APPLE II Operation

    SciTech Connect

    Schmidt, T.; Zimoch, D.

    2007-01-19

    The operation of an APPLE II based undulator beamline with all its polarization states (linear horizontal and vertical, circular and elliptical, and continous variation of the linear vector) requires an effective description allowing an automated calculation of gap and shift parameter as function of energy and operation mode. The extension of the linear polarization range from 0 to 180 deg. requires 4 shiftable magnet arrrays, permitting use of the APU (adjustable phase undulator) concept. Studies for a pure fixed gap APPLE II for the SLS revealed surprising symmetries between circular and linear polarization modes allowing for simplified operation. A semi-analytical model covering all types of APPLE II and its implementation will be presented.

  12. Mod II engine performance

    NASA Technical Reports Server (NTRS)

    Richey, Albert E.; Huang, Shyan-Cherng

    1987-01-01

    The testing of a prototype of an automotive Stirling engine, the Mod II, is discussed. The Mod II is a one-piece cast block with a V-4 single-crankshaft configuration and an annular regenerator/cooler design. The initial testing of Mod II concentrated on the basic engine, with auxiliaries driven by power sources external to the engine. The performance of the engine was tested at 720 C set temperature and 820 C tube temperature. At 720 C, it is observed that the power deficiency is speed dependent and linear, with a weak pressure dependency, and at 820 C, the power deficiency is speed and pressure dependent. The effects of buoyancy and nozzle spray pattern on the heater temperature spread are investigated. The characterization of the oil pump and the operating cycle and temperature spread tests are proposed for further evaluation of the engine.

  13. SAGE II Ozone Analysis

    NASA Technical Reports Server (NTRS)

    Cunnold, Derek; Wang, Ray

    2002-01-01

    Publications from 1999-2002 describing research funded by the SAGE II contract to Dr. Cunnold and Dr. Wang are listed below. Our most recent accomplishments include a detailed analysis of the quality of SAGE II, v6.1, ozone measurements below 20 km altitude (Wang et al., 2002 and Kar et al., 2002) and an analysis of the consistency between SAGE upper stratospheric ozone trends and model predictions with emphasis on hemispheric asymmetry (Li et al., 2001). Abstracts of the 11 papers are attached.

  14. THE ORIGIN AND OPTICAL DEPTH OF IONIZING RADIATION IN THE 'GREEN PEA' GALAXIES

    SciTech Connect

    Jaskot, A. E.; Oey, M. S.

    2013-04-01

    Although Lyman-continuum (LyC) radiation from star-forming galaxies likely drove the reionization of the universe, observations of star-forming galaxies at low redshift generally indicate low LyC escape fractions. However, the extreme [O III]/[O II] ratios of the z = 0.1-0.3 Green Pea galaxies may be due to high escape fractions of ionizing radiation. To analyze the LyC optical depths and ionizing sources of these rare, compact starbursts, we compare nebular photoionization and stellar population models with observed emission lines in the Peas' Sloan Digital Sky Survey (SDSS) spectra. We focus on the six most extreme Green Peas, the galaxies with the highest [O III]/[O II] ratios and the best candidates for escaping ionizing radiation. The Balmer line equivalent widths and He I {lambda}3819 emission in the extreme Peas support young ages of 3-5 Myr, and He II {lambda}4686 emission in five extreme Peas signals the presence of hard ionizing sources. Ionization by active galactic nuclei or high-mass X-ray binaries is inconsistent with the Peas' line ratios and ages. Although stacked spectra reveal no Wolf-Rayet (WR) features, we tentatively detect WR features in the SDSS spectra of three extreme Peas. Based on the Peas' ages and line ratios, we find that WR stars, chemically homogeneous O stars, or shocks could produce the observed He II emission. If hot stars are responsible, then the Peas' optical depths are ambiguous. However, accounting for emission from shocks lowers the inferred optical depth and suggests that the Peas may be optically thin. The Peas' ages likely optimize the escape of LyC radiation; they are old enough for supernovae and stellar winds to reshape the interstellar medium, but young enough to possess large numbers of UV-luminous O or WR stars.

  15. Spectropolarimetry of the Type Ib Supernova iPTF 13bvn: revealing the complex explosion geometry of a stripped-envelope core-collapse supernova

    NASA Astrophysics Data System (ADS)

    Reilly, Emma; Maund, Justyn R.; Baade, Dietrich; Wheeler, J. Craig; Silverman, Jeffrey M.; Clocchiatti, Alejandro; Patat, Ferdinando; Höflich, Peter; Spyromilio, Jason; Wang, Lifan; Zelaya, Paula

    2016-03-01

    We present six epochs of spectropolarimetric observations and one epoch of spectroscopy of the Type Ib SN iPTF 13bvn. The epochs of these observations correspond to -10 to +61 d with respect to the r-band light-curve maximum. The continuum is intrinsically polarized to the 0.2-0.4 per cent level throughout the observations, implying asphericities of ˜10 per cent in the shape of the photosphere. We observe significant line polarization associated with the spectral features of Ca II IR3, He I/Na I D, He I λλ6678, 7065, Fe II λ4924 and O I λ7774. We propose that an absorption feature at ˜6200 Å, usually identified as Si II λ6355, is most likely to be high-velocity H α at -16 400 km s-1. Two distinctly polarized components, separated in velocity, are detected for both He I/Na I D and Ca II IR3 , indicating the presence of two discrete line-forming regions in the ejecta in both radial velocity space and in the plane of the sky. We use the polarization of He I λ5876 as a tracer of sources of non-thermal excitation in the ejecta; finding that the bulk of the radioactive nickel was constrained to lie interior to ˜50-65 per cent of the ejecta radius. The observed polarization is also discussed in the context of the possible progenitor system of iPTF 13bvn, with our observations favouring the explosion of a star with an extended, distorted envelope rather than a compact Wolf-Rayet star.

  16. THE MAGELLAN/IMACS CATALOG OF OPTICAL SUPERNOVA REMNANT CANDIDATES IN M83

    SciTech Connect

    Blair, William P.; Winkler, P. Frank; Long, Knox S. E-mail: winkler@middlebury.edu

    2012-11-15

    We present a new optical imaging survey of supernova remnants (SNRs) in M83, using data obtained with the Magellan I 6.5 m telescope and IMACS instrument under conditions of excellent seeing. Using the criterion of strong [S II] emission relative to H{alpha}, we confirm all but three of the 71 SNR candidates listed in our previous survey, and expand the SNR candidate list to 225 objects, more than tripling the earlier sample. Comparing the optical survey with a new deep X-ray survey of M83 with Chandra, we find that 61 of these SNR candidates have X-ray counterparts. We also identify an additional list of 46 [O III]-selected nebulae for follow-up as potential ejecta-dominated remnants, seven of which have associated X-ray emission that makes them strong candidates. Some of the other [O III]-bright objects could also be normal interstellar medium (ISM) dominated SNRs with shocks fast enough to doubly ionize oxygen, but with H{alpha} and [S II] emission faint enough to have been missed. A few of these objects may also be H II regions with abnormally high [O III] emission compared with the majority of M83 H II regions, compact nebulae excited by young Wolf-Rayet stars, or even background active galactic nuclei. The SNR H{alpha} luminosity function in M83 is shifted by a factor of {approx}4.5 times higher than for M33 SNRs, indicative of a higher mean ISM density in M83. We describe the search technique used to identify the SNR candidates and provide basic information and finder charts for the objects.

  17. Instant Insanity II

    ERIC Educational Resources Information Center

    Richmond, Tom; Young, Aaron

    2013-01-01

    "Instant Insanity II" is a sliding mechanical puzzle whose solution requires the special alignment of 16 colored tiles. We count the number of solutions of the puzzle's classic challenge and show that the more difficult ultimate challenge has, up to row permutation, exactly two solutions, and further show that no…

  18. Dissecting Diversity Part II

    ERIC Educational Resources Information Center

    Matthews, Frank

    2005-01-01

    This article presents "Dissecting Diversity, Part II," the conclusion of a wide-ranging two-part roundtable discussion on diversity in higher education. The participants were as follows: Lezli Baskerville, J.D., President and CEO of the National Association for Equal Opportunity (NAFEO); Dr. Gerald E. Gipp, Executive Director of the…

  19. Listen & Learn II.

    ERIC Educational Resources Information Center

    Community Building Resources, Spruce Grove (Alberta).

    Six community builders in Edmonton, Alberta, planned, developed, and implemented Listen and Learn II, a reflective research project in asset-based community building, over a 6-month period in 1998. They met regularly over 2 months to plan the research and design a method that was open to participation at any stage, encouraged exchange of…

  20. A la Mode II.

    ERIC Educational Resources Information Center

    Stowe, Richard A.

    This paper describes two modes of educational decision-making: Mode I, in which the instructor makes such decisions as what to teach, to whom, when, in what order, at what pace, and at what complexity level; and Mode II, in which the learner makes the decisions. While Mode I comprises most of what is regarded as formal education, the learner in…

  1. Periodontics II: Course Proposal.

    ERIC Educational Resources Information Center

    Dordick, Bruce

    A proposal is presented for Periodontics II, a course offered at the Community College of Philadelphia to give the dental hygiene/assisting student an understanding of the disease states of the periodontium and their treatment. A standardized course proposal cover form is given, followed by a statement of purpose for the course, a list of major…

  2. Class II Microcins

    NASA Astrophysics Data System (ADS)

    Vassiliadis, Gaëlle; Destoumieux-Garzón, Delphine; Peduzzi, Jean

    Class II microcins are 4.9- to 8.9-kDa polypeptides produced by and active against enterobacteria. They are classified into two subfamilies according to their structure and their gene cluster arrangement. While class IIa microcins undergo no posttranslational modification, class IIb microcins show a conserved C-terminal sequence that carries a salmochelin-like siderophore motif as a posttranslational modification. Aside from this C-terminal end, which is the signature of class IIb microcins, some sequence similarities can be observed within and between class II subclasses, suggesting the existence of common ancestors. Their mechanisms of action are still under investigation, but several class II microcins use inner membrane proteins as cellular targets, and some of them are membrane-active. Like group B colicins, many, if not all, class II microcins are TonB- and energy-dependent and use catecholate siderophore receptors for recognition/­translocation across the outer membrane. In that context, class IIb microcins are considered to have developed molecular mimicry to increase their affinity for their outer membrane receptors through their salmochelin-like posttranslational modification.

  3. Inhibitory role of peroxiredoxin II (Prx II) on cellular senescence.

    PubMed

    Han, Ying-Hao; Kim, Hyun-Sun; Kim, Jin-Man; Kim, Sang-Keun; Yu, Dae-Yeul; Moon, Eun-Yi

    2005-08-29

    Reactive oxygen species (ROS) were generated in all oxygen-utilizing organisms. Peroxiredoxin II (Prx II) as one of antioxidant enzymes may play a protective role against the oxidative damage caused by ROS. In order to define the role of Prx II in organismal aging, we evaluated cellular senescence in Prx II(-/-) mouse embryonic fibroblast (MEF). As compared to wild type MEF, cellular senescence was accelerated in Prx II(-/-) MEF. Senescence-associated (SA)-beta-galactosidase (Gal)-positive cell formation was about 30% higher in Prx II(-/-) MEF. N-Acetyl-l-cysteine (NAC) treatment attenuated SA-beta-Gal-positive cell formation. Prx II(-/-) MEF exhibited the higher G2/M (41%) and lower S (1.6%) phase cells as compared to 24% and 7.3% [corrected] in wild type MEF, respectively. A high increase in the p16 and a slight increase in the p21 and p53 levels were detected in PrxII(-/-) MEF cells. The cellular senescence of Prx II(-/-) MEF was correlated with the organismal aging of Prx II(-/-) mouse skin. While extracellular signal-regulated kinase (ERK) and p38 activation was detected in Prx II(-/-) MEF, ERK and c-Jun N-terminal kinase (JNK) activation was detected in Prx II(-/-) skin. These results suggest that Prx II may function as an enzymatic antioxidant to prevent cellular senescence and skin aging.

  4. Role of Bound Zn(II) in the CadC Cd(II)/Pb(II)/Zn(II)-Responsive Repressor

    SciTech Connect

    Kandegedara, A.; Thiyagarajan, S; Kondapalli, K; Stemmler, T; Rosen, B

    2009-01-01

    The Staphylococcus aureus plasmid pI258 cadCA operon encodes a P-type ATPase, CadA, that confers resistance to Cd(II)/Pb(II)/Zn(II). Expression is regulated by CadC, a homodimeric repressor that dissociates from the cad operator/promoter upon binding of Cd(II), Pb(II), or Zn(II). CadC is a member of the ArsR/SmtB family of metalloregulatory proteins. The crystal structure of CadC shows two types of metal binding sites, termed Site 1 and Site 2, and the homodimer has two of each. Site 1 is the physiological inducer binding site. The two Site 2 metal binding sites are formed at the dimerization interface. Site 2 is not regulatory in CadC but is regulatory in the homologue SmtB. Here the role of each site was investigated by mutagenesis. Both sites bind either Cd(II) or Zn(II). However, Site 1 has higher affinity for Cd(II) over Zn(II), and Site 2 prefers Zn(II) over Cd(II). Site 2 is not required for either derepression or dimerization. The crystal structure of the wild type with bound Zn(II) and of a mutant lacking Site 2 was compared with the SmtB structure with and without bound Zn(II). We propose that an arginine residue allows for Zn(II) regulation in SmtB and, conversely, a glycine results in a lack of regulation by Zn(II) in CadC. We propose that a glycine residue was ancestral whether the repressor binds Zn(II) at a Site 2 like CadC or has no Site 2 like the paralogous ArsR and implies that acquisition of regulatory ability in SmtB was a more recent evolutionary event.

  5. Massive stars exploding in a He-rich circumstellar medium - VIII. PSN J07285387+3349106, a highly reddened supernova Ibn

    NASA Astrophysics Data System (ADS)

    Pastorello, A.; Tartaglia, L.; Elias-Rosa, N.; Morales-Garoffolo, A.; Terreran, G.; Taubenberger, S.; Noebauer, U. M.; Benetti, S.; Cappellaro, E.; Ciabattari, F.; Dennefeld, M.; Dimai, A.; Ishida, E. E. O.; Harutyunyan, A.; Leonini, S.; Ochner, P.; Sollerman, J.; Taddia, F.; Zaggia, S.

    2015-12-01

    We present spectroscopic and photometric observations for the Type Ibn supernova (SN) dubbed PSN J07285387+3349106. Using data provided by amateur astronomers, we monitored the photometric rise of the SN to maximum light, occurred on 2015 February 18.8 UT (JDmax(V) = 245 7072.0 ± 0.8). PSN J07285387+3349106 exploded in the inner region of an infrared luminous galaxy, and is the most reddened SN Ibn discovered so far. We apply multiple methods to derive the total reddening to the SN, and determine a total colour excess E(B - V)tot = 0.99 ± 0.48 mag. Accounting for the reddening correction, which is affected by a large uncertainty, we estimate a peak absolute magnitude of MV = -20.30 ± 1.50. The spectra are dominated by continuum emission at early phases, and He I lines with narrow P-Cygni profiles are detected. We also identify weak Fe III and N II features. All these lines show an absorption component which is blueshifted by about 900-1000 km s-1. The spectra also show relatively broad He I line wings with low contrast, which extend to above 3000 km s-1. From about two weeks past maximum, broad lines of O I, Mg II and the Ca II near-infrared triplet are identified. The composition and the expansion velocity of the circumstellar material, and the presence of He I and α-elements in the SN ejecta indicate that PSN J07285387+3349106 was produced by the core collapse of a stripped-envelope star. We suggest that the precursor was WNE-type Wolf-Rayet star in its dense, He-rich circumstellar cocoon.

  6. EXTENDED NARROW-LINE EMISSION IN THE BRIGHT SEYFERT 1.5 GALAXY HE 2211-3903

    SciTech Connect

    Scharwaechter, J.; Dopita, M. A.; Zuther, J.; Fischer, S.; Eckart, A.; Komossa, S.

    2011-08-15

    Extended narrow-line regions (ENLRs) and extended emission-line regions have been the focus of integral field spectroscopy aiming at the inner kiloparsecs of nearby Seyfert galaxies as well as the larger environment of high-redshift QSOs. Based on observations with the Wide Field Spectrograph at the 2.3 m telescope of the Australian National University, we present spatially resolved emission-line diagnostics of the bright Seyfert 1.5 galaxy HE 2211-3903 which is drawn from a sample of the brightest Seyfert galaxies at z < 0.06 with luminosities around the classical Seyfert/QSO demarcation. In addition to the previously known spiral arms of HE 2211-3903, the emission-line maps reveal a large-scale ring with a radius of about 6 kpc which is connected to the active galactic nucleus (AGN) through a bar-like structure. The overall gas kinematics indicates a disk rotation pattern. The emission-line ratios show Seyfert-type, H II region-type, and composite classifications, while there is no strong evidence of LINER-type ratios. Shock ionization is likely to be negligible throughout the galaxy. The composite line ratios are explained via a mixing line between AGN and H II region photoionization. Composite line ratios are predominantly found in between the H II regions in the circum-nuclear region, the bar-like structure to the east of the nucleus, and the eastern half of the ring, suggesting AGN photoionization of the low-density interstellar medium in an ENLR on galaxy scales. The line ratios in the nucleus indicate N enrichment, which is discussed in terms of chemical enrichment by Wolf-Rayet and asymptotic giant branch stars during past and ongoing nuclear starburst activity.

  7. 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.

  8. The Detection Rate of Early UV Emission from Supernovae: A Dedicated Galex/PTF Survey and Calibrated Theoretical Estimates

    NASA Astrophysics Data System (ADS)

    Ganot, Noam; Gal-Yam, Avishay; Ofek, Eran. O.; Sagiv, Ilan; Waxman, Eli; Lapid, Ofer; Kulkarni, Shrinivas R.; Ben-Ami, Sagi; Kasliwal, Mansi M.; The ULTRASAT Science Team; Chelouche, Doron; Rafter, Stephen; Behar, Ehud; Laor, Ari; Poznanski, Dovi; Nakar, Ehud; Maoz, Dan; Trakhtenbrot, Benny; WTTH Consortium, The; Neill, James D.; Barlow, Thomas A.; Martin, Christofer D.; Gezari, Suvi; the GALEX Science Team; Arcavi, Iair; Bloom, Joshua S.; Nugent, Peter E.; Sullivan, Mark; Palomar Transient Factory, The

    2016-03-01

    The radius and surface composition of an exploding massive star, as well as the explosion energy per unit mass, can be measured using early UV observations of core-collapse supernovae (SNe). We present the first results from a simultaneous GALEX/PTF search for early ultraviolet (UV) emission from SNe. Six SNe II and one Type II superluminous SN (SLSN-II) are clearly detected in the GALEX near-UV (NUV) data. We compare our detection rate with theoretical estimates based on early, shock-cooling UV light curves calculated from models that fit existing Swift and GALEX observations well, combined with volumetric SN rates. We find that our observations are in good agreement with calculated rates assuming that red supergiants (RSGs) explode with fiducial radii of 500 R ⊙, explosion energies of 1051 erg, and ejecta masses of 10 M ⊙. Exploding blue supergiants and Wolf-Rayet stars are poorly constrained. We describe how such observations can be used to derive the progenitor radius, surface composition, and explosion energy per unit mass of such SN events, and we demonstrate why UV observations are critical for such measurements. We use the fiducial RSG parameters to estimate the detection rate of SNe during the shock-cooling phase (<1 day after explosion) for several ground-based surveys (PTF, ZTF, and LSST). We show that the proposed wide-field UV explorer ULTRASAT mission is expected to find >85 SNe per year (˜0.5 SN per deg2), independent of host galaxy extinction, down to an NUV detection limit of 21.5 mag AB. Our pilot GALEX/PTF project thus convincingly demonstrates that a dedicated, systematic SN survey at the NUV band is a compelling method to study how massive stars end their life.

  9. Multiple endocrine neoplasia (MEN) II

    MedlinePlus

    Sipple syndrome; MEN II; Pheochromocytoma - MEN II; Thyroid cancer - pheochromocytoma; Parathyroid cancer - pheochromocytoma ... often not cancerous (benign). Medullary carcinoma of the thyroid is ... fatal cancer, but early diagnosis and surgery can often lead ...

  10. FIRE II - Cirrus Data Sets

    Atmospheric Science Data Center

    2013-07-26

    FIRE II - Cirrus Data Sets First ISCCP Regional Experiment (FIRE) II Cirrus was conducted in southeastern Kansas. It was designed to improve the ... stratocumulus systems, the radiative properties of these clouds and their interactions. Relevant Documents:  FIRE ...

  11. RADTRAN II user guide

    SciTech Connect

    Madsen, M M; Wilmot, E L; Taylor, J M

    1983-02-01

    RADTRAN II is a flexible analytical tool for calculating both the incident-free and accident impacts of transporting radioactive materials. The consequences from incident-free shipments are apportioned among eight population subgroups and can be calculated for several transport modes. The radiological accident risk (probability times consequence summed over all postulated accidents) is calculated in terms of early fatalities, early morbidities, latent cancer fatalities, genetic effects, and economic impacts. Groundshine, inhalation, direct exposure, resuspension, and cloudshine dose pathways are modeled to calculate the radiological health risks from accidents. Economic impacts are evaluated based on costs for emergency response, cleanup, evacuation, income loss, and land use. RADTRAN II can be applied to specific scenario evaluations (individual transport modes or specified combinations), to compare alternative modes or to evaluate generic radioactive material shipments. Unit-risk factors can easily be evaluated to aid in performing generic analyses when several options must be compared with the amount of travel as the only variable.

  12. Results from SAGE II

    SciTech Connect

    Nico, J.S.

    1994-10-01

    The Russian-American Gallium solar neutrino Experiment (SAGE) began the second phase of operation (SAGE II) in September of 1992. Monthly measurements of the integral flux of solar neutrinos have been made with 55 tonnes of gallium. The K-peak results of the first nine runs of SAGE II give a capture rate of 66{sub -13}{sup +18} (stat) {sub -7}{sup +5} (sys) SNU. Combined with the SAGE I result of 73{sub -16}{sup +18} (stat) {sub -7}{sup 5} (sys) SNU, the capture rate is 69{sub -11}{sup +11} (stat) {sub -7}{sup +5} (sys) SNU. This represents only 52%--56% of the capture rate predicted by different Standard Solar Models.

  13. Ribosomal Database Project II

    DOE Data Explorer

    The Ribosomal Database Project (RDP) provides ribosome related data and services to the scientific community, including online data analysis and aligned and annotated Bacterial small-subunit 16S rRNA sequences. As of March 2008, RDP Release 10 is available and currently (August 2009) contains 1,074,075 aligned 16S rRNA sequences. Data that can be downloaded include zipped GenBank and FASTA alignment files, a histogram (in Excel) of the number of RDP sequences spanning each base position, data in the Functional Gene Pipeline Repository, and various user submitted data. The RDP-II website also provides numerous analysis tools.[From the RDP-II home page at http://rdp.cme.msu.edu/index.jsp

  14. Operation Everest II

    PubMed Central

    2010-01-01

    Abstract Wagner, Peter D. Operation Everest II. High Alt. Med. Biol. 11:111–119, 2010.—In October 1985, 25 years ago, 8 subjects and 27 investigators met at the United States Army Research Institute for Environmental Medicine (USARIEM) altitude chambers in Natick, Massachusetts, to study human responses to a simulated 40-day ascent of Mt. Everest, termed Operation Everest II (OE II). Led by Charlie Houston, John Sutton, and Allen Cymerman, these investigators conducted a large number of investigations across several organ systems as the subjects were gradually decompressed over 40 days to the Everest summit equivalent. There the subjects reached a \\documentclass{aastex}\\usepackage{amsbsy}\\usepackage{amsfonts}\\usepackage{amssymb}\\usepackage{bm}\\usepackage{mathrsfs}\\usepackage{pifont}\\usepackage{stmaryrd}\\usepackage{textcomp}\\usepackage{portland,xspace}\\usepackage{amsmath,amsxtra}\\pagestyle{empty}\\DeclareMathSizes{10}{9}{7}{6} \\begin{document} \\begin{align*} \\dot{\\rm V}{\\sc O}_2{\\rm max} \\end{align*} \\end{document} of 15.3 mL/kg/min (28% of initial sea-level values) at 100 W and arterial Po2 and Pco2 of ∼28 and ∼10 mm Hg, respectively. Cardiac function resisted hypoxia, but the lungs could not: ventilation–perfusion inequality and O2 diffusion limitation reduced arterial oxygenation considerably. Pulmonary vascular resistance was increased, was not reversible after short-term hyperoxia, but was reduced during exercise. Skeletal muscle atrophy occurred, but muscle structure and function were otherwise remarkably unaffected. Neurological deficits (cognition and memory) persisted after return to sea level, more so in those with high hypoxic ventilatory responsiveness, with motor function essentially spared. Nine percent body weight loss (despite an unrestricted diet) was mainly (67%) from muscle and exceeded the 2% predicted from energy intake–expenditure balance. Some immunological and lipid metabolic changes occurred, of uncertain

  15. AWIPS II Extended - Data Delivery

    NASA Astrophysics Data System (ADS)

    Henry, R.; Schotz, S.; Calkins, J.; Gockel, B.; Ortiz, C.; Peter, R.

    2012-12-01

    AWIPS II Technology Infusion is a multiphase program. The first phase is the migration of the Weather Forecast Offices (WFOs) and River Forecast Centers (RFCs) AWIPS I capabilities into a Service Oriented Architecture (SOA), referred to as AWIPS II. AWIPS II is currently being deployed to Operational Test and Evaluation (OTE) and other select deployment sites. The subsequent phases of AWIPS Technology Infusion, known as AWIPS II Extended, include several projects that will improve technological capabilities of AWIPS II in order to enhance the NWS enterprise and improve services to partners. This paper summarizes AWIPS II Extended - Data Delivery project and reports on its status. Data Delivery enables AWIPS II users to discover, subscribe and access web-enabled data provider systems including the capability to subset datasets by space, time and parameter.

  16. Chandra and XMM monitoring of the black hole X-ray binary IC 10 X-1

    NASA Astrophysics Data System (ADS)

    Laycock, Silas G. T.; Cappallo, Rigel C.; Moro, Matthew J.

    2015-01-01

    The massive black hole (BH)+Wolf-Rayet (WR) binary IC 10 X-1 was observed in a series of 10 Chandra and two XMM-Newton observations spanning 2003-2012, showing consistent variability around 7 × 1037 erg s-1, with a spectral hardening event in 2009. We phase connected the entire light curve by folding the photon arrival times on a series of trial periods spanning the known orbital period and its uncertainty, refining the X-ray period to P = 1.45175(1) d. The duration of minimum flux in the X-ray eclipse is ˜5 h which together with the optical radial velocity (RV) curve for the companion yields a radius for the eclipsing body of 8-10 R⊙ for the allowed range of masses. The orbital separation (a1 + a2) = 18.5-22 R⊙ then provides a limiting inclination i > 63° for total eclipses to occur. The eclipses are asymmetric (egress duration ˜0.9 h) and show energy dependence, suggestive of an accretion disc hotspot and corona. The eclipse is much (˜5×) wider than the 1.5-2 R⊙ WR star, pointing to absorption/scattering in the dense wind of the WR star. The same is true of the close analog NGC 300 X-1. RV measurements of the He II [λλ4686] line from the literature show a phase shift with respect to the X-ray ephemeris such that the velocity does not pass through zero at mid-eclipse. The X-ray eclipse leads inferior conjunction of the RV curve by ˜90°, so either the BH is being eclipsed by a trailing shock/plume, or the He II line does not directly trace the motion of the WR star and instead originates in a shadowed partially ionized region of the stellar wind.

  17. The physical conditions, metallicity and metal abundance ratios in a highly magnified galaxy at z = 3.6252

    SciTech Connect

    Bayliss, Matthew B.; Rigby, Jane R.; Sharon, Keren; Johnson, Traci; Wuyts, Eva; Florian, Michael; Gladders, Michael D.; Oguri, Masamune

    2014-08-01

    We present optical and near-IR imaging and spectroscopy of SGAS J105039.6+001730, a strongly lensed galaxy at z = 3.6252 magnified by >30×, and derive its physical properties. We measure a stellar mass of log(M{sub *}/M{sub ☉}) = 9.5 ± 0.35, star formation rates from [O II] λλ3727 and Hβ of 55 ± 25 and 84 ± 24 M{sub ☉} yr{sup –1}, respectively, an electron density of n{sub e} ≤ 10{sup 3} cm{sup –2}, an electron temperature of T{sub e} ≤ 14,000 K, and a metallicity of 12 + log(O/H) = 8.3 ± 0.1. The strong C III] λλ1907,1909 emission and abundance ratios of C, N, O, and Si are consistent with well-studied starbursts at z ∼ 0 with similar metallicities. Strong P Cygni lines and He II λ1640 emission indicate a significant population of Wolf-Rayet stars, but synthetic spectra of individual populations of young, hot stars do not reproduce the observed integrated P Cygni absorption features. The rest-frame UV spectral features are indicative of a young starburst with high ionization, implying either (1) an ionization parameter significantly higher than suggested by rest-frame optical nebular lines, or (2) differences in one or both of the initial mass function and the properties of ionizing spectra of massive stars. We argue that the observed features are likely the result of a superposition of star forming regions with different physical properties. These results demonstrate the complexity of star formation on scales smaller than individual galaxies, and highlight the importance of systematic effects that result from smearing together the signatures of individual star forming regions within galaxies.

  18. Delta II Mars Pathfinder

    NASA Technical Reports Server (NTRS)

    1998-01-01

    Final preparations for lift off of the DELTA II Mars Pathfinder Rocket are shown. Activities include loading the liquid oxygen, completing the construction of the Rover, and placing the Rover into the Lander. After the countdown, important visual events include the launch of the Delta Rocket, burnout and separation of the three Solid Rocket Boosters, and the main engine cutoff. The cutoff of the main engine marks the beginning of the second stage engine. After the completion of the second stage, the third stage engine ignites and then cuts off. Once the third stage engine cuts off spacecraft separation occurs.

  19. Run II luminosity progress

    SciTech Connect

    Gollwitzer, K.; /Fermilab

    2007-06-01

    The Fermilab Tevatron Collider Run II program continues at the energy and luminosity frontier of high energy particle physics. To the collider experiments CDF and D0, over 3 fb{sup -1} of integrated luminosity has been delivered to each. Upgrades and improvements in the Antiproton Source of the production and collection of antiprotons have led to increased number of particles stored in the Recycler. Electron cooling and associated improvements have help make a brighter antiproton beam at collisions. Tevatron improvements to handle the increased number of particles and the beam lifetimes have resulted in an increase in luminosity.

  20. SAGE II aerosol data validation - Comparative studies of SAGE II and SAM II data sets

    NASA Technical Reports Server (NTRS)

    Yue, G. K.; Mccormick, M. P.; Chu, W. P.; Wang, P. H.; Osborn, M. T.

    1989-01-01

    Data from the Stratospheric Aerosol and Gas Experiment (SAGE II) satellite are compared with data from the Stratospheric Aerosol Measurement (SAM II) satellite. Both experiments produce aerosol extinction profiles by measuring the attenuation of solar radiation during each sunrise and sunset observed by the satelltie. The SAGE II obtains profiles at 1.02 microns and three smaller wavelengths, whereas the SAM II measures at only one radiometric channel at 1.0 microns. It is found that the differences between the two sets of data are generally within the error bars associated with each measurement. In addition, the sunrise and sunset data from SAGE II are analyzed.

  1. The Belle II Detector

    NASA Astrophysics Data System (ADS)

    Piilonen, Leo; Belle Collaboration, II

    2017-01-01

    The Belle II detector is now under construction at the KEK laboratory in Japan. This project represents a substantial upgrade of the Belle detector (and the KEKB accelerator). The Belle II experiment will record 50 ab-1 of data, a factor of 50 more than that recorded by Belle. This large data set, combined with the low backgrounds and high trigger efficiencies characteristic of an e+e- experiment, should provide unprecedented sensitivity to new physics signatures in B and D meson decays, and in τ lepton decays. The detector comprises many forefront subsystems. The vertex detector consists of two inner layers of silicon DEPFET pixels and four outer layers of double-sided silicon strips. These layers surround a beryllium beam pipe having a radius of only 10 mm. Outside of the vertex detector is a large-radius, small-cell drift chamber, an ``imaging time-of-propagation'' detector based on Cerenkov radiation for particle identification, and scintillating fibers and resistive plate chambers used to identify muons. The detector will begin commissioning in 2017.

  2. Effect of Cu(II), Cd(II) and Zn(II) on Pb(II) biosorption by algae Gelidium-derived materials.

    PubMed

    Vilar, Vítor J P; Botelho, Cidália M S; Boaventura, Rui A R

    2008-06-15

    Biosorption of Pb(II), Cu(II), Cd(II) and Zn(II) from binary metal solutions onto the algae Gelidium sesquipedale, an algal industrial waste and a waste-based composite material was investigated at pH 5.3, in a batch system. Binary Pb(II)/Cu(II), Pb(II)/Cd(II) and Pb(II)/Zn(II) solutions have been tested. For the same equilibrium concentrations of both metal ions (1 mmol l(-1)), approximately 66, 85 and 86% of the total uptake capacity of the biosorbents is taken by lead ions in the systems Pb(II)/Cu(II), Pb(II)/Cd(II) and Pb(II)/Zn(II), respectively. Two-metal results were fitted to a discrete and a continuous model, showing the inhibition of the primary metal biosorption by the co-cation. The model parameters suggest that Cd(II) and Zn(II) have the same decreasing effect on the Pb(II) uptake capacity. The uptake of Pb(II) was highly sensitive to the presence of Cu(II). From the discrete model it was possible to obtain the Langmuir affinity constant for Pb(II) biosorption. The presence of the co-cations decreases the apparent affinity of Pb(II). The experimental results were successfully fitted by the continuous model, at different pH values, for each biosorbent. The following sequence for the equilibrium affinity constants was found: Pb>Cu>Cd approximately Zn.

  3. II Zwicky 23 and Family

    NASA Astrophysics Data System (ADS)

    Wehner, E. H.; Gallagher, J. S.; Rudie, G. C.; Cigan, P. J.

    II Zwicky 23 (UGC 3179) is a luminous (MB ~ -21) nearby compact narrow emission line st arburst galaxy with blue optical colors and strong emission lines. We present a photometric and morphological study of II Zw 23 and its interacting companions using data obtained with the WIYN 3.5-m telescope in Kitt Peak, Arizona. II Zwicky 23 has a highly disturbed outer structure with long trails of debris that may be feeding tidal dwarfs.

  4. Belle II Software

    NASA Astrophysics Data System (ADS)

    Kuhr, T.; Ritter, M.; Belle Software Group, II

    2016-10-01

    Belle II is a next generation B factory experiment that will collect 50 times more data than its predecessor, Belle. The higher luminosity at the SuperKEKB accelerator leads to higher background levels and requires a major upgrade of the detector. As a consequence, the simulation, reconstruction, and analysis software must also be upgraded substantially. Most of the software has been redesigned from scratch, taking into account the experience from Belle and other experiments and utilizing new technologies. The large amount of experimental and simulated data requires a high level of reliability and reproducibility, even in parallel environments. Several technologies, tools, and organizational measures are employed to evaluate and monitor the performance of the software during development.

  5. He II-Emitting Galaxies

    NASA Astrophysics Data System (ADS)

    Heap, Sara R.

    2014-01-01

    A small fraction of star-forming galaxies at redshift, 3, show He II at 1640 A as a narrow emission line (Cassata et al. 2012), but the source of this emission is not understood. Does the He II emission arise in the stars or in the surrounding nebula? To answer this question, we use I Zw 18, a well studied blue compact dwarf galaxy showing narrow He II line emission as a test case. We consider if/how He II narrow emission lines could originate in the nearby nebulosity, or in the winds of hot, massive stars, both those on the main sequence and post-MS evolutionary phases.

  6. Mode II fatigue crack propagation.

    NASA Technical Reports Server (NTRS)

    Roberts, R.; Kibler, J. J.

    1971-01-01

    Fatigue crack propagation rates were obtained for 2024-T3 bare aluminum plates subjected to in-plane, mode I, extensional loads and transverse, mode II, bending loads. These results were compared to the results of Iida and Kobayashi for in-plane mode I-mode II extensional loads. The engineering significance of mode I-mode II fatigue crack growth is considered in view of the present results. A fatigue crack growth equation for handling mode I-mode II fatigue crack growth rates from existing mode I data is also discussed.

  7. Phase II Final Report

    SciTech Connect

    Schuknecht, Nate; White, David; Hoste, Graeme

    2014-09-11

    The SkyTrough DSP will advance the state-of-the-art in parabolic troughs for utility applications, with a larger aperture, higher operating temperature, and lower cost. The goal of this project was to develop a parabolic trough collector that enables solar electricity generation in the 2020 marketplace for a 216MWe nameplate baseload power plant. This plant requires an LCOE of 9¢/kWhe, given a capacity factor of 75%, a fossil fuel limit of 15%, a fossil fuel cost of $6.75/MMBtu, $25.00/kWht thermal storage cost, and a domestic installation corresponding to Daggett, CA. The result of our optimization was a trough design of larger aperture and operating temperature than has been fielded in large, utility scale parabolic trough applications: 7.6m width x 150m SCA length (1,118m2 aperture), with four 90mm diameter × 4.7m receivers per mirror module and an operating temperature of 500°C. The results from physical modeling in the System Advisory Model indicate that, for a capacity factor of 75%: The LCOE will be 8.87¢/kWhe. SkyFuel examined the design of almost every parabolic trough component from a perspective of load and performance at aperture areas from 500 to 2,900m2. Aperture-dependent design was combined with fixed quotations for similar parts from the commercialized SkyTrough product, and established an installed cost of $130/m2 in 2020. This project was conducted in two phases. Phase I was a preliminary design, culminating in an optimum trough size and further improvement of an advanced polymeric reflective material. This phase was completed in October of 2011. Phase II has been the detailed engineering design and component testing, which culminated in the fabrication and testing of a single mirror module. Phase II is complete, and this document presents a summary of the comprehensive work.

  8. Recent results on the connection between massive stars and supernovae

    NASA Astrophysics Data System (ADS)

    Hillier, D. John

    2015-08-01

    With the dramatic increase in observational data on supernovae (SNe), SN studies are undergoing a renaissance. It is known that Type II SN IIP arise from the explosion of a red supergiant (RSG). In several cases the RSG is seen in pre-explosion images, but it is absent in post-SN images — unambiguous proof that the RSG has exploded. Surprisingly, all RSG progenitors identified have a mass less than approximately 20 M⊙. To date, there has been no direct detection of the progenitor of a Type Ib or Ic SN. Because their ejecta masses are generally low (3 to 5 M⊙), these SNe are believed to arise from a relatively low mass star in a binary system. Such systems dominate the statistics due to the initial mass function. The broad-lined Ic SNe tend to have higher mass, and some of these may be associated with classic Wolf-Rayet (W-R) stars. Type IIn SNe are a heterogeneous class of SN — they arise when the SN ejecta interacts with preexisting circumstellar material. Their spectra often exhibit narrow emission lines, and they can be particularly luminous due to the efficient conversion of kinetic energy into radiation. The origin of Type IIn SN and their connection to stellar evolution is the subject of fierce debate and controversy. The final class to be discussed are the pair-instability supernovae (PISNe) which arise from a nuclear detonation. PISNe have a distinct chemical signature, and the observational evidence for the existence of this class of SN is ambiguous and controversial. While much progress has been made, it is still difficult to get models of core-collapse SNe to explode from first principles. The problem is inherently 3D and numerous questions remain unanswered. How much material falls back onto the core? What is the nature and extent of mixing in the ejecta? What are the chemical yields? Do all massive stars end their life as a luminous SN?

  9. SPITZER/INFRARED SPECTROGRAPH INVESTIGATION OF MIPSGAL 24 {mu}m COMPACT BUBBLES

    SciTech Connect

    Flagey, N.; Noriega-Crespo, A.; Carey, S. J.; Billot, N.

    2011-11-01

    The MIPSGAL 24 {mu}m Galactic Plane Survey has revealed more than 400 compact-extended objects. Less than 15% of these MIPSGAL bubbles (MBs) are known and identified as evolved stars. We present Spitzer observations of four MBs obtained with the InfraRed Spectrograph to determine the origin of the mid-IR emission. We model the mid-IR gas lines and the dust emission to infer physical conditions within the MBs and consequently their nature. Two MBs show a dust-poor spectrum dominated by highly ionized gas lines of [O IV], [Ne III], [Ne V], [S III], and [S IV]. We identify them as planetary nebulae with a density of a few 10{sup 3} cm{sup -3} and a central white dwarf of {approx}>200,000 K. The mid-IR emission of the two other MBs is dominated by a dust continuum and lower-excitation lines. Both of them show a central source in the near-IR (Two Micron All Sky Survey and IRAC) broadband images. The first dust-rich MB matches a Wolf-Rayet star of {approx}60,000 K at 7.5 kpc with dust components of {approx}170 and {approx}1750 K. Its mass is about 10{sup -3} M{sub sun} and its mass loss is about 10{sup -6} M{sub sun} yr{sup -1}. The second dust-rich MB has recently been suggested as a Be/B[e]/luminous blue variable candidate. The gas lines of [Fe II] as well as hot continuum components ({approx}300 and {approx}1250 K) arise from the inside of the MB while its outer shell emits a colder dust component ({approx}75 K). The distance to the MB remains highly uncertain. Its mass is about 10{sup -3} M{sub sun} and its mass loss is about 10{sup -5} M{sub sun} yr{sup -1}.

  10. Kupier prize lecture: Sources of solar-system carbon

    NASA Technical Reports Server (NTRS)

    Anders, Edward; Zinner, Ernst

    1994-01-01

    We have tried to deconvolve Solar-System carbon into its sources, on the basis of C-12/C-13 ratios (equivalent to R). Interstellar SiC in meteorites, representing greater than 4.6-Ga-old stardust from carbon stars, is isotopically heavier (bar R = 38 +/- 2) than Solar-System carbon (89), implying that the latter contains an additional, light component. A likely source are massive stars, mainly Type II supernovae and Wolf-Rayet stars, which, being O-rich, eject their C largely as CO rather than carbonaceous dust. The fraction of such light C in the Solar System depends on R(sub light) in the source. For R(sub light) = 180-1025 (as in 'Group 4' meteoritic graphite spherules, which apparently came from massive stars greater than 4.6 Ga ago), the fraction of light C is 0.79-0.61. Similar results are obtained for present-day data on red giants and interstellar gas. Although both have become enriched in C-13 due to galactic evolution (to bar-R = 20 and 57), the fraction of the light component in interstellar gas again is near 0.7. (Here bar R represents the mean of a mixture calculated via atom fractions; it is not identical to the arithmetic mean R). Interstellar graphite, unlike SiC, shows a large peak at R approximately equal 90, near the solar value. Although some of the grains may be of local origin, others show anomalies in other elements and hence are exotic. Microdiamonds, with R = 93, also are exotic on the basis of their Xe and N. Apparently R approximately 90 was a fairly common composition 4.6 Ga ago, of stars as well as the ISM.

  11. THE STAR FORMATION HISTORY AND METAL CONTENT OF THE GREEN PEAS. NEW DETAILED GTC-OSIRIS SPECTROPHOTOMETRY OF THREE GALAXIES

    SciTech Connect

    Amorin, R.; Perez-Montero, E.; Vilchez, J. M.

    2012-04-20

    We present deep broadband imaging and long-slit spectroscopy of three compact, low-mass starburst galaxies at redshift z {approx} 0.2-0.3, also referred to as Green Peas (GP). We measure physical properties of the ionized gas and derive abundances for several species with high precision. We find that the three GPs display relatively low extinction, low oxygen abundances, and remarkably high nitrogen-to-oxygen ratios. We also report on the detection of clear signatures of Wolf-Rayet (W-R) stars in these galaxies. We carry out a pilot spectral synthesis study using a combination of both population and evolutionary synthesis models. Their outputs are in qualitative agreement, strongly suggesting a formation history dominated by starbursts. In agreement with the presence of W-R stars, these models show that these GPs currently undergo a major starburst producing between {approx}4% and {approx}20% of their stellar mass. However, as models imply, they are old galaxies that formed most of their stellar mass several Gyr ago. The presence of old stars has been spectroscopically verified in one of the galaxies by the detection of Mg I {lambda}{lambda}5167, 5173 absorption lines. Additionally, we perform a surface photometry study based on Hubble Space Telescope data, which indicates that the three galaxies possess an exponential low surface brightness envelope. If due to stellar emission, the latter is structurally compatible with the evolved hosts of luminous blue compact dwarf (BCD)/H II galaxies, suggesting that GPs are identifiable with major episodes in the assembly history of local BCDs. These conclusions highlight the importance of these objects as laboratories for studying galaxy evolution at late cosmic epochs.

  12. UNUSUAL {sup 29,30}Si-RICH SiCs OF MASSIVE STAR ORIGIN FOUND WITHIN GRAPHITES FROM THE MURCHISON METEORITE

    SciTech Connect

    Croat, T. K.; Stadermann, F. J.; Bernatowicz, T. J.

    2010-06-15

    Correlated transmission electron microscopy and NanoSIMS isotopic studies have revealed two unusual SiCs with large {sup 29,30}Si enrichments within micron-sized graphites from the Murchison meteorite. Such anomalies are rare among the overall SiC population (in <<0.01% of SiCs yet measured), whereas two of the three SiCs found within graphite show {sup 29,30}Si enrichments, in one case as large as {sup 29}Si/{sup 28}Si = (2.28 {+-} 0.03) x solar and {sup 30}Si/{sup 28}Si = (2.03 {+-} 0.03)x solar. C-burning and Ne-burning in massive stars (>8 M{sub sun} initial mass) during their post-main-sequence development are the only processes capable of producing sufficiently large {sup 29,30}Si enrichments. This material with heavy Si isotopic enrichments from the O/Ne and O/Si layers is later incorporated into carbonaceous stardust, either in ejecta from Type II supernovae or perhaps in the colliding winds of Wolf-Rayet binaries. Although often too small for Si isotopic measurements, four other SiC-containing graphites show other signatures of a massive star origin. Abundance estimates suggest that such unusual SiCs are present within {approx}1% of high-density graphites. This abundance can be reconciled with the much lower abundance in the overall SiC population if these unusual SiCs are naturally smaller ({approx}200 nm or less) than SiCs from other isotopic subgroups and if differential destruction of small unusual SiCs occurs in massive star outflows unless these SiCs are encapsulated in graphite.

  13. Probing Shock Breakout and Progenitors of Stripped-envelope Supernovae through their Early Radio Emissions

    NASA Astrophysics Data System (ADS)

    Maeda, Keiichi

    2013-01-01

    We study properties of early radio emission from stripped-envelope supernovae (SNe; those of Type IIb/Ib/Ic). We suggest there is a sub-class of stripped-envelope SNe based on their radio properties, including the optically well-studied Type Ic SNe (SNe Ic) 2002ap and 2007gr, showing a rapid rise to a radio peak within ~10 days and reaching a low luminosity (at least an order of magnitude fainter than a majority of SNe IIb/Ib/Ic). They show a decline after the peak that is shallower than that of other stripped-envelope SNe while their spectral index is similar. We show that all these properties are naturally explained if the circumstellar material (CSM) density is low and therefore the forward shock is expanding into the CSM without deceleration. Since the forward shock velocity in this situation, as estimated from the radio properties, still records the maximum velocity of the SN ejecta following the shock breakout, observing these SNe in radio wavelengths provides new diagnostics on the nature of both the breakout and the progenitor which otherwise require a quite rapid follow-up in other wavelengths. The inferred post-shock breakout velocities of SNe Ic 2002ap and 2007gr are sub-relativistic, ~0.3c. These are higher than that inferred for SN II 1987A, in line with suggested compact progenitors. However, these are lower than expected for a Wolf-Rayet (W-R) progenitor. It may reflect an as yet unresolved nature of the progenitors just before the explosion, and we suggest that the W-R progenitor envelopes might have been inflated which could quickly reduce the maximum ejecta velocity from the initial shock breakout velocity.

  14. THE INTERSTELLAR MEDIUM AND FEEDBACK IN THE PROGENITORS OF THE COMPACT PASSIVE GALAXIES AT z ∼ 2

    SciTech Connect

    Williams, Christina C.; Giavalisco, Mauro; Lee, Bomee; Tundo, Elena; Mobasher, Bahram; Nayyeri, Hooshang; Ferguson, Henry C.; Koekemoer, Anton; Grogin, Norman; Trump, Jonathan R.; Cassata, Paolo; Dekel, Avishai; Guo, Yicheng; Pentericci, Laura; Castellano, Marco; Fontana, Adriano; Grazian, Andrea; Bell, Eric F.; Finkelstein, Steven L.; and others

    2015-02-10

    Quenched galaxies at z > 2 are nearly all very compact relative to z ∼ 0, suggesting a physical connection between high stellar density and efficient, rapid cessation of star-formation. We present rest-frame UV spectra of Lyman-break galaxies (LBGs) at z ∼ 3 selected to be candidate progenitors of the quenched galaxies at z ∼ 2 based on their compact rest-frame-optical sizes and high Σ{sub SFR}. We compare their UV properties to those of more extended LBGs of similar mass and star-formation rate (non-candidates). We find that candidate progenitors have faster bulk interstellar medium (ISM) gas velocities and higher equivalent widths of interstellar absorption lines, implying larger velocity spread among absorbing clouds. Candidates deviate from the relationship between equivalent widths of Lyα and interstellar absorption lines in that their Lyα emission remains strong despite high interstellar absorption, possibly indicating that the neutral H I fraction is patchy, such that Lyα photons can escape. We detect stronger C IV P-Cygni features (emission and absorption) and He II emission in candidates, indicative of larger populations of metal-rich Wolf-Rayet stars compared to non-candidates. The faster bulk motions, broader spread of gas velocity, and Lyα properties of candidates are consistent with their ISM being subject to more energetic feedback than non-candidates. Together with their larger metallicity (implying more evolved star-formation activity) this leads us to propose, if speculatively, that they are likely to quench sooner than non-candidates, supporting the validity of selection criteria used to identify them as progenitors of z ∼ 2 passive galaxies. We propose that massive, compact galaxies undergo more rapid growth of their stellar mass content, perhaps because the gas accretion mechanisms are different, and quench sooner than normally sized LBGs at these (early) epochs.

  15. Medium-resolution spectroscopy of FORJ0332-3557: probing the interstellar medium and stellar populations of a lensed Lyman-break galaxy at z = 3.77

    NASA Astrophysics Data System (ADS)

    Cabanac, Rémi A.; Valls-Gabaud, David; Lidman, Chris

    2008-06-01

    We recently reported the discovery of FORJ0332-3557, a lensed Lyman-break galaxy at z = 3.77 in a remarkable example of strong galaxy-galaxy gravitational lensing. We present here a medium-resolution rest-frame ultraviolet (UV) spectrum of the source, which appears to be similar to the well-known Lyman-break galaxy MS1512-cB58 at z = 2.73. The spectral energy distribution is consistent with a stellar population of less than 30Ma, with an extinction of Av = 0.5 mag and an extinction-corrected star formation rate SFRUV of 200-300h-170Msolara-1. The Lyα line exhibits a damped profile in absorption produced by a column density of about NHI = (2.5 +/- 1.0) × 1021cm-2, superimposed on an emission line shifted both spatially (0.5 arcsec with respect to the UV continuum source) and in velocity space (+830kms-1 with respect to the low-ionization absorption lines from its interstellar medium), a clear signature of outflows with an expansion velocity of about 270kms-1. A strong emission line from HeII λ164.04 nm indicates the presence of Wolf-Rayet stars and reinforces the interpretation of a very young starburst. The metallic lines indicate subsolar abundances of elements Si, Al and C in the ionized gas phase. Based on observations made at the ESO VLT under programmes 74.A-0536 and 78.A-0240. E-mail: remi.cabanac@ast.obs-mip.fr (RAC); david.valls-gabaud@obspm.fr (DV-G); clidman@eso.org (CL)

  16. The Interstellar Medium and Feedback in the Progenitors of the Compact Passive Galaxies at z ~ 2

    NASA Astrophysics Data System (ADS)

    Williams, Christina C.; Giavalisco, Mauro; Lee, Bomee; Tundo, Elena; Mobasher, Bahram; Nayyeri, Hooshang; Ferguson, Henry C.; Koekemoer, Anton; Trump, Jonathan R.; Cassata, Paolo; Dekel, Avishai; Guo, Yicheng; Lee, Kyoung-Soo; Pentericci, Laura; Bell, Eric F.; Castellano, Marco; Finkelstein, Steven L.; Fontana, Adriano; Grazian, Andrea; Grogin, Norman; Kocevski, Dale; Koo, David C.; Lucas, Ray A.; Ravindranath, Swara; Santini, Paola; Vanzella, Eros; Weiner, Benjamin J.

    2015-02-01

    Quenched galaxies at z > 2 are nearly all very compact relative to z ~ 0, suggesting a physical connection between high stellar density and efficient, rapid cessation of star-formation. We present rest-frame UV spectra of Lyman-break galaxies (LBGs) at z ~ 3 selected to be candidate progenitors of the quenched galaxies at z ~ 2 based on their compact rest-frame-optical sizes and high ΣSFR. We compare their UV properties to those of more extended LBGs of similar mass and star-formation rate (non-candidates). We find that candidate progenitors have faster bulk interstellar medium (ISM) gas velocities and higher equivalent widths of interstellar absorption lines, implying larger velocity spread among absorbing clouds. Candidates deviate from the relationship between equivalent widths of Lyα and interstellar absorption lines in that their Lyα emission remains strong despite high interstellar absorption, possibly indicating that the neutral H I fraction is patchy, such that Lyα photons can escape. We detect stronger C IV P-Cygni features (emission and absorption) and He II emission in candidates, indicative of larger populations of metal-rich Wolf-Rayet stars compared to non-candidates. The faster bulk motions, broader spread of gas velocity, and Lyα properties of candidates are consistent with their ISM being subject to more energetic feedback than non-candidates. Together with their larger metallicity (implying more evolved star-formation activity) this leads us to propose, if speculatively, that they are likely to quench sooner than non-candidates, supporting the validity of selection criteria used to identify them as progenitors of z ~ 2 passive galaxies. We propose that massive, compact galaxies undergo more rapid growth of their stellar mass content, perhaps because the gas accretion mechanisms are different, and quench sooner than normally sized LBGs at these (early) epochs.

  17. Are superluminous supernovae and long GRBs the products of dynamical processes in young dense star clusters?

    SciTech Connect

    Van den Heuvel, E. P. J.; Portegies Zwart, S. F.

    2013-12-20

    Superluminous supernovae (SLSNe) occur almost exclusively in small galaxies (Small/Large Magellanic Cloud (SMC/LMC)-like or smaller), and the few SLSNe observed in larger star-forming galaxies always occur close to the nuclei of their hosts. Another type of peculiar and highly energetic supernovae are the broad-line Type Ic SNe (SN Ic-BL) that are associated with long-duration gamma-ray bursts (LGRBs). Also these have a strong preference for occurring in small (SMC/LMC-like or smaller) star-forming galaxies, and in these galaxies LGRBs always occur in the brightest spots. Studies of nearby star-forming galaxies that are similar to the hosts of LGRBs show that these brightest spots are giant H II regions produced by massive dense young star clusters with many hundreds of O- and Wolf-Rayet-type stars. Such dense young clusters are also found in abundance within a few hundred parsecs from the nucleus of larger galaxies like our own. We argue that the SLSNe and the SNe Ic-BL/LGRBs are exclusive products of two types of dynamical interactions in dense young star clusters. In our model the high angular momentum of the collapsing stellar cores required for the engines of an SN Ic-BL results from the post-main-sequence mergers of dynamically produced cluster binaries with almost equal-mass components. The merger produces a critically rotating single helium star with sufficient angular momentum to produce an LGRB; the observed 'metal aversion' of LGRBs is a natural consequence of the model. We argue that, on the other hand, SLSNe could be the products of runaway multiple collisions in dense clusters, and we present (and quantize) plausible scenarios of how the different types of SLSNe can be produced.

  18. Modeling the X-ray light curves of Cygnus X-3. Possible role of the jet

    NASA Astrophysics Data System (ADS)

    Vilhu, O.; Hannikainen, D. C.

    2013-02-01

    Context. We address the physics behind the soft X-ray light curve asymmetries in Cygnus X-3, a well-known microquasar. Aims: Observable effects of the jet close to the line-of-sight were investigated and interpreted within the frame of light curve physics. Methods: The path of a hypothetical imprint of the jet, advected by the Wolf-Rayet-wind, was computed and its crossing with the line-of-sight during the binary orbit determined. We explored the possibility that physically this "imprint" is a formation of dense clumps triggered by jet bow shocks in the wind ("clumpy trail"). Models for X-ray continuum and emission line light curves were constructed using two absorbers: mass columns along the line-of-sight of i) the WR wind and ii) the clumpy trail, as seen from the compact star. These model light curves were compared with the observed ones from the RXTE/ASM (continuum) and Chandra/HETG (emission lines). Results: We show that the shapes of the Cyg X-3 light curves can be explained by the two absorbers using the inclination and true anomaly angles of the jet as derived from gamma-ray Fermi/LAT observations. The clumpy trail absorber is much larger for the lines than for the continuum. We suggest that the clumpy trail is a mixture of equilibrium and hot (shock heated) clumps. Conclusions: A possible way for studying jets in binary stars when the jet axis and the line-of-sight are close to each other is demonstrated. The X-ray continuum and emission line light curves of Cygnus X-3 can be explained by two absorbers: the WR companion wind plus an absorber lying in the jet path (clumpy trail). We propose that the clumpy trail absorber is due to dense clumps triggered by jet bow shocks.

  19. Determination of Mass-Loss Rates of PG 1159 Stars from Far-Ultraviolet Spectroscopy

    NASA Astrophysics Data System (ADS)

    Koesterke, Lars; Werner, Klaus

    1998-06-01

    We determine the mass-loss rates of four hot, low-gravity PG 1159 stars that are regarded as immediate descendants of Wolf-Rayet central stars of planetary nebulae (i.e., early spectral type [WCE]). The sample consists of classical hydrogen-deficient PG 1159 stars (K1-16, NGC 246, and RX J2117.1+3412) as well as one object of the very rare ``hybrid'' subtype, which also exhibits hydrogen lines (NGC 7094). The sample is complemented by the famous [WC]-PG 1159 transition object Abell 78. Our analysis is based on the O VI λλ1032, 1038 resonance line, which is the strongest wind feature in these objects. Far-UV observations were performed with the Berkeley spectrograph during the ORFEUS-SPAS II mission. One spectrum is taken from archive data of the ORFEUS-SPAS I mission, and another one was obtained with the Hopkins Ultraviolet Telescope during the Astro-2 mission. We find mass-loss rates in the range log(Ṁ/Msolar yr-1)=-8,...,-7, as compared to the [WCE] stars that have mass-loss rates of about log(Ṁ/Msolar yr-1)=-5.5,...,-6.5. By comparing with theory, we conclude that the wind of PG 1159 stars is driven by radiation pressure. Based on the development and utilization of ORFEUS (Orbiting and Retrievable Far and Extreme Ultraviolet Spectrometers), a collaboration of the Institute for Astronomy and Astrophysics at the University of Tübingen, the Space Astrophysics Group of the University of California at Berkeley, and the Landessternwarte Heidelberg.

  20. 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.

  1. HOST GALAXIES OF LUMINOUS TYPE 2 QUASARS AT z {approx} 0.5

    SciTech Connect

    Liu Xin; Greene, Jenny E.; Strauss, Michael A.; Zakamska, Nadia L.; Krolik, Julian H.; Heckman, Timothy M.

    2009-09-10

    We present deep Gemini GMOS optical spectroscopy of nine luminous quasars at redshifts z {approx} 0.5, drawn from the Sloan Digital Sky Survey type 2 quasar sample. Our targets were selected to have high intrinsic luminosities (M{sub V} < -26 mag) as indicated by the [O III] {lambda}5007 A emission-line luminosity (L[{sub OIII}]). Our sample has a median black hole mass of {approx}10{sup 8.8} M{sub sun} inferred assuming the local M {sub BH}-{sigma}{sub *} relation and a median Eddington ratio of {approx}0.7, using stellar velocity dispersions {sigma}{sub *} measured from the G band. We estimate the contamination of the stellar continuum from scattered quasar light based on the strength of broad H{beta}, and provide an empirical calibration of the contamination as a function of L {sub [OIII]}; the scattered-light fraction is {approx}30% of L{sub 5100} for objects with L {sub [OIII]} = 10{sup 9.5} L{sub sun}. Population synthesis indicates that young poststarburst populations (<0.1 Gyr) are prevalent in luminous type 2 quasars, in addition to a relatively old population (>1 Gyr) which dominates the stellar mass. Broad emission complexes around He II {lambda}4686 A with luminosities up to 10{sup 8.3} L{sub sun} are unambiguously detected in three out of the nine targets, indicative of Wolf-Rayet (WR) populations. Population synthesis shows that {approx}5 Myr poststarburst populations contribute substantially to the luminosities (>50% of L{sub 5100}) of all three objects with WR detections. We find two objects with double cores and four with close companions. Our results may suggest that luminous type 2 quasars trace an early stage of galaxy interaction, perhaps responsible for both the quasar and the starburst activity.

  2. THE SPITZER ATLAS OF STELLAR SPECTRA (SASS)

    SciTech Connect

    Ardila, David R.; Van Dyk, Schuyler D.; Makowiecki, Wojciech; Stauffer, John; Rho, Jeonghee; Fajardo-Acosta, Sergio; Hoard, D. W.; Wachter, Stefanie; Song, Inseok

    2010-12-15

    We present the Spitzer Atlas of Stellar Spectra, which includes 159 stellar spectra (5-32 {mu}m; R {approx} 100) taken with the Infrared Spectrograph on the Spitzer Space Telescope. This Atlas gathers representative spectra of a broad section of the Hertzsprung-Russell diagram, intended to serve as a general stellar spectral reference in the mid-infrared. It includes stars from all luminosity classes, as well as Wolf-Rayet (WR) objects. Furthermore, it includes some objects of intrinsic interest, such as blue stragglers and certain pulsating variables. All of the spectra have been uniformly reduced, and all are available online. For dwarfs and giants, the spectra of early-type objects are relatively featureless, characterized by the presence of hydrogen lines in A spectral types. Besides these, the most noticeable photospheric features correspond to water vapor and silicon monoxide in late-type objects and methane and ammonia features at the latest spectral types. Most supergiant spectra in the Atlas present evidence of circumstellar gas and/or dust. The sample includes five M supergiant spectra, which show strong dust excesses and in some cases polycyclic aromatic hydrocarbon features. Sequences of WR stars present the well-known pattern of lines of He I and He II, as well as forbidden lines of ionized metals. The characteristic flat-top shape of the [Ne III] line is evident even at these low spectral resolutions. Several Luminous Blue Variables and other transition stars are present in the Atlas and show very diverse spectra, dominated by circumstellar gas and dust features. We show that the [8]-[24] Spitzer colors (IRAC and MIPS) are poor predictors of spectral type for most luminosity classes.

  3. PROBING SHOCK BREAKOUT AND PROGENITORS OF STRIPPED-ENVELOPE SUPERNOVAE THROUGH THEIR EARLY RADIO EMISSIONS

    SciTech Connect

    Maeda, Keiichi

    2013-01-01

    We study properties of early radio emission from stripped-envelope supernovae (SNe; those of Type IIb/Ib/Ic). We suggest there is a sub-class of stripped-envelope SNe based on their radio properties, including the optically well-studied Type Ic SNe (SNe Ic) 2002ap and 2007gr, showing a rapid rise to a radio peak within {approx}10 days and reaching a low luminosity (at least an order of magnitude fainter than a majority of SNe IIb/Ib/Ic). They show a decline after the peak that is shallower than that of other stripped-envelope SNe while their spectral index is similar. We show that all these properties are naturally explained if the circumstellar material (CSM) density is low and therefore the forward shock is expanding into the CSM without deceleration. Since the forward shock velocity in this situation, as estimated from the radio properties, still records the maximum velocity of the SN ejecta following the shock breakout, observing these SNe in radio wavelengths provides new diagnostics on the nature of both the breakout and the progenitor which otherwise require a quite rapid follow-up in other wavelengths. The inferred post-shock breakout velocities of SNe Ic 2002ap and 2007gr are sub-relativistic, {approx}0.3c. These are higher than that inferred for SN II 1987A, in line with suggested compact progenitors. However, these are lower than expected for a Wolf-Rayet (W-R) progenitor. It may reflect an as yet unresolved nature of the progenitors just before the explosion, and we suggest that the W-R progenitor envelopes might have been inflated which could quickly reduce the maximum ejecta velocity from the initial shock breakout velocity.

  4. Solar Type II Radio Bursts and IP Type II Events

    NASA Technical Reports Server (NTRS)

    Cane, H. V.; Erickson, W. C.

    2005-01-01

    We have examined radio data from the WAVES experiment on the Wind spacecraft in conjunction with ground-based data in order to investigate the relationship between the shocks responsible for metric type II radio bursts and the shocks in front of coronal mass ejections (CMEs). The bow shocks of fast, large CMEs are strong interplanetary (IP) shocks, and the associated radio emissions often consist of single broad bands starting below approx. 4 MHz; such emissions were previously called IP type II events. In contrast, metric type II bursts are usually narrowbanded and display two harmonically related bands. In addition to displaying complete dynamic spectra for a number of events, we also analyze the 135 WAVES 1 - 14 MHz slow-drift time periods in 2001-2003. We find that most of the periods contain multiple phenomena, which we divide into three groups: metric type II extensions, IP type II events, and blobs and bands. About half of the WAVES listings include probable extensions of metric type II radio bursts, but in more than half of these events, there were also other slow-drift features. In the 3 yr study period, there were 31 IP type II events; these were associated with the very fastest CMEs. The most common form of activity in the WAVES events, blobs and bands in the frequency range between 1 and 8 MHz, fall below an envelope consistent with the early signatures of an IP type II event. However, most of this activity lasts only a few tens of minutes, whereas IP type II events last for many hours. In this study we find many examples in the radio data of two shock-like phenomena with different characteristics that occur simultaneously in the metric and decametric/hectometric bands, and no clear example of a metric type II burst that extends continuously down in frequency to become an IP type II event. The simplest interpretation is that metric type II bursts, unlike IP type II events, are not caused by shocks driven in front of CMEs.

  5. Technology II: Implementation Planning Guide.

    ERIC Educational Resources Information Center

    California Community Colleges, Sacramento. Office of the Chancellor.

    The California Community Colleges (CCC) are facing a number of challenges, including the explosive use of the Internet, the digital divide, the need for integrating technology into teaching and learning, the impact of Tidal Wave II, and the need to ensure that technology is accessible to persons with disabilities. The CCCs' Technology II Strategic…

  6. PARIS II: DESIGNING GREENER SOLVENTS

    EPA Science Inventory

    PARIS II (the program for assisting the replacement of industrial solvents, version II), developed at the USEPA, is a unique software tool that can be used for customizing the design of replacement solvents and for the formulation of new solvents. This program helps users avoid ...

  7. National Synchrotron Light Source II

    ScienceCinema

    Steve Dierker

    2016-07-12

    The National Synchrotron Light Source II (NSLS-II) at the U.S. Department of Energy's Brookhaven National Laboratory is a proposed new state-of-the-art medium energy storage ring designed to deliver world-leading brightness and flux with top-off operation

  8. Annex II technical documentation assessed.

    PubMed

    van Drongelen, A W; Roszek, B; van Tienhoven, E A E; Geertsma, R E; Boumans, R T; Kraus, J J A M

    2005-12-01

    Annex II of the Medical Device Directive (MDD) is used frequently by manufacturers to obtain CE-marking. This procedure relies on a full quality assurance system and does not require an assessment of the individual medical device by a Notified Body. An investigation into the availability and the quality of technical documentation for Annex II devices revealed severe shortcomings, which are reported here.

  9. National Synchrotron Light Source II

    SciTech Connect

    Steve Dierker

    2008-03-12

    The National Synchrotron Light Source II (NSLS-II) at the U.S. Department of Energy's Brookhaven National Laboratory is a proposed new state-of-the-art medium energy storage ring designed to deliver world-leading brightness and flux with top-off operation

  10. The global structure of hot star winds: Constraints from spectropolarimetry

    NASA Astrophysics Data System (ADS)

    Eversberg, Thomas

    2000-11-01

    Chapter 1. We present time-series of ultra-high S/N, high resolution spectra of the He II λ 4686 Å emission line in the O4I(n)f supergiant ζ Puppis, the brightest early-type O-star in the sky. These reveal stochastic, variable substructures in the line, which tend to move away from the line-center with time. Similar scaled-up features are well established in the strong winds of Wolf-Rayet stars (the presumed descendants of O stars), where they are explained by outward moving inhomogeneities (e.g., blobs, clumps, shocks) in the winds. If all hot-star winds are clumped like that of ζ Pup, as is plausible, then mass-low rates based on recombination-line intensities will have to be revised downwards. Using a standard `β' velocity law we deduce a value of β = 1.0-1.2 to account for the kinematics of these structures in the wind of ζ Pup. In addition to the small-scale stochastic variations we also find a slow systematic variation of the mean central absorption reversal. Chapter 2. We introduce a new polarimeter unit which, mounted at the Cassegrain focus of any telescope and fiber-connected to a fixed CCD spectrograph, is able to measure all Stokes parameters I, Q, U and V across spectral lines of bright stellar targets and other point sources in a quasi-simultaneous manner. Applying standard reduction techniques for linearly and circularly polarized light we are able to obtain photon-noise limited line polarization. We briefly outline the technical design of the polarimeter unit and the linear algebraic Mueller calculus for obtaining polarization parameters of any point source. In addition, practical limitations of the optical elements are outlined. We present first results obtained with our spectropolarimeter for four bright, hot-star targets: We confirm previous results for Hα in the bright Be star γ Cas and find linear depolarization features across the emission line complex C III/C IV (λ 5696/λ 5808 Å) of the WR+O binary γ2 Vel. We also find circular

  11. Symbiotic stars and other Hα emission-line stars towards the Galactic bulge

    NASA Astrophysics Data System (ADS)

    Miszalski, Brent; Mikołajewska, Joanna; Udalski, Andrzej

    2013-07-01

    identified. These include central stars of planetary nebulae (PNe) [one (WC10-11) Wolf-Rayet and five with high-density cores], two novae, two WN6 Wolf-Rayet stars, two possible Be stars, a B[e] star with a bipolar outflow, an ultracompact H II region and a dMe flare star. Dust obscuration events were found in two central stars of PNe, increasing the known cases to five, as well as one WN6 star. There is considerable scope to uncover several more symbiotic stars towards the bulge, many of which are currently misclassified as PNe, provided that deep spectroscopy is combined with optical and near-infrared light curves.

  12. Crystal Structure of Rat Carnitine Palmitoyltransferase II (CPT-II)

    SciTech Connect

    Hsiao,Y.; Jogl, G.; Esser, V.; Tong, L.

    2006-01-01

    Carnitine palmitoyltransferase II (CPT-II) has a crucial role in the {beta}-oxidation of long-chain fatty acids in mitochondria. We report here the crystal structure of rat CPT-II at 1.9 Angstroms resolution. The overall structure shares strong similarity to those of short- and medium-chain carnitine acyltransferases, although detailed structural differences in the active site region have a significant impact on the substrate selectivity of CPT-II. Three aliphatic chains, possibly from a detergent that is used for the crystallization, were found in the structure. Two of them are located in the carnitine and CoA binding sites, respectively. The third aliphatic chain may mimic the long-chain acyl group in the substrate of CPT-II. The binding site for this aliphatic chain does not exist in the short- and medium-chain carnitine acyltransferases, due to conformational differences among the enzymes. A unique insert in CPT-II is positioned on the surface of the enzyme, with a highly hydrophobic surface. It is likely that this surface patch mediates the association of CPT-II with the inner membrane of the mitochondria.

  13. Rhizobium etli asparaginase II

    PubMed Central

    Huerta-Saquero, Alejandro; Evangelista-Martínez, Zahaed; Moreno-Enriquez, Angélica; Perez-Rueda, Ernesto

    2013-01-01

    Bacterial l-asparaginase has been a universal component of therapies for childhood acute lymphoblastic leukemia since the 1970s. Two principal enzymes derived from Escherichia coli and Erwinia chrysanthemi are the only options clinically approved to date. We recently reported a study of recombinant l-asparaginase (AnsA) from Rhizobium etli and described an increasing type of AnsA family members. Sequence analysis revealed four conserved motifs with notable differences with respect to the conserved regions of amino acid sequences of type I and type II l-asparaginases, particularly in comparison with therapeutic enzymes from E. coli and E. chrysanthemi. These differences suggested a distinct immunological specificity. Here, we report an in silico analysis that revealed immunogenic determinants of AnsA. Also, we used an extensive approach to compare the crystal structures of E. coli and E. chrysantemi asparaginases with a computational model of AnsA and identified immunogenic epitopes. A three-dimensional model of AsnA revealed, as expected based on sequence dissimilarities, completely different folding and different immunogenic epitopes. This approach could be very useful in transcending the problem of immunogenicity in two major ways: by chemical modifications of epitopes to reduce drug immunogenicity, and by site-directed mutagenesis of amino acid residues to diminish immunogenicity without reduction of enzymatic activity. PMID:22895060

  14. Angiotensin II receptor heterogeneity

    SciTech Connect

    Herblin, W.F.; Chiu, A.T.; McCall, D.E.; Ardecky, R.J.; Carini, D.J.; Duncia, J.V.; Pease, L.J.; Wong, P.C.; Wexler, R.R.; Johnson, A.L. )

    1991-04-01

    The possibility of receptor heterogeneity in the angiotensin II (AII) system has been suggested previously, based on differences in Kd values or sensitivity to thiol reagents. One of the authors earliest indications was the frequent observation of incomplete inhibition of the binding of AII to adrenal cortical membranes. Autoradiographic studies demonstrated that all of the labeling of the rat adrenal was blocked by unlabeled AII or saralasin, but not by DuP 753. The predominant receptor in the rat adrenal cortex (80%) is sensitive to dithiothreitol (DTT) and DuP 753, and is designated AII-1. The residual sites in the adrenal cortex and almost all of the sites in the rat adrenal medulla are insensitive to both DTT and DuP 753, but were blocked by EXP655. These sites have been confirmed by ligand binding studies and are designated AII-2. The rabbit adrenal cortex is unique in yielding a nonuniform distribution of AII-2 sites around the outer layer of glomerulosa cells. In the rabbit kidney, the sites on the glomeruli are AII-1, but the sites on the kidney capsule are AII-2. Angiotensin III appears to have a higher affinity for AII-2 sites since it inhibits the binding to the rabbit kidney capsule but not the glomeruli. Elucidation of the distribution and function of these diverse sites should permit the development of more selective and specific therapeutic strategies.

  15. Mycotoxins revisited: Part II.

    PubMed

    Berger, Kyan J; Guss, David A

    2005-02-01

    Mushrooms are ubiquitous in nature. They are an important source of nutrition, however, certain varieties contain chemicals that can be highly toxic to humans. Industrially cultivated mushrooms are historically very safe, whereas foraging for mushrooms or accidental ingestion of mushrooms in the environment can result in serious illness and death. The emergency department is the most common site of presentation for patients suffering from acute mushroom poisoning. Although recognition can be facilitated by identification of a characteristic toxidrome, the presenting manifestations can be variable and have considerable overlap with more common and generally benign clinical syndromes. The goal of this two-part article is to review the knowledge base on this subject and provide information that will assist the clinician in the early consideration, diagnosis and treatment of mushroom poisoning. Part I reviewed the epidemiology and demographics of mushroom poisoning, the physical characteristics of the most toxic varieties, the classification of the toxic species, and presented an overview of the cyclopeptide-containing mushroom class. Part II is focused on the presentation of the other classes of toxic mushrooms along with an up-to-date review of the most recently identified poisonous varieties.

  16. Options Study - Phase II

    SciTech Connect

    R. Wigeland; T. Taiwo; M. Todosow; W. Halsey; J. Gehin

    2010-09-01

    The Options Study has been conducted for the purpose of evaluating the potential of alternative integrated nuclear fuel cycle options to favorably address the issues associated with a continuing or expanding use of nuclear power in the United States. The study produced information that can be used to inform decisions identifying potential directions for research and development on such fuel cycle options. An integrated nuclear fuel cycle option is defined in this study as including all aspects of the entire nuclear fuel cycle, from obtaining natural resources for fuel to the ultimate disposal of used nuclear fuel (UNF) or radioactive wastes. Issues such as nuclear waste management, especially the increasing inventory of used nuclear fuel, the current uncertainty about used fuel disposal, and the risk of nuclear weapons proliferation have contributed to the reluctance to expand the use of nuclear power, even though it is recognized that nuclear power is a safe and reliable method of producing electricity. In this Options Study, current, evolutionary, and revolutionary nuclear energy options were all considered, including the use of uranium and thorium, and both once-through and recycle approaches. Available information has been collected and reviewed in order to evaluate the ability of an option to clearly address the challenges associated with the current implementation and potential expansion of commercial nuclear power in the United States. This Options Study is a comprehensive consideration and review of fuel cycle and technology options, including those for disposal, and is not constrained by any limitations that may be imposed by economics, technical maturity, past policy, or speculated future conditions. This Phase II report is intended to be used in conjunction with the Phase I report, and much information in that report is not repeated here, although some information has been updated to reflect recent developments. The focus in this Options Study was to

  17. Biosatellite II mission.

    PubMed

    Reynolds, O E

    1969-01-01

    Biosatellite B was launched from Cape Kennedy, Florida, on a two-stage DELTA launch vehicle at 6:04 p.m. on 7 September, 1967. Approximately nine minutes later the 435 kg spacecraft biological laboratory was placed into a satisfactory 315 km near-circular earth orbit, successfully separated from the launch vehicle's second stage and was designated Biosatellite II. The scientific payload consisting of thirteen selected general biology and radiation experiments were subjected to planned, carefully controlled environmental conditions during 45 hours of earth-orbital flight. The decision was made to abbreviate the scheduled 3-day mission by approximately one day because of a threatening tropical storm in the recovery area, and a problem of communication with the spacecraft from the tracking stations. Highest priority was placed on recovery which was essential to obtain the scientific results on all the experiments. The operational phase of the mission came to a successful conclusion with the deorbit of the recovery capsule, deployment of the parachute system and air recovery by the United States Air Force. The 127 kg recovery capsule was returned to biology laboratories at Hickam Air Force Base, Hawaii, for disassembly and immediate inspection and analysis of the biological materials by the experimenters. It was evident immediately that the quality of the biology was excellent and this fact gave promise of a high return of scientific data. The environmental conditions provided to the experimental material in the spacecraft, provisions for experimental controls, and operational considerations are presented as they relate to interpretation of the experimental results.

  18. Retrovirus Epidemiology Donor Study-II (REDS-II)

    ClinicalTrials.gov

    2016-04-14

    Acquired Immunodeficiency Syndrome; Blood Donors; Blood Transfusion; HIV Infections; HIV-1; HIV-2; HTLV-I; HTLV-II; Retroviridae Infections; Hepatitis, Viral, Human; Hepatitis B; Hepacivirus; West Nile Virus

  19. Quininium tetra-chloridozinc(II).

    PubMed

    Chen, Li-Zhuang

    2009-09-05

    The asymmetric unit of the title compound {systematic name: 2-[hydr-oxy(6-meth-oxy-quinolin-1-ium-4-yl)meth-yl]-8-vinyl-quinuclidin-1-ium tetra-chlorido-zinc(II)}, (C(20)H(26)N(2)O(2))[ZnCl(4)], consists of a double proton-ated quininium cation and a tetra-chloridozinc(II) anion. The Zn(II) ion is in a slightly distorted tetra-hedral coordination environment. The crystal structure is stabilized by inter-molecular N-H⋯Cl and O-H⋯Cl hydrogen bonds.

  20. The Monomeric Pentacyanocobaltate (II) Anion.

    ERIC Educational Resources Information Center

    Mosha, Donnati M. S.

    1982-01-01

    Laboratory procedures, background information, and discussion of experimental results are provided for the preparation of Thallium (I) Pentacyanocobaltate (II). The preparation of this pale green salt is carried out in an aqueous medium. (Author/JN)

  1. Antibacterial Co(II), Cu(II), Ni(II) and Zn(II) Complexes of Thiadiazoles Schiff Bases

    PubMed Central

    Jaffery, Maimoon F.; Supuran, Claudiu T.

    2001-01-01

    Schiff bases were obtained by condensation of 2-amino-l,3,4-thiadiazole with 5-substituted-salicylaldehydes which were further used to obtain complexes of the type [M(L)2]Cl2, where M=Co(II), Cu(II), Ni(II) or Zn(II). The new compounds described here have been characterized by physical, spectral and analytical data, and have been screened for antibacterial activity against several bacterial strains such as Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa. The antibacterial potency of these Schiff bases increased upon chelation/complexation, against the tested bacterial species, opening new aproaches in the fight against antibiotic resistant strains. PMID:18475981

  2. Preparation, characterization and biological activity of Fe(III), Fe(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and UO 2(II) complexes of new cyclodiphosph(V)azane of sulfaguanidine

    NASA Astrophysics Data System (ADS)

    Sharaby, Carmen M.

    2005-11-01

    Novel hexachlorocyclodiphosph(V)azane of sulfaguanidine, H 4L, l,3-[ N'-amidino-sulfanilamide]-2,2,2,4,4,4-hexachlorocyclodiphosph(V)azane was prepared and its coordination behaviour towards the transition metal ions Fe(III), Fe(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and UO 2(II) was studied. The structures of the isolated products are proposed based on elemental analyses, IR, UV-vis, 1H NMR, mass spectra, reflectance, magnetic susceptibility measurements and thermogravimetric analysis (TGA). The hyperfine interactions in the isolated complex compounds were studied using 14.4 keV γ-ray from radioactive 57Co (Mössbauer spectroscopy). The data show that the ligand are coordinated to the metal ions via the sulfonamide O and deprotonated NH atoms in an octahedral manner. The H 4L ligand forms complexes of the general formulae [(MX z) 2(H 2L)H 2O) n] and [(FeSO 4) 2 (H 4L) (H 2O) 4], where X = NO 3 in case of UO 2(II) and Cl in case of Fe(III), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II). The molar conductance data show that the complexes are non-electrolytes. The thermal behaviour of the complexes was studied and different thermodynamic parameters were calculated using Coats-Redfern method. Most of the prepared complexes showed high bactericidal activity and some of the complexes show more activity compared with the ligand and standards.

  3. Optical Waveguide Scattering Reduction. II.

    DTIC Science & Technology

    1980-12-01

    FAD-AOAR 815 BATTELLEWCOLUMBUS LABS ON F/S 20/6 OPTICAL WAVEGUIDE SCATTER ING REDUC TION. II.(U) 7 DEC 80 0 W VAHEY, N F HARTMAN, R C SHERMAN F3361... OPTICAL WAVEGUIDE SCATTERING REDUCTION II M BATTELLE COLUMBUS LABORATORIES 505 KING AVENUE COLUMBUS, OHIO 43201 DTIC ELECTEf MAY 12 198111 December...reviewed and is approved for publication. DOUGLAS AWIWILLE, Project Engineer KENNETH R. HUTCHINSON, Chief Electro- Optics Techniques and Electro- Optics

  4. Determination of Fe(II)Fe(II) ratio in glass

    SciTech Connect

    Baumann, E.W.

    1989-07-26

    The procedure was designed for the simple, rapid determination of the Fe(II)/Fe(III) ratio in glass samples. The procedure consists of the following steps: dissolution of the pulverized glass sample in a sulfuric-hydrofluoric acid mixture, containing ammonium vanadate, which preserves the Fe(II) content; addition of boric acid to destroy iron-fluoride complexes, making the iron available for color formation with Ferrozine; addition of pH 5 buffer and Ferrozine reagent to form the magenta-colored ferrous-Ferrozine complex, with measurement of the absorbance for the determination of Fe(II) content; and, addition of ascorbic acid to reduce Fe(III) to Fe(II), with a second absorbance measurement that determines total Fe. Directions for the preparation of glass from non-radioactive sludge samples are provided. The analysis of this prepared glass for the Fe(II)/Fe(III) ratio is an indication of the ratio that would be in a plant batch of glass if made from this sludge.

  5. Adsorption of Cu(II), Ni(II) and Zn(II) on modified jute fibres.

    PubMed

    Shukla, S R; Pai, Roshan S

    2005-09-01

    The potential of a lignocellulosic fibre, jute, was assessed for adsorption of heavy metal ions like Cu(II), Ni(II) and Zn(II) from their aqueous solutions. The fibre was also used as adsorbent after chemically modifying it by two different techniques viz, loading of a dye with specific structure, C.I. Reactive Orange 13, and oxidising with hydrogen peroxide. Both the modified jute fibres gave higher metal ion adsorption. Thus, the dye loaded jute fibres showed metal ion uptake values of 8.4, 5.26 and 5.95 mg/g for Cu(II), Ni(II) and Zn(II), respectively, while the corresponding values for oxidised jute fibres were 7.73, 5.57 and 8.02 mg/g, as against 4.23, 3.37 and 3.55 mg/g for unmodified jute fibres. Adsorption isotherm models indicated best fit for Langmuir model for the modified jute fibres. The adsorption values decreased with lowering of pH. The desorption efficiency, regenerative and reuse capacity of these adsorbents were also assessed for three successive adsorption-desorption cycles. The adsorptive capacity was retained only when the caustic soda regeneration is carried out as an intermediate step after desorption. Possible mechanism has been given.

  6. The CDF SVX II upgrade for the Tevatron Run II

    SciTech Connect

    Bortoletto, Daniela

    1997-04-01

    A microstrip silicon detector SVX II has been proposed for the upgrade of CDF to be installed in 1999 for Run II of the Tevatron. Three barrels of five layers of double-sided silicon microstrip detectors will cover the interaction region. A description of the project status will be presented. Emphasis will be given to the R&D program for silicon sensors which includes capacitance minimization, the study of coupling capacitor integrity, the operation of the detectors in conjunction with the SVXH and SVX2 readout chips in two beam tests and the determination of the detectors performance deterioration due to radiation damage.

  7. BEATRIX-II, phase II: Data summary report

    SciTech Connect

    Slagle, O.D.; Hollenberg, G.W.

    1996-05-01

    The BEATRIX-II experimental program was an International Energy Agency sponsored collaborative effort between Japan, Canada, and the United States to evaluate the performance of ceramic solid breeder materials in a fast-neutron environment at high burnup levels. This report addresses the Phase II activities, which included two in situ tritium-recovery canisters: temperature-change and temperature-gradient. The temperature-change canister contained a Li{sub 2}O ring specimen that had a nearly uniform temperature profile and was capable of temperature changes between 530 and 640{degrees}C. The temperature-gradient canister contained a Li{sub 2}ZrO{sub 3} pebble bed operating under a thermal gradient of 440 to 1100{degrees}C. Postirradiation examination was carried out to characterize the Phase II in situ specimens and a series of nonvented capsules designed to address the compatibility of beryllium with lithium-ceramic solid-breeder materials. The results of the BEATRIX-II, Phase II, irradiation experiment provided an extensive data base on the in situ tritium-release characteristics of Li{sub 2}O and Li{sub 2}ZrO{sub 3} for lithium burnups near 5%. The composition of the sweep gas was found to be a critical parameter in the recovery of tritium from both Li{sub 2}O and Li{sub 2}ZrO{sub 3}. Tritium inventories measured confirmed that Li{sub 2}O and Li{sub 2}ZrO{sub 3} exhibited very low tritium retention during the Phase II irradiation. Tritium inventories in Li{sub 2}ZrO{sub 3} after Phase II tended to be larger than those found for Li{sub 2}ZrO{sub 3} in other in situ experiments, but the larger values may reflect the larger generation rates in BEATRIX-II. A series of 20 capsules was irradiated to determine the compatibility of lithium ceramics and beryllium under conditions similar to a fusion blanket. It is concluded that Li{sub 2}O and Li{sub 2}ZrO{sub 3} should remain leading candidates for use in a solid-breeder fusion-blanket application.

  8. EBR-II Data Digitization

    SciTech Connect

    Yoon, Su-Jong; Rabiti, Cristian; Sackett, John

    2014-08-01

    1. Objectives To produce a validation database out of those recorded signals it will be necessary also to identify the documents need to reconstruct the status of reactor at the time of the beginning of the recordings. This should comprehends the core loading specification (assemblies type and location and burn-up) along with this data the assemblies drawings and the core drawings will be identified. The first task of the project will be identify the location of the sensors, with respect the reactor plant layout, and the physical quantities recorded by the Experimental Breeder Reactor-II (EBR-II) data acquisition system. This first task will allow guiding and prioritizing the selection of drawings needed to numerically reproduce those signals. 1.1 Scopes and Deliverables The deliverables of this project are the list of sensors in EBR-II system, the identification of storing location of those sensors, identification of a core isotopic composition at the moment of the start of system recording. Information of the sensors in EBR-II reactor system was summarized from the EBR-II system design descriptions listed in Section 1.2.

  9. A temperature correction method for expanding atmospheres

    NASA Astrophysics Data System (ADS)

    Hamann, W.-R.; Gräfener, G.

    2003-11-01

    Model atmospheres form the basis for the interpretation of stellar spectra. A major problem in those model calculations is to establish the temperature stratification from the condition of radiative equilibrium. Dealing with non-LTE models for spherically expanding atmospheres of Wolf-Rayet stars, we developed a new temperature correction method. Its basic idea dates back to 1955 when it was proposed by Unsöld for grey, static and plane-parallel atmospheres in LTE. The equations were later generalized to the non-grey case by Lucy. In the present paper we furthermore drop the Eddington approximation, proceed to spherical geometry and allow for expansion of the atmosphere. Finally the concept of an ``approximate lambda operator'' is employed to speed up the convergence. Tests for Wolf-Rayet type models demonstrate that the method works fine even in situations of strong non-LTE.

  10. The Belle II Physics Program

    NASA Astrophysics Data System (ADS)

    Piilonen, Leo; Belle Collaboration, II

    2017-01-01

    The Belle II experiment at the asymmetric e+e- SuperKEKB collider is a major upgrade of the Belle experiment, which ran at the KEKB collider at the KEK laboratory in Japan. The design luminosity of SuperKEKB is 8 ×1035 cm-2 s-1, which is about 40 times higher than that of KEKB. The expected integrated luminosity of Belle II is 50 ab-1 in five years of running. The experiment will focus on searches for new physics beyond the Standard Model via high precision measurements of heavy flavor decays, and searches for rare signals. To reach these goals, the accelerator, detector, electronics, software, and computing systems are all being substantially upgraded. In this talk we discuss the physics program and the expected sensitivity to new physics of the Belle II data set.

  11. Belle II Silicon Vertex Detector

    NASA Astrophysics Data System (ADS)

    Dutta, D.; Adamczyk, K.; Aihara, H.; Angelini, C.; Aziz, T.; Babu, V.; Bacher, S.; Bahinipati, S.; Barberio, E.; Baroncelli, Ti.; Baroncelli, To.; Basith, A. K.; Batignani, G.; Bauer, A.; Behera, P. K.; Bergauer, T.; Bettarini, S.; Bhuyan, B.; Bilka, T.; Bosi, F.; Bosisio, L.; Bozek, A.; Buchsteiner, F.; Bulla, L.; Caria, G.; Casarosa, G.; Ceccanti, M.; Červenkov, D.; Chendvankar, S. R.; Dash, N.; De Pietro, G.; Divekar, S. T.; Doležal, Z.; Forti, F.; Friedl, M.; Hara, K.; Higuchi, T.; Horiguchi, T.; Irmler, C.; Ishikawa, A.; Jeon, H. B.; Joo, C.; Kandra, J.; Kambara, N.; Kang, K. H.; Kawasaki, T.; Kodyš, P.; Kohriki, T.; Koike, S.; Kolwalkar, M. M.; Kumar, R.; Kun, W.; Kvasnička, P.; La Licata, C.; Lanceri, L.; Lettenbicher, J.; Libby, J.; Lueck, T.; Maki, M.; Mammini, P.; Mayekar, S. N.; Mohanty, G. B.; Mohanty, S.; Morii, T.; Nakamura, K. R.; Natkaniec, Z.; Onuki, Y.; Ostrowicz, W.; Paladino, A.; Paoloni, E.; Park, H.; Pilo, F.; Profeti, A.; Rashevskaya, I.; Rao, K. K.; Rizzo, G.; Resmi, P. K.; Rozanska, M.; Sasaki, J.; Sato, N.; Schultschik, S.; Schwanda, C.; Seino, Y.; Shimizu, N.; Stypula, J.; Suzuki, J.; Tanaka, S.; Taylor, G. N.; Thalmeier, R.; Thomas, R.; Tsuboyama, T.; Uozumi, S.; Urquijo, P.; Vitale, L.; Watanuki, S.; Watanabe, M.; Watson, I. J.; Webb, J.; Wiechczynski, J.; Williams, S.; Würkner, B.; Yamamoto, H.; Yin, H.; Yoshinobu, T.; Zani, L.

    2017-02-01

    The Belle II experiment at the SuperKEKB asymmetric energy e+e‑ collider in KEK, Japan will operate at an instantaneous luminosity 40 times larger than that of its predecessor, Belle. It is built with an aim of collecting a huge amount of data (50 ab‑1 by 2025) for precise CP violation measurements and new physics search. Thus, we need an accurate vertex determination and reconstruction of low momentum tracks which will be achieved with the help of vertex detector (VXD). The Belle II VXD consists of two layers of DEPFET pixels (`Pixel Detector') and four layers of double-sided silicon microstrip sensors (`Silicon Vertex Detector'), assembled over carbon fibre ribs. In this paper, we discuss about the Belle II Silicon Vertex Detector, especially its design and key features; we also present its module (`ladder') assembly and testing procedures.

  12. NSLS-II INJECTION CONCEPT.

    SciTech Connect

    SHAFTAN, T.; PINAYEV, I.; ROSE, J.; WANG, X.J.; ET AL.

    2005-05-16

    Currently the facility upgrade project is in progress at the NSLS (at Brookhaven National Laboratory). The goal of the NSLS-II is a 3 GeV ultra-low-emittance storage ring that will increase radiation brightness by three orders of magnitude over that of the present NSLS X-ray ring. The low emittance of the high brightness ring's lattice results in a short lifetime, so that a top-off injection mode becomes an operational necessity. Therefore, the NSLS-II injection system must provide, and efficiently inject, an electron beam at a high repetition rate. In this paper, we present our concept of the NSLS-II injection system and discuss the conditions for, and constraints on, its design.

  13. Spacelab Mission Simulation-II

    NASA Technical Reports Server (NTRS)

    Sawin, C. F.; Shumate, W. H.

    1976-01-01

    The NASA Johnson Space Center conducted the second in a series of Spacelab mission simulations during the week of January 26-February 1, 1976. The facilities that supported the Spacelab Mission Simulation-II (SMS-II) included mock-ups of Spacelab, the Orbiter mid-deck and aft flight deck areas, and support areas simulating a mission control area and a payload operation control area. The SMS-II encompassed presently identified Spacelab mission requirements including experiment solicitation, evaluation, selection, and prioritization; crew selection and training; experiment hardware development, integration, and evaluation. The payload chosen included a cosmic ray physics experiment which was located on a pallet aft of the Spacelab and 20 biomedical experiments which were performed in the Spacelab. This paper will summarize simulation experience to date and list areas requiring substantial evaluation in the future.

  14. Titan II secondary payload capability

    NASA Astrophysics Data System (ADS)

    Butts, Aubrey J.; Nance, Milo; Odle, Roger C.

    Small satellite programs are often faced with the prospect of flying as a secondary payload because of size or funding considerations. This paper discusses a concept for flying such payloads on flights already scheduled on the Titan II SLV program over the next decade. The Titan II has the capability of inserting over 4200 lbs into LEO and larger payloads on ballistic trajectories from which higher orbits can be achieved when kick motors are used. Orbit changes are possible depending on the specific altitudes and payloads involved. Of the existing 13 remaining missions currently scheduled to fly on the Titan II SLV, excess performance is available on several missions that could be used to insert secondary payloads of up to 3000 lbs into their final orbit. This paper outlines an approach that would implement a secondary payload mission and allow small satellites to schedule a launch at a predetermined date through the year 2000.

  15. A new chelating resin for preconcentration and determination of Mn(II), Ni(II), Cu(II), Zn(II), Cd(II), and Pb(II) by flame atomic absorption spectrometry.

    PubMed

    Maheswari, Mohan A; Subramanian, Mandakolathur S

    2003-01-01

    A new polychelatogen, AXAD-16-1,2-diphenylethanolamine, was developed by chemically modifying Amberlite XAD-16 with 1,2-diphenylethanolamine to produce an effective metal-chelating functionality for the preconcentration of Mn(II), Ni(II), Cu(II), Zn(II), Cd(II), and Pb(II) and their determination by flame atomic absorption spectrometry. Various physiochemical parameters that influence the quantitative preconcentration and recovery of metal were optimized by both static and dynamic techniques. The resin showed superior extraction efficiency with high-metal loading capacity values of 0.73, 0.80, 0.77, 0.87, 0.74, and 0.81 mmol/g for Mn(II), Ni(II), Cu(II), Zn(II), Cd(II), and Pb(II), respectively. The system also showed rapid metal-ion extraction and stripping, with complete saturation in the sorbent phase within 15 min for all the metal ions. The optimum condition for effective metal-ion extraction was found to be a neutral pH, which is a great advantage in the preconcentration of trace metal ions from natural water samples without any chemical pretreatment of the sample. The resin also demonstrated exclusive ion selectivity toward targeted metal ions by showing greater resistivity to various complexing species and more common metal ions during analyte concentration, which ultimately led to high preconcentration factors of 700 for Cu(II); 600 for Mn(II), Ni(II), and Zn(II); and 500 for Cd(II) and Pb(II), arising from a larger sample breakthrough volume. The lower limits of metal-ion detection were 7 ng/mL for Mn(II) and Ni(II); 5 ng/mL for Cu(II), Zn(II), and Cd(II), and 10 ng/mL for Pb(II). The developed resin was successful in preconcentrating metal ions from synthetic and real water samples, multivitamin-multimineral tablets, and curry leaves (Murraya koenigii) with relative standard deviations of < or = 3.0% for all analytical measurements, which demonstrated its practical utility.

  16. Administrative Plans. STIP II (Skill Training Improvement Programs Round II).

    ERIC Educational Resources Information Center

    Los Angeles Community Coll. District, CA.

    Personnel policies, job responsibilities, and accounting procedures are summarized for the Los Angeles Community College District's Skill Training Improvement Programs (STIP II). This report first cites references to the established personnel and affirmative action procedures governing the program and then presents an organizational chart for the…

  17. Propulsion Systems for Aircraft. Aerospace Education II. Instructional Unit II.

    ERIC Educational Resources Information Center

    Elmer, James D.

    This curriculum guide accompanies another publication in the Aerospace Education II series entitled "Propulsion Systems for Aircraft." The guide includes specific guidelines for teachers on each chapter in the textbook. Suggestions are included for objectives (traditional and behavioral), suggested outline, orientation, suggested key…

  18. Helium II level measurement techniques

    NASA Astrophysics Data System (ADS)

    Celik, D.; Hilton, D. K.; Zhang, T.; Van Sciver, S. W.

    2001-05-01

    In this paper, a survey of cryogenic liquid level measurement techniques applicable to superfluid helium (He II) is given. The survey includes both continuous and discrete measurement techniques. A number of different probes and controlling circuits for this purpose have been described in the literature. They fall into one of the following categories: capacitive liquid level gauges, superconducting wire liquid level gauges, thermodynamic (heat transfer-based) liquid level gauges, resistive gauges, ultrasound and transmission line-based level detectors. The present paper reviews these techniques and their suitability for He II service. In addition to these methods, techniques for measuring the total liquid volume and mass gauging are also discussed.

  19. Belle II Early Physics Program

    NASA Astrophysics Data System (ADS)

    Stottler, Zachary; Belle Collaboration, II

    2017-01-01

    The Belle II experiment at the SuperKEKB collider is a major upgrade of the KEK `` B factory'' facility in Tsukuba, Japan. First beams are planned for early 2017 and first physics data will be recorded in the middle of 2018 during Phase 2 commissioning, while the Belle II detector is still missing its vertex detector system. In this talk we describe the physics program for this early data. The program will focus on bottomonium spectroscopy at different center-of-mass energies, in particular at the ϒ(3 S) and ϒ(6 S) resonances, amongst other energy points.

  20. Distributed Computing at Belle II

    NASA Astrophysics Data System (ADS)

    Bansal, Vikas; Belle Collaboration, II

    2016-03-01

    The Belle II experiment at the SuperKEKB collider in Tsukuba, Japan, will start physics data taking in 2018 and will accumulate 50 ab-1 of e+e- collision data, about 50 times larger than the data set of the earlier Belle experiment. The computing requirements of Belle II are comparable to those of a RUN I high-pT LHC experiment. Computing will make full use of high speed networking and of the Computing Grids in North America, Asia and Europe. Results of an initial MC simulation campaign with 5 ab-1 equivalent luminosity will be described.

  1. The PEP-II design

    SciTech Connect

    Sullivan, M.K.

    1995-05-01

    The Stanford Linear Accelerator Center (SLAC), Lawrence Berkeley Laboratory (LBL), Lawrence Livermore National Laboratory (LLNL) Positron Electron Project-II (PEP-II) is a design for a high-luminosity, asymmetric energy, electron-positron colliding beam accelerator that will operate at the center-of-mass energy of the {Upsilon}4S (10.58 GeV). The goal of the design is to achieve a large enough integrated luminosity with a moving center-of-mass reference frame to he able to observe the predicted rare decay modes of the {Upsilon}4S that do not conserve charge parity (CP).

  2. First results from SAGE II

    SciTech Connect

    Abdurashitov, J.N.; Faizov, E.L.; Gavrin, V.N.

    1994-07-01

    The Russian-American Gallium solar neutrino Experiment (SAGE) began the second phase of operation (SAGE II) in September of 1992. Monthly measurements of the integral flux of solar neutrinos have been made with 55 tonnes of gallium. The K-peak results of the first five runs of SAGE II give a capture rate of 76{sub {minus}18}{sup +21} (stat) {sub {minus}7}{sup +5} (sys) SNU. combined with the SAGE I result, the capture rate is 74{sub {minus}12}{sup +13} (stat) {sub {minus}7}{sup +5} (sys) SNU. This represents only 56%--60% of the capture rate predicted by different Standard Solar Models.

  3. Heavy Stars Thrive among Heavy Elements

    NASA Astrophysics Data System (ADS)

    2002-08-01

    VLT Observes Wolf-Rayet Stars in Virgo Cluster Galaxies [1] Summary Do very massive stars form in metal-rich regions of the Universe and in the nuclei of galaxies ? Or does "heavy element poisoning" stop stellar growth at an early stage, before young stars reach the "heavyweight class"? What may at the first glance appear as a question for specialists actually has profound implications for our understanding of the evolution of galaxies, those systems of billions of stars - the main building blocks of the Universe. With an enormous output of electromagnetic radiation and energetic elementary particles, massive stars exert a decisive influence on the surrounding (interstellar) gas and dust clouds . They also eject large amounts of processed elements, thereby participating in the gradual build-up of the many elements we see today. Thus the presence or absence of such stars at the centres of galaxies can significantly change the overall development of those regions and hence, presumably, that of the entire galaxy. A team of European astronomers [2] has now directly observed the presence of so-called Wolf-Rayet stars (born with masses of 60 - 90 times that of the Sun or more) within metal-rich regions in some galaxies in the Virgo cluster, some 50 million light-years away. This is the first unambiguous detection of such massive stellar objects in metal-rich regions . PR Photo 20a/02 : H II regions in the Virgo cluster galaxy NGC 4254 . PR Photo 20b/02 : Multi-object-slit observation of galaxy NGC 4303 . PR Photo 20c/02 : Spectrum of H II region in NGC 4254 with Wolf-Rayet signatures. Production of heavy elements in the Universe Most scientists agree that the Universe in which we live underwent a dramatic event, known as the Big Bang , approximately 15,000 million years ago. During the early moments, elementary particles were formed which after some time united into more complex nuclei and in turn resulted in the production of hydrogen and helium atoms and their isotopes

  4. Preparation and characterization of multi-carboxyl-functionalized silica gel for removal of Cu (II), Cd (II), Ni (II) and Zn (II) from aqueous solution

    NASA Astrophysics Data System (ADS)

    Li, Min; Li, Ming-yu; Feng, Chang-gen; Zeng, Qing-xuan

    2014-09-01

    In this paper, the multi-carboxyl-functionalized silica gel was prepared by surface grafting method and applied for the removal of Cu (II), Cd (II), Ni (II) and Zn (II) from aqueous solution. The adsorbent was characterized by FT-IR, thermogravimetry, Brunauer-Emmett-Teller surface area measurement and elemental analysis, and it proved that the organic functional group, carboxyl group, was grafted successfully onto the silica gel surface. The effect of solution pH on removal efficiencies of Cu (II), Cd (II), Ni (II) and Zn (II) was investigated and it was found that with the exception of Zn (II), the removal efficiencies of the rest of metal ions increased with the increasing of pH in the solution, the maximum removal efficiency occurred at pH 6.0, whereas the maximum removal efficiency for Zn (II) was found to be at pH 7.0. Adsorption equilibrium data were well fitted to Langmuir than Freundlich isotherm model and the maximum adsorption capacity for Cu (II), Cd (II), Ni (II) and Zn (II) was 47.07, 41.48, 30.80 and 39.96 mg/g, respectively. Competitive adsorption experiments demonstrated that the adsorbent material had excellent adsorption amount and high affinity for the Cu (II) in the binary systems. In addition, the column experiments were used to investigate stability and reusability of the adsorbent, the dynamic adsorption performance, and desorption of metal ions absorbed from the adsorbent. The results confirmed that the adsorbent presents good dynamic adsorption performance for Cu (II), Cd (II), Ni (II) and Zn (II) and these metal ions adsorbed were easy to be desorbed from the adsorbent. The adsorption capacities of metal ions did not present an obvious decrease after five cycles of adsorption-desorption.

  5. Spectroscopic Monitoring of Southern Galactic O and WN Stars

    NASA Astrophysics Data System (ADS)

    Gamen, R.; Barbá, R. H.; Morrell, N. I.; Arias, J.; Maíz Apellániz, J.

    2008-08-01

    We are conducting a spectroscopic monitoring of O- and WN-type stars for which there is no indication of multiplicity in the Galactic O-Stars Catalog (Maíz-Apellániz et al. 2004) or in the VIIth Catalog of Galactic Wolf-Rayet Stars (van der Hucht 2001). We search for radial-velocity (RV) variations indicative of orbital motion.

  6. A study of spectra of Cyg X-3 observed by BeppoSAX

    NASA Astrophysics Data System (ADS)

    Szostek, A.; Zdziarski, A. A.

    2005-06-01

    We model the ~1-200 keV spectra of Cygnus X-3 observed by BeppoSAX. The continuum, modeled by Comptonization in a hybrid plasma, is modified by the strongly ionized plasma of the stellar wind of the Wolf-Rayet companion star. Discrete absorption and emission spectral features are modeled with XSTAR. The model has been applied to phase-resolved spectra in the hard and soft spectral states.

  7. Electromagnetic calorimeter for Belle II

    NASA Astrophysics Data System (ADS)

    Belle-ECL; Aulchenko, V.; Bobrov, A.; Bondar, A.; Cheon, B. G.; Eidelman, S.; Epifanov, D.; Garmash, Yu; Goh, Y. M.; Kim, S. H.; Krokovny, P.; Kuzmin, A.; Lee, I. S.; Matvienko, D.; Miyabayashi, K.; Nakamura, I.; Shebalin, V.; Shwartz, B.; Unno, Y.; Usov, Yu; Vinokurova, A.; Vorobjev, V.; Zhilich, V.; Zhulanov, V.

    2015-02-01

    The electromagnetic calorimeter of the BELLE II detector for experiments at Super B-factory SuperKEKB is briefly described. The project of the calorimeter upgrade to meet severe background conditions expected at the upgraded KEK B factory is presented.

  8. Solar Ca II K Observations

    NASA Astrophysics Data System (ADS)

    Bertello, Luca; Pevtsov, Alexei A.; Tlatov, Andrey; Singh, Jagdev

    2016-07-01

    Some of the most important archives of past and current long-term solar synoptic observations in the resonance line of Ca II K are described here. These observations are very important for understanding the state of the solar magnetism on time scales up to several decades. The first observations of this kind began in 1904 at the Kodaikanal Observatory (India), followed by similar programs at different other locations. Regular full-disk Ca II K monitoring programs started in 1915 at the Mount Wilson Observatory (USA) and in 1917 at the National Solar Observatory of Japan. Beginning in 1919 and in 1926 regular observations were taken also at the Paris-Meudon Observatory (France) and at the "Donati solar tower telescope of the Arcetri Astrophysical Observatory in Italy, respectively. In 1926 the the Astronomical Observatory of the Coimbra University in Portugal started its own program of Ca II K observations. Although some of these programs have been terminated over the years, their data archives constitute a unique resource for studies of solar variability. In the early 1970s, the National Solar Observatory (NSO) at Sacramento Peak (USA) started a new program of daily Sun-as-a-star observations in the Ca II K line. Today the NSO is continuing these observations through its Synoptic Optical Long-term Investigations of the Sun (SOLIS) facility.

  9. The Bender-Gestalt II.

    PubMed

    Brannigan, Gary G; Decker, Scott L

    2006-01-01

    In 2003, the Bender-Gestalt II was published. In the present article, the revision process is described, and major changes to the test are discussed. These changes include additional designs, a memory (recall) phase, Motor and Perception supplementary tests, a detailed observation form, a global scoring system, and a large, nationally representative normative base. Directions for future research are also provided.

  10. National Synchrotron Light Source II

    SciTech Connect

    Hill, John; Dooryhee, Eric; Wilkins, Stuart; Miller, Lisa; Chu, Yong

    2016-04-25

    NSLS-II is a synchrotron light source helping researchers explore solutions to the grand energy challenges faced by the nation, and open up new regimes of scientific discovery that will pave the way to discoveries in physics, chemistry, and biology — advances that will ultimately enhance national security and help drive the development of abundant, safe, and clean energy technologies.

  11. Tech Area II: A history

    SciTech Connect

    Ullrich, R.

    1998-07-01

    This report documents the history of the major buildings in Sandia National Laboratories` Technical Area II. It was prepared in support of the Department of Energy`s compliance with Section 106 of the National Historic Preservation Act. Technical Area II was designed and constructed in 1948 specifically for the final assembly of the non-nuclear components of nuclear weapons, and was the primary site conducting such assembly until 1952. Both the architecture and location of the oldest buildings in the area reflect their original purpose. Assembly activities continued in Area II from 1952 to 1957, but the major responsibility for this work shifted to other sites in the Atomic Energy Commission`s integrated contractor complex. Gradually, additional buildings were constructed and the original buildings were modified. After 1960, the Area`s primary purpose was the research and testing of high-explosive components for nuclear weapons. In 1994, Sandia constructed new facilities for work on high-explosive components outside of the original Area II diamond-shaped parcel. Most of the buildings in the area are vacant and Sandia has no plans to use them. They are proposed for decontamination and demolition as funding becomes available.

  12. National Synchrotron Light Source II

    ScienceCinema

    Hill, John; Dooryhee, Eric; Wilkins, Stuart; Miller, Lisa; Chu, Yong

    2016-07-12

    NSLS-II is a synchrotron light source helping researchers explore solutions to the grand energy challenges faced by the nation, and open up new regimes of scientific discovery that will pave the way to discoveries in physics, chemistry, and biology — advances that will ultimately enhance national security and help drive the development of abundant, safe, and clean energy technologies.

  13. NSLS-II RF SYSTEMS

    SciTech Connect

    Rose, J.; Gash, W.; Holub, B.; Kawashima, Y.; Ma, H.; Towne, N.; Yeddulla, M.

    2011-03-28

    The NSLS-II is a new third generation light source being constructed at Brookhaven Lab. The storage ring is optimized for low emittance by use of damping wigglers to reduce the emittance to below 1 nm-rad. The RF systems are designed to provide stable beam through tight RF phase and amplitude stability requirements.

  14. 40 K Fastrac II Test

    NASA Technical Reports Server (NTRS)

    1997-01-01

    A 40 K Fastrac II duration test performed at Marshall Test Stand 116. The purpose of this test was to gauge the length of time between contact of TEA (Triethylenealuminum) and LOX (liquid oxygen) as an ignitor for the Fastrac engine.

  15. Achondrogenesis type II with polydactyly.

    PubMed

    Rittler, M; Orioli, I M

    1995-11-06

    We report on a newborn male infant who presented the typical findings of achondrogenesis type II (Langer-Saldino), and who also showed postaxial polydactyly on both feet and bilateral microtia. Polydactyly is frequently part of the short-rib syndromes, but has not been reported in achondrogenesis. The hypothesis of polydactyly as part of a contiguous gene syndrome is discussed.

  16. Military Aerospace. Aerospace Education II.

    ERIC Educational Resources Information Center

    Smith, J. C.

    This book is a revised publication in the series on Aerospace Education II. It describes the employment of aerospace forces, their methods of operation, and some of the weapons and equipment used in combat and combat support activities. The first chapter describes some of the national objectives and policies served by the Air Force in peace and…

  17. Application Programming in AWIPS II

    NASA Technical Reports Server (NTRS)

    Smit, Matt; McGrath, Kevin; Burks, Jason; Carcione, Brian

    2012-01-01

    Since its inception almost 8 years ago, NASA's Short-term Prediction Research and Transition (SPoRT) Center has integrated NASA data into the National Weather Service's decision support system (DSS) the Advanced Weather Interactive Processing System (AWIPS). SPoRT has, in some instances, had to shape and transform data sets into various formats and manipulate configurations to visualize them in AWIPS. With the advent of the next generation of DSS, AWIPS II, developers will be able to develop their own plugins to handle any type of data. Raytheon is developing AWIPS II to be a more extensible package written mainly in Java, and built around a Service Oriented Architecture. A plugin architecture will allow users to install their own code modules, and (if all the rules have been properly followed) they will work hand-in-hand with AWIPS II as if it were originally built in. Users can bring in new datasets with existing plugins, tweak plugins to handle a nuance or desired new functionality, or create an entirely new visualization layout for a new dataset. SPoRT is developing plugins to ensure its existing NASA data will be ready for AWIPS II when it is delivered, and to prepare for the future of new instruments on upcoming satellites.

  18. Comparative studies of aerosol extinction measurements made by the SAM II and SAGE II satellite experiments

    NASA Technical Reports Server (NTRS)

    Yue, Glenn K.; Mccormick, M. P.; Chu, W. P.; Wang, P.; Osborn, M. T.

    1989-01-01

    Results from the Stratospheric Aerosol Measurement (SAM) II and Stratospheric Aerosol and Gas Experiment (SAGE) II are compared for measurement locations which are coincident in time and space. At 1.0 micron, the SAM II and SAGE II aerosol extinction profiles are similar within their measurement errors. In addition, sunrise and sunset aerosol extinction data at four different wavelengths are compared for occasions when the SAGE II and SAM II measurements are nearly coincident in space and about 12 hours apart.

  19. Synthesis, spectroscopic, antimicrobial and DNA cleavage studies of new Co(II), Ni(II), Cu(II), Cd(II), Zn(II) and Hg(II) complexes with naphthofuran-2-carbohydrazide Schiff base

    NASA Astrophysics Data System (ADS)

    Halli, Madappa B.; Sumathi, R. B.

    2012-08-01

    A series of Co(II), Ni(II), Cu(II), Cd(II), Zn(II) and Hg(II) complexes have been synthesized with newly synthesized Schiff base derived from naphthofuran-2-carbohydrazide and cinnamaldehyde. The elemental analyses of the complexes are confined to the stoichiometry of the type MLCl2 [M = Co(II) and Cu(II)], ML2Cl2 [M = Ni(II), Cd(II), Zn(II) and Hg(II)] respectively, where L is Schiff base ligand. Structures have been proposed from elemental analyses, IR, electronic, mass, 1H NMR, ESR spectral data, magnetic, and thermal studies. The measured low molar conductance values in DMF indicate that the complexes are non-electrolytes. Spectroscopic studies suggest coordination occurs through azomethine nitrogen and carbonyl oxygen of the ligand with the metal ions. The Schiff base and its complexes have been screened for their antibacterial (Escherichia coli, Staphylococcus aureus, Bacillus subtilis and Salmonella typhi) and antifungal (Aspergillus niger, Aspergillus flavus, Cladosporium and Candida albicans) activities by minimum inhibitory concentration (MIC) method. The DNA cleavage studies by agarose gel electrophoresis method was studied for all the complexes.

  20. Epilepsy Care in Developing Countries: Part II of II

    PubMed Central

    Birbeck, Gretchen L

    2010-01-01

    Although 80% of people with epilepsy reside in resource poor, developing countries, epilepsy care in these regions remains limited and the majority of epilepsy patients go untreated. Cost-effective, sustainable epilepsy care services, delivering first-line antiepileptic drugs through established primary health care facilities, are needed to decrease these treatment gaps. Neurologists with local experience and knowledge of the culture, who are willing to serve as educators, policy advisors, and advocates, can make a difference. This is Part II of a two-part article. Part I reviewed the burden of epilepsy and the current state of resources for treatment in developing countries, while Part II will now discuss various aspects of care in these countries. PMID:20944819

  1. Possible binary progenitors for the Type Ib supernova iPTF13bvn

    NASA Astrophysics Data System (ADS)

    Eldridge, J. J.; Fraser, Morgan; Maund, Justyn R.; Smartt, Stephen J.

    2015-01-01

    Cao et al. reported a possible progenitor detection for the Type Ib supernovae iPTF13bvn for the first time. We find that the progenitor is in fact brighter than the magnitudes previously reported by approximately 0.7-0.2 mag with a larger error in the bluer filters. We compare our new magnitudes to our large set of binary evolution models and find that many binary models with initial masses in the range of 10-20 M⊙ match this new photometry and other constraints suggested from analysing the supernova. In addition, these lower mass stars retain more helium at the end of the model evolution indicating that they are likely to be observed as Type Ib supernovae rather than their more massive, Wolf-Rayet counter parts. We are able to rule out typical Wolf-Rayet models as the progenitor because their ejecta masses are too high and they do not fit the observed SED unless they have a massive companion which is the observed source at the supernova location. Therefore only late-time observations of the location will truly confirm if the progenitor was a helium giant and not a Wolf-Rayet star.

  2. Sloan Digital Sky Survey II (SDSS-II) Supernova Data

    DOE Data Explorer

    The Sloan Digital Sky Survey (SDSS) is a series of three interlocking imaging and spectroscopic surveys, carried out over an eight-year period with a dedicated 2.5m telescope located at Apache Point Observatory in Southern New Mexico. The SDSS Supernova Survey was one of those three components of SDSS and SDSS-II, a 3-year extension of the original SDSS that operated from July 2005 to July 2008. The Supernova Survey was a time-domain survey, involving repeat imaging of the same region of sky every other night, weather permitting. The primary scientific motivation was to detect and measure light curves for several hundred supernovae through repeat scans of the SDSS Southern equatorial stripe 82 (about 2.5? wide by ~120? long). Over the course of three 3-month campaigns SDSS-II SN discovered and measured multi-band lightcurves for ~500 spectroscopically confirmed Type Ia supernovae in the redshift range z=0.05-0.4. In addition, the project harvested a few hundred light curves for SNe Ia and discovered about 80 spectroscopically confirmed core-collapse supernovae (supernova types Ib/c and II).

  3. Cytotoxic copper(II), cobalt(II), zinc(II), and nickel(II) coordination compounds of clotrimazole.

    PubMed

    Betanzos-Lara, Soledad; Gómez-Ruiz, Celedonio; Barrón-Sosa, Lidia R; Gracia-Mora, Isabel; Flores-Álamo, Marcos; Barba-Behrens, Noráh

    2012-09-01

    Sixteen novel mononuclear Cu(II), Co(II), Zn(II), and Ni(II) complexes of the biologically active ligand clotrimazole (clotri) of the forms [M(clotri)(2)Cl(2)]·nH(2)O (1-4), [M(clotri)(2)Br(2)]·nH(2)O (5-7), [M(clotri)(3)Br(2)] (8), [M(clotri)(3)NO(3)]NO(3)·nH(2)O (9, 11), [M(clotri)(3)(NO(3))(2)]·nH(2)O (10), and [M(clotri)(3)(OH(2))(2)NO(3)]NO(3)·nH(2)O (12) were synthesized and fully characterized. Dinuclear [Cu(2)(clotri)(4)μ(2)-Cl(4)]·2H(2)O (1a) and [Cu(2)(clotri)(4)μ(2)-Br(2)]·2H(2)O (5b) as well as tetranuclear [Cu(4)(clotri)(4)μ(4)-Br(6)μ(4)-O] (5a) complexes were also isolated. Complexes 1-7, 9, and 11 present a tetrahedral geometry; complex 8 exhibits a pentacoordinated structure; complexes 1a, 10 and 12 an octahedral geometry. X-ray crystal structures of [Cu(clotri)(2)Cl(2)](1), [Cu(clotri)(2)(EtOH)Cl(2)](1·EtOH), [Zn(clotri)(2)Cl(2)] (3), [Zn(clotri)(2)Br(2)] (7), and [Cu(4)(clotri)(4)μ(4)-Br(6)μ(4)-O] (5a) were obtained. Complexes 1-12 were tested for cytotoxic activity against the human carcinoma cell lines HeLa (cervix-uterine), PC3 (prostate), and HCT-15 (colon) displaying IC(50) values <30 μM. Confocal microscopy and nuclear dying (DAPI) for complex 1 showed condensation of cromatin and nuclear membrane fragmentation. Immunocytochemical detection/expression of biomarkers suggests that complexes 1 and 9 induce cell death via apoptosis. TUNEL assay detected DNA fragmentation in HeLa cells, resulting from apoptotic signaling cascades induced by Cu(II) complexes 1 and 9. (1)H NMR studies of the Zn(II) complexes showed that they can bind to nucleotides.

  4. VLT/GIRAFFE spectroscopic observations of the metal-poor blue compact dwarf galaxy SBS 0335-052E

    NASA Astrophysics Data System (ADS)

    Izotov, Y. I.; Schaerer, D.; Blecha, A.; Royer, F.; Guseva, N. G.; North, P.

    2006-11-01

    .01, respectively. We derive the He mass fraction taking into account all systematic effects. The He mass fraction Y = 0.2463 ± 0.0030, derived from the emission of the whole H II region, is consistent with the primordial value predicted by the standard Big Bang nucleosynthesis model. We confirm the presence of Wolf-Rayet stars in cluster 3.

  5. Spectral, IR and magnetic studies of Mn(II), Co(II), Ni(II) and Cu(II) complexes with pyrrole-2-carboxyaldehyde thiosemicarbazone (L).

    PubMed

    Chandra, Sulekh; Kumar, Anil

    2007-11-01

    Mn(II), Co(II), Ni(II) and Cu(II) complexes are synthesized with thiosemicarbazone (L) derived from pyrrole-2-carboxyaldehyde. These complexes are characterized by elemental analysis, molar conductance, magnetic susceptibility measurement, mass, IR, electronic and EPR spectral studies. The molar conductance measurement of the complexes in DMSO indicates that the complexes are non-electrolyte except Co(L)2(NO3)2 and Ni(L)2(NO3)2 complexes which are 1:2 electrolyte. All the complexes are of high-spin type. On the basis of spectral studies an octahedral geometry may be assigned for Mn(II), Co(II) and Ni(II) complexes except Co(L)2(NO3)2 and Ni(L)2(NO3)2 which are of tetrahedral geometry. A tetragonal geometry may be suggested for Cu(II) complexes.

  6. Jefferson Lab's Trim Card II

    SciTech Connect

    Trent Allison; Sarin Philip; C. Higgins; Edward Martin; William Merz

    2005-05-01

    Jefferson Lab's Continuous Electron Beam Accelerator Facility (CEBAF) uses Trim Card I power supplies to drive approximately 1900 correction magnets. These trim cards have had a long and illustrious service record. However, some of the employed technology is now obsolete, making it difficult to maintain the system and retain adequate spares. The Trim Card II is being developed to act as a transparent replacement for its aging predecessor. A modular approach has been taken in its development to facilitate the substitution of sections for future improvements and maintenance. The resulting design has been divided into a motherboard and 7 daughter cards which has also allowed for parallel development. The Trim Card II utilizes modern technologies such as a Field Programmable Gate Array (FPGA) and a microprocessor to embed trim card controls and diagnostics. These reprogrammable devices also provide the versatility to incorporate future requirements.

  7. Belle II silicon vertex detector

    NASA Astrophysics Data System (ADS)

    Adamczyk, K.; Aihara, H.; Angelini, C.; Aziz, T.; Babu, V.; Bacher, S.; Bahinipati, S.; Barberio, E.; Baroncelli, Ti.; Baroncelli, To.; Basith, A. K.; Batignani, G.; Bauer, A.; Behera, P. K.; Bergauer, T.; Bettarini, S.; Bhuyan, B.; Bilka, T.; Bosi, F.; Bosisio, L.; Bozek, A.; Buchsteiner, F.; Casarosa, G.; Ceccanti, M.; Červenkov, D.; Chendvankar, S. R.; Dash, N.; Divekar, S. T.; Doležal, Z.; Dutta, D.; Enami, K.; Forti, F.; Friedl, M.; Hara, K.; Higuchi, T.; Horiguchi, T.; Irmler, C.; Ishikawa, A.; Jeon, H. B.; Joo, C. W.; Kandra, J.; Kang, K. H.; Kato, E.; Kawasaki, T.; Kodyš, P.; Kohriki, T.; Koike, S.; Kolwalkar, M. M.; Kvasnička, P.; Lanceri, L.; Lettenbicher, J.; Maki, M.; Mammini, P.; Mayekar, S. N.; Mohanty, G. B.; Mohanty, S.; Morii, T.; Nakamura, K. R.; Natkaniec, Z.; Negishi, K.; Nisar, N. K.; Onuki, Y.; Ostrowicz, W.; Paladino, A.; Paoloni, E.; Park, H.; Pilo, F.; Profeti, A.; Rashevskaya, I.; Rao, K. K.; Rizzo, G.; Rozanska, M.; Sandilya, S.; Sasaki, J.; Sato, N.; Schultschik, S.; Schwanda, C.; Seino, Y.; Shimizu, N.; Stypula, J.; Suzuki, J.; Tanaka, S.; Tanida, K.; Taylor, G. N.; Thalmeier, R.; Thomas, R.; Tsuboyama, T.; Uozumi, S.; Urquijo, P.; Vitale, L.; Volpi, M.; Watanuki, S.; Watson, I. J.; Webb, J.; Wiechczynski, J.; Williams, S.; Würkner, B.; Yamamoto, H.; Yin, H.; Yoshinobu, T.

    2016-09-01

    The Belle II experiment at the SuperKEKB collider in Japan is designed to indirectly probe new physics using approximately 50 times the data recorded by its predecessor. An accurate determination of the decay-point position of subatomic particles such as beauty and charm hadrons as well as a precise measurement of low-momentum charged particles will play a key role in this pursuit. These will be accomplished by an inner tracking device comprising two layers of pixelated silicon detector and four layers of silicon vertex detector based on double-sided microstrip sensors. We describe herein the design, prototyping and construction efforts of the Belle-II silicon vertex detector.

  8. Particle Identification at Belle II

    NASA Astrophysics Data System (ADS)

    Sandilya, S.; Belle Collaboration, II

    2016-11-01

    We report on the charged particle identification (PID) systems for the upcoming Belle II experiment. The time of propagation counter in the central region and the proximity focusing ring imaging Cherenkov counters with aerogel radiator in the forward region will be used as the PID devices. They are expected to provide a kaon identification efficiency of more than 94% at a low pion misidentification probability of 4%. The motivation for the upgrade, method and status of both systems are discussed.

  9. Sorption of lead (II), cobalt (II) and copper (II) ions from aqueous solutions by γ-MnO2 nanostructure

    NASA Astrophysics Data System (ADS)

    Chung Le, Ngoc; Van Phuc, Dinh

    2015-01-01

    Manganese dioxide γ-MnO2 was synthesized via the reduction-oxidation reaction between KMnO4 and C2H5OH at room temperature and characterized with x-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Brunauer-Emmet-Teller nitrogen adsorption (BET-N2 adsorption). The results showed that γ-MnO2 was about 10-18 nm in size and the BET surface area was about 65 m2 g-1. The feasibility of γ-MnO2 used as a low cost adsorbent for the adsorption of Pb(II), Co(II) and Cu(II) from aqueous solutions was explored. During the adsorption process, batch technique was used, and the effects of contact time and pH on adsorption efficiency under room temperature were studied. The adsorption data showed that the Freundlich, Langmuir and Redlich-Peterson isotherms are a good model for the sorption of Co(II) and Cu(II), while the Langmuir and Redlich-Peterson isotherms provide a reasonable fit to the experimental data for Pb(II). By using the Langmuir isotherm, the adsorption capacities for Pb(II), Co(II) and Cu(II) are found to be 200 mg g-1, 90.91 mg g-1 and 83.33 mg g-1, respectively. The effectiveness of γ-MnO2 in the sorption of the three metal ions from aqueous system has the order Pb(II) > Co(II) > Cu(II). Kinetic studies showed that a pseudo-second-order model was more suitable than the pseudo-first-order model. Also, the intra-particle diffusion models were used to ascertain the mechanism of the sorption process. It is concluded that γ-MnO2 can be used as an effective adsorbent for removing Pb(II), Co(II) and Cu(II) from aqueous solutions.

  10. Topaz II preliminary safety assessment

    NASA Astrophysics Data System (ADS)

    Marshall, Albert C.; Standley, Vaughn; Voss, Susan S.; Haskin, Eric

    1993-01-01

    The Strategic Defense Initiative Organization (SDIO) decided to investigate the possibility of launching a Russian Topaz II space nuclear power system. A preliminary safety assessment was conducted to determine whether or not a space mission could be conducted safely and within budget constraints. As part of this assessment, a safety policy and safety functional requirements were developed to guide both the safety assessment and future Topaz II activities. A review of the Russian flight safety program was conducted and documented. Our preliminary safety assessment included a top level event tree, neutronic analysis of normal and accident configurations, an evaluation of temperature coefficients of reactivity, a reentry and disposal analysis, and analysis of postulated launch abort impact accidents, and an analysis of postulated propellant fire and explosion accidents. Based on the assessment, it appears that it will be possible to safely launch the Topaz II system in the U.S. with some possible system modifications. The principal system modifications will probably include design changes to preclude water flooded criticality and to assure intact reentry.

  11. Testing the Gossamer Albatross II

    NASA Technical Reports Server (NTRS)

    1980-01-01

    The Gossamer Albatross II is seen here during a test flight at NASA's Dryden Flight Research Center, Edwards, California. The original Gossamer Albatross is best known for completing the first completely human powered flight across the English Channel on June 12, 1979. The Albatross II was the backup craft for the Channel flight. It was fitted with a small battery-powered electric motor and flight instruments for the NASA research program in low-speed flight. NASA completed its flight testing of the Gossamer Albatross II and began analysis of the results in April, 1980. During the six week program, 17 actual data gathering flights and 10 other flights were flown here as part of the joint NASA Langley/Dryden flight research program. The lightweight craft, carrying a miniaturized instrumentation system, was flown in three configurations; using human power, with a small electric motor, and towed with the propeller removed. Results from the program contributed to data on the unusual aerodynamic, performance, stability, and control characteristics of large, lightweight aircraft that fly at slow speeds for application to future high altitude aircraft. The Albatross' design and research data contributed to numerous later high altitude projects, including the Pathfinder.

  12. PEP-II Operations Report

    SciTech Connect

    Zisman, Michael S.

    2000-11-01

    PEP-II is a two-ring asymmetric B factory operating at the Upsilon(4S) resonance. It was constructed by a SLAC-LBNL-LLNL collaboration. The collider comprises two rings, a High-Energy Ring (HER) storing 9 GeV electrons, and a Low-Energy Ring (LER) storing 3.1 GeV positrons. Commissioning of the HER began in mid-1997 and commissioning of the LER began in mid-1998. First evidence for collisions was obtained on July 23, 1998. The BaBar detector was installed in early 1999, and commissioning with the detector commenced in May 1999. By September 1999, PEP-II had reached a peak luminosity of 1.35 x 10{sup 33} cm{sup {minus}2} s{sup {minus}1}. In the present run, which began in October 1999, the peak luminosity has reached 3.1 x 10{sup 33} cm{sup {minus}2} s{sup {minus}1} and the integrated luminosity delivered is 25 fb{sup {minus}1}. At present, PEP-II is the world's highest luminosity collider. In this paper we describe the startup experience and summarize the operational experience during fiscal year 2000 (from October 1999 through September 2000). Plan s for luminosity upgrades are briefly described.

  13. Light echoes - Type II supernovae

    NASA Technical Reports Server (NTRS)

    Schaefer, Bradley E.

    1987-01-01

    Type II supernovae (SNs) light curves show a remarkable range of shapes. Data have been collected for the 12 Type II SNs that have light curve information for more than four months past maximum. Contrary to previous reports, it is found that (1) the decay rate after 100 days past maximum varies by almost an order of magnitude and (2) the light curve shapes are not bimodally distributed, but actually form a continuum. In addition, it is found that the extinctions to the SNs are related to the light curve shapes. This implies that the absorbing dust is local to the SNs. The dust is likely to be part of a circumstellar shell emitted by the SN progenitor that Dwek (1983) has used to explain infrared echoes. The optical depth of the shell can get quite large. In such cases, it is found that the photons scattered and delayed by reflection off dust grains will dominate the light curve several months after peak brightness. This 'light echo' offers a straightforward explanation of the diversity of Type II SN light curves.

  14. Topaz II preliminary safety assessment

    SciTech Connect

    Marshall, A.C. ); Standley, V. ); Voss, S.S. ); Haskin, E. )

    1993-01-10

    The Strategic Defense Initiative Organization (SDIO) decided to investigate the possibility of launching a Russian Topaz II space nuclear power system. A preliminary safety assessment was conducted to determine whether or not a space mission could be conducted safely and within budget constraints. As part of this assessment, a safety policy and safety functional requirements were developed to guide both the safety assessment and future Topaz II activities. A review of the Russian flight safety program was conducted and documented. Our preliminary safety assessment included a top level event tree, neutronic analysis of normal and accident configurations, an evaluation of temperature coefficients of reactivity, a reentry and disposal analysis, and analysis of postulated launch abort impact accidents, and an analysis of postulated propellant fire and explosion accidents. Based on the assessment, it appears that it will be possible to safely launch the Topaz II system in the U.S. with some possible system modifications. The principal system modifications will probably include design changes to preclude water flooded criticality and to assure intact reentry.

  15. Biosorption of Cu(II), Zn(II), Ni(II) and Pb(II) ions by cross-linked metal-imprinted chitosans with epichlorohydrin.

    PubMed

    Chen, Chia-Yun; Yang, Cheng-Yu; Chen, Arh-Hwang

    2011-03-01

    Cross-linked metal-imprinted chitosan microparticles were prepared from chitosan, using four metals (Cu(II), Zn(II), Ni(II), and Pb(II)) as templates, and epichlorohydrin as the cross-linker. The microparticles were characterized by Fourier transform infrared spectroscopy, solid state (13)C nuclear magnetic resonance spectroscopy, and energy-dispersive X-ray spectroscopy. They were used for comparative biosorption of Cu(II), Zn(II), Ni(II) and Pb(II) ions in an aqueous solution. The results showed that the sorption capacities of Cu(II), Zn(II), Ni(II), and Pb(II) on the templated microparticles increased from 25 to 74%, 13 to 46%, 41 to 57%, and 12 to 43%, respectively, as compared to the microparticles without metal ion templates. The dynamic study showed that the sorption process followed the second-order kinetic equation. Three sorption models, Langmuir, Freundlich, and Dubinin-Radushkevich, were applied to the equilibrium isotherm data. The result showed that the Langmuir isotherm equation best fitted for monolayer sorption processes. Furthermore, the microparticles can be regenerated and reused for the metal removal.

  16. 21 CFR 1308.12 - Schedule II.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 9 2010-04-01 2010-04-01 false Schedule II. 1308.12 Section 1308.12 Food and Drugs DRUG ENFORCEMENT ADMINISTRATION, DEPARTMENT OF JUSTICE SCHEDULES OF CONTROLLED SUBSTANCES Schedules § 1308.12 Schedule II. (a) Schedule II shall consist of the drugs and other substances,...

  17. Masfile--II Pilot Project. Final Report.

    ERIC Educational Resources Information Center

    Five Associated Univ. Libraries, Syracuse, NY.

    The report prepared for the Five Associated University Libraries (FAUL) by the Technical Information Dissemination Bureau (TIDB) at Suny-Buffalo is divided into nine sections: (1) a summary of procedures used to accomplish the specified MASFILE-II tasks; (2) a graphic comparison of the MARC-II and the MASFILE-II formats; (3) recommend…

  18. Neurofibromatosis type II presenting as vertical diplopia.

    PubMed

    Sokwala, Ahmed; Knapp, Christopher; Gottlob, Irene

    2004-09-01

    Neurofibromatosis type II (NF II) is rare and most commonly presents with hearing loss, tinnitus and/or vestibular disturbance in the third decade of life. The authors describe a rare case presenting with NF II with vertical diplopia due to IV(th) nerve palsy. The patient was otherwise asymptomatic despite multiple extensive lesions on MRI.

  19. Macrocyclic receptor showing extremely high Sr(II)/Ca(II) and Pb(II)/Ca(II) selectivities with potential application in chelation treatment of metal intoxication.

    PubMed

    Ferreirós-Martínez, Raquel; Esteban-Gómez, David; Tóth, Éva; de Blas, Andrés; Platas-Iglesias, Carlos; Rodríguez-Blas, Teresa

    2011-04-18

    Herein we report a detailed investigation of the complexation properties of the macrocyclic decadentate receptor N,N'-Bis[(6-carboxy-2-pyridil)methyl]-4,13-diaza-18-crown-6 (H(2)bp18c6) toward different divalent metal ions [Zn(II), Cd(II), Pb(II), Sr(II), and Ca(II)] in aqueous solution. We have found that this ligand is especially suited for the complexation of large metal ions such as Sr(II) and Pb(II), which results in very high Pb(II)/Ca(II) and Pb(II)/Zn(II) selectivities (in fact, higher than those found for ligands widely used for the treatment of lead poisoning such as ethylenediaminetetraacetic acid (edta)), as well as in the highest Sr(II)/Ca(II) selectivity reported so far. These results have been rationalized on the basis of the structure of the complexes. X-ray crystal diffraction, (1)H and (13)C NMR spectroscopy, as well as theoretical calculations at the density functional theory (B3LYP) level have been performed. Our results indicate that for large metal ions such as Pb(II) and Sr(II) the most stable conformation is Δ(δλδ)(δλδ), while for Ca(II) our calculations predict the Δ(λδλ)(λδλ) form being the most stable one. The selectivity that bp18c6(2-) shows for Sr(II) over Ca(II) can be attributed to a better fit between the large Sr(II) ions and the relatively large crown fragment of the ligand. The X-ray crystal structure of the Pb(II) complex shows that the Δ(δλδ)(δλδ) conformation observed in solution is also maintained in the solid state. The Pb(II) ion is endocyclically coordinated, being directly bound to the 10 donor atoms of the ligand. The bond distances to the donor atoms of the pendant arms (2.55-2.60 Å) are substantially shorter than those between the metal ion and the donor atoms of the crown moiety (2.92-3.04 Å). This is a typical situation observed for the so-called hemidirected compounds, in which the Pb(II) lone pair is stereochemically active. The X-ray structures of the Zn(II) and Cd(II) complexes show that

  20. Pb(II), Cu(II) and Cd(II) removal through untreated rice husk; thermodynamics and kinetics.

    PubMed

    Guiso, Maria Giovanna; Alberti, Giancarla; Emma, Giovanni; Pesavento, Maria; Biesuz, Raffaela

    2012-01-01

    The sorption properties of rice husk towards Cu(II), Cd(II) and Pb(II) were studied. The sorption isotherms are described by the Langmuir equation, and Pb(II) shows a higher affinity for rice husk compared to Cu(II) and Cd(II) under the same conditions. The kinetics of sorption obeys to a pseudo second-order equation for all metals. The sorption profiles as a function of the pH were used to characterize the stoichiometry of the sorption reaction. The competition for metal complexation by any ligand in solution is also accounted for. Upon increasing the ionic strength, the sorption curves of Pb(II) move to basic pH; this shift can be explained by considering the effect of nitrate complexes on the free metal ion concentration, since KNO(3) is used as the ionic medium. An attempt to employ rice husk in a dynamic system is presented.

  1. Phosphorylation of DNA topoisomerase II by casein kinase II: modulation of eukaryotic topoisomerase II activity in vitro.

    PubMed Central

    Ackerman, P; Glover, C V; Osheroff, N

    1985-01-01

    The phosphorylation of Drosophila melanogaster DNA topoisomerase II by purified casein kinase II was characterized in vitro. Under the conditions used, the kinase incorporated a maximum of 2-3 molecules of phosphate per homodimer of topoisomerase II. No autophosphorylation of the topoisomerase was observed. The only amino acid residue modified by casein kinase II was serine. Apparent Km and Vmax values for the phosphorylation reaction were 0.4 microM topoisomerase II and 3.3 mumol of phosphate incorporated per min per mg of kinase, respectively. Phosphorylation stimulated the DNA relaxation activity of topoisomerase II by 3-fold over that of the dephosphorylated enzyme, and the effects of modification could be reversed by treatment with alkaline phosphatase. Therefore, this study demonstrates that post-translational enzymatic modifications can be used to modulate the interaction between topoisomerase II and DNA. Images PMID:2987912

  2. Spectroscopic and mycological studies of Co(II), Ni(II) and Cu(II) complexes with 4-aminoantipyrine derivative

    NASA Astrophysics Data System (ADS)

    Sharma, Amit Kumar; Chandra, Sulekh

    2011-10-01

    Complexes of the type [M(L)X 2], where M = Co(II), Ni(II) and Cu(II), have been synthesized with novel NO-donor Schiff's base ligand, 1,4-diformylpiperazine bis(4-imino-2,3-dimethyl-1-phenyl-3-pyrazolin-5-one) which is obtained by the acid catalyzed condensation of 1,4-diformylpiperazine with 4-aminoantipyrine. The elemental analyses, molar conductance measurements, magnetic susceptibility measurements, IR, UV, NMR, mass and EPR studies of the compounds led to the conclusion that the ligand acts as tetradentate chelate. The Schiff's base ligand forms hexacoordinated complexes having octahedral geometry for Ni(II) and tetragonal geometry for Co(II) and Cu(II) complexes. The mycological studies of the compounds were examined against the several opportunistic pathogens, i.e., Alternaria brassicae, Aspergillus niger and Fusarium oxysporum. The Cu(II) complexes were found to have most fungicidal behavior.

  3. 40 CFR Table II-1 to Subpart II of... - Emission Factors

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 22 2013-07-01 2013-07-01 false Emission Factors II Table II-1 to Subpart II of Part 98 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) MANDATORY GREENHOUSE GAS REPORTING Industrial Wastewater Treatment Pt. 98, Subpt. II, Table...

  4. 40 CFR Table II-1 to Subpart II of... - Emission Factors

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 21 2014-07-01 2014-07-01 false Emission Factors II Table II-1 to Subpart II of Part 98 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) MANDATORY GREENHOUSE GAS REPORTING Industrial Wastewater Treatment Pt. 98, Subpt. II, Table...

  5. The Practice SSAT-II. [and] Test Administration Manual for the Practice SSAT-II.

    ERIC Educational Resources Information Center

    Florida State Dept. of Education, Tallahassee. Student Assessment Section.

    The Florida Statewide Assessment Program provides "The Practice SSAT-II," for students who will be taking the State Student Assessment Test, Part II (SSAT-II). This practice test may be administered to tenth grade students taking the test for the first time and to eleventh and twelfth graders if they have previously failed the SSAT-II.…

  6. Mixed metal copper(II)-nickel(II) and copper(II)-zinc(II) complexes of multihistidine peptide fragments of human prion protein.

    PubMed

    Jószai, Viktória; Turi, Ildikó; Kállay, Csilla; Pappalardo, Giuseppe; Di Natale, Giuseppe; Rizzarelli, Enrico; Sóvágó, Imre

    2012-07-01

    Mixed metal copper(II)-nickel(II) and copper(II)-zinc(II) complexes of four peptide fragments of human prion protein have been studied by potentiometric, UV-vis and circular dichroism spectroscopic techniques. One peptide contained three histidyl residues: HuPrP(84-114) with H85 inside and H96, H111 outside the octarepeat domain. The other three peptides contained two histidyl residues; H96 and H111 for HuPrP(91-115) and HuPrP(84-114)H85A while HuPrP(84-114)H96A contained the histidyl residues at positions 85 and 111. It was found that both histidines of the latter peptides can simultaneously bind copper(II) and nickel(II) ions and dinuclear mixed metal complexes can exist in slightly alkaline solution. One molecule of the peptide with three histidyl residues can bind two copper(II) and one nickel(II) ions. H85 and H111 were identified as the major copper(II) and H96 as the preferred nickel(II) binding sites in mixed metal species. The studies on the zinc(II)-PrP peptide binary systems revealed that zinc(II) ions can coordinate to the 31-mer PrP peptide fragments in the form of macrochelates with two or three coordinated imidazol-nitrogens but the low stability of these complexes cannot prevent the hydrolysis of the metal ion in slightly alkaline solution. These data provide further support for the outstanding affinity of copper(II) ions towards the peptide fragments of prion protein but the binding of nickel(II) can significantly modify the distribution of copper(II) among the available metal binding sites.

  7. Synthesis, spectral characterization and biological evaluation of Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) complexes with thiosemicarbazone ending by pyrazole and pyridyl rings

    NASA Astrophysics Data System (ADS)

    Yousef, T. A.; Abu El-Reash, G. M.; Al-Jahdali, M.; El-Rakhawy, El-Bastawesy R.

    2014-08-01

    Here we present the synthesis of the new Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) complexes with chelating ligand (Z)-(2-((1,3-diphenyl-1H-pyrazol-4-yl)methylene) hydrazinyl)(pyridin-2-ylamino)methanethiol. All the complexes were characterized by elemental analysis, IR, 1H NMR, UV-vis, magnetic susceptibility measurements and EPR spectral studies. IR spectra of complexes showed that the ligand behaves as NN neutral bidentate, NSN mononegative tridentate and NSNN mononegative tetradentate. The electronic spectra and the magnetic measurements suggested the octahedral geometry for all complexes as well as the EPR confirmed the tetragonal distorted octahedral for Cu(II) complex. Cd(II) complex showed the highest inhibitory antioxidant activity either using ABTS method. The SOD-like activity exhibited those Cd(II) and Zn(II) complexes have strong antioxidative properties. We tested the synthesized compounds for antitumor activity and showed that the ability to kill liver (HePG2) and breast (MCF-7) cancer cells definitely.

  8. Topoisomerase II from Human Malaria Parasites

    PubMed Central

    Mudeppa, Devaraja G.; Kumar, Shiva; Kokkonda, Sreekanth; White, John; Rathod, Pradipsinh K.

    2015-01-01

    Historically, type II topoisomerases have yielded clinically useful drugs for the treatment of bacterial infections and cancer, but the corresponding enzymes from malaria parasites remain understudied. This is due to the general challenges of producing malaria proteins in functional forms in heterologous expression systems. Here, we express full-length Plasmodium falciparum topoisomerase II (PfTopoII) in a wheat germ cell-free transcription-translation system. Functional activity of soluble PfTopoII from the translation lysates was confirmed through both a plasmid relaxation and a DNA decatenation activity that was dependent on magnesium and ATP. To facilitate future drug discovery, a convenient and sensitive fluorescence assay was established to follow DNA decatenation, and a stable, truncated PfTopoII was engineered for high level enzyme production. PfTopoII was purified using a DNA affinity column. Existing TopoII inhibitors previously developed for other non-malaria indications inhibited PfTopoII, as well as malaria parasites in culture at submicromolar concentrations. Even before optimization, inhibitors of bacterial gyrase, GSK299423, ciprofloxacin, and etoposide exhibited 15-, 57-, and 3-fold selectivity for the malarial enzyme over human TopoII. Finally, it was possible to use the purified PfTopoII to dissect the different modes by which these varying classes of TopoII inhibitors could trap partially processed DNA. The present biochemical advancements will allow high throughput chemical screening of compound libraries and lead optimization to develop new lines of antimalarials. PMID:26055707

  9. 2-line ferrihydrite: synthesis, characterization and its adsorption behaviour for removal of Pb(II), Cd(II), Cu(II) and Zn(II) from aqueous solutions.

    PubMed

    Rout, K; Mohapatra, M; Anand, S

    2012-03-21

    Nano-structured 2-line ferrihydrite was synthesized by a pH-controlled precipitation technique at 90 °C. Chemical, X-ray diffraction (XRD), Fourier transform infrared (FTIR) and Raman analyses confirmed the sample to be 2-line ferrihydrite. The nano nature of the prepared sample was studied by transmission electron microscopy (TEM). The surface area obtained by the Brunauer-Emmett-Teller (BET) method was 175.8 m(2) g(-1). The nanopowder so obtained was used to study its behaviour for the removal of Pb(II), Cd(II), Cu(II) and Zn(II) from aqueous solutions. The relative importance of experimental parameters such as solution pH, contact time and concentration of adsorbate on the uptake of various cations was evaluated. By increasing the pH from 2.0 to 5.5, adsorption of the four cations increased. The kinetics parameters were compared by fitting the contact time data to both linear as well as non-linear forms of pseudo-second-order models. Linear forms of both Langmuir and Freundlich models fitted the equilibrium data of all the cations except for Pb(II) which was also fitted to the non-linear forms of both the models as it gave a low R(2) value of 0.85 for the Langmuir model. High Langmuir monolayer capacities of 366, 250, 62.5 and 500 mg g(-1) were obtained for Pb(II), Cd(II), Cu(II) and Zn(II), respectively. Presence of chloride or sulfate had an adverse effect on cation adsorption. The interactive effects on adsorption from solutions containing two, three or four cations were studied. Surprisingly no Cd(II) adsorption was observed in Pb(II)-Cd(II), Pb(II)-Cd(II)-Zn(II) and Pb(II)-Cd(II)-Cu(II)-Zn(II) systems under the studied concentration range. The overall loading capacity of the adsorbent decreased in mixed cation systems. Metal ion loaded adsorbents were characterized by XRD, FTIR and Raman techniques. The high adsorption capability of the 2-lines ferrihydrite makes it a potentially attractive adsorbent for the removal of cations from aqueous solutions.

  10. Commissioning of NSLS-II

    SciTech Connect

    Willeke, F.

    2015-05-03

    NSLS-II, the new 3rd generation light source at BNL was designed for a brightness of 1022 photons s-1mm-2mrad-2 (0.1%BW)-1. It was constructed between 2009 and 2014. The storage ring was commissioned in April 2014 which was followed by insertion device and beamline commissioning in the fall of 2014. All ambitious design parameters of the facility have already been achieved except for commissioning the full beam intensity of 500mA which requires more RF installation. This paper reports on the results of commissioning.

  11. Zeeman effect of As II.

    NASA Technical Reports Server (NTRS)

    Li, H.; Andrew, K. L.

    1972-01-01

    Spectrograms of As electrodeless-discharge tubes operated in a field of 24,025 G have given Zeeman patterns for 232 As II spectral lines from 2361 to 10,556 A and yielded 80 Lande g factors, of which more than half are new. There is agreement between these and the g values calculated by least-squares fitting for single configurations or for multiconfigurations, where configuration interaction is noticeable. All of the measured g values as well as the energy levels are used in the fitting process.

  12. MALDI time-of-flight mass spectrometry and thermogravimetric analysis of Mg(II), Ca(II), Cu(II), Zn(II) and Pt(II) adducts with monomethoxypolyethylene glycol 5000

    NASA Astrophysics Data System (ADS)

    Mwelase, S. R.; Bariyanga, J.

    2002-05-01

    We have prepared and isolated complexes of Mg(II), Ca(II), Cu(II), Zn(II) and Pt(II) with monomethoxypolyethylene glycol 5000 in a pH 7 buffer at 40 °C in order to study the interaction of this polymer carrier with the ions likely to be found in the human body. Their characterization was done by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, Fourier transform infrared, UV-Vis spectrophotometry, thermogravimetry and elemental analysis. The mass spectra allowed us to determine not only the molecular weights but also the nature of the complexes and the findings were in agreement with the elementary analysis data. The calcium ion was found not directly linked to polyethylene glycol but through water molecules. The overall results indicated strong bonding for Cu(II) and Zn(II) complexes and weak interactions for Mg(II), Ca(II) and Pt(II).

  13. Ii Chain Controls the Transport of Major Histocompatibility Complex Class II Molecules to and from Lysosomes

    PubMed Central

    Brachet, Valérie; Raposo, Graça; Amigorena, Sebastian; Mellman, Ira

    1997-01-01

    Major histocompatibility complex class II molecules are synthesized as a nonameric complex consisting of three αβ dimers associated with a trimer of invariant (Ii) chains. After exiting the TGN, a targeting signal in the Ii chain cytoplasmic domain directs the complex to endosomes where Ii chain is proteolytically processed and removed, allowing class II molecules to bind antigenic peptides before reaching the cell surface. Ii chain dissociation and peptide binding are thought to occur in one or more postendosomal sites related either to endosomes (designated CIIV) or to lysosomes (designated MIIC). We now find that in addition to initially targeting αβ dimers to endosomes, Ii chain regulates the subsequent transport of class II molecules. Under normal conditions, murine A20 B cells transport all of their newly synthesized class II I-Ab αβ dimers to the plasma membrane with little if any reaching lysosomal compartments. Inhibition of Ii processing by the cysteine/serine protease inhibitor leupeptin, however, blocked transport to the cell surface and caused a dramatic but selective accumulation of I-Ab class II molecules in lysosomes. In leupeptin, I-Ab dimers formed stable complexes with a 10-kD NH2-terminal Ii chain fragment (Ii-p10), normally a transient intermediate in Ii chain processing. Upon removal of leupeptin, Ii-p10 was degraded and released, I-Ab dimers bound antigenic peptides, and the peptide-loaded dimers were transported slowly from lysosomes to the plasma membrane. Our results suggest that alterations in the rate or efficiency of Ii chain processing can alter the postendosomal sorting of class II molecules, resulting in the increased accumulation of αβ dimers in lysosome-like MIIC. Thus, simple differences in Ii chain processing may account for the highly variable amounts of class II found in lysosomal compartments of different cell types or at different developmental stages. PMID:9105036

  14. BNL ATF II beamlines design

    SciTech Connect

    Fedurin, M.; Jing, Y.; Stratakis, D.; Swinson, C.

    2015-05-03

    The Brookhaven National Laboratory. Accelerator Test Facility (BNL ATF) is currently undergoing a major upgrade (ATF-II). Together with a new location and much improved facilities, the ATF will see an upgrade in its major capabilities: electron beam energy and quality and CO2 laser power. The electron beam energy will be increased in stages, first to 100-150 MeV followed by a further increase to 500 MeV. Combined with the planned increase in CO2 laser power (from 1-100 TW), the ATF-II will be a powerful tool for Advanced Accelerator research. A high-brightness electron beam, produced by a photocathode gun, will be accelerated and optionally delivered to multiple beamlines. Besides the energy range (up to a possible 500 MeV in the final stage) the electron beam can be tailored to each experiment with options such as: small transverse beam size (<10 um), short bunch length (<100 fsec) and, combined short and small bunch options. This report gives a detailed overview of the ATFII capabilities and beamlines configuration.

  15. [S-II symptom questionnaire].

    PubMed

    Aleksandrowicz, J W

    2000-01-01

    "S-II" Symptom Check-list which allows for a fast diagnosis of neurotic disorders. A result of 165 points suggests the incidence of such disorders with the probability of 90%. The methodology of the construction of the check-list intends for the application of questions most common in those ill due to neurotic disorders (owing to the change in frequency) and the most possibly equal amount of questions on the symptoms common to women and men. Thanks to this the norm for women and men is identical. SCL S-II Symptom Check-list is a shortened and actualised version of the "O" Symptom Check-list, developed in 1975. It is similar to the SCL-90 and highly correlated with it, but it does not contain the variables concerning the psychotic symptoms. Thanks to this, its' accuracy (specificity) in the diagnosis of neurotic disorders is high. 4 pairs of questions allow for the judgement of answer reliability. 10 scales were singled out in the questionnaire. They are only of a helpful value and do not allow for a one-sided diagnosis of the type of the disorder, listed in the ICD-10. The scale results can, however make the correct diagnosis easier.

  16. The Spectrum of Fe II

    NASA Astrophysics Data System (ADS)

    Nave, Gillian; Johansson, Sveneric

    2013-01-01

    The spectrum of singly ionized iron (Fe II) has been recorded using high-resolution Fourier transform (FT) and grating spectroscopy over the wavelength range 900 Å to 5.5 μm. The spectra were observed in high-current continuous and pulsed hollow cathode discharges using FT spectrometers at the Kitt Peak National Observatory, Tucson, AZ and Imperial College, London and with the 10.7 m Normal Incidence Spectrograph at the National Institute of Standards and Technology. Roughly 12,900 lines were classified using 1027 energy levels of Fe II that were optimized to measured wavenumbers. The wavenumber uncertainties of lines in the FT spectra range from 10-4 cm-1 for strong lines around 4 μm to 0.05 cm-1 for weaker lines around 1500 Å. The wavelength uncertainty of lines in the grating spectra is 0.005 Å. The ionization energy of (130,655.4 ± 0.4) cm-1 was estimated from the 3d6(5D)5g and 3d6(5D)6h levels.

  17. Topaz II preliminary safety assessment

    SciTech Connect

    Marshall, A.C. ); Standley, V. ); Voss, S.S. ); Haskin, E. . Dept. of Chemical and Nuclear Engineering)

    1992-01-01

    The Strategic Defense Initiative Organization (SDIO) decided to investigate the possibility of launching a Russian Topaz 11 space nuclear power system. A preliminary safety assessment was conducted to determine whether or not a space mission could be conducted safely and within budget constraints. As part of this assessment, a safety policy and safety functional requirements were developed to guide both the safely assessment and future Topaz II activities. A review of the Russian flight safety program was conducted and documented. Our preliminary safety assessment included a top level event tree, neutronic analysis of normal and accident configurations, an evaluation of temperature coefficients of reactivity, a reentry and disposal analysis, and analysis of postulated launch abort impact accidents, and an analysis of postulated propellant fire and explosion accidents. Based on the assessment, it appears that it will be possible to safely launch the Topaz II system in the US with some possible system modifications. The principal system modifications will probably include design changes to preclude water flooded criticality and to assure intact reentry.

  18. Synthesis, structural characterization, thermal and electrochemical studies of Mn(II), Co(II), Ni(II) and Cu(II) complexes containing thiazolylazo ligands

    NASA Astrophysics Data System (ADS)

    Chavan, S. S.; Sawant, V. A.

    2010-02-01

    Some thiazolylazo derivatives and their metal complexes of the type [M(L)(H 2O)Cl]; M = Mn(II), Co(II), Ni(II), Cu(II) and L = 6-(2'-thiazolylazo)-2-mercapto-quinazolin-4-one (HL 1), 6-(4'-phenyl-2'-thiazolylazo)-2-mercapto-quinazolin-4-one (HL 2), 6-(2'-thiazolylazo)-2-mercapto-3-( m-tolyl)-quinazolin-4-one (HL 3) and 6-(4'-phenyl-2'-thiazolylazo)-2-mercapto-3-( m-tolyl)-quinazolin-4-one (HL 4) have been prepared. All the complexes were characterized on the basis of elemental analysis, molar conductance, magnetic moment, IR, UV-vis, ESR, TG-DTA and powder X-ray diffraction studies. IR spectra of these complexes reveal that the complex formation occurred through thiazole nitrogen, azo nitrogen, imino nitrogen and sulfur atom of the ligands. On the basis of electronic spectral data and magnetic susceptibility measurement octahedral geometry has been proposed for the Mn(II), Co(II) and Ni(II) complexes and distorted octahedral geometry for the Cu(II) complexes. Electrochemical behavior of Ni(II) complexes exhibit quasireversible oxidation corresponding to Ni(III)/Ni(II) couple along with ligand reduction. X-ray diffraction study is used to elucidate the crystal structure of the complexes.

  19. Quiet High Speed Fan II (QHSF II): Final Report

    NASA Technical Reports Server (NTRS)

    Kontos, Karen; Weir, Don; Ross, Dave

    2012-01-01

    This report details the aerodynamic, mechanical, structural design and fabrication of a Honey Engines Quiet High Speed Fan II (lower hub/tip ratio and higher specific flow than the Baseline I fan). This fan/nacelle system incorporates features such as advanced forward sweep and an advanced integrated fan/fan exit guide vane design that provides for the following characteristics: (1) Reduced noise at supersonic tip speeds, in comparison to current state-of-the-art fan technology; (2) Improved aeroelastic stability within the anticipated operating envelope; and (3) Aerodynamic performance consistent with current state-of-the-art fan technology. This fan was fabricated by Honeywell and tested in the NASA Glenn 9- by 15-Ft Low Speed Wind Tunnel for aerodynamic, aeromechanical, and acoustic performance.

  20. Removal of Pb(II), Cd(II), Cu(II) and trichloroethylene from water by Nanofer ZVI.

    PubMed

    Eglal, Mahmoud M; Ramamurthy, Amruthur S

    2015-01-01

    Zero-valent iron nanoparticle (Nanofer ZVI) is a new reagent due to its unique structure and properties. Images of scanning electron microscopy/electron dispersive spectroscopy (SEM/EDS), transmission electron microscopy and X-ray diffraction revealed that Nanofer ZVI is stable, reactive and has a unique structure. The particles exhibited a spherical shape, a chain-like structure with a particle size of 20 to 100 nm and a surface area between 25-30 m2g(-1). The time interval for particles to agglomerate and settle was between 4-6 h. SEM/EDS Images showed that particle size increased to 2 µm due to agglomeration. Investigation of adsorption and oxidation behavior of Nanofer ZVI used for the removal of Cu(II), Pb(II), Cd(II) ions and trichloroethylene (TCE) from aqueous solutions showed that the optimal pH for Pb(II), Cu(II), Cd(II) and TCE removal were 4.5 and 4.8, 5.0 and 6.5, respectively. Test data were used to form Langmuir and Freundlich isotherms. The maximum contaminant loading was estimated as 270, 170, 110, 130 mg per gram of Nanofer ZVI for Cu(II), Pb(II), Cd(II) and TCE respectively. Removal of metal ions is interpreted in terms of their hydrated ionic radii and their electronegativity. TCE oxidation followed the dechlorination pathway resulting in nonhazardous by-products.

  1. Chelation of Cu(II), Zn(II), and Fe(II) by tannin constituents of selected edible nuts.

    PubMed

    Karamać, Magdalena

    2009-12-22

    The tannin fractions isolated from hazelnuts, walnuts and almonds were characterised by colorimetric assays and by an SE-HPLC technique. The complexation of Cu(II) and Zn(II) was determined by the reaction with tetramethylmurexide, whereas for Fe(II), ferrozine was employed. The walnut tannins exhibited a significantly weaker reaction with the vanillin/HCl reagent than hazelnut and almond tannins, but the protein precipitation capacity of the walnut fraction was high. The SE-HPLC chromatogram of the tannin fraction from hazelnuts revealed the presence of oligomers with higher molecular weights compared to that of almonds. Copper ions were most effectively chelated by the constituents of the tannin fractions of hazelnuts, walnuts and almonds. At a 0.2 mg/assay addition level, the walnut tannins complexed almost 100% Cu(II). The Fe(II) complexation capacities of the tannin fractions of walnuts and hazelnuts were weaker in comparison to that of the almond tannin fraction, which at a 2.5 mg/assay addition level, bound Fe(II) by approximately 90%. The capacity to chelate Zn(II) was quite varied for the different nut tannin fractions: almond tannins bound as much as 84% Zn(II), whereas the value for walnut tannins was only 8.7%; and for hazelnut tannins, no Zn(II) chelation took place at the levels tested.

  2. [Biosorption of Cd(II), Cu(II), Pb(II) and Zn(II) in aqueous solutions by fruiting bodies of macrofungi (Auricularia polytricha and Tremella fuciformis)].

    PubMed

    Mo, Yu; Pan, Rong; Huang, Hai-wei; Cao, Li-xiang; Zhang, Ren-duo

    2010-07-01

    Batch experiments were conducted to study the ability of fruiting bodies of Auricularia polytricha and Tremella fuciformis to adsorb Cd(II), Cu(II), Pb(II) and Zn(II) from aqueous solutions, including biosorption ability of the biomass to remove heavy metals from solutions with different concentrations, kinetics of adsorption, influence of co-cations, and biosorption affinity in multi-metalsystem. Results showed that in the solutions with individual metal, the maximum biosorption amounts of Cd(II), Cu(II), Pb(II), Zn(II) by A. polytricha were 18.91, 18.69, 20.33, 12.42 mg x g(-1), respectively, and the highest removal rates for all cases were more than 85%. The maximum biosorption amounts of Cd(II), Cu(II), Pb(II), Zn(II) by T. fuciformis were 19.98, 20.15, 19.16, 16.41 mg x g(-1), respectively, and highest removal rates for all cases were more than 75%. In the solutions with initial concentrations of 10, 50 and 100 mg x L(-1), the biosorption amounts increased but the removal rates decreased as the initial concentrations increasing. The pseudo-second-order reaction model described adsorption kinetics of heavy metal ions by fruiting bodies of A. polytricha and T. fuciformis better than the pseudo-first-order reaction model. In the solutions with multi metals, the biosorption amounts of heavy metals by two biosorbent were in the order of Ph(II) > Cd(II) > Cu(II) > Zn(II). The ions with more negative charges were preferential to be sorbed. The biosorption ability of A. polytricha was inhibited in multi-metal solutions. In multi-metal solutions, T. fuciformis sorbed a higher amount of Pb(II) but lower amounts of other three ions than that in the individual metal solutions. The results indicated that both fruiting bodies of A. polytricha and T. fuciformis were potential biosorbents.

  3. Double quantum coherence electron spin resonance on coupled Cu(II)-Cu(II) electron spins

    NASA Astrophysics Data System (ADS)

    Becker, James S.; Saxena, Sunil

    2005-10-01

    We demonstrate for the first time the ability to generate double quantum coherences (DQCs) for the case of Cu(II). We show that small splittings (˜7 MHz) from the Cu(II)-Cu(II) electron-electron magnetic dipolar interaction can be reliably resolved even though the inhomogeneously broadened Cu(II) linewidth is ˜2 GHz. A Cu(II)-Cu(II) distance of 2.0 nm was measured on a model peptide system, thus, demonstrating that distances on the nanometer scale may be measured using DQC electron spin resonance (ESR).

  4. Software Aspects of PuMa-II

    NASA Astrophysics Data System (ADS)

    Karuppusamy, R.; Stappers, B.; Stappers, B.

    2006-08-01

    The Pulsar Machine II (PuMa-II) is a state of the art pulsar machine-installed at the Westerbork Synthesis Radio Telescope (WSRT), in December 2005. PuMa-II is a flexible instrument and is designed around an ensemble of 44 high-performance computers running the Linux operating system. Much of the flexibility of PuMa-II comes from the software that is being developed for this instrument. The radio signals reaching the telescope undergo several stages of electronic and software processing before a scientifically useful data product is generated. The electronic processing of signals includes the usual RF to IF conversion, analogue to digital conversion and telescope dependent electronic digital delay compensation that happen in the signal chain of WSRT. Within PuMa-II, this data is acquired, stored and suitably processed. In this poster we present various aspects of PuMa-II software and illustrate its pulsar signal processing capabilities.

  5. The Impact of Massive Starbursts on the Chemical Evolution of Galaxies

    NASA Astrophysics Data System (ADS)

    Kobulnicky, Henry A.

    Young, compact star clusters containing hundreds to thousands of the most massive OB and Wolf-Rayet type stars are common features of actively star-forming galaxies. Radio-wave H scI and millimeter-wave CO aperture synthesis observations of the interstellar gas in several such systems reveal strong evidence for recent collisions or mergers with other galaxies which probably triggered the present burst. Most of the oxygen in the universe, and to a lesser extent carbon and nitrogen, is synthesized within massive stars and returned to the interstellar gas by stellar winds and supernova explosions as these stars evolve. Yet, spatially-resolved spectroscopic investigations of the ionized gas in several starburst galaxies fail to find any sign of recent nucleosynthesis products in the vicinity of evolved starclusters. The chemical abundances of O, N, He, and probably C, appear very homogeneous on scales of ~1 kpc or less, despite the fact that models of the chemical enrichment expected from a single 106/ Msolar burst show that large localized chemical enhancements should occur. That there is no evidence of localized chemical enrichment within the H scII regions of most metal-poor galaxies suggests the recently-released heavy elements are 'hiding' either in a hot, 106 phase or in a cool neutral atomic or molecular phase. In either case, the timescale for visible enrichment in galaxies appears to exceed the lifetimes of the H scII regions and the spatial scales must exceed 1 kpc. These data are inconsistent with the H scII region 'self-enrichment' or 'pollution' hypothesis. For now, heavy elements produced in starbursts can be considered 'missing', but upcoming X-ray observatories may be able to establish their physical phase and location. Hubble Space Telescope spectroscopic measurements show evidence for a correlation between C and N abundances among galaxies with similar metallicity (O/H). The existence of such a correlation implies that C and N production mechanisms

  6. The spin rates of O stars in WR + O binaries - I. Motivation, methodology, and first results from SALT

    NASA Astrophysics Data System (ADS)

    Shara, Michael M.; Crawford, Steven M.; Vanbeveren, Dany; Moffat, Anthony F. J.; Zurek, David; Crause, Lisa

    2017-01-01

    The black holes (BH) in merging BH-BH binaries are likely progeny of binary O stars. Their properties, including their spins, will be strongly influenced by the evolution of their progenitor O stars. The remarkable observation that many single O stars spin very rapidly can be explained if they accreted angular momentum from a mass-transferring, O-type or Wolf-Rayet (WR) companion before that star blew up as a supernova. To test this prediction, we have measured the spin rates of eight O stars in WR + O binaries, increasing the total sample size of such O stars' measured spins from 2 to 10. Polarimetric and other determinations of these systems' sin i allow us to determine an average equatorial rotation velocity from He I (He II) lines of ve = 348 (173) km s-1 for these O stars, with individual star's ve from He I (He II) lines ranging from 482 (237) to 290 (91) km s-1. We argue that the ˜100 per cent difference between He I and He II speeds is due to gravity darkening. Supersynchronous spins, now observed in all 10 O stars in WR + O binaries where it has been measured, are strong observational evidence that Roche lobe overflow mass transfer from a WR progenitor companion has played a critical role in the evolution of WR + OB binaries. While theory predicts that this mass transfer rapidly spins up the O-type mass gainer to a nearly breakup rotational velocity of ve ˜ 530 km s-1, the observed average ve of the O-type stars in our sample is 65 per cent of that speed. This demonstrates that, even over the relatively short WR-phase time-scale, tidal and/or other effects causing rotational spin-down must be efficient. A challenge to tidal synchronization theory is that the two longest period binaries in our sample (with periods of 29.7 and 78.5 d) unexpectedly display supersynchronous rotation.

  7. First detections of FS Canis Majoris stars in clusters. Evolutionary state as constrained by coeval massive stars

    NASA Astrophysics Data System (ADS)

    de la Fuente, D.; Najarro, F.; Trombley, C.; Davies, B.; Figer, D. F.

    2015-03-01

    Context. FS CMa stars are low-luminosity objects showing the B[e] phenomenon whose evolutionary state remains a puzzle. These stars are surrounded by compact disks of warm dust of unknown origin. Hitherto, membership of FS CMa stars to coeval populations has never been confirmed. Aims: The discovery of low-luminosity line emitters in the young massive clusters Mercer 20 and Mercer 70 prompts us to investigate the nature of such objects. We intend to confirm membership to coeval populations in order to characterize these emission-line stars through the cluster properties. Methods: Based on ISAAC/VLT medium-resolution spectroscopy and NICMOS/HST photometry of massive cluster members, new characterizations of Mercer 20 and Mercer 70 are performed. Coevality of each cluster and membership of the newly-discovered B[e] objects are investigated using our observations as well as literature data of the surroundings. Infrared excess and narrow-band photometric properties of the B[e] stars are also studied. Results: We confirm and classify 22 new cluster members, including Wolf-Rayet stars and blue hypergiants. Spectral types (O9-B1.5 V) and radial velocities of B[e] objects are compatible with the remaining cluster members, while emission features of Mg ii, Fe ii], and [Fe ii] are identified in their spectra. The ages of these stars are 4.5 and 6 Myr, and they show mild infrared excesses. Conclusions: We confirm the presence of FS CMa stars in the coeval populations of Mercer 20 and Mercer 70. We discuss the nature and evolutionary state of FS CMa stars, discarding a post-AGB nature and introducing a new hypothesis about mergers. A new search method for FS CMa candidates in young massive clusters based on narrow-band Paschen-α photometry is proposed and tested in photometric data of other clusters, yielding three new candidates. Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere, Chile, under program IDs 083.D

  8. Sample Exchange Evaluation (SEE) Report - Phase II

    SciTech Connect

    Winters, W.I.

    1994-09-28

    This report describes the results from Phase II of the Sample Exchange Evaluation (SEE) Program, a joint effort to compare analytical laboratory performance on samples from the Hanford Site`s high-level waste tanks. In Phase II, the program has been expanded to include inorganic constituents in addition to radionuclides. Results from Phase II that exceeded 20% relative percent difference criteria are identified.

  9. Start II, red ink, and Boris Yeltsin

    SciTech Connect

    Arbatov, A.

    1993-04-01

    Apart from the vulnerability implied by the START II treaty, it will bear the burden of the general political opposition to the Yeltsin administration. START II will be seen as part of an overall Yeltsin-Andrei Kozyrev foreign policy that is under fire for selling out Russian national interests in Yugoslavia, the Persian Gulf, and elsewhere. This article discusses public opinion concerning START II, the cost of its implementation, and the general purpose of the treaty.

  10. Telemetry Tests Of The Advanced Receiver II

    NASA Technical Reports Server (NTRS)

    Hinedi, Sami M.; Bevan, Roland P.; Marina, Miguel

    1993-01-01

    Report describes telemetry tests of Advanced Receiver II (ARX-II): digital radio receiving subsystem operating on intermediate-frequency output of another receiving subsystem called "multimission receiver" (MMR), detecting carrier, subcarrier, and data-symbol signals transmitted by spacecraft, and extracts Doppler information from signals. Analysis of data shows performance of MMR/ARX-II system comparable and sometimes superior to performances of Blk-III/BPA and Blk-III/SDA/SSA systems.

  11. AGEX II: Technical quarterly, Volume 2

    SciTech Connect

    Ekdahl, C.

    1995-03-01

    The AGEX II Technical Quarterly publishes short technical contributions on above ground experiments that use pulsed power and laser drivers. The Quarterly is intended to provide rapid exposure of timely technical ideas and results as well as a means for documenting AGEX II progress and scientific quality for the AGEX II community. Suitable topics include experimental results, diagnostic apparatus, theoretical design, and scaling, among others.

  12. SAGE II aerosol correlative observations - Profile measurements

    NASA Technical Reports Server (NTRS)

    Osborn, M. T.; Rosen, J. M.; Mccormick, M. P.; Wang, Pi-Huan; Livinfston, J. M.

    1989-01-01

    Profiles of the aerosol extinction measurements from the Stratospheric Aerosol and Gas Experiment (SAGE) II are compared with profiles from five correlative experiments between November 1984 and July 1986. The correlative profiles were derived from six-channel dustsonde measurements and two-wavelength lidar backscatter data. The correlation between the dustsonde- and lidar-derived measurements and the SAGE II data is good, validating the SAGE II lower stratospheric aerosol extinction measurements.

  13. Polymeric potassium triformatocobalt(II)

    PubMed Central

    Wöhlert, Susanne; Wriedt, Mario; Jess, Inke; Näther, Christian

    2011-01-01

    In the crystal structure of the title compound, poly[tri-μ-formato-cobalt(II)potassium], [CoK(CHO2)3]n the Co2+ cations are coordinated by six O-bonded formate anions in an octa­hedral coordination mode and the K+ cations are eightfold coordinated by seven O-bonded formate anions within irregular polyhedra. The Co2+ cations are connected by bridging formate anions into a three-dimensional coordination network in which the K+ cations are embedded. The asymmetric unit consits of one Co2+ cation located on a center of inversion, one K+ cation located on a twofold axis and two crystallographically independent formato anions, of which one is located on a twofold axis and the other occupies a general position. PMID:21753951

  14. PEP-II prototype klystron

    SciTech Connect

    Fowkes, W.R.; Caryotakis, G.; Lee, T.G.; Pearson, C.; Wright, E.L.

    1993-04-01

    A 540-kW continuous-wave (cw) klystron operating at 476 MHz was developed for use as a power source for testing PEP-II rf accelerating cavities and rf windows. It also serves as a prototype for a 1.2 MW cw klystron presently being developed as a potential rf source for asymmetric colliding ring use. The design incorporates the concepts and many of the parts used in the original 353 MHz PEP klystron developed sixteen years ago. The superior computer simulation codes available today result in improved performance with the cavity frequencies, drift lengths, and output circuit optimized for the higher frequency.The design and operating results of this tube are described with particular emphasis on the factors which affect efficiency and stability.

  15. Probing outflows in z = 1 ∼ 2 galaxies through Fe II/Fe II* multiplets

    SciTech Connect

    Tang, Yuping; Giavalisco, Mauro; Guo, Yicheng

    2014-10-01

    We report on a study of the 2300-2600 Å Fe II/Fe II* multiplets in the rest-UV spectra of star-forming galaxies at 1.0 < z < 2.6 as probes of galactic-scale outflows. We extracted a mass-limited sample of 97 galaxies at z ∼ 1.0-2.6 from ultra-deep spectra obtained during the GMASS spectroscopic survey in the GOODS South field with the Very Large Telescope and FORS2. We obtain robust measures of the rest equivalent width of the Fe II absorption lines down to a limit of W{sub r} > 1.5 Å and of the Fe II* emission lines to W{sub r} > 0.5 Å. Whenever we can measure the systemic redshift of the galaxies from the [O II] emission line, we find that both the Fe II and Mg II absorption lines are blueshifted, indicating that both species trace gaseous outflows. We also find, however, that the Fe II gas has generally lower outflow velocity relative to that of Mg II. We investigate the variation of Fe II line profiles as a function of the radiative transfer properties of the lines, and find that transitions with higher oscillator strengths are more blueshifted in terms of both line centroids and line wings. We discuss the possibility that Fe II lines are suppressed by stellar absorptions. The lower velocities of the Fe II lines relative to the Mg II doublet, as well as the absence of spatially extended Fe II* emission in two-dimensional stacked spectra, suggest that most clouds responsible for Fe II absorption lie close (3 ∼ 4 kpc) to the disks of galaxies. We show that the Fe II/Fe II* multiplets offer unique probes of the kinematic structure of galactic outflows.

  16. Carbonic anhydrase isozymes IV and II in urinary membranes from carbonic anhydrase II-deficient patients.

    PubMed Central

    Sato, S; Zhu, X L; Sly, W S

    1990-01-01

    Carbonic anhydrase II (CA II) deficiency has been shown to be the primary defect in the recessively inherited syndrome of osteopetrosis with renal tubular acidosis. Until now, the absence of CA II in kidney of CA II-deficient patients has not been shown directly, and the status of the membrane-associated CA in kidney of CA II-deficient patients has been unclear. To address these questions, we analyzed urinary membranes and soluble fractions from normal and CA II-deficient subjects. The CA activity in membrane fractions of normal urine was found to comprise two components--(i) a vesicle-enclosed, sodium dodecyl sulfate (SDS)-sensitive fraction, which was shown immunochemically to be the 29-kDa CA II, and (ii) an SDS-resistant fraction, which was due to native and cleaved forms of the 35-kDa, membrane-anchored isozyme CA IV. Urinary membranes from CA II-deficient patients showed little or no SDS-sensitive activity and no immunoreactivity for CA II, providing direct evidence that their mutation, which produces CA II deficiency in erythrocytes, also affects CA II in kidney. CA IV activity and immunoreactivity were present in normal amounts in urinary membranes from CA II-deficient patients. We conclude from the enzymatic and immunological evidence presented that both CA II and CA IV are present in urinary membranes from normal subjects, that renal CA IV is present but renal CA II is absent in urinary membranes from patients with the CA II-deficiency syndrome, and that the methods presented should be useful in studying renal CA II and renal CA IV in other disorders of impaired bicarbonate reabsorption. Images PMID:2117271

  17. RNA polymerase II transcription: structure and mechanism.

    PubMed

    Liu, Xin; Bushnell, David A; Kornberg, Roger D

    2013-01-01

    A minimal RNA polymerase II (pol II) transcription system comprises the polymerase and five general transcription factors (GTFs) TFIIB, -D, -E, -F, and -H. The addition of Mediator enables a response to regulatory factors. The GTFs are required for promoter recognition and the initiation of transcription. Following initiation, pol II alone is capable of RNA transcript elongation and of proofreading. Structural studies reviewed here reveal roles of GTFs in the initiation process and shed light on the transcription elongation mechanism. This article is part of a Special Issue entitled: RNA Polymerase II Transcript Elongation.

  18. Antibacterial cobalt (II), copper (II), nickel (II) and zinc (II) complexes of mercaptothiadiazole--derived furanyl, thienyl, pyrrolyl, salicylyl and pyridinyl Schiff bases.

    PubMed

    Chohan, Zahid H; Pervez, Humayun; Rauf, Abdul; Khan, Khalid M; Supuran, Claudiu T

    2006-04-01

    A series of Co (II), Cu (II), Ni (II) and Zn (II) complexes of mercaptothiadiazole-derived furanyl, thienyl, pyrrorlyl, salicylyl and pyridinyl Schiff bases were synthesized, characterized and screened for their in vitro antibacterial activity against four Gram-negative, Escherichia coli, Pseudomonas aeruginosa, Salmonella typhi and Shigella fexneri, and two Gram-positive; Bacillus subtilis and Staphylococcus aureous bacterial strains. The results of these studies show the metal complexes to be more antibacterial as compared to the prepared un-complexed Schiff bases.

  19. Spectroscopic and fluorescence studies on Mn(II), Co(II), Ni(II) and Cu(II) complexes with NO donor fluorescence dyes

    NASA Astrophysics Data System (ADS)

    Refat, Moamen S.; El-Metwaly, Nashwa M.

    2011-10-01

    The reactions of the two common dyes [2TMPACT and 4PENI] with Mn(II), Co(II), Ni(II) and Cu(II) ions were done. All the isolated complexes have been characterized by physicochemical and spectroscopic techniques. The IR data reflect the bidentate mode of 2TMPACT towards the mononuclear complex [Mn(II)] even its tetradentate in binuclear complexes [Co(II) and Cu(II)]. However, the bidentate mode is the only behavior of 4PENI ligand towards each metal ion in its mononuclear complexes. The UV-vis spectral analysis beside the magnetic moment measurements are proposed different geometries concerning each metal ions with the two ligands under investigation, as the Mn(II)-2TMPACT complex is an octahedral but Mn(II)-4PENI is a tetrahedral geometry. All the synthesized compounds are thermogravimetrically investigated. The proposed thermal decomposition was discussed for each compound with each step as well as, the kinetic parameters were calculated for all preferrible decomposition steps. The mass spectroscopy tool was used to emphasis on the suitable molecular formula proposed and the fragmentation patterns were displayed. The fluorescence properties of the synthesized ligands and their complexes were studied in DMSO at room temperature.

  20. Spectroscopic and fluorescence studies on Mn(II), Co(II), Ni(II) and Cu(II) complexes with NO donor fluorescence dyes.

    PubMed

    Refat, Moamen S; el-Metwaly, Nashwa M

    2011-10-15

    The reactions of the two common dyes [2TMPACT and 4PENI] with Mn(II), Co(II), Ni(II) and Cu(II) ions were done. All the isolated complexes have been characterized by physicochemical and spectroscopic techniques. The IR data reflect the bidentate mode of 2TMPACT towards the mononuclear complex [Mn(II)] even its tetradentate in binuclear complexes [Co(II) and Cu(II)]. However, the bidentate mode is the only behavior of 4PENI ligand towards each metal ion in its mononuclear complexes. The UV-vis spectral analysis beside the magnetic moment measurements are proposed different geometries concerning each metal ions with the two ligands under investigation, as the Mn(II)-2TMPACT complex is an octahedral but Mn(II)-4PENI is a tetrahedral geometry. All the synthesized compounds are thermogravimetrically investigated. The proposed thermal decomposition was discussed for each compound with each step as well as, the kinetic parameters were calculated for all preferrible decomposition steps. The mass spectroscopy tool was used to emphasis on the suitable molecular formula proposed and the fragmentation patterns were displayed. The fluorescence properties of the synthesized ligands and their complexes were studied in DMSO at room temperature.

  1. Optimization of simultaneous electrochemical determination of Cd(II), Pb(II), Cu(II) and Hg(II) at carbon nanotube-modified graphite electrodes.

    PubMed

    Pikna, L'ubomír; Heželová, Mária; Kováčová, Zuzana

    2015-01-01

    The health of the environment is worsening every day. Monitoring of potentially toxic elements and remediation of environmental pollution are necessary. Therefore, the research and development of simple, inexpensive, portable and effective sensors is important. Electrochemistry is a useful component of the field of environment monitoring. The present study focuses on evaluating and comparing three types of electrodes (PIGE, PIGE/MWCNT/HNO3 and PIGE/MWCNT/EDTA/HNO3) employed for the simultaneous electrochemical determination of four potentially toxic elements: Cd(II), Pb(II), Cu(II) and Hg(II). Cyclic voltammograms were measured in an acetate buffer. The LOD, LOQ, the standard and relative precisions of the method and a prediction intervals were calculated (according to the technical procedure DIN 32 645) for the three electrodes and for each measured element. The LOD for PIGE/CNT/HNO3 (the electrode with narrowest calculated prediction intervals) was 2.98 × 10(-7) mol L(-1) for Cd(II), 4.83 × 10(-7) mol L(-1) for Pb(II), 3.81 × 10(-7) mol L(-1) for Cu(II), 6.79 × 10(-7) mol L(-1) for Hg(II). One of the benefits of this study was the determination of the amount of Hg(II) in the mixture of other elements.

  2. A substituted sulfonamide and its Co (II), Cu (II), and Zn (II) complexes as potential antifungal agents.

    PubMed

    Diaz, Jorge R A; Fernández Baldo, Martín; Echeverría, Gustavo; Baldoni, Héctor; Vullo, Daniela; Soria, Delia B; Supuran, Claudiu T; Camí, Gerardo E

    2016-01-01

    A sulfonamide 1-tosyl-1-H-benzo(d)imidazol-2-amine (TBZA) and three new complexes of Co(II), Cu(II), and Zn(II) have been synthesized. The compounds have been characterized by elemental analyses, FTIR, (1)H, and (13)C-NMR spectroscopy. The structure of the TBZA, and its Co(II) and Cu(II) complexes, was determined by X-ray diffraction methods. TBZA and its Co(II) complex crystallize in the triclinic P-1 space group, while the Cu(II) complex crystallizes in the monoclinic P21/c space group. Antifungal activity was screened against eight pathogenic yeasts: Candida albicans (DMic 972576), Candida krusei (DMic 951705), Candida glabrata (DMic 982882), Candida tropicalis (DMic 982884), Candida dubliniensis (DMic 93695), Candida guilliermondii (DMic 021150), Cryptococcus neoformans (ATCC 24067), and Cryptococcus gattii (ATCC MYA-4561). Results on the inhibition of various human (h) CAs, hCA I, II, IV, VII, IX, and XII, and pathogenic beta and gamma CAs are also reported.

  3. Kinetics of Formation of Cobalt(II)- and Nickel(II) Carbonic Anhydrase.

    ERIC Educational Resources Information Center

    McQuate, Robert S.; Reardon, John E.

    1978-01-01

    Discusses the kinetic behavior associated with the interaction of metal ions with apocarbonic anhydrase, focusing on the formation of two metallocarbonic anhydrase--the biochemically active Co(II) and the inactive Ni(II)derivatives. (GA)

  4. ACCURATE RITZ WAVELENGTHS OF PARITY-FORBIDDEN [Co II] AND [V II] LINES OF ASTROPHYSICAL INTEREST

    SciTech Connect

    Ruffoni, M. P.; Pickering, J. C.

    2013-08-15

    We report a comprehensive list of accurate Ritz wavelengths for parity-forbidden [Co II] and [V II] lines obtained from the analysis of energy levels measured in the laboratory with Fourier transform emission spectroscopy. Such lines, particularly those in the infrared, are in demand for the analysis of low-density astrophysical plasmas in and around objects such as planetary nebulae, star-forming regions, and active galactic nuclei. Transitions between all known metastable levels of Co II and V II are included in our analysis, producing wavelengths for 1477 [V II] lines and 782 [Co II] lines. Of these, 170 [V II] lines and 171 [Co II] lines arise from transitions with calculated transition probabilities greater than 1 Multiplication-Sign 10{sup -2} s{sup -1} and upper level excitations of less than 5 eV, and thus are likely to be observed in astrophysical spectra.

  5. Heteroleptic bis(dipyrrinato)copper(II) and nickel(II) complexes.

    PubMed

    Toyoda, Ryojun; Tsuchiya, Mizuho; Sakamoto, Ryota; Matsuoka, Ryota; Wu, Kuo-Hui; Hattori, Yohei; Nishihara, Hiroshi

    2015-09-14

    Heteroleptic bis(dipyrrinato)copper(II) and nickel(II) complexes are synthesized. Their structures are determined by X-ray diffraction analysis, and their properties are investigated by using cyclic voltammetry, chronocoulometry, and UV/vis absorption spectroscopy.

  6. Voltammetric analysis of Cu (II), Cd (II) and Zn (II) complexes and their cyclic voltammetry with several cephalosporin antibiotics.

    PubMed

    Abo El-Maali, N; Osman, A H; Aly, A A M; Al-Hazmi, G A A

    2005-02-01

    Both osteryoung square wave voltammetry and cyclic voltammetry have been utilized to elucidate and confirm the possible complexation reaction that occur between the various cephalosporin antibiotics and either the toxic, non-essential metal ion, viz. Cd (II), or the essential but toxic (when their concentration exceeds certain level in serum) metal ions, viz. Cu (II) and Zn (II). Voltammetric measurements indicated the existence of 1:1 metal-to-ligand ratio (as in cephalexin and cephapirin complexes), 1:2 ratio (such as in cefamandole, cefuroxime and cefotaxime complexes) and 2:1 ratio in case of ceftazidime complexes. Adsorption behavior was evidenced for Cu (II)-cefuroxime or ceftazidime complexes as well as for those for Zn (II)-cephalexin or cephapirin. This phenomenon could be used for the determination of either the antibiotic or the metal ion using adsorptive stripping voltammetry. Detection limits down to 7x10(-10) M have been easily achieved.

  7. Adsorption of Cd(II) and Pb(II) from aqueous solutions on activated alumina.

    PubMed

    Naiya, Tarun Kumar; Bhattacharya, Ashim Kumar; Das, Sudip Kumar

    2009-05-01

    The ability of activated alumina as synthetic adsorbent was investigated for adsorptive removal of Cd(II) and Pb(II) ions from aqueous solutions. Various physico-chemical parameters such as pH, initial metal ion concentration, and adsorbent dosage level and equilibrium contact time were studied. The optimum solution pH for adsorption of Cd(II) and Pb(II) from aqueous solutions was found to be 5. Kinetics data were best described by pseudo-second order model. The effective particle diffusion coefficient of Cd(II) and Pb(II) are of the order of 10(-10) m(2)/s. Values of mass transfer coefficient were estimated as 4.868x10(-6) cm/s and 6.85x10(-6) cm/s for Cd(II) and Pb(II) adsorption respectively. The equilibrium adsorption data for Cd(II) and Pb(II) were better fitted to Langmuir adsorption isotherm model. The thermodynamic studies indicated that the adsorption was spontaneous and exothermic for Cd(II) adsorption and endothermic for Pb(II). The sorption energy calculated from Dubinin-Radushkevich isotherm were 11.85 kJ/mol and 11.8 kJ/mol for the adsorption of Cd(II) and Pb(II) respectively which indicated that both the adsorption processes were chemical in nature. Desorption studies were carried out using dilute mineral acids. Application studies carried out using industrial waste water samples containing Cd(II) and Pb(II) showed the suitability of activated alumina in waste water treatment plant operation.

  8. 40 CFR Table II-2 to Subpart II - Collection Efficiencies of Anaerobic Processes

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 22 2013-07-01 2013-07-01 false Collection Efficiencies of Anaerobic Processes II Table II-2 to Subpart II Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) MANDATORY GREENHOUSE GAS REPORTING Industrial Wastewater Treatment Pt....

  9. 40 CFR Table II-2 to Subpart II - Collection Efficiencies of Anaerobic Processes

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 21 2014-07-01 2014-07-01 false Collection Efficiencies of Anaerobic Processes II Table II-2 to Subpart II Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) MANDATORY GREENHOUSE GAS REPORTING Industrial Wastewater Treatment Pt....

  10. Sorption hysteresis of Cd(II) and Pb(II) on natural zeolite and bentonite.

    PubMed

    Hamidpour, Mohsen; Kalbasi, Mahmoud; Afyuni, Majid; Shariatmadari, Hossein; Holm, Peter E; Hansen, Hans Christian Brunn

    2010-09-15

    Sorption hysteresis in natural sorbents has important environmental implications for pollutant transport and bioavailability. We examined sorption reversibility of Cd(II) and Pb(II) on zeolite and bentonite. Sorption isotherms were derived by sorption of Cd(II) and Pb(II) from solutions containing a range of the metal concentrations corresponding to 10-100% maximum sorption capacity (SCmax) of the sorbents. The desorption experiments were performed immediately following the completion of sorption experiments. Sorption and desorption isotherms of Cd(II) and Pb(II) were well described by the Freundlich model. The results revealed that the desorption isotherms of Cd(II) and Pb(II) from zeolite significantly deviated from the sorption isotherms indicating irreversible or very slowly reversible sorption. For bentonite sorption/desorption isotherms were similar indicating reversible sorption. The extent of hysteresis was evaluated from sorption and desorption Freundlich parameters (K(f) and n) through the apparent hysteresis index (HI = n(desorb)/n(sorb); n is the exponent in the Freundlich equation) and differences in Freundlich K(f) parameters. Higher sorption irreversibility was obtained for Pb(II) as compared to Cd(II). The amounts of Cd(II) and Pb(II) desorbed from bentonite were more than from zeolite, indicating that zeolite was a more effective sorbent for water and wastewater treatment.

  11. Calix[4]arene based chemosensor for selective complexation of Cd(II) and Cu(II)

    NASA Astrophysics Data System (ADS)

    Qazi, Mansoor Ahmed; Qureshi, Imdadullah; Memon, Shahabuddin

    2010-06-01

    The present article describes synthesis, characterization and a detailed complexation study of calix[4]arene based chemosensor ( 4) bearing two anthracenyl units as signaling groups on its coordination sphere. The complex formation ability of 4 toward selected transition metals such as Cd(II), Co(II), Cu(II), Ni(II) and Pb(II) has been investigated by UV-visible spectroscopy. Assessment of results reveal that the chemosensor is selective toward Cd(II) and Cu(II). The FT-IR spectroscopic method was applied for further confirmation of the complexation phenomenon. Besides this, a study regarding interference of other metals on complex formation in solution has also supported the efficient binding preference of 4 for Cd(II) and Cu(II). From the results it has been concluded that 4 has compatible coordination sphere to accommodate these metals. The similarities and differences revealed that being soft nature of both metals and because of diagonal relationship in the periodic table their coordination behavior toward N/O-donor ligand may be treated as a test on possibility of the Cu(II) ions to be displaced by Cd(II). The study certainly will help in understanding the hazards of Cd(II) in biological systems.

  12. Diet History Questionnaire II & Canadian Diet History Questionnaire II: Web-based DHQ

    Cancer.gov

    The Web-based versions of DHQ II and C-DHQ II are identical in content to the paper forms. By automating the DHQ II and providing versions on the Web for public use, researchers have another tool to collect and analyze food frequency questionnaire data.

  13. Spectral and thermodynamic properties of Ag(I), Au(III), Cd(II), Co(II), Fe(III), Hg(II), Mn(II), Ni(II), Pb(II), U(IV), and Zn(II) binding by methanobactin from Methylosinus trichosporium OB3b.

    PubMed

    Choi, Dong W; Do, Young S; Zea, Corbin J; McEllistrem, Marcus T; Lee, Sung-W; Semrau, Jeremy D; Pohl, Nicola L; Kisting, Clint J; Scardino, Lori L; Hartsel, Scott C; Boyd, Eric S; Geesey, Gill G; Riedel, Theran P; Shafe, Peter H; Kranski, Kim A; Tritsch, John R; Antholine, William E; DiSpirito, Alan A

    2006-12-01

    Methanobactin (mb) is a novel chromopeptide that appears to function as the extracellular component of a copper acquisition system in methanotrophic bacteria. To examine this potential physiological role, and to distinguish it from iron binding siderophores, the spectral (UV-visible absorption, circular dichroism, fluorescence, and X-ray photoelectron) and thermodynamic properties of metal binding by mb were examined. In the absence of Cu(II) or Cu(I), mb will bind Ag(I), Au(III), Co(II), Cd(II), Fe(III), Hg(II), Mn(II), Ni(II), Pb(II), U(VI), or Zn(II), but not Ba(II), Ca(II), La(II), Mg(II), and Sr(II). The results suggest metals such as Ag(I), Au(III), Hg(II), Pb(II) and possibly U(VI) are bound by a mechanism similar to Cu, whereas the coordination of Co(II), Cd(II), Fe(III), Mn(II), Ni(II) and Zn(II) by mb differs from Cu(II). Consistent with its role as a copper-binding compound or chalkophore, the binding constants of all the metals examined were less than those observed with Cu(II) and copper displaced other metals except Ag(I) and Au(III) bound to mb. However, the binding of different metals by mb suggests that methanotrophic activity also may play a role in either the solubilization or immobilization of many metals in situ.

  14. FOREWORD: HELAS II International Conference

    NASA Astrophysics Data System (ADS)

    Gizon, Laurent; Roth, Markus

    2008-07-01

    Volume 118 (2008) of Journal of Physics: Conference Series provides a written record of the talks and posters presented at the HELAS II International Conference `Helioseismology, Asteroseismology and MHD Connections'. The conference was held during the week 20-24 August 2007 in Göttingen, Germany, jointly hosted by the Max Planck Institute for Solar System Research and the Faculty of Physics of the University of Göttingen. A total of 140 scientists from all over the world attended. The Scientific Organizing Committee consisted of Conny Aerts, Annie Baglin, Jørgen Christensen-Dalsgaard, Thierry Corbard, Jadwiga Daszyńska-Daszkiewicz, Stefan Dreizler, Yvonne Elsworth, Laurent Gizon (Chairman), Wolfgang Glatzel, Frank Hill, Donald Kurtz, Oskar von der Lühe, Maria Pia Di Mauro, Mário Monteiro, Pere Pallé, Markus Roth, Philip Scherrer, Manfred Schüssler, and Michael Thompson. HELAS stands for the European Helio- and Asteroseismology Network, a Coordination Action supported by the sixth Framework Programme of the European Union. It aims to bring together researchers in the fields of solar and stellar oscillations. This volume consists of 91 articles organized into sections that reflect the scientific programme of the conference: 012001-07 Wave diagnostics in physics, geophysics and astrophysics 012008-09 Perspectives on helio- and asteroseismology 012010-17 Asteroseismology: Observations 012018-25 Asteroseismology: Theory 012026-32 Global helioseismology and solar models 012033-38 Local helioseismology and magnetic activity 012039-44 Future observational projects in helio- and asteroseismology 012045-91 Poster papers. The overwhelming majority of papers discuss the seismology of the Sun and stars. Papers in the first section provide a broader perspective on wave phenomena and techniques for probing other physical systems, from living beings to the universe as a whole. We were extremely fortunate to have particularly distinguished experts to cover these topics

  15. Moderately luminous Type II supernovae

    NASA Astrophysics Data System (ADS)

    Inserra, C.; Pastorello, A.; Turatto, M.; Pumo, M. L.; Benetti, S.; Cappellaro, E.; Botticella, M. T.; Bufano, F.; Elias-Rosa, N.; Harutyunyan, A.; Taubenberger, S.; Valenti, S.; Zampieri, L.

    2013-07-01

    Context. Core-collapse Supernovae (CC-SNe) descend from progenitors more massive than about 8 M⊙. Because of the young age of the progenitors, the ejecta may eventually interact with the circumstellar medium (CSM) via highly energetic processes detectable in the radio, X-ray, ultraviolet (UV) and, sometimes, in the optical domains. Aims: In this paper we present ultraviolet, optical and near infrared observations of five Type II SNe, namely SNe 2009dd, 2007pk, 2010aj, 1995ad, and 1996W. Together with few other SNe they form a group of moderately luminous Type II events. We investigate the photometric similarities and differences among these bright objects. We also attempt to characterise them by analysing the spectral evolutions, in order to find some traces of CSM-ejecta interaction. Methods: We collected photometry and spectroscopy with several telescopes in order to construct well-sampled light curves and spectral evolutions from the photospheric to the nebular phases. Both photometry and spectroscopy indicate a degree of heterogeneity in this sample. Modelling the data of SNe 2009dd, 2010aj and 1995ad allows us to constrain the explosion parameters and the properties of the progenitor stars. Results: The light curves have luminous peak magnitudes (-16.95 < MB < -18.70). The ejected masses of 56Ni for three SNe span a wide range of values (2.8 × 10-2 M⊙ < M(56Ni)< 1.4 × 10-1 M⊙), while for a fourth (SN 2010aj) we could determine a stringent upper limit (7 × 10-3 M⊙). Clues of interaction, such as the presence of high velocity (HV) features of the Balmer lines, are visible in the photospheric spectra of SNe 2009dd and 1996W. For SN 2007pk we observe a spectral transition from a Type IIn to a standard Type II SN. Modelling the observations of SNe 2009dd, 2010aj and 1995ad with radiation hydrodynamics codes, we infer kinetic plus thermal energies of about 0.2-0.5 foe, initial radii of 2-5 × 1013 cm and ejected masses of ~5.0-9.5 M⊙. Conclusions: These

  16. Adsorption of Cd(II), Cu(II) and Ni(II) ions by cross-linking chitosan/rectorite nano-hybrid composite microspheres.

    PubMed

    Zeng, Lixuan; Chen, Yufei; Zhang, Qiuyun; Guo, Xingmei; Peng, Yanni; Xiao, Huijuan; Chen, Xiaocheng; Luo, Jiwen

    2015-10-05

    Chitosan/rectorie (CTS/REC) nano-hybrid composite microsphere was prepared by changing the proportion of CTS/REC with 2:1, 3:1 and 4:1. Compared with the pure cross-linking chitosan microsphere, the nano-hybrid composite microsphere was proved to have better sorption capacity of Cd(II), Cu(II) and Ni(II), especially 2:1(CTS/REC-1). The adsorption behavior of the microsphere of Cd(II), Cu(II) and Ni(II) was investigated in single and binary metal systems. In single system, the equilibrium studies showed that the adsorption of Cd(II), Cu(II) and Ni(II) followed the Langmuir model and the pseudo-second-order kinetic model. The negative values of (ΔG) suggested that the adsorption process was spontaneous. In binary system, the combined action of the metals was found to be antagonistic and the metal sorption followed the order of Cu(II)>Cd(II)>Ni(II). The regeneration studies indicated that EDTA desorbed Cd(II), Cu(II) and Ni(II) from cross-linking microspheres better than HCl. The FT-IR and XPS spectra showed that coordination bonds were formed between Cd(II), Cu(II) and Ni(II) and the nitrogen atoms of cross-linking CTS/REC nano-hybrid composite microspheres.

  17. World War II Homefront: A Historiography.

    ERIC Educational Resources Information Center

    Winkler, Allan M.

    2002-01-01

    Highlights the scholarship that exists on the World War II homefront covering topics such as World War II as a good war, Franklin D. Roosevelt, economic policy, propaganda, status of women and women's employment, the role of African Americans, racial violence, and the Japanese American experience. (CMK)

  18. Addressing Instructional Avoidance with Tier II Supports

    ERIC Educational Resources Information Center

    Anderson, Cynthia M.; Turtura, Jessica; Parry, Michael

    2013-01-01

    In a 3-tiered, prevention-oriented framework, Tier II (secondary, targeted) interventions are designed for students whose problem behaviors have not responded to Tier I but are not severe enough to warrant an individualized Tier III intervention. Tier II interventions are implemented similarly across students receiving the intervention and can be…

  19. The CNET Automated Budget System (CABS) II.

    ERIC Educational Resources Information Center

    Middleton, Morris G.; And Others

    The Chief of Naval Education and Training (CNET) Automated Budget System II (CABS II) is an improved and expanded version of an earlier system which was developed by the Training Analysis and Evaluation Group (TAEG) to provide an efficient, easy means of handling the large volume of data necessary to produce budget documents. Intended as a guide…

  20. Children Teaching Children II. [CD-ROM].

    ERIC Educational Resources Information Center

    California State Dept. of Education, Sacramento. Office of School Improvement.

    Children Teaching Children (CTC): Collection II is a CD-ROM created at 6 elementary schools in the West Contra Costa Unified School District (California) as part of the Coaching Odyssey for school improvement. CTC II, published by the California Department of Education, is an effective early literacy intervention that integrates the development of…

  1. World War II: A Technology Lesson Plan.

    ERIC Educational Resources Information Center

    Hagar, Suzy

    1990-01-01

    Presents a class activity on the history, causes, and consequences of World War II. Focuses on the development and deployment of the atomic bomb. Utilizes a Video Encyclopedia Program for historical background. Divides the class into groups that are responsible for researching and preparing a videotape on a World War II topic. (RW)

  2. Geology of the Phase II System

    SciTech Connect

    Laney, R.; Laughlin, A. William

    1980-11-19

    This is a report on the analysis of EE-2 cuttings and thin sections, geologic characterization of the Phase II system, comparison with Phase 1, and geologic speculations and recommendations concerning Phase II. The EE-2 litholog has been included in the pocket.

  3. World War II Memorial Learning Activities.

    ERIC Educational Resources Information Center

    Tennessee State Dept. of Education, Nashville.

    These learning activities can help students get the most out of a visit to the Tennessee World War II Memorial, a group of ten pylons located in Nashville (Tennessee). Each pylon contains informational text about the events of World War II. The ten pylons are listed as: (1) "Pylon E-1--Terror: America Enters the War against Fascism, June…

  4. Fits, pyridoxine, and hyperprolinaemia type II.

    PubMed

    Walker, V; Mills, G A; Peters, S A; Merton, W L

    2000-03-01

    The rare inherited disorder hyperprolinaemia type II presents with fits in childhood, usually precipitated by infection. A diagnosis of hyperprolinaemia type II and vitamin B(6) deficiency was made in a well nourished child with fits. It is thought that pyridoxine deficiency was implicated in her fits and was the result of inactivation of the vitamin by the proline metabolite, pyrroline-5-carboxylate.

  5. Hearing Restoration in Neurofibromatosis Type II Patients

    PubMed Central

    Lee, Jeon Mi; Chang, Jin Woo; Choi, Jae Young

    2016-01-01

    Patients with neurofibromatosis type II will eventually succumb to bilateral deafness. For patients with hearing loss, modern medical science technology can provide efficient hearing restoration through a number of various methods. In this article, several hearing restoration methods for patients with neurofibromatosis type II are introduced. PMID:27189272

  6. TRUPACT-II procedures and maintenance instructions

    SciTech Connect

    1994-01-14

    The purpose of this document is to provide the technical requirements for operation, inspection and maintenance of a TRUPACT-II Shipping Package and directly related components. This document shall supply the minimum requirements as specified in the TRUPACT-II Safety Analysis Report for Packaging (SARP) and Certificate of Compliance (C of C) 9218. In the event there is a conflict between this document and the TRUPACT-II SARP (NRC Certificate of Compliance No. 9218), the TRUPACT-II SARP shall govern. This document details the operations, maintenance, repair, replacement of components, as well as the documentation required and the procedures to be followed to maintain the integrity of the TRUPACT-II container. These procedures may be modified for site use, but as a minimum all parameters and format listed herein must be included in any site modified version. For convenience and where applicable steps may be performed out of sequence. Packaging and payload handling equipment and transport trailers have been specifically designed for use with the TRUPACT-II Packaging. This document discusses the minimum required procedures for use of the adjustable center of gravity lift fixture and the TRUPACT-II transport trailer in conjunction with the TRUPACT-II Packaging.

  7. Biology II Curriculum Guide. Bulletin 1820.

    ERIC Educational Resources Information Center

    Louisiana State Dept. of Education, Baton Rouge. Div. of Academic Programs.

    In 1986, the Louisiana State Board of Elementary and Secondary Education requested that an advanced course in Biology II be developed. The resulting curriculum guide contains grade appropriate goals, skills, and competencies; suggested activities; suggested materials of instruction; and minimum time allotments for instruction. Biology II is a…

  8. Run II data analysis on the grid

    SciTech Connect

    Igor Mandrichenko, Igor Terekhov and Frank Wurthwein

    2002-12-02

    In this document, we begin the technical design for the distributed RunII computing for CDF and D0. The present paper defines the three components of the data handling area of Run II computing, namely the Data Handling System, the Storage System and the Application. We outline their functionality and interaction between them. We identify necessary and desirable elements of the interfaces.

  9. Synthesis, DFT Calculation, and Antimicrobial Studies of Novel Zn(II), Co(II), Cu(II), and Mn(II) Heteroleptic Complexes Containing Benzoylacetone and Dithiocarbamate

    PubMed Central

    Ekennia, Anthony C.; Onwudiwe, Damian C.; Olasunkanmi, Lukman O.; Osowole, Aderoju A.; Ebenso, Eno E.

    2015-01-01

    Heteroleptic complexes of zinc(II), copper(II), manganese(II), and cobalt(II) of the types [MLL′(H2O)2]·nH2O and [MLL′]·nH2O have been synthesized using sodium N-methyl-N-phenyldithiocarbamate (L) and benzoylacetone (L′). The metal complexes were characterized by elemental analysis, electrical conductance, magnetic susceptibility, infrared (IR), and UV-visible spectroscopic studies. The electrical conductance measurements revealed the nonelectrolytic nature of the synthesized complexes. The results of the elemental analyses, magnetic susceptibility measurements, and electronic spectra inferred that the Zn(II) complex adopted a four-coordinate geometry while the Co(II), Cu(II), and Mn(II) complexes assumed octahedral geometries. The IR spectra showed that the metal ions coordinated with the ligands via the S- and O-donor atoms. The geometry, electronic, and thermodynamic parameters of the complexes were obtained from density functional theory (DFT) calculations. The spin density distributions, relative strength of H–bonds, and thermodynamic parameters revealed that the order of stability of the metal complexes is Mn < Co < Cu > Zn. The agar diffusion methods were used to study the antimicrobial activity of the complexes against two Gram positive bacteria (S. aureus and S. pneumoniae), one Gram negative bacterium (E. coli), and two fungi organisms (A. niger and A. candida) and the complexes showed a broad spectrum of activities against the microbes. PMID:26681931

  10. Micro Channel/Multibus-II Interface Circuit

    NASA Technical Reports Server (NTRS)

    D'Ambrose, John J.; Jaworski, Richard C.; Heise, Nyles N.; Thornton, David N.

    1991-01-01

    Micro Channel/Multibus-II interface circuit provides electrical interconnections enabling communications between Micro Channels of IBM Personal System/2 computers and IEEE 1296 standard Multibus-II parallel system bus (iPSB). Made mostly of commercially available parts, interface enables independent Micro Channels to communicate over iPSB without modification.

  11. The merging dwarf galaxy UM 448: chemodynamics of the ionized gas from VLT integral field spectroscopy

    NASA Astrophysics Data System (ADS)

    James, B. L.; Tsamis, Y. G.; Barlow, M. J.; Walsh, J. R.; Westmoquette, M. S.

    2013-01-01

    Using Very Large Telescope/Fibre Large Array Multi Element Spectrograph optical integral field unit observations, we present a detailed study of UM 448, a nearby blue compact galaxy (BCG) previously reported to have an anomalously high N/O abundance ratio. New Technology Telescope/Superb-Seeing Imager images reveal a morphology suggestive of a merger of two systems of contrasting colour, whilst our Hα emission maps resolve UM 448 into three separate regions that do not coincide with the stellar continuum peaks. UM 448 exhibits complex emission line profiles, with most lines consisting of a narrow [full width at half-maximum (FWHM) ≲ 100 km s-1], central component, an underlying broad component (FWHM ˜ 150-300 km s-1) and a third, narrow blueshifted component. Radial velocity maps of all three components show signs of solid body rotation across UM 448, with a projected rotation axis that correlates with the continuum morphology of the galaxy. A spatially resolved, chemodynamical analysis, based on the [O iii] λλ4363, 4959, [N ii] λ6584, [S ii] λλ6716, 6731 and [Ne iii] λ3868 line maps, is presented. Whilst the eastern tail of UM 448 has electron temperatures (Te) that are typical of BCGs, we find a region within the main body of the galaxy where the narrow and broad [O iii] λ4363 line components trace temperatures differing by 5000 K and oxygen abundances differing by 0.4 dex. We measure spatially resolved and integrated ionic and elemental abundances for O, N, S and Ne throughout UM 448, and find that they do not agree, possibly due the flux weighting of Te from the integrated spectrum. This has significant implications for abundances derived from long-slit and integrated spectra of star-forming galaxies in the nearby and distant universe. A region of enhanced N/O ratio is indeed found, extended over a ˜0.6 kpc2 region within the main body of the galaxy. Contrary to previous studies, however, we do not find evidence for a large Wolf-Rayet (WR

  12. Interpreting the H II Region Luminosity Function

    NASA Astrophysics Data System (ADS)

    Oey, M. S.; Clarke, C. J.

    1998-12-01

    We construct Monte Carlo simulations of the H II region luminosity function (H II LF), drawing ionizing stars from a constant stellar IMF, and the number of ionizing stars from a power-law distribution of constant slope. We find that observed variations in the form of the H II LF across the Hubble sequence can be explained by a trend in the maximum number of ionizing stars per nebula. In addition, variations in the form of the H II LF between arm and interarm populations of spiral galaxies can be explained by evolutionary effects. The H II LF can thus reveal features in the most recent (< 10 Myr) star formation history of the host galaxies.

  13. TRUPACT-II Operating and Maintenance Instructions

    SciTech Connect

    Westinghouse Electric Corporation, Waste Isolation Division

    1999-12-31

    The purpose of this document is to provide the technical requirements for preparation for use, operation, inspection, and maintenance of a Transuranic Package Transporter Model II (TRUPACT-II) Shipping Package and directly related components. This document complies with the minimum requirements as specified in the TRUPACT-II Safety Analysis Report for Packaging (SARP) and Nuclear Regulatory Commission (NRC) Certificate of Compliance (C of C) 9218. In the event there is a conflict between this document and the TRUPACT-II SARP, the TRUPACT-II SARP shall govern. TRUPACT-II C of C number 9218 states, ''... each package must be prepared for shipment and operated in accordance with the procedures described in Chapter 7.0, Operating Procedures, of the application.'' It further states, ''... each package must be tested and maintained in accordance with the procedures described in Chapter 8.0, Acceptance Tests and Maintenance Program of the application.'' Chapter 9 of the TRUPACT-II SARP charges the Westinghouse Electric Corporation Waste Isolation Division (WID) with assuring that the TRUPACT-II is used in accordance with the requirements of the C of C. To meet this requirement and verify consistency of operations when loading and unloading the TRUPACT-II on the trailer, placing a payload in the packaging, unloading the payload from the packaging, or performing maintenance, the U.S. Department of Energy Carlsbad Area Office (U.S. DOE/CAO) finds it necessary to implement the changes that follow. This TRUPACT-II maintenance document represents a change to previous philosophy regarding site specific procedures for the use of the TRUPACT-II. This document details the instructions to be followed to consistently operate and maintain the TRUPACT-II. The intent of these instructions is to ensure that all users of the TRUPACT-II follow the same or equivalent instructions. Users may achieve this intent by any of the following methods: (1) Utilizing these instructions as is, or (2

  14. TRUPACT-II, a regulatory perspective

    SciTech Connect

    Gregory, P.C.; Spooner, O.R.

    1995-12-31

    The Transuranic Package Transporter II (TRUPACT-II) is a US Nuclear Regulatory Commission (NRC) certified Type B packaging for the shipment of contact-handled transuranic (CH-TRU) material by the US Department of Energy (DOE). The NRC approved the TRUPACT-II design as meeting the requirements of Title 10, Code of Federal Regulations, Part 71 (10 CFR 71) and issued Certificate of Compliance (CofC) Number 9218 to the DOE. There are currently 15 certified TRUPACT-IIs. Additional TRUPACT-IIs will be required to make more than 15,000 shipments of CH-TRU waste to the Waste Isolation Pilot Plant (WIPP) site near Carlsbad, New Mexico. The TRUPACT-II may also be used for the DOE inter-site and intra-site shipments of CH-TRU waste. The Land Withdrawal Act (Public Law 102-579), enacted by the US Congress, October 30, 1992, and an agreement between the DOE and the State of New Mexico, signed August 4, 1987, both stipulate that only NRC approved packaging may be used for shipments of TRU waste to the WIPP. Early in the TRUPACT-II development phase it was decided that the transportation system (tractor, trailer, and TRUPACT-II) should be highway legal on all routes without the need for oversize and/or overweight permits. In large measure, public acceptance of the DOE`s efforts to safely transport CH-TRU waste depends on the public`s perception that the TRUPACT-II is in compliance with all applicable regulations, standards, and quality assurance requirements. This paper addresses some of the numerous regulations applicable to Type B packaging, and it describes how the TRUPACT-II complies with these regulations.

  15. Ozone Conference II: Abstract Proceedings

    SciTech Connect

    1999-11-01

    Ozone Conference II: Pre- and Post-Harvest Applications Two Years After Gras, was held September 27-28, 1999 in Tulare, California. This conference, sponsored by EPRI's Agricultural Technology Alliance and Southern California Edison's AgTAC facility, was coordinated and organized by the on-site ATA-AgTAC Regional Center. Approximately 175 people attended the day-and-a-half conference at AgTAC. During the Conference twenty-two presentations were given on ozone food processing and agricultural applications. Included in the presentations were topics on: (1) Ozone fumigation; (2) Ozone generation techniques; (3) System and design applications; (4) Prewater treatment requirements; (5) Poultry water reuse; (6) Soil treatments with ozone gas; and (7) Post-harvest aqueous and gaseous ozone research results. A live videoconference between Tulare and Washington, D.C. was held to discuss the regulators' view from inside the beltway. Attendees participated in two Roundtable Question and Answer sessions and visited fifteen exhibits and demonstrations. The attendees included university and governmental researchers, regulators, consultants and industry experts, technology developers and providers, and corporate and individual end-users. This report is comprised of the Abstracts of each presentation, biographical sketches for each speaker and a registration/attendees list.

  16. II-VI widegap superlattices

    NASA Astrophysics Data System (ADS)

    Taguchi, T.; Yamada, Y.; Endoh, Y.; Nozue, Y.; Mullins, J. T.; Ohno, T.; Masumoto, Y.; Takeda, S.

    We review our recent results of the excitonic properties in ZnSeZnS and Cd xZn 1-xSZnS strained-layer superlattices (SLSs). The most important physical insights in the II-VI widegap superlattices are to understand the relationship between the optical properties of quasi-two-dimensional exciton and strain because the well layer frequently receives biaxial compression or tension. The strain thus causes the significant shifts of the bandgap and splitting of the valence band. Semi-quantative calculations lead to an expectation that ZnSeZnS SLS always exhibits a type I band lineup within 100 Å thicknesses of the ZnSe well at a constant ZnS barrier width of several tens angstrom. This is in good agreement with the experimental results of exciton absorption and its luminescence excitation spectra. The Cd 0.3Zn 0.7SZnS SLSs with a range of well widths can produce intense excitonic emissions around 3.4 eV at room temperature due to the quantum confinement of excitons in the ternary CdZnS well. In order to elucidate localisation and relaxation processes of excitons, we have for the first time reported a multiple-LO-phonon emission process in the excitation spectra. The electric-field studies suggest that the concomitant decrease in intensity and the energy downshift of the exciton line may originate from the quantum confined Stark effect.

  17. PEP-II operations report

    NASA Astrophysics Data System (ADS)

    Zisman, Michael S.

    2001-04-01

    PEP-II is a two-ring asymmetric B factory operating at the ϒ(4S) resonance. It was constructed by a SLAC-LBNL-LLNL collaboration. The collider comprises two rings, a High-Energy Ring (HER) storing 9 GeV electrons, and a Low-Energy Ring (LER) storing 3.1 GeV positrons. Commissioning of the HER began in mid-1997 and commissioning of the LER began in mid-1998. First evidence for collisions was obtained on July 23, 1998. The B AB AR detector was installed in early 1999, and commissioning with the detector commenced in May 1999. In the present run, which began in October 1999, the peak luminosity has reached 3.1×10 33 cm-2 s-1 and the integrated luminosity delivered is 25 fb-1. In this paper we describe the startup experience and summarize the operational experience during fiscal year 2000 (from October 1999 through September 2000). Plans for luminosity upgrades are briefly described.

  18. Early failure of Class II resin composite versus Class II amalgam restorations placed by dental students.

    PubMed

    Overton, J D; Sullivan, Diane J

    2012-03-01

    Using the information from remake request slips in a dental school's predoctoral clinic, we examined the short-term survival of Class II resin composite restorations versus Class II dental amalgam restorations. In the student clinic, resin composite is used in approximately 58 percent of Class II restorations placed, and dental amalgam is used in the remaining 42 percent. In the period examined, Class II resin composite restorations were ten times more likely to be replaced at no cost to the patient than Class II dental amalgam restorations. A total of eighty-four resin composite restorations and six amalgam restorations were replaced due to an identified failure.

  19. Synthesis and characterization of Co(II), Ni(II) and Cu(II) complexes involving hydroxy antipyrine azodyes

    NASA Astrophysics Data System (ADS)

    Gaber, M.; Hassanein, A. M.; Lotfalla, A. A.

    2008-03-01

    The complexes formed between some hydroxy antipyrine azodyes and Co(II), Ni(II) and Cu(II) ions were studied spectrophotometrically in solution. The stoichiometry and stability constants of the metal chelates were determined. The spectrophotometric determination of the titled metal ions and titration using EDTA were reported. The chelating behaviour of the azodyes was confirmed by preparing the solid chelates in which their structures are elucidated using molar conductance, elemental, thermogravimetric (TGA) analyses, IR, ESR and electronic spectra as well as the magnetic measurements. Kinetic parameters are computed from the thermal decomposition data. The electrical properties for the metal complexes are measured from which the activation energies are calculated.

  20. Adsorption of Cu(II), Hg(II), and Ni(II) ions by modified natural wool chelating fibers.

    PubMed

    Monier, M; Ayad, D M; Sarhan, A A

    2010-04-15

    The graft copolymerization of ethyl acrylate (EA) onto natural wool fibers initiated by potassium persulphate and Mohr's salt redox initiator system in limited aqueous medium was carried out in heterogeneous media. Ester groups of the grafted copolymers were partially converted into hydrazide function groups followed by hydrazone formation through reaction with isatin. Also the application of the modified fibers for metal ion uptake was studied using Cu(II), Hg(II) and Ni(II). The modified chelating fibers were characterized using FTIR spectroscopy, SEM and X-ray diffraction.

  1. Effects of Mg II and Ca II ionization on ab-initio solar chromosphere models

    NASA Technical Reports Server (NTRS)

    Rammacher, W.; Cuntz, M.

    1991-01-01

    Acoustically heated solar chromosphere models are computed considering radiation damping by (non-LTE) emission from H(-) and by Mg II and Ca II emission lines. The radiative transfer equations for the Mg II k and Ca II K emission lines are solved using the core-saturation method with complete redistribution. The Mg II k and Ca II K cooling rates are compared with the VAL model C. Several substantial improvements over the work of Ulmschneider et al. (1987) are included. It is found that the rapid temperature rises caused by the ionization of Mg II are not formed in the middle chromosphere, but occur at larger atmospheric heights. These models represent the temperature structure of the 'real' solar chromosphere much better. This result is a major precondition for the study of ab-initio models for solar flux tubes based on MHD wave propagation and also for ab-initio models for the solar transition layer.

  2. Solid-phase extraction of Mn(II), Co(II), Ni(II), Cu(II), Cd(II) and Pb(II) ions from environmental samples by flame atomic absorption spectrometry (FAAS).

    PubMed

    Duran, Celal; Gundogdu, Ali; Bulut, Volkan Numan; Soylak, Mustafa; Elci, Latif; Sentürk, Hasan Basri; Tüfekci, Mehmet

    2007-07-19

    A new method using a column packed with Amberlite XAD-2010 resin as a solid-phase extractant has been developed for the multi-element preconcentration of Mn(II), Co(II), Ni(II), Cu(II), Cd(II), and Pb(II) ions based on their complex formation with the sodium diethyldithiocarbamate (Na-DDTC) prior to flame atomic absorption spectrometric (FAAS) determinations. Metal complexes sorbed on the resin were eluted by 1 mol L(-1) HNO3 in acetone. Effects of the analytical conditions over the preconcentration yields of the metal ions, such as pH, quantity of Na-DDTC, eluent type, sample volume and flow rate, foreign ions etc. have been investigated. The limits of detection (LOD) of the analytes were found in the range 0.08-0.26 microg L(-1). The method was validated by analyzing three certified reference materials. The method has been applied for the determination of trace elements in some environmental samples.

  3. Chitosan film loaded with silver nanoparticles-sorbent for solid phase extraction of Al(III), Cd(II), Cu(II), Co(II), Fe(III), Ni(II), Pb(II) and Zn(II).

    PubMed

    Djerahov, Lubomir; Vasileva, Penka; Karadjova, Irina; Kurakalva, Rama Mohan; Aradhi, Keshav Krishna

    2016-08-20

    The present study describes the ecofriendly method for the preparation of chitosan film loaded with silver nanoparticles (CS-AgNPs) and application of this film as efficient sorbent for separation and enrichment of Al(III), Cd(II), Cu(II), Co(II), Fe(III), Ni(II), Pb(II) and Zn(II). The stable CS-AgNPs colloid was prepared by dispersing the AgNPs sol in chitosan solution at appropriate ratio and further used to obtain a cast film with very good stability under storage and good mechanical strength for easy handling in aqueous medium. The incorporation of AgNPs in the structure of CS film and interaction between the polymer matrix and nanoparticles were confirmed by UV-vis and FTIR spectroscopy. The homogeneously embedded AgNPs (average diameter 29nm, TEM analysis) were clearly observed throughout the film by SEM. The CS-AgNPs nanocomposite film shows high sorption activity toward trace metals under optimized chemical conditions. The results suggest that the CS-AgNPs nanocomposite film can be feasibly used as a novel sorbent material for solid-phase extraction of metal pollutants from surface waters.

  4. New Rh2(II,II) Architecture for the Catalytic Reduction of H⁺.

    PubMed

    White, Travis A; Witt, Suzanne E; Li, Zhanyong; Dunbar, Kim R; Turro, Claudia

    2015-10-19

    Formamidinate-bridged Rh2(II,II) complexes containing diimine ligands of the formula cis-[Rh2(II,II)(μ-DTolF)2(NN)2](2+) (Rh2-NN2), where DTolF = p-ditolylformamidinate and NN = dppn (benzo[i]dipyrido[3,2-a:2',3'-h]quinoxaline), dppz (dipyrido[3,2-a:2',3'-c]phenazine), and phen (1,10-phenanthroline), electrocatalytically reduce H(+) to H2 in DMF solutions containing CH3COOH at a glassy carbon electrode. Cathodic scans in the absence of acid display a Rh(III,II/II,II) reduction at -0.90 V vs Fc(+)/Fc followed by NN(0/-) reduction at -1.13, -1.36, and -1.65 V for Rh2-dppn2, Rh2-dppz2, and Rh2-phen2, respectively. Upon the addition of acid, Rh2-dppn2 and Rh2-dppz2 undergo reduction-protonation-reduction at each pyrazine-containing NN ligand prior to the Rh2(II,II/II,I) reduction. The Rh2(II,I) species is then protonated at one of the metal centers, resulting in the formation of the corresponding Rh2(II,III)-hydride. In the case of Rh2-phen2, the reduction of the phen ligand is followed by intramolecular electron transfer to the Rh2(II,II) core in the presence of protons to form a Rh2(II,III)-hydride species. Further reduction and protonation at the Rh2 core for all three complexes rapidly catalyzes H2 formation with varied calculated turnover frequencies (TOF) and overpotential values (η): 2.6 × 10(4) s(-1) and 0.56 V for Rh2-dppn, 2.8 × 10(4) s(-1) and 0.50 V for Rh2-dppz2, and 5.9 × 10(4) s(-1) and 0.64 V for Rh2-phen2. Bulk electrolysis confirmed H2 formation, and further CH3COOH addition regenerates H2 production, attesting to the robust nature of the architecture. The cis-[Rh2(II,II)(μ-DTolF)2(NN)2](2+) architecture benefits by combining electron-rich formamidinate bridges, a redox-active Rh2(II,II) core, and electron-accepting NN diimine ligands to allow for the electrocatalysis of H(+) substrate to H2 fuel.

  5. Inhibition of chymotrypsin by heparin cofactor II.

    PubMed Central

    Church, F C; Noyes, C M; Griffith, M J

    1985-01-01

    Human heparin cofactor II is a plasma protein that is known to inhibit thrombin. The rate of thrombin inhibition by heparin cofactor II is accelerated (greater than or equal to 1000-fold) in the presence of the glycosaminoglycans, heparin and dermatan sulfate. We have found that chymotrypsin A alpha is also inhibited by heparin cofactor II with a second-order rate constant value of 1.8 X 10(6) M-1 X min-1 at pH 8.0 and 25 degrees C. However, there was no measurable effect of heparin or dermatan sulfate on the rate of chymotrypsin inhibition. Arginine-modified heparin cofactor II showed a comparable percentage loss of both antichymotrypsin and antithrombin activities. Heparin cofactor II and chymotrypsin formed a stable complex with a Mr value near 90,000 when analyzed by NaDodSO4/polyacrylamide gel electrophoresis; this suggests a 1:1 reaction stoichiometry. The chymotrypsin cleavage site in heparin cofactor II was the same as that for thrombin, and primary structure analysis of the inhibitor showed a P'1-P'8 sequence of Ser-Thr-Gln-Val-Arg-Phe-Thr-Val ... . The results indicate that, in contrast to alpha 1-antichymotrypsin, which does not inhibit trypsin-like enzymes, including thrombin, heparin cofactor II can effectively inhibit both thrombin and chymotrypsin. PMID:3863104

  6. Dinuclear Metallacycles with Single M-X-M Bridges (X = Cl(-), Br(-); M = Fe(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II)): Strong Antiferromagnetic Superexchange Interactions.

    PubMed

    Reger, Daniel L; Pascui, Andrea E; Foley, Elizabeth A; Smith, Mark D; Jezierska, Julia; Wojciechowska, Agnieszka; Stoian, Sebastian A; Ozarowski, Andrew

    2017-03-06

    A series of monochloride-bridged, dinuclear metallacycles of the general formula [M2(μ-Cl)(μ-L)2](ClO4)3 have been prepared using the third-generation, ditopic bis(pyrazolyl)methane ligands L = m-bis[bis(1-pyrazolyl)methyl]benzene (Lm), M = Cu(II), Zn(II), and L = m-bis[bis(3,5-dimethyl-1-pyrazolyl)methyl]benzene (Lm*), M = Fe(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II). These complexes were synthesized from the direct reactions of M(ClO4)2·6H2O, MCl2, and the ligand, Lm or Lm*, in the appropriate stoichiometric amounts. Three analogous complexes of the formula [M2(μ-Cl)(μ-L)2](BF4)3, L = Lm, M = Cu(II), and L = Lm*, M = Co(II), Cu(II), were prepared from the reaction of [M2(μ-F)(μ-L)2](BF4)3 and (CH3)3SiCl. The bromide-bridged complex [Cu2(μ-Br)(μ-Lm*)2](ClO4)3 was prepared by the first method. Three acyclic complexes, [Co2(μ-Lm)μ-Cl4], [Co2(μ-Lm*)Cl4], and [Co2(μ-Lm*)Br4], were also prepared. The structures of all [M2(μ-X)(μ-L)2](3+) (X = Cl(-), Br(-)) complexes have two ditopic bis(pyrazolyl)methane ligands bridging two metals in a metallacyclic arrangement. The fifth coordination site of the distorted trigonal bipyramidal metal centers is filled by a bridging halide ligand that has an unusual linear or nearly linear M-X-M angle. The NMR spectra of [Zn2(μ-Cl)(μ-Lm*)2](ClO4)3 and especially [Cd2(μ-Cl)(μ-Lm*)2](ClO4)3 demonstrate that the metallacycle structure is maintained in solution. Solid state magnetic susceptibility data for the copper(II) compounds show very strong antiferromagnetic exchange interactions, with -J values of 536 cm(-1) for [Cu2(μ-Cl)(μ-Lm)2](ClO4)3·xCH3CN, 720 cm(-1) for [Cu2(μ-Cl)(μ-Lm*)2](ClO4)3, and 945 cm(-1) for [Cu2(μ-Br)(μ-Lm*)2](ClO4)3·2CH3CN. Smaller but still substantial antiferromagnetic interactions are observed with other first row transition metals, with -J values of 98 cm(-1) for [Ni2(μ-Cl)(μ-Lm*)2](ClO4)3, 55 cm(-1) for [Co2(μ-Cl)(μ-Lm*)2](ClO4)3, and 34 cm(-1) for [Fe2(μ-Cl)(μ-Lm*)2](ClO4

  7. Angiotensin II receptors in testes

    SciTech Connect

    Millan, M.A.; Aguilera, G.

    1988-05-01

    Receptors for angiotensin II (AII) were identified and characterized in testes of rats and several primate species. Autoradiographic analysis of the binding of 125I-labeled (Sar1,Ile8)AII to rat, rhesus monkey, cebus monkey, and human testicular slide-mounted frozen sections indicated specific binding to Leydig cells in the interstitium. In rat collagenase-dispersed interstitial cells fractionated by Percoll gradient, AII receptor content was parallel to that of hCG receptors, confirming that the AII receptors are in the Leydig cells. In rat dispersed Leydig cells, binding was specific for AII and its analogs and of high affinity (Kd, 4.8 nM), with a receptor concentration of 15 fmol/10(6) cells. Studies of AII receptors in rat testes during development reveals the presence of high receptor density in newborn rats which decreases toward the adult age (4934 +/- 309, 1460 +/- 228, 772 +/- 169, and 82 +/- 12 fmol/mg protein at 5, 15, 20, and 30 days of age, respectively) with no change in affinity. At all ages receptors were located in the interstitium, and the decrease in binding was parallel to the decrease in the interstitial to tubular ratio observed with age. AII receptor properties in membrane-rich fractions from prepuberal testes were similar in the rat and rhesus monkey. Binding was time and temperature dependent, reaching a plateau at 60 min at 37 C, and was increased by divalent cations, EGTA, and dithiothreitol up to 0.5 mM. In membranes from prepuberal monkey testes, AII receptors were specific for AII analogs and of high affinity (Kd, 4.2 nM) with a receptor concentration of 7599 +/- 1342 fmol/mg protein. The presence of AII receptors in Leydig cells in rat and primate testes in conjunction with reports of the presence of other components of the renin-angiotensin system in the testes suggests that the peptide has a physiological role in testicular function.

  8. Probing Our Heliospheric History II

    NASA Astrophysics Data System (ADS)

    Wyman, Katherine; Redfield, S.

    2012-05-01

    A physical relationship between our local interstellar medium (ISM), galactic cosmic rays (GCR), and our planetary environment has long been a subject of interest to the astronomical community. Clouds of sufficient density to compress the heliosphere to within 1 AU are commonly seen throughout the galactic environment, including within the Local Bubble (LB). Such a compression would lead to an increase in the GCR flux at 1 AU and would have drastic consequences for many planetary processes such as atmospheric chemistry, lightning production, cloud cover, and DNA mutation rates for surface organisms. Prior to this work, we derived a column density profile of the ISM toward 49 bright stars along a narrow cone centered on the historical solar path. High resolution spectra were taken of NaI and CaII absorption out to a distance of 610 pc, with a median separation distance of 11 pc between adjacent stars. No absorption is seen out to a distance of 120 pc (consistent with the LB), but a complex number of absorbers is seen beyond. We now present the detection of several distinct clouds, their associated column densities, radial velocities, inferred distances, and size constraints. This combination of cloud properties allows us to derive a volume density profile of the ISM in the Sun's “rear-view mirror,” which represents one plausible record of actual ISM encounters for the Sun. We also make use of empirical relations to determine the effect these clouds would have on the historical heliosphere. Our analysis suggests that within the last 10 million years, if the Sun encountered a cloud with the same properties as we have detected along the solar historical trajectory, the Sun's termination shock would have resided inside the orbit of Uranus, with a GCR flux at Earth an order of magnitude greater than it is currently.

  9. The VRI colours of H II galaxies

    NASA Astrophysics Data System (ADS)

    Telles, Eduardo; Terlevich, Roberto

    1997-03-01

    We present a high spatial resolution CCD surface photometry study in the optical V, R and I broad-band filters of a sample of 15 H II galaxies. Narrow-band imaging allows the separation of the emission-line region from the extended parts of the galaxy. The latter are assumed to represent the underlying galaxy in H II galaxies; thus the colours of the underlying galaxy are measured. The colours of the underlying stellar continuum within the starburst are also derived by subtracting the contribution of the emission lines falling in the broad-band filters. The distribution of colours of the underlying galaxy in H II galaxies is similar to the colours of other late-type low surface brightness galaxies, which suggests a close kinship of these with the quiescent phases of H II galaxies. However, comparison wtih recent evolutionary population synthesis models shows that the observational errors and the uncertainties in the models are still too large to put strict constraints on their past star formation history. Our analysis of the morphology and structural properties, from contour maps and luminosity profiles, of this sample of 15 H II galaxies agrees with what has been found by Telles and Telles, Melnick & Terlevich, namely that H II galaxies comprise two broad classes segregated by their luminosity; Type I H II galaxies are luminous and have disturbed and irregular outer shapes, while Type II H II galaxies are less luminous and have regular shapes. The outer parts of their profiles are well represented by an exponential, as in other types of known dwarf galaxy.

  10. Characteristics of He II Proximity Profiles

    NASA Astrophysics Data System (ADS)

    Zheng, Wei; Syphers, David; Meiksin, Avery; Kriss, Gerard A.; Schneider, Donald P.; York, Donald G.; Anderson, Scott F.

    2015-06-01

    The proximity profile in the spectra of z≈ 3 quasars, where fluxes extend blueward of the He ii Lyα wavelength 304 (1+z) Å, is one of the most important spectral features in the study of the intergalactic medium (IGM). Based on the Hubble Space Telescope spectra of 24 He ii quasars, we find that the majority of them display a proximity profile, corresponding to an ionization radius as large as 20 Mpc in the source's rest frame. In comparison with those in the H i spectra of the quasars at z ≈ 6, the He ii proximity effect is more prominent and is observed over a considerably longer period of reionization. The He ii proximity zone sizes decrease at higher redshifts, particularly at z\\gt 3.3. This trend is similar to that for H i, signaling an onset of He ii reionization at z≳ 4. For quasar SDSS1253+6817 (z = 3.48), the He ii absorption trough displays a gradual decline and serves as a good case for modeling the He ii reionization. To model such a broad profile requires a quasar radiation field whose energy distribution between 4 and 1 Rydberg is considerably harder than normally assumed. The UV continuum of this quasar is indeed exceptionally steep, and the He ii ionization level in the quasar vicinity is higher than the average level in the IGM. These results are evidence that a very hard EUV continuum from this quasar produces a large ionized zone around it. Distinct exceptions are the two brightest He ii quasars at z ≈ 2.8, for which no significant proximity profile is present, probably implying that they are very young.

  11. LHC II system sensitivity to magnetic fluids

    NASA Astrophysics Data System (ADS)

    Cotae, Vlad; Creanga, Ioan

    2005-03-01

    Experiments have been designed to reveal the influences of ferrofluid treatment and static magnetic field exposure on the photosynthetic system II, where the light harvesting complex (LHC II) controls the ratio chlorophyll a/ chlorophyll b (revealing, indirectly, the photosynthesis rate). Spectrophotometric measurement of chlorophyll content revealed different influences for relatively low ferrofluid concentrations (10-30 μl/l) in comparison to higher concentrations (70-100 μl/l). The overlapped effect of the static magnetic field shaped better the stimulatory ferrofluid action on LHC II system in young poppy plantlets.

  12. CAPPS II: the foundation of aviation security?

    PubMed

    Barnett, Arnold

    2004-08-01

    A new computer system is being developed to classify U.S. air travelers by the degree of terrorist threat they might pose. Reports indicate that the system--called CAPPS II--would use large amounts of information about each passenger, perhaps including such personal details as his or her magazine-subscription behavior. We argue that what is publicly known about CAPPS II raises questions about how substantially the system would improve aviation security. We discuss conditions under which CAPPS II could yield safety benefits, but suggest that it might be more prudent to view the system as one component of future security arrangements rather than the centerpiece of these arrangements.

  13. Level II Ergonomic Analyses, Dover AFB, DE

    DTIC Science & Technology

    1999-02-01

    IERA-RS-BR-TR-1999-0002 UNITED STATES AIR FORCE IERA Level II Ergonomie Analyses, Dover AFB, DE Andrew Marcotte Marilyn Joyce The Joyce...Project (070401881, Washington, DC 20503. 1. AGENCY USE ONLY (Leave blank) 2. REPORT DATE 4. TITLE AND SUBTITLE Level II Ergonomie Analyses, Dover...1.0 INTRODUCTION 1-1 1.1 Purpose Of The Level II Ergonomie Analyses : 1-1 1.2 Approach 1-1 1.2.1 Initial Shop Selection and Administration of the

  14. Belle II Physics Prospects, Status and Schedule

    NASA Astrophysics Data System (ADS)

    Bennett, J.

    2016-11-01

    The second generation B-factory at the SuperKEKB facility in Tsukuba, Japan is beginning to take shape. The highly anticipated Belle II experiment will have a rich physics program at the intensity frontier, in complement to existing experiments in the energy frontier. Accelerator commissioning has been making good progress, as has the construction and installation of the Belle II detector. An overview of the physics prospects at Belle II, as well as the status and schedule of the experiment, is presented.

  15. Genetics Home Reference: distal hereditary motor neuropathy, type II

    MedlinePlus

    ... distal hereditary motor neuropathy, type II distal hereditary motor neuropathy, type II Enable Javascript to view the ... PDF Open All Close All Description Distal hereditary motor neuropathy, type II is a progressive disorder that ...

  16. T lymphocytes and dendritic cells are activated by the deletion of peroxiredoxin II (Prx II) gene.

    PubMed

    Moon, Eun-Yi; Noh, Young-Wook; Han, Ying-Hao; Kim, Sun-Uk; Kim, Jin-Man; Yu, Dae-Yeul; Lim, Jong-Seok

    2006-02-15

    Peroxiredoxin II (Prx II) is a member of antioxidant enzyme family and it plays a protective role against oxidative damage. Constitutive production of endogenous reactive oxygen species was detected in spleen and bone marrow cells lacking Prx II. Here, we investigated the role of Prx II in immune responses. The total number of splenocytes (especially, the population of S-phase cells and CD3(+) T cells) was significantly higher in Prx II(-/-) mice than in wild type. Number of peripheral blood mononuclear cells (PBMCs) in Prx II(-/-) mice was also higher than wild type. Differentiation of Prx II(-/-) mouse bone marrow cells into CD11c-positive dendritic cells was greater than that of wild type. Transplantation of Prx II(-/-) bone marrow cells into wild type mice increased PBMCs in blood and bone marrow-derived dendritic cells. Prx II deletion enhances concanavalin A (ConA)-induced splenocyte proliferation and mixed lymphocyte reaction (MLR) activity of bone marrow-derived CD11c-positive dendritic cells to stimulate recipient splenocytes. Collectively, these data suggest that Prx II inhibits the immune cell responsiveness, which may be regulated by scavenging the low amount of reactive oxygen species (ROS).

  17. Selected methods for dissolved iron (II, III) and dissolved sulfide (-II) determinations in geothermal waters

    USGS Publications Warehouse

    Vivit, D.V.; Jenne, E.A.

    1985-01-01

    Dissolved sulfide (-II) and dissolved iron (II, III) were determined in geothermal well water samples collected at Cerro Prieto, Mexico. Most samples consisted of liquid and gas (two phases) at the instant of collection; and a subset of samples, referred to as ' flashed ' samples, consisted of pressurized steam samples which were allowed to condense. Sulfide was determined by sulfide specific ion electrode; Fe(II) and Fe(III) plus Fe(II) were determined spectrophotometrically. The precision and accuracy of the methods were evaluated for these high-silica waters with replicate analyses, spike recoveries, and an alternate method. Direct current (d.c.) argon plasma emission spectrometry was the alternate method used for Fe(III)-plus-Fe(II) analyses. Mean dissolved iron concentrations ranged from 20.2 to 834 micrograms/L (ug/L) as Fe(II) and 26.8 to 904 ug/L as Fe(III) plus Fe(II). Mean sulfide concentrations ranged from about 0.01 to 5.3 mg/L (S-II) Generally, higher S(-II) values and larger Fe(II)/Fe(III) ratios were found in the two-phase samples. These findings suggest that the ' flashed ' samples are at a less reduced state than the two-phase samples. (Author 's abstract)

  18. Increased association of dynamin II with myosin II in ras transformed NIH3T3 cells.

    PubMed

    Jeong, Soon-Jeong; Kim, Su-Gwan; Yoo, Jiyun; Han, Mi-Young; Park, Joo-Cheol; Kim, Heung-Joong; Kang, Seong-Soo; Choi, Baik-Dong; Jeong, Moon-Jin

    2006-08-01

    Dynamin has been implicated in the formation of nascent vesicles through both endocytic and secretory pathways. However, dynamin has recently been implicated in altering the cell membrane shape during cell migration associated with cytoskeleton-related proteins. Myosin II has been implicated in maintaining cell morphology and in cellular movement. Therefore, reciprocal immunoprecipitation was carried out to identify the potential relationship between dynamin II and myosin II. The dynamin II expression level was higher when co-expressed with myosin II in Ras transformed NIH3T3 cells than in normal NIH3T3 cells. Confocal microscopy also confirmed the interaction between these two proteins. Interestingly, exposing the NIH3T3 cells to platelet-derived growth factor altered the interaction and localization of these two proteins. The platelet-derived growth factor treatment induced lamellipodia and cell migration, and dynamin II interacted with myosin II. Grb2, a 24 kDa adaptor protein and an essential element of the Ras signaling pathway, was found to be associated with dynamin II and myosin II gene expression in the Ras transformed NIH3T3 cells. These results suggest that dynamin II acts as an intermediate messenger in the Ras signal transduction pathway leading to membrane ruffling and cell migration.

  19. Pecan nutshell as biosorbent to remove Cu(II), Mn(II) and Pb(II) from aqueous solutions.

    PubMed

    Vaghetti, Julio C P; Lima, Eder C; Royer, Betina; da Cunha, Bruna M; Cardoso, Natali F; Brasil, Jorge L; Dias, Silvio L P

    2009-02-15

    In the present study we reported for the first time the feasibility of pecan nutshell (PNS, Carya illinoensis) as an alternative biosorbent to remove Cu(II), Mn(II) and Pb(II) metallic ions from aqueous solutions. The ability of PNS to remove the metallic ions was investigated by using batch biosorption procedure. The effects such as, pH, biosorbent dosage on the adsorption capacities of PNS were studied. Four kinetic models were tested, being the adsorption kinetics better fitted to fractionary-order kinetic model. Besides that, the kinetic data were also fitted to intra-particle diffusion model, presenting three linear regions, indicating that the kinetics of adsorption should follow multiple sorption rates. The equilibrium data were fitted to Langmuir, Freundlich, Sips and Redlich-Peterson isotherm models. Taking into account a statistical error function, the data were best fitted to Sips isotherm model. The maximum biosorption capacities of PNS were 1.35, 1.78 and 0.946mmolg(-1) for Cu(II), Mn(II) and Pb(II), respectively.

  20. Adsorption of copper (II), chromium (III), nickel (II) and lead (II) ions from aqueous solutions by meranti sawdust.

    PubMed

    Rafatullah, M; Sulaiman, O; Hashim, R; Ahmad, A

    2009-10-30

    The present study proposed the use of meranti sawdust in the removal of Cu(II), Cr(III), Ni(II) and Pb(II) ions from synthetic aqueous solutions. Batch adsorption studies showed that meranti sawdust was able to adsorb Cu(II), Cr(III), Ni(II) and Pb(II) ions from aqueous solutions in the concentration range 1-200mg/L. The adsorption was favoured with maximum adsorption at pH 6, whereas the adsorption starts at pH 1 for all metal ions. The effects of contact time, initial concentration of metal ions, adsorbent dosage and temperature have been reported. The applicability of Langmuir, Freundlich, and Dubinin-Radushkevich (D-R) isotherm was tried for the system to completely understand the adsorption isotherm processes. The adsorption kinetics tested with pseudo-first-order and pseudo-second-order models yielded high R(2) values from 0.850 to 0.932 and from 0.991 to 0.999, respectively. The meranti sawdust was found to be cost effective and has good efficiency to remove these toxic metal ions from aqueous solution.

  1. Synthesis and studies on Cu(II), Co(II), Ni(II) complexes of Knoevenagel β-diketone ligands.

    PubMed

    Sumathi, S; Tharmaraj, P; Sheela, C D; Anitha, C

    2012-11-01

    Transition metal complexes of various acetylacetone based ligands of the type ML [where M=Cu(II), Ni(II), Co(II); L=3-(aryl)-pentane-2,4-dione] have been synthesized. The structural features have been derived from their elemental analysis, magnetic susceptibility, molar conductance, IR, UV-Vis, (1)H NMR, Mass and ESR spectral studies. Conductivity measurements reveal that all the complexes are non-electrolytic in nature. Spectroscopic and other analytical data of the complexes suggest octahedral geometry for other metal(II) complexes. The redox behavior of the copper(II) complexes have been studied by cyclic voltammetry. The free ligands and their metal complexes have been screened for their in vitro biological activities against the bacteria Pseudomonas aeruginosa, Escherichia coli and Staphylococcus aureus as well as the fungus Candida albicans by well diffusion method. The zone of inhibition value indicates that the most of the metal(II) complexes are found to possess increased activities compared to those of the free ligands. All synthesized compounds may serve as potential photoactive materials as indicated from their characteristic fluorescence properties. The second harmonic generation (SHG) efficiency of the ligands (L1-L3) was found to be considerable effect than that of urea and KDP (potassium dihydrogen phosphate).

  2. Synthesis and studies on Cu(II), Co(II), Ni(II) complexes of Knoevenagel β-diketone ligands

    NASA Astrophysics Data System (ADS)

    Sumathi, S.; Tharmaraj, P.; Sheela, C. D.; Anitha, C.

    2012-11-01

    Transition metal complexes of various acetylacetone based ligands of the type ML [where M = Cu(II), Ni(II), Co(II); L = 3-(aryl)-pentane-2,4-dione] have been synthesized. The structural features have been derived from their elemental analysis, magnetic susceptibility, molar conductance, IR, UV-Vis, 1H NMR, Mass and ESR spectral studies. Conductivity measurements reveal that all the complexes are non-electrolytic in nature. Spectroscopic and other analytical data of the complexes suggest octahedral geometry for other metal(II) complexes. The redox behavior of the copper(II) complexes have been studied by cyclic voltammetry. The free ligands and their metal complexes have been screened for their in vitro biological activities against the bacteria Pseudomonas aeruginosa, Escherichia coli and Staphylococcus aureus as well as the fungus Candida albicans by well diffusion method. The zone of inhibition value indicates that the most of the metal(II) complexes are found to possess increased activities compared to those of the free ligands. All synthesized compounds may serve as potential photoactive materials as indicated from their characteristic fluorescence properties. The second harmonic generation (SHG) efficiency of the ligands (L1-L3) was found to be considerable effect than that of urea and KDP (potassium dihydrogen phosphate).

  3. Kinetics of homogeneous and surface-catalyzed mercury(II) reduction by iron(II)

    USGS Publications Warehouse

    Amirbahman, Aria; Kent, Douglas B.; Curtis, Gary P.; Marvin-DiPasquale, Mark C.

    2013-01-01

    Production of elemental mercury, Hg(0), via Hg(II) reduction is an important pathway that should be considered when studying Hg fate in environment. We conducted a kinetic study of abiotic homogeneous and surface-catalyzed Hg(0) production by Fe(II) under dark anoxic conditions. Hg(0) production rate, from initial 50 pM Hg(II) concentration, increased with increasing pH (5.5–8.1) and aqueous Fe(II) concentration (0.1–1 mM). The homogeneous rate was best described by the expression, rhom = khom [FeOH+] [Hg(OH)2]; khom = 7.19 × 10+3 L (mol min)−1. Compared to the homogeneous case, goethite (α-FeOOH) and hematite (α-Fe2O3) increased and γ-alumina (γ-Al2O3) decreased the Hg(0) production rate. Heterogeneous Hg(0) production rates were well described by a model incorporating equilibrium Fe(II) adsorption, rate-limited Hg(II) reduction by dissolved and adsorbed Fe(II), and rate-limited Hg(II) adsorption. Equilibrium Fe(II) adsorption was described using a surface complexation model calibrated with previously published experimental data. The Hg(0) production rate was well described by the expression rhet = khet [>SOFe(II)] [Hg(OH)2], where >SOFe(II) is the total adsorbed Fe(II) concentration; khet values were 5.36 × 10+3, 4.69 × 10+3, and 1.08 × 10+2 L (mol min)−1 for hematite, goethite, and γ-alumina, respectively. Hg(0) production coupled to reduction by Fe(II) may be an important process to consider in ecosystem Hg studies.

  4. Copper(II) and lead(II) removal from aqueous solution by water treatment residues.

    PubMed

    Castaldi, Paola; Silvetti, Margherita; Garau, Giovanni; Demurtas, Daniela; Deiana, Salvatore

    2015-01-01

    In this study, we investigated the ability of Fe- and Al-based water treatment residues (Fe- and Al-WTR) to accumulate Pb(II) and Cu(II) at pH 4.5. The role of the inorganic and organic fractions of WTRs in metals sorption was also assessed. Sorption isotherms showed a higher sorption of Pb(II) by both WTRs with respect to Cu(II) (e.g. 0.105 and 0.089 mmol g(-1) of Pb(II) and Cu(II) respectively sorbed by Fe-WTR). Fe-WTR revealed a stronger sorbent for both metals than Al-WTR. The amount of Pb(II) and Cu(II) sorbed by Fe-WTR was about the 69% and 63% higher than that sorbed by the Al-WTR. The organic matter of Fe- and Al-WTR contributed to about 26% and 8.5% respectively in the sorption of both metals. The sequential extraction procedure showed that the greatest amount of metals sorbed by both WTRs were tightly bound and not extractable, and this was particularly apparent for Cu(II). The FT-IR spectra indicated the formation of inner-sphere complexes between the Fe(Al)-O nucleus and Pb(II) and Cu(II). Moreover, the FT-IR spectra also suggested that the humic fraction of WTRs interacted, through the carboxylate groups, with Cu(II) and Pb(II) by forming mainly monodentate and bidentate complexes, respectively.

  5. Rapid and wide-range determination of Cd(II), Pb(II), Cu(II) and Hg(II) in fish tissues using light addressable potentiometric sensor.

    PubMed

    Zhang, Wen; Xu, Yiwei; Tahir, Haroon E; Zou, Xiaobo; Wang, Ping

    2017-04-15

    A rapid and wide-range method, based on light addressable potentiometric sensor (LAPS), is introduced into determination of Cd(II), Pb(II), Cu(II) and Hg(II) in fish tissues. A compact LAPS module is prepared by integrating four LAPS chips specifically sensitive to target elements. Its responses in digestions from various settings are investigated to find suitable factors. Analytical properties of this method are evaluated in consequent experiments under optimized conditions. Measurement range for each target element exceeds 0.1 to 1000mgL(-1), and response time is less than 10s. Accuracy, precision and selectivity of the proposed method are also well defined in measurements. It is successively performed to detect the target elements in real fish samples from 4 species, and obtained results are consistent with certified method.

  6. Psychological Action and Structure in "Richard II."

    ERIC Educational Resources Information Center

    Toole, William B., III

    1978-01-01

    Explores the theme that the suffering arising from Richard II's loss of power, a power that consisted more of appearance than of intrinsic worth, led him to spiritual growth and the development of real value as a person. (MB)

  7. Resistance domain in type II superconductors

    SciTech Connect

    Gurevich, A.V.; Mints, R.G.

    1980-01-05

    We show that traveling domains with a finite resistance can exist in type II superconductors in the presence of a transport current. An experiment in which this effect generates an alternating electric field and current is proposed.

  8. Zodiac II: Debris Disk Imaging Potential

    NASA Technical Reports Server (NTRS)

    Traub Wesley; Bryden, Geoff; Stapelfeldt, Karl; Chen, Pin; Trauger, John

    2011-01-01

    Zodiac II is a proposed coronagraph on a balloon-borne platform, for the purpose of observing debris disks around nearby stars. Zodiac II will have a 1.2-m diameter telescope mounted in a balloon-borne gondola capable of arcsecond quality pointing, and with the capability to make long-duration (several week) flights. Zodiac II will have a coronagraph able to make images of debris disks, meaning that its scattered light speckles will be at or below an average contrast level of about 10(exp -7) in three narrow (7 percent) bands centered on the V band, and one broad (20%) one at I band. We will discuss the potential science to be done with Zodiac II.

  9. Far Outer Galaxy H II Regions

    NASA Technical Reports Server (NTRS)

    Rudolph, A. L.; deGues, E. J.; Brand, J.; Wouterloot, J. G. A.; Gross, Anthony R. (Technical Monitor)

    1994-01-01

    We have made a multifrequency (6, 3.6, and 2 cm), high-resolution (3"-6"), radio continuum survey of IRAS selected sources from the catalogue of Wouterloot & Brand (1989) to search for and study H II regions in the far outer Galaxy. We identified 31 sources in this catalog with well determined galactocentric distances, and with R approx.. greater than 15 kpc and L(sub FIR) approx.greater than 10(exp 4) solar luminosity, indicating the presence of high-mass star-formation. We have observed 11 of these sources with the Very Large Array (VLA). We observed the sources at 6 and 2 cm using "scaled arrays", making possible a direct and reliable comparison of the data at these two wavelengths for the determination of spectral indices. We detected a total of 12 radio sources, of which 10 have spectral indices consistent with optically-thin free-free emission from H II regions. Combined with previous VLA observations by other investigators, we have data on a total of 15 H II regions at galactocentric distances of 15 to 18.2kpc, among the most remote H II regions found in our Galaxy. The sizes of the H II regions range from approx. less than 0.10 to 2.3 pc. Using the measured fluxes and sizes, we determine the electron densities, emission measures, and excitation parameters of the H II regions, as well as the fluxes of Lyman continuum photons needed to keep the nebulae ionized. The sizes and electron densities are consistent with most of the sources detected in this survey being compact or ultracompact H II regions. Seven of the fifteen H II regions have sizes approx. less than 0.20 pc. Assuming simple pressure-driven expansion of the H II regions, these sizes indicate ages approx. less than 5 x 10(exp 4) yr, or only 1% of the lifetime of an O star, which implies an unlikely overabundance of O stars in the outer Galaxy. Thus, the large number of compact H II regions suggests that the time these regions spend in a compact phase must be much longer than their dynamical

  10. Courseware Review: Vernier Software: Precision Timer II.

    ERIC Educational Resources Information Center

    Park, John C.

    1988-01-01

    Reviews "Vernier Software: Precision Timer II" for high school through college mechanics. Introduces 14 different modes including pulse time, pendulum timer, bouncer timer, gate timer, collision timers, and stroke calibration. Provides two typical displays and ratings of the software. (YP)

  11. Enzymatic synthesis of lipid II and analogues.

    PubMed

    Huang, Lin-Ya; Huang, Shih-Hsien; Chang, Ya-Chih; Cheng, Wei-Chieh; Cheng, Ting-Jen R; Wong, Chi-Huey

    2014-07-28

    The emergence of antibiotic resistance has prompted active research in the development of antibiotics with new modes of action. Among all essential bacterial proteins, transglycosylase polymerizes lipid II into peptidoglycan and is one of the most favorable targets because of its vital role in peptidoglycan synthesis. Described in this study is a practical enzymatic method for the synthesis of lipid II, coupled with cofactor regeneration, to give the product in a 50-70% yield. This development depends on two key steps: the overexpression of MraY for the synthesis of lipid I and the use of undecaprenol kinase for the preparation of polyprenol phosphates. This method was further applied to the synthesis of lipid II analogues. It was found that MraY and undecaprenol kinase can accept a wide range of lipids containing various lengths and configurations. The activity of lipid II analogues for bacterial transglycolase was also evaluated.

  12. PEP-II Status and Outlook

    SciTech Connect

    Wienands, H.U.; Biagini, M.E.; Decker, F.J.; Donald, M.H.; Ecklund, S.; Fisher, A.; Holtzapple, R.L.; Iverson, R.H.; Krejcik, P.; Kulikov, A.V.; Meyer, T.; Nelson, J.; Novokhatski, A.; Reichel, I.; Sullivan, M.; Seeman, J.T.; Turner, J.; Steier, C.; Zisman, M.S.; /LBL, Berkeley

    2012-04-24

    PEP-II/BABAR are presently in their second physics run. With machine and detector performance and reliability at an all-time high, almost 51 fb{sup -1} have been integrated by BABAR up to mid-October 2001. PEP-II luminosity has reached 4.4 x 10{sup 33} cm{sup -2} s{sup -1} and our highest monthly delivered luminosity has been above 6 pb{sup -1}, exceeding the performance parameters given in the PEP-II CDR by almost 50%. The increase compared to the first run in 2000 has been achieved by a combination of beam-current increase and beam-size decrease. In this paper we will summarize the PEP-II performance and the present limitations as well as our plans to further increase machine performance.

  13. Achondrogenesis type II, abnormalities of extracellular matrix.

    PubMed

    Horton, W A; Machado, M A; Chou, J W; Campbell, D

    1987-09-01

    Immune and lectin histochemical and microchemical methods were employed to study growth cartilage from seven cases of achondrogenesis type II (Langer-Saldino). The normal architecture of the epiphyseal and growth plate cartilage was replaced by a morphologically heterogeneous tissue. Some areas were comprised of vascular canals surrounded by extensive fibrous tissue and enlarged cells that had the appearance and histochemical characteristics of hypertrophic chondrocytes. Other areas contained a mixture of cells ranging from small to the enlarged chondrocytes. The extracellular matrix in the latter areas was more abundant and had characteristics of both precartilage mesenchymal matrix and typical cartilage matrix; it contained types I and II collagen, cartilage proteoglycan, fibronectin, and peanut agglutinin binding glycoconjugate(s). Peptide mapping of cyanogen bromide cartilage collagen peptides revealed the presence of types I and II collagen. These observations could be explained by a defect in the biosynthesis of type II collagen or in chondrocyte differentiation.

  14. Achondrogenesis II-hypochondrogenesis: variability versus heterogeneity.

    PubMed

    Borochowitz, Z; Ornoy, A; Lachman, R; Rimoin, D L

    1986-06-01

    Recently hypochondrogenesis was described as a form of neonatally lethal dwarfism said to resemble spondyloepiphyseal dysplasia congenita radiographically and achondrogenesis II morphologically. Because of the difficulty in distinguishing radiographically between mild achondrogenesis II and severe hypochondrogenesis, we performed a clinical, radiographic, and morphologic study of 24 cases originally classified as either achondrogenesis II or hypochondrogenesis, in an attempt to distinguish between heterogeneity and clinical variability. Review of the radiographic findings in these cases show a fairly continuous spectrum of bony defects, rather than two distinct radiographic syndromes. Chondro-osseous histology and ultrastructure was similar in all cases regardless of severity and was characterized by hypervascularity and hypercellularity of the cartilage with multiple small, round dilated cysternae of rough endoplasmic reticulum. These findings suggest that hypochondrogenesis and achondrogenesis type II represent a spectrum with marked phenotypic variability.

  15. NSLS-II Transport Line Progress

    SciTech Connect

    Fliller R. P.; Wahl, W.; Anderson, A.; Benish, B.; DeBoer, W.; Ganetis, G.; Heese, R.; Hseuh, H.-C.; Hu, J.-P.; Johanson, M.P.; Kosciuk, B.N.; Padrazo, D.; Roy, K.; Shaftan, T.; Singh, O.; Tuozzolo, J.; Wang, G.

    2012-05-20

    The National Synchrotron Light Source II (NSLS-II) is a state-of-the-art 3-GeV third generation light source currently under construction at Brookhaven National Laboratory. The NSLS-II injection system consists of a 200 MeV linac, a 3-GeV booster synchrotron and associated transfer lines. The first part of the Linac to Booster Transport (LBT) line has been installed for linac commissioning. This part includes all components necessary to commission the NSLS-II linac. The second part of this transport line is undergoing installation. Initial results of hardware commissioning will be discussed. The Booster to Storage Ring (BSR) transport line underwent a design review. The first part of the BSR transport line, consisting of all components necessary to commission the booster will be installed in 2012 for booster commissioning. We report on the final design of the BSR line along with the plan to commission the booster.

  16. Neutral (bis-beta-diketonato) iron(III), cobalt(II), nickel(II), copper(II) and zinc(II) metallocycles: structural, electrochemical and solvent extraction studies.

    PubMed

    Clegg, Jack K; Bray, David J; Gloe, Kerstin; Gloe, Karsten; Hayter, Michael J; Jolliffe, Katrina A; Lawrance, Geoffrey A; Meehan, George V; McMurtrie, John C; Lindoy, Leonard F; Wenzel, Marco

    2007-05-07

    Neutral dimeric metallocyclic complexes of type [M(2)(L(1))(2)B(n)] (where M = cobalt(II), nickel(II) and zinc(II), L(1) is the doubly deprotonated form of a 1,3-aryl linked bis-beta-diketone ligand of type 1,3-bis(RC(O)CH(2)C(O))C(6)H(4) (R=Me, n-Pr, t-Bu) and B is pyridine (Py) or 4-ethylpyridine (EtPy)) have been synthesised, adding to similar complexes already reported for copper(II). New lipophilic ligand derivatives with R = octyl or nonyl were also prepared for use in solvent extraction experiments. Structural, electrochemical and solvent extraction investigations of selected metal complex systems from the above series are reported, with the X-ray structures of [Co(2)(L(1))(2)(Py)(4)] x 2.25CHCl(3) x 0.5H(2)O (R=Pr), [Co(2)(L(1))(2)(EtPy)(4)] (R=t-Bu), [Ni(2)(L(1))(2)(EtPy)(4)] (R=t-Bu), [Zn(2)(L(1))(2)(EtPy)(2)] (R=Me) and [Zn(2)(L(1))(2)(EtPy)(4)] (R=t-Bu) being presented. The electrochemistry of H(2)L(1) (R=t-Bu) and of [Fe(2)(L(1))(3)], [Co(2)(L(1))(2)(Py)(4)], [Ni(2)(L(1))(2)(Py)(4)], [Cu(2)(L(1))(2)] and [Zn(2)(L(1))(2)(Py)(2)] has been examined. Oxidative processes for the complexes are dominantly irreversible, but several examples of quasireversible behaviour were observed and support the assignment of an anodic process, seen between +1.0 and +1.6 V, as a metal-centred oxidation. The reduction processes for the respective metal complexes are not simple, and irreversible in most cases. Solvent extraction studies (water/chloroform) involving variable concentrations of metal, bis-beta-diketone and heterocyclic base have been performed for cobalt(II) and zinc(II) using a radiotracer technique to probe the stoichiometries of the extracted species in each case. Synergism was observed when 4-ethylpyridine was added to the bis-beta-diketone ligand in the chloroform phase. Competitive extraction studies show a clear uptake preference for copper(II) over cobalt(II), nickel(II), zinc(II) and cadmium(II).

  17. Host Galaxies of Luminous Type 2 Quasars at z ~ 0.5

    NASA Astrophysics Data System (ADS)

    Liu, Xin; Zakamska, Nadia L.; Greene, Jenny E.; Strauss, Michael A.; Krolik, Julian H.; Heckman, Timothy M.

    2009-09-01

    We present deep Gemini GMOS optical spectroscopy of nine luminous quasars at redshifts z ~ 0.5, drawn from the Sloan Digital Sky Survey type 2 quasar sample. Our targets were selected to have high intrinsic luminosities (MV < -26 mag) as indicated by the [O III] λ5007 Å emission-line luminosity (L [O III]). Our sample has a median black hole mass of ~108.8 M sun inferred assuming the local M BH-σ* relation and a median Eddington ratio of ~0.7, using stellar velocity dispersions σ* measured from the G band. We estimate the contamination of the stellar continuum from scattered quasar light based on the strength of broad Hβ, and provide an empirical calibration of the contamination as a function of L [O III]; the scattered-light fraction is ~30% of L 5100 for objects with L [O III] = 109.5 L sun. Population synthesis indicates that young poststarburst populations (<0.1 Gyr) are prevalent in luminous type 2 quasars, in addition to a relatively old population (>1 Gyr) which dominates the stellar mass. Broad emission complexes around He II λ4686 Å with luminosities up to 108.3 L sun are unambiguously detected in three out of the nine targets, indicative of Wolf-Rayet (WR) populations. Population synthesis shows that ~5 Myr poststarburst populations contribute substantially to the luminosities (>50% of L 5100) of all three objects with WR detections. We find two objects with double cores and four with close companions. Our results may suggest that luminous type 2 quasars trace an early stage of galaxy interaction, perhaps responsible for both the quasar and the starburst activity. Based, in part, 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

  18. Macroclumping as solution of the discrepancy between Hα and P v mass loss diagnostics for O-type stars

    NASA Astrophysics Data System (ADS)

    Šurlan, B.; Hamann, W.-R.; Aret, A.; Kubát, J.; Oskinova, L. M.; Torres, A. F.

    2013-11-01

    Context. Recent studies of O-type stars have demonstrated that discrepant mass-loss rates are obtained when different diagnostic methods are employed. Fitting the unsaturated UV resonance lines (e.g., P v) gives drastically lower values than obtained from the Hα emission. Wind inhomogeneity (so-called "clumping") may be the main cause of this discrepancy. Aims: In a previous paper, we presented 3D Monte-Carlo calculations for the formation of scattering lines in a clumped stellar wind. In the present paper we select five O-type supergiants (from O4 to O7) and test whether the reported discrepancies can be resolved this way. Methods: In the first step, the analyses started with simulating the observed spectra with Potsdam Wolf-Rayet (PoWR) non-LTE model atmospheres. The mass-loss rates are adjusted to fit to the observed Hα emission lines best. For the unsaturated UV resonance lines (i.e., P v) we then applied our 3D Monte-Carlo code, which can account for wind clumps of any optical depths ("macroclumping"), a non-void interclump medium, and a velocity dispersion inside the clumps. The ionization stratifications and underlying photospheric spectra were adopted from the PoWR models. The properties of the wind clumps were constrained by fitting the observed resonance line profiles. Results: Our results show that with the mass-loss rates that fit Hα (and other Balmer and He ii lines), the UV resonance lines (especially the unsaturated doublet of P v) can also be reproduced with no problem when macroclumping is taken into account. There is no need to artificially reduce the mass-loss rates or to assume a subsolar phosphorus abundance or an extremely high clumping factor, unlike what was claimed by other authors. These consistent mass-loss rates are lower by a factor of 1.3 to 2.6, compared to the mass-loss rate recipe from Vink et al. Conclusions: Macroclumping resolves the previously reported discrepancy between Hα and P v mass-loss diagnostics. Based on

  19. Spatially resolved integral field spectroscopy of the ionized gas in IZw18

    NASA Astrophysics Data System (ADS)

    Kehrig, C.; Vílchez, J. M.; Pérez-Montero, E.; Iglesias-Páramo, J.; Hernández-Fernández, J. D.; Duarte Puertas, S.; Brinchmann, J.; Durret, F.; Kunth, D.

    2016-07-01

    We present a detailed 2D study of the ionized ionized interstellar medium (ISM) of IZw18 using new Potsdam Multi-Aperture Spectrophotometer-integral field unit (PMAS-IFU) optical observations. IZw18 is a high-ionization galaxy which is among the most metal-poor starbursts in the local Universe. This makes IZw18 a local benchmark for understanding the properties most closely resembling those prevailing at distant starbursts. Our IFU aperture (˜1.4 × 1.4 kpc2) samples the entire IZw18 main body and an extended region of its ionized gas. Maps of relevant emission lines and emission line ratios show that higher-excitation gas is preferentially located close to the north-west knot and thereabouts. We detect a Wolf-Rayet feature near the north-west knot. We derive spatially resolved and integrated physical-chemical properties for the ionized gas in IZw18. We find no dependence between the metallicity indicator R23 and the ionization parameter (as traced by [O III]/[O II]) across IZw18. Over ˜0.30 kpc2, using the [O III] λ4363 line, we compute Te[O III] values (˜15 000-25 000 K), and oxygen abundances are derived from the direct determinations of Te[O III]. More than 70 per cent of the higher-Te[O III] (≳22 000 K) spaxels are He IIλ4686-emitting spaxels too. From a statistical analysis, we study the presence of variations in the ISM physical-chemical properties. A galaxy-wide homogeneity, across hundreds of parsecs, is seen in O/H. Based on spaxel-by-spaxel measurements, the error-weighted mean of 12 + log(O/H) = 7.11 ± 0.01 is taken as the representative O/H for IZw18. Aperture effects on the derivation of O/H are discussed. Using our IFU data we obtain, for the first time, the IZw18 integrated spectrum.

  20. SN 2007uy - metamorphosis of an aspheric Type Ib explosion

    NASA Astrophysics Data System (ADS)

    Roy, Rupak; Kumar, Brijesh; Maund, Justyn R.; Schady, Patricia; Olivares, E. Felipe; Malesani, Daniele; Leloudas, Giorgos; Nandi, Sumana; Tanvir, Nial; Milisavljevic, Dan; Hjorth, Jens; Misra, Kuntal; Kumar, Brajesh; Pandey, S. B.; Sagar, Ram; Chandola, H. C.

    2013-09-01

    The supernovae (SNe) of Type Ibc are rare and the detailed characteristics of these explosions have been studied only for a few events. Unlike Type II SNe, the progenitors of Type Ibc have never been detected in pre-explosion images. So, to understand the nature of their progenitors and the characteristics of the explosions, investigation of proximate events is necessary. Here we present the results of multiwavelength observations of Type Ib SN 2007uy in the nearby (˜29.5 Mpc) galaxy NGC 2770. Analysis of the photometric observations revealed this explosion as an energetic event with peak absolute R-band magnitude -18.5 ± 0.16, which is about 1 mag brighter than the mean value (-17.6 ± 0.6) derived for well observed Type Ibc events. The SN is highly extinguished, E(B - V) = 0.63 ± 0.15 mag, mainly due to foreground material present in the host galaxy. From optical light curve modelling we determine that about 0.3 M⊙ radioactive 56Ni is produced and roughly 4.4 M⊙ material is ejected during this explosion with liberated energy ˜15 × 1051 erg, indicating the event to be an energetic one. Through optical spectroscopy, we have noticed a clear aspheric evolution of several line-forming regions, but no dependency of asymmetry is seen on the distribution of 56Ni inside the ejecta. The SN shock interaction with the circumstellar material is clearly noticeable in radio follow-up, presenting a synchrotron self-absorption dominated light curve with a contribution of free-free absorption during the early phases. Assuming a Wolf-Rayet (WR) star, with wind velocity ≳ 103 km s- 1, as a progenitor, we derive a lower limit to the mass-loss rate inferred from the radio data as M˙ ⪆ 2.4 × 10-5 M⊙ yr-1, which is consistent with the results obtained for other Type Ibc SNe bright at radio frequencies.

  1. Orbital modulation of X-ray emission lines in Cygnus X-3

    NASA Astrophysics Data System (ADS)

    Vilhu, O.; Hakala, P.; Hannikainen, D. C.; McCollough, M.; Koljonen, K.

    2009-07-01

    Aims: We address the problem where the X-ray emission lines are formed and investigate orbital dynamics using Chandra HETG observations, photoionizing calculations and numerical wind-particle simulations. The aims were to set constraints on the masses of the components of this close binary system consisting of a Wolf-Rayet (WR) star and a compact component and to investigate the nature of the latter (neutron star or black hole). The goal was also to investigate P Cygni signatures in line profiles. Methods: The observed Si xiv (6.185 Å) and S xvi (4.733 Å) line profiles at four orbital phases were fitted with P Cygni-type profiles consisting of an emission and a blue-shifted absorption component. Numerical models were constructed using photoionizing calculations and particle simulations. In the models, the emission originates in the photoionized wind of the WR companion illuminated by a hybrid source: the X-ray radiation of the compact star and the photospheric EUV-radiation from the WR star. Results: Spectral lines with moderate excitation (such as Si xiv and S xvi) arise in the photoionized wind. The emission component exhibits maximum blue-shift at phase 0.5 (when the compact star is in front), while the velocity of the absorption component is constant (around -900 km s-1). Both components, like the continuum flux, have intensity maxima around phase 0.5. The simulated Fe xxvi Lyα line (1.78 Å, H-like) from the wind is weak compared to the observed one. We suggest that it originates in the vicinity of the compact star, with a maximum blue shift at phase 0.25 (compact star approaching). By combining the mass function derived with that from the infrared He i absorption (arising from the WR companion), we constrain the masses and the inclination of the system. Conclusions: The Si xiv and S xvi lines and their radial velocity curves can be understood in the framework of a photoionized wind involving a hybrid ionizer. Constraints on the compact star mass and

  2. Removal of Pb(II), Cd(II), Cu(II), and Zn(II) by hematite nanoparticles: effect of sorbent concentration, pH, temperature, and exhaustion.

    PubMed

    Shipley, Heather J; Engates, Karen E; Grover, Valerie A

    2013-03-01

    Nanoparticles offer the potential to improve environmental treatment technologies due to their unique properties. Adsorption of metal ions (Pb(II), Cd(II), Cu(II), Zn(II)) to nanohematite was examined as a function of sorbent concentration, pH, temperature, and exhaustion. Adsorption experiments were conducted with 0.05, 0.1, and 0.5 g/L nanoparticles in a pH 8 solution and in spiked San Antonio tap water. The adsorption data showed the ability of nanohematite to remove Pb, Cd, Cu, and Zn species from solution with adsorption increasing as the nanoparticle concentration increased. At 0.5 g/L nanohematite, 100 % Pb species adsorbed, 94 % Cd species adsorbed, 89 % Cu species adsorbed and 100 % Zn species adsorbed. Adsorption kinetics for all metals tested was described by a pseudo second-order rate equation with lead having the fastest rate of adsorption. The effect of temperature on adsorption showed that Pb(II), Cu(II), and Cd(II) underwent an endothermic reaction, while Zn(II) underwent an exothermic reaction. The nanoparticles were able to simultaneously remove multiple metals species (Zn, Cd, Pb, and Cu) from both a pH 8 solution and spiked San Antonio tap water. Exhaustion experiments showed that at pH 8, exhaustion did not occur for the nanoparticles but adsorption does decrease for Cd, Cu, and Zn species but not Pb species. The strong adsorption coupled with the ability to simultaneously remove multiple metal ions offers a potential remediation method for the removal of metals from water.

  3. NSLS-II Radio Frequency Systems

    SciTech Connect

    Rose J.; Gao F.; Goel, A.; Holub, B.; Kulpin, J.; Marques, C.; Yeddulla, M.

    2015-05-03

    The National Synchrotron Light Source II is a 3 GeV X-ray user facility commissioned in 2014. The NSLS-II RF system consists of the master oscillator, digital low level RF controllers, linac, booster and storage ring RF sub-systems, as well as a supporting cryogenic system. Here we will report on RF commissioning and early operation experience of the system.

  4. Nickel(II) biosorption by Rhodotorula glutinis.

    PubMed

    Suazo-Madrid, Alicia; Morales-Barrera, Liliana; Aranda-García, Erick; Cristiani-Urbina, Eliseo

    2011-01-01

    The present study reports the feasibility of using Rhodotorula glutinis biomass as an alternative low-cost biosorbent to remove Ni(II) ions from aqueous solutions. Acetone-pretreated R. glutinis cells showed higher Ni(II) biosorption capacity than untreated cells at pH values ranging from 3 to 7.5, with an optimum pH of 7.5. The effects of other relevant environmental parameters, such as initial Ni(II) concentration, shaking contact time and temperature, on Ni(II) biosorption onto acetone-pretreated R. glutinis were evaluated. Significant enhancement of Ni(II) biosorption capacity was observed by increasing initial metal concentration and temperature. Kinetic studies showed that the kinetic data were best described by a pseudo-second-order kinetic model. Among the two-, three-, and four-parameter isotherm models tested, the Fritz-Schluender model exhibited the best fit to experimental data. Thermodynamic parameters (activation energy, and changes in activation enthalpy, activation entropy, and free energy of activation) revealed that the biosorption of Ni(II) ions onto acetone-pretreated R. glutinis biomass is an endothermic and non-spontaneous process, involving chemical sorption with weak interactions between the biosorbent and Ni(II) ions. The high sorption capacity (44.45 mg g(-1) at 25°C, and 63.53 mg g(-1) at 70°C) exhibited by acetone-pretreated R. glutinis biomass places this biosorbent among the best adsorbents currently available for removal of Ni(II) ions from aqueous effluents.

  5. NSLS-II Beam Diagnostics Overview

    SciTech Connect

    Singh,O.; Alforque, R.; Bacha, B.; Blednykh, A.; Cameron, P.; Cheng, W.; Dalesio, L. B.; Della Penna, A. J.; doom, L.; Fliller, R. P.; Ganetis, G.; Heese, R.; Hseuh, H-C.; Johnson, E. D.; Kosciuk, b. N.; Kramer, S. L.; Krinsky, S.; Mead, J.; Ozaki, S.; Padrazo, D.; Pinayev, I.; Ravindranath, R. V.; Rose, J.; Shaftan, T.; Sharma, S.; Skaritka, J.; Tanabe, T.; Tian, Y.; Willeke, F. J.; Yu, L-H.

    2009-05-04

    A new 3rd generation light source (NSLS-II) is in the early stages of construction at Brookhaven National Laboratory. The NSLS-II facility will provide ultra high brightness and flux with exceptional beam stability. It presents several challenges for diagnostics and instrumentation, related to the extremely small emittance. In this paper, we present an overview of all planned instrumentation systems, results from research and development activities; and then focus on other challenging aspects.

  6. Mechanisms of angiotensin II natriuresis and antinatriuresis.

    PubMed

    Olsen, M E; Hall, J E; Montani, J P; Guyton, A C; Langford, H G; Cornell, J E

    1985-08-01

    The aim of this study was to determine the role of changes in renal arterial pressure (RAP), renal hemodynamics, and tubular reabsorption in mediating the natriuretic and antinatriuretic actions of angiotensin II (ANG II). In seven anesthetized dogs, endogenous ANG II formation was blocked with captopril, and ANG II was infused intravenously at rates of 5-1,215 ng X kg-1 X min-1 while RAP was either servo-controlled at the preinfusion level or permitted to increase. When RAP was servo-controlled, ANG II infusion at all rates from 5-1,215 ng X kg-1 X min-1 decreased urinary sodium excretion (UNaV) and fractional sodium excretion (FENa) while increasing fractional reabsorption of lithium (FRLi) (an index of proximal tubular fractional sodium reabsorption) and causing no change in calculated distal tubule fractional sodium reabsorption (FRDNa). When RAP was permitted to increase, ANG II infusion rates up to 45 ng X kg-1. min-1 also decreased UNaV and FENa while increasing FRLi and causing no change in FRDNa. However, at 135 ng X kg-1 X min-1 and above, UNaV and FENa increased while FRLi and FRDNa decreased when RAP was allowed to rise, even though renal blood flow and filtration fraction were not substantially different from the values observed when RAP was servo-controlled. Filtered sodium load was slightly higher when RAP was permitted to increase during ANG II infusion compared with when RAP was servo-controlled, although the differences were not statistically significant. Thus, even very large doses of ANG II cause antinatriuresis when RAP is prevented from increasing.(ABSTRACT TRUNCATED AT 250 WORDS)

  7. Antenatal diagnosis of achondrogenesis type II.

    PubMed

    Kodandapani, S; Ramkumar, V

    2009-01-01

    Achondrogenesis is a lethal congenital chondrodystrophy characterized by extreme micromelia, small thorax and polyhydramnios. We describe a case of achondrogenesis type II (Langer-Saldino achondrogenesis). Prenatal ultrasonography at 22-weeks gestation revealed a fetus with large head, short neck and chest, prominent abdomen and short limbs. Pregnancy was terminated. Radiologic examination of neonate revealed features of achondrogenesis type II. Routine ultrasound screening made early detection and timely management possible.

  8. The Ssart of Run II at CDF

    SciTech Connect

    Marco Rescigno

    2002-10-29

    After a hiatus of almost 6 years and an extensive upgrade, Tevatron, the world largest proton-antiproton collider, has resumed the operation for the so called RUN II. In this paper we give a brief overview of the many new features of the Tevatron complex and of the upgraded CDF experiment, and show the presently achieved detector performances as well as highlights of the RUN II physics program in the beauty and electroweak sector.

  9. Status of the CDF II experiment

    SciTech Connect

    S. Rolli

    2002-08-14

    The status of the CDF II experiment is described. Since operations start-up for run II data taking in March 2001, the CDF detector has been commissioned using about 20 pb{sup -1} of data provided by the Tevatron (utilized about 4-8). Most detector components are ready for physics quality data. The goal is to present the first physics results by summer-fall 2002.

  10. Synthesis and characterization of hydroxyapatite nanoparticles impregnated on apple pomace to enhanced adsorption of Pb(II), Cd(II), and Ni(II) ions from aqueous solution.

    PubMed

    Chand, Piar; Pakade, Yogesh B

    2015-07-01

    Hydroxyapatite nanoparticles were synthesized, characterized, and impregnated onto apple pomace surface (HANP@AP) for efficient removal of Pb(II), Cd(II), and Ni(II) ions from water. HANP@AP was characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), transmission electron microscope (TEM), X-ray diffraction (XRD), and surface area analysis. Batch sorption studies were carried out to investigate the influence of different parameters as amount of dose (g), pH, time (min), and initial concentration (mg L(-1)) on adsorption process. Experimental kinetic data followed pseudo-second-order model and equilibrium data well fitted to Langmuir adsorption model with maximum adsorption capacities of 303, 250, and 100 mg g(-1) for Pb(II), Cd(II), and Ni(II) ions, respectively. Competitive adsorption of Pb(II), Cd(II), and Ni(II) ions in presences of each other was studied to evaluate the removal efficiency of HANP@AP against multi metal-loaded water. HANP@AP was successfully applied to real industrial wastewater with 100 % removal of all three metal ions even at high concentration. HANP@AP could be recycled for four, four, and three cycles in case of Pb(II), Cd(II) and Ni(II), respectively. The study showed that HANP@AP is fast, cost effective, and environmental friendly adsorbent for removal of Pb(II), Cd(II), and Ni(II) ions from real industrial wastewater.

  11. Preferred crystallographic orientation in the ice I ← II transformation and the flow of ice II

    USGS Publications Warehouse

    Bennett, K.; Wenk, H.-R.; Durham, W.B.; Stern, L.A.; Kirby, S.H.

    1997-01-01

    The preferred crystallographic orientation developed during the ice I ← II transformation and during the plastic flow of ice II was measured in polycrystalline deuterium oxide (D2O) specimens using low-temperature neutron diffraction. Samples partially transformed from ice I to II under a non-hydrostatic stress developed a preferred crystallographic orientation in the ice II. Samples of pure ice II transformed from ice I under a hydrostatic stress and then when compressed axially, developed a strong preferred orientation of compression axes parallel to (1010). A match to the observed preferred orientation using the viscoplastic self-consistent theory was obtained only when (1010) [0001] was taken as the predominant slip system in ice II.

  12. Pb(II) and Cd(II) removal from aqueous solutions by olive cake.

    PubMed

    Doyurum, Sabriye; Celik, Ali

    2006-11-02

    The removal of heavy metals from wastewater using olive cake as an adsorbent was investigated. The effect of the contact time, pH, temperature, and concentration of adsorbate on adsorption performance of olive cake for Pb(II) and Cd(II) ions were examined by batch method. Adsorption of Pb(II) and Cd(II) in aqueous solution onto olive cake was studied in single component. After establishing the optimum conditions, elution of these ions from the adsorbent surface was also examined. The optimum sorption conditions were determined for two elements. Maximum desorption of the Pb(II) and Cd(II) ions were found to be 95.92 and 53.97% by 0.5M HNO(3) and 0.2M HCl, respectively. The morphological analysis of the olive cake was performed by the scanning electron microscopy (SEM).

  13. Differential effect of solution conditions on the conformation of the actinoporins Sticholysin II and Equinatoxin II.

    PubMed

    Fauth, Edson V F; Cilli, Eduardo M; Ligabue-Braun, Rodrigo; Verli, Hugo

    2014-12-01

    Actinoporins are a family of pore-forming proteins with hemolytic activity. The structural basis for such activity appears to depend on their correct folding. Such folding encompasses a phosphocholine binding site, a tryptophan-rich region and the activity-related N-terminus segment. Additionally, different solution conditions are known to be able to influence the pore formation by actinoporins, as for Sticholysin II (StnII) and Equinatoxin II (EqtxII). In this context, the current work intends to characterize the influence of distinct solution conditions in the conformational behavior of these proteins through molecular dynamics (MD) simulations. The obtained data offer structural insights into actinoporins dynamics in solution, characterizing its conformational behavior at the atomic level, in accordance with previous experimental data on StnII and EqtxII hemolytic activities.

  14. Genetic heterogeneity of Usher syndrome type II.

    PubMed Central

    Pieke Dahl, S; Kimberling, W J; Gorin, M B; Weston, M D; Furman, J M; Pikus, A; Möller, C

    1993-01-01

    Usher syndrome is an autosomal recessive disorder characterised by retinitis pigmentosa and congenital sensorineural hearing loss. A gene for Usher syndrome type II (USH2) has been localised to chromosome 1q32-q41. DNA from a family with four of seven sibs affected with clinical characteristics of Usher syndrome type II was genotyped using markers spanning the 1q32-1q41 region. These included D1S70 and D1S81, which are believed to flank USH2. Genotypic results and subsequent linkage analysis indicated non-linkage of this family to these markers. The A test analysis for heterogeneity with this family and 32 other Usher type II families was statistically significant at p < 0.05. Further clinical evaluation of this family was done in light of the linkage results to determine if any phenotypic characteristics would allow for clinical identification of the unlinked type. No clear phenotypic differences were observed; however, this unlinked family may represent a previously unreported subtype of Usher type II characterised by a milder form of retinitis pigmentosa and mild vestibular abnormalities. Heterogeneity of Usher syndrome type II complicates efforts to isolate and clone Usher syndrome genes using linkage analysis and limits the use of DNA markers in early detection of Usher type II. Images PMID:7901420

  15. Group II Introns and Their Protein Collaborators

    NASA Astrophysics Data System (ADS)

    Solem, Amanda; Zingler, Nora; Pyle, Anna Marie; Li-Pook-Than, Jennifer

    Group II introns are an abundant class of autocatalytic introns that excise themselves from precursor mRNAs. Although group II introns are catalytic RNAs, they require the assistance of proteins for efficient splicing in vivo. Proteins that facilitate splicing of organellar group II introns fall into two main categories: intron-encoded maturases and host-encoded proteins. This chapter will focus on the host proteins that group II introns recruited to ensure their function. It will discuss the great diversity of these proteins, define common features, and describe different strategies employed to achieve specificity. Special emphasis will be placed on DEAD-box ATPases, currently the best studied example of host-encoded proteins with a role in group II intron splicing. Since the exact mechanisms by which splicing is facilitated is not known for any of the host proteins, general mechanistic strategies for protein-mediated RNA folding are described and assessed for their potential role in group II intron splicing.

  16. 40 CFR Table 1 to Subpart II of... - General Provisions of Applicability to Subpart II

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Reference Applies to subpart II Comment 63.1(a)(1)-(3) Yes. 63.1(a)(4) Yes Subpart II clarifies the applicability of each paragraph in subpart A to sources subject to subpart II. 63.1(a)(5)-(7) Yes 63.1(a)(8) No Discusses State programs. 63.1(a)(9)-(14) Yes 63.1(b)(1) Yes § 63.781 specifies applicability in more...

  17. Competitive sorption of Pb(II), Cu(II) and Ni(II) on carbonaceous nanofibers: A spectroscopic and modeling approach.

    PubMed

    Ding, Congcong; Cheng, Wencai; Wang, Xiangxue; Wu, Zhen-Yu; Sun, Yubing; Chen, Changlun; Wang, Xiangke; Yu, Shu-Hong

    2016-08-05

    The competitive sorption of Pb(II), Cu(II) and Ni(II) on the uniform carbonaceous nanofibers (CNFs) was investigated in binary/ternary-metal systems. The pH-dependent sorption of Pb(II), Cu(II) and Ni(II) on CNFs was independent of ionic strength, indicating that inner-sphere surface complexation dominated sorption Pb(II), Cu(II) and Ni(II) on CNFs. The maximum sorption capacities of Pb(II), Cu(II) and Ni(II) on CNFs in single-metal systems at a pH 5.5±0.2 and 25±1°C were 3.84 (795.65mg/g), 3.21 (204.00mg/g) and 2.67 (156.70mg/g)mmol/g, respectively. In equimolar binary/ternary-metal systems, Pb(II) exhibited greater inhibition of the sorption of Cu(II) and Ni(II), demonstrating the stronger affinity of CNFs for Pb(II). The competitive sorption of heavy metals in ternary-metal systems was predicted quite well by surface complexation modeling derived from single-metal data. According to FTIR, XPS and EXAFS analyses, Pb(II), Cu(II) and Ni(II) were specifically adsorbed on CNFs via covalent bonding. These observations should provide an essential start in simultaneous removal of multiple heavy metals from aquatic environments by CNFs, and open the doorways for the application of CNFs.

  18. Phosphate effects on copper(II) and lead(II) sorption to ferrihydrite

    NASA Astrophysics Data System (ADS)

    Tiberg, Charlotta; Sjöstedt, Carin; Persson, Ingmar; Gustafsson, Jon Petter

    2013-11-01

    Transport of lead(II) and copper(II) ions in soil is affected by the soil phosphorus status. Part of the explanation may be that phosphate increases the adsorption of copper(II) and lead(II) to iron (hydr)oxides in soil, but the details of these interactions are poorly known. Knowledge about such mechanisms is important, for example, in risk assessments of contaminated sites and development of remediation methods. We used a combination of batch experiments, extended X-ray absorption fine structure (EXAFS) spectroscopy and surface complexation modeling with the three-plane CD-MUSIC model to study the effect of phosphate on sorption of copper(II) and lead(II) to ferrihydrite. The aim was to identify the surface complexes formed and to derive constants for the surface complexation reactions. In the batch experiments phosphate greatly enhanced the adsorption of copper(II) and lead(II) to ferrihydrite at pH < 6. The largest effects were seen for lead(II).

  19. Cu(II) and Zn(II) adsorption capacity of three different clay liner materials.

    PubMed

    Musso, T B; Parolo, M E; Pettinari, G; Francisca, F M

    2014-12-15

    Sorption of Cu(II) and Zn(II) on three natural clays meeting the international requirements for use as liners was evaluated by means of batch tests. The purpose of this research was to determine the retention capacities of the clays for metal cations commonly present in urban solid waste leachates. The pH and ionic strength conditions were set at values frequently found in real leachates. The changes observed in the XRD patterns and FTIR spectra upon adsorption can be considered an evidence of clay-metal electrostatic interaction. The Langmuir model was found to best describe the sorption processes, offering maximum sorption capacities from 8.16 to 56.89 mg/g for Cu(II) and from 49.59 to 103.83 mg/g for Zn(II). All samples remove more Zn(II) than Cu(II), which may be related to the different geometry of the hydrated Cu(II) cation. The total amount of metal sorption was strongly influenced by the total specific surface area, the presence of carbonates and the smectite content of the clays. In addition to their known quality as physical barriers, the adsorbed amounts obtained indicate the suitability of the tested clays to contribute to the retardation of Cu(II) and Zn(II) transport through clay liners.

  20. Adsorption character for removal Cu(II) by magnetic Cu(II) ion imprinted composite adsorbent.

    PubMed

    Ren, Yueming; Wei, Xizhu; Zhang, Milin

    2008-10-01

    A novel magnetic Cu(II) ion imprinted composite adsorbent (Cu(II)-MICA) was synthesized, characterized and applied for the selective removal Cu(II) from aqueous solution in the batch system. The adsorption-desorption and selectivity characteristics were investigated. The maximum adsorption occurred at pH 5-6. The equilibrium time was 6.0h, and a pseudo-second-order model could best describe adsorption kinetics. The adsorption equilibrium data fit Langmuir isotherm equation well with a maximum adsorption capacity of 46.25mg/g and Langmuir adsorption equilibrium constant of 0.0956L/mg at 298K. Thermodynamic parameters analysis predicted an exothermic nature of adsorption and a spontaneous and favourable process that could be mainly governed by physisorption mechanism. The relative selectivity coefficients of Cu(II)-MICA for Cu(II)/Zn(II) and Cu(II)/Ni(II) were 2.31, 2.66 times greater than the magnetic non-imprinted composite adsorbent (MNICA). Results suggested that Cu(II)-MICA was a material of efficient, low-cost, convenient separation under magnetic field and could be reused five times with about 14% regeneration loss.

  1. STELLAR POPULATIONS AND THE STAR FORMATION HISTORIES OF LOW SURFACE BRIGHTNESS GALAXIES. II. H II REGIONS

    SciTech Connect

    Schombert, James; McGaugh, Stacy; Maciel, Tamela E-mail: stacy.mcgaugh@case.edu

    2013-08-01

    The luminosities, colors, and H{alpha} emission for 429 H II regions in 54 low surface brightness (LSB) galaxies are presented. While the number of H II regions per galaxy is lower in LSB galaxies compared to star-forming irregulars and spirals, there is no indication that the size or luminosity function of H II regions differs from other galaxy types. The lower number of H II regions per galaxy is consistent with their lower total star formation rates. The fraction of the total L{sub H{alpha}} contributed by H II regions varies from 10% to 90% in LSB galaxies (the rest of the H{alpha} emission being associated with a diffuse component) with no correlation with galaxy stellar or gas mass. Bright H II regions have bluer colors, similar to the trend in spirals; their number and luminosities are consistent with the hypothesis that they are produced by the same H II luminosity function as spirals. Comparison with stellar population models indicates that the brightest H II regions in LSB galaxies range in cluster mass from a few 10{sup 3} M{sub Sun} (e.g., {rho} Oph) to globular-cluster-sized systems (e.g., 30 Dor) and that their ages are consistent with clusters from 2 to 15 Myr old. The faintest H II regions are comparable to those in the LMC powered by a single O or B star. Thus, star formation in LSB galaxies covers the full range of stellar cluster mass.

  2. Determination of circulating levels of insulin-like growth factor II (IGF-II) in swine.

    PubMed

    Buonomo, F C; Grohs, D L; Baile, C A; Campion, D R

    1988-10-01

    A heterologous radioimmunoassay system was developed for the determination of circulating IGF-II concentrations in swine. The assay utilized a monoclonal antibody against human IGF-II (Amano Intl. Ez, VA) and bovine IGF-II (Monsanto Co., MO) as the cold standard and iodinated ligand. Serial dilutions of acid-ethanol extracted normal swine sera resulted in a curve which was parallel to the bovine IGF-II standard curve. Recovery of unlabeled standard added to extracted swine sera was 101%. Neither IGF-I nor insulin were capable of cross-reacting in this assay at levels up to 100-fold excess. Using this assay, serum IGF-II levels were determined to be significantly lower when subnormal growth hormone (GH) levels existed such as in hypophysectomized swine. However, in contrast to serum IGF-I concentrations, supranormal levels of porcine GH (pGH) did not elevate serum IGF-II concentrations after 13 wk of treatment in 25 kg hogs (initial body wt). In addition, serum IGF-II levels were reduced in fasted swine, despite a significant increase in circulating GH concentrations. Thus, although normal concentrations of GH are required for maintenance of physiological levels of IGF-II in swine, the mechanism for stimulation of IGF-II secretion is less GH-dependent than IGF-I.

  3. Radiative lifetimes, branching rations, and absolute transition probabilities in Cr II and Zn II

    NASA Technical Reports Server (NTRS)

    Bergeson, S. D.; Lawler, J. E.

    1993-01-01

    New absolute atomic transition probability measurements are reported for 12 transitions in Cr II and two transitions in Zn II. These transition probabilities are determined by combining branching ratios measured by classical techniques and radiative lifetimes measured by time-resolved laser-induced fluorescence. The measurements are compared with branching fractions, radiative lifetimes, and transition probabilities in the literature. The 206 nm resonance multiplets in Cr II and Zn II are included in this work. These multiplets are very useful in determining the distribution of the elements in the gas versus grain phases in the interstellar medium.

  4. Ion paired chromatography of iron (II,III), nickel (II) and copper (II) as their 4,7-Diphenyl-1,10-phenanthroline chelates.

    PubMed

    Mudasir; Yoshioka, N; Inoue, H

    1997-07-01

    A reversed phase ion-paired chromatographic method that can be used to determine trace amounts of iron (II,III), nickel (II) and copper (II) was developed and applied to the determination of iron (II) and iron (III) levels in natural water. The separation of these metal ions as their 4,7-diphenyl-1,10-phenanthroline (bathophenanthroline) chelates on an Inertsil ODS column was investigated by using acetonitrile-water (80/20, v/v) containing 0.06 M perchloric acid as mobile phase and diode array spectrophotometric detection at 250-650 nm. Chromatographic parameters such as composition of mobile phase and concentration of perchloric acid in mobile phase were optimized. The calibration graphs of iron (II), nickel (II) and copper (II) ions were linear (r > 0.991) in the concentration range 0-0.5, 0-2.0 and 0-4.0 mug ml(-1), respectively. The detection limit of iron (II), nickel (II) and copper (II) were 2.67, 5.42 and 18.2 ng ml(-1) with relative standard deviation (n = 5) of 3.11, 5.81 and 7.16% at a concentration level of 10 ng ml(-1) for iron (II) and nickel (II) and 25 ng ml(-1) for copper (II), respectively. The proposed method was applied to the determination of iron(II) and iron(III) in tap water and sea water samples without any interference from other common metal ions.

  5. Electrochemical studies of DNA interaction and antimicrobial activities of MnII, FeIII, CoII and NiII Schiff base tetraazamacrocyclic complexes

    NASA Astrophysics Data System (ADS)

    Kumar, Anuj; Vashistha, Vinod Kumar; Tevatia, Prashant; Singh, Randhir

    2017-04-01

    Tetraazamacrocyclic complexes of MnII, FeIII, CoII and NiII have been synthesized by template method. These tetraazamacrocycles have been analyzed with various techniques like molar conductance, IR, UV-vis, mass spectral and cyclic voltammetric studies. On the basis of all these studies, octahedral geometry has been assigned to these tetraazamacrocyclic complexes. The DNA binding properties of these macrocyclic complexes have been investigated by electronic absorption spectra, fluorescence spectra, cyclic voltammetric and differential pulse voltammetric studies. The cyclic voltammetric data showed that ipc and ipa were effectively decreased in the presence of calf thymus DNA, which is a strong evidence for the interaction of these macrocyclic complexes with the calf thymus DNA (ct-DNA). The heterogeneous electron transfer rate constant found in the order: KCoII > KNiII > KMnII which indicates that CoII macrocyclic complex has formed a strong intercalated intermediate. The Stern-Volmer quenching constant (KSV) and voltammetric binding constant were found in the order KSV(CoII) > KSV(NiII) > KSV(MnII) and K+(CoII) > K+(NiII) > K+(MnII) which shows that CoII macrocyclic complex exhibits the high interaction affinity towards ct-DNA by the intercalation binding. Biological studies of the macrocyclic complexes compared with the standard drug like Gentamycin, have shown antibacterial activities against E. coli, P. aeruginosa, B. cereus, S. aureus and antifungal activity against C. albicans.

  6. [Angiotensin II receptor antagonists: different or equivalent?].

    PubMed

    Mounier-Vehier, C; Devos, P

    ARA-II: Angiotensin II receptor antagonists (ARA-II) belong to a recent class of antihypertensive drugs whose mechanism of action is similar to converting enzyme inhibitors (CEI). ARA-II are particularly interesting due to the excellent clinical and biological tolerance, similar to placebo, and their antihypertensive efficacy, comparable with classical drug classes. PUBLISHED TRIALS: A meta-analysis, published by Conlin in the American Journal of Hypertension, suggests that ARA-II, specifically losartan, valsartan, irbesartan and candesartan, have an equipotent blood pressure lowering effect. The careful lecture of this meta-analysis however discloses a faulty methodology from which no valid conclusion can be drawn. Since this early publication, several other comparative studies have been published. These multicentric, randomized double-blind studies enrolled a sufficient number of patients and demonstrated a clinical difference between certain ARA-II at usual dosages. CLINICAL PRACTICE: These studies do have an impact on everyday practice. For the practitioner, the goal is to obtain and then maintain a long-term and optimal reduction in the blood pressure level (reduction or prevention of target-organ disorders and cardiovascular complications of high blood pressure). This reduction in the cardiovascular risk will also depend directly on tolerance and compliance to the antihypertensive treatment. This element must also be considered in assessing treatment efficacy, independent of the blood pressure lowering effect. The results of several other studies will be published in 2001-2003. These large-scale studies on ARA-II related morbidity and mortality will be most useful in determining the role of these drugs in different therapeutic strategies compared with other drug classes.

  7. Immobilization of Pb(II), Cd(II) and Ni(II) ions on kaolinite and montmorillonite surfaces from aqueous medium.

    PubMed

    Sen Gupta, Susmita; Bhattacharyya, Krishna G

    2008-04-01

    The present study investigates the immobilization of Pb(II), Cd(II) and Ni(II) on clays (kaolinite and montmorillonite) in aqueous medium through the process of adsorption under a set of variables (concentration of metal ion, amount of clay, pH, time and temperature of interaction). Increasing pH favours the removal of metal ions till they are precipitated as the insoluble hydroxides. The uptake is rapid with maximum adsorption being observed within 180 min for Pb(II) and Ni(II) and 240 min for Cd(II). A number of available models like the Lagergren pseudo first-order kinetics, second-order kinetics, Elovich equation, liquid film diffusion and intra-particle diffusion are utilized to evaluate the kinetics and the mechanism of the immobilization interactions. Two isotherm equations due to Langmuir and Freundlich showed good fits with the experimental data. Kaolinite and montmorillonite have considerable Langmuir monolayer capacity with respect to Pb(II), Cd(II) and Ni(II), the values being in the range of 6.8-11.5mg/g (kaolinite) and 21.1-31.1mg/g (montmorillonite). The Freundlich adsorption capacity follows a similar order. The thermodynamics of the immobilization process indicates the same to be exothermic with Pb(II) and Ni(II), but endothermic with Cd(II). The interactions with Pb(II) and Ni(II) are accompanied by decrease in entropy and Gibbs energy while the endothermic immobilization of Cd(II) is supported by an increase in entropy and an appreciable decrease in Gibbs energy. The results have established good potentiality for kaolinite and montmorillonite to remove heavy metals like Pb(II), Cd(II) and Ni(II) from aqueous medium through adsorption-mediated immobilization.

  8. Selective Hg(II) adsorption from aqueous solutions of Hg(II) and Pb(II) by hydrolyzed acrylamide-grafted PET films.

    PubMed

    Rahman, Nazia; Sato, Nobuhiro; Sugiyama, Masaaki; Hidaka, Yoshiki; Okabe, Hirotaka; Hara, Kazuhiro

    2014-01-01

    Selective Hg(II) adsorption from aqueous solutions of Hg(II) and Pb(II) using hydrolyzed acrylamide (AAm)-grafted polyethylene terephthalate (PET) films was examined to explore the potential reuse of waste PET materials. Selective recovery of Hg(II) from a mixture of soft acids with similar structure, such as Hg(II) and Pb(II), is important to allow the reuse of recovered Hg(II). An adsorbent for selective Hg(II) adsorption was prepared by γ-ray-induced grafting of AAm onto PET films followed by partial hydrolysis through KOH treatment. The adsorption capacity of the AAm-grafted PET films for Hg(II) ions increased from 15 to 70 mg/g after partial hydrolysis because of the reduction of hydrogen bonding between -CONH2 groups and the corresponding improved access of metal ions to the amide groups. The prepared adsorbent was characterized by Fourier transform infrared spectroscopy and scanning electron microscopy. The absorbent film showed high selectivity for the adsorption of Hg(II) over Pb(II) throughout the entire initial metal concentration range (100-500 mg/L) and pH range (2.2-5.6) studied. The high selectivity is attributed to the ability of Hg(II) ions to form covalent bonds with the amide groups. The calculated selectivity coefficient for the adsorbent binding Hg(II) over Pb(II) was 19.2 at pH 4.5 with an initial metal concentration of 100 mg/L. Selective Hg(II) adsorption equilibrium data followed the Langmuir model and kinetic data were well fitted by a pseudo-second-order equation. The adsorbed Hg(II) and Pb(II) ions were effectively desorbed from the adsorbent film by acid treatment, and the regenerated film showed no marked loss of adsorption capacity upon reuse for selective Hg(II) adsorption.

  9. Luminosity function of [O II] emission-line galaxies in the MassiveBlack-II simulation

    NASA Astrophysics Data System (ADS)

    Park, KwangHo; Di Matteo, Tiziana; Ho, Shirley; Croft, Rupert; Wilkins, Stephen M.; Feng, Yu; Khandai, Nishikanta

    2015-11-01

    We examine the luminosity function (LF) of [O II] emission-line galaxies in the high-resolution cosmological simulation MassiveBlack-II (MBII). From the spectral energy distribution of each galaxy, we select a sub-sample of star-forming galaxies at 0.06 ≤ z ≤ 3.0 using the [O II] emission line luminosity L([O II]). We confirm that the specific star formation rate matches that in the Galaxy And Mass Assembly survey. We show that the [O II] LF at z = 1.0 from the MBII shows good agreement with the LFs from several surveys below L([O II]) = 1043.0 erg s-1 while the low redshifts (z ≤ 0.3) show an excess in the prediction of bright [O II] galaxies, but still displaying a good match with observations below L([O II]) = 1041.6 erg s-1. Based on the validity in reproducing the properties of [O II] galaxies at low redshift (z ≤ 1), we forecast the evolution of the [O II] LF at high redshift (z ≤ 3), which can be tested by upcoming surveys such as the Hobby-Eberly Telescope Dark Energy Experiment and Dark Energy Spectroscopic Instrument. The slopes of the LFs at bright and faint ends range from -3 to -2 showing minima at z = 2. The slope of the bright end evolves approximately as (z + 1)-1 at z ≤ 2 while the faint end evolves as ˜3(z + 1)-1 at 0.6 ≤ z ≤ 2. In addition, a similar analysis is applied for the evolution of [O III] LFs, which is to be explored in the forthcoming survey Wide-Field InfraRed Survey Telescope-Astrophysics Focused Telescope Assets. Finally, we show that the auto-correlation function of [O II] and [O III] emitting galaxies shows a rapid evolution from z = 2 to 1.

  10. Synthesis, physico-chemical studies of manganese(II), cobalt(II), nickel(II), copper(II) and zinc(II) complexes with some p-substituted acetophenone benzoylhydrazones and their antimicrobial activity.

    PubMed

    Singh, Vinod P; Singh, Shweta; Katiyar, Anshu

    2009-04-01

    Complexes of the type [M(pabh)(H2O)Cl], [M(pcbh)(H2O)Cl] and [M(Hpabh)(H2O)2 (SO4)] where, M = Mn(II), Co(II), Ni(II), Cu(II) and Zn(II); Hpabh = p-amino acetophenone benzoyl hydrazone and Hpcbh = p-chloro acetophenone benzoyl hydrazone have been synthesized and characterized with the help of elemental analyses, electrical conductance, magnetic susceptibility measurements, electronic, ESR and IR spectra, thermal (TGA & DTA) and X-ray diffraction studies. Co(II), Ni(II) and Cu(II) chloride complexes are square planar, whereas their sulfate complexes have spin-free octahedral geometry. ESR spectra of Cu(II) complexes with Hpabh are axial and suggest d(x(2)-y(2) as the ground state. The ligand is bidentate bonding through > C = N--and deprotonated enolate group in all the chloro complexes, whereas, >C = N and >C = O groups in all the sulfato complexes. Thermal studies (TGA & DTA) on [Cu(Hpabh)(H2O)2(SO4)] indicate a multistep decomposition pattern, which are both exothermic and endothermic in nature. X-ray powder diffraction parameters for [Co(pabh)(H2O)Cl] and [Ni(Hpabh)(H2O)2(SO4)] correspond to tetragonal and orthorhombic crystal lattices, respectively. The ligands as well as their complexes show a significant antifungal and antibacterial activity. The metal complexes are more active than the ligand.

  11. Dinuclear cadmium(II), zinc(II), and manganese(II), trinuclear nickel(II), and pentanuclear copper(II) complexes with novel macrocyclic and acyclic Schiff-base ligands having enantiopure or racemic camphoric diamine components.

    PubMed

    Jiang, Jue-Chao; Chu, Zhao-Lian; Huang, Wei; Wang, Gang; You, Xiao-Zeng

    2010-07-05

    Four novel [3 + 3] Schiff-base macrocyclic ligands I-IV condensed from 2,6-diformyl-4-substituted phenols (R = CH(3) or Cl) and enantiopure or racemic camphoric diamines have been synthesized and characterized. Metal-ion complexations of these enantiopure and racemic [3 + 3] macrocyclic ligands with different cadmium(II), zinc(II), manganese(II), nickel(II), and copper(II) salts lead to the cleavage of Schiff-base C horizontal lineN double bonds and subsequent ring contraction of the macrocyclic ligands due to the size effects and the spatial restrictions of the coordination geometry of the central metals, the steric hindrance of ligands, and the counterions used. As a result, five [2 + 2] and one [1 + 2] dinuclear cadmium(II) complexes (1-6), two [2 + 2] dinuclear zinc(II) (7 and 8), and two [2 + 2] dinuclear manganese(II) (9 and 10) complexes together with one [1 + 1] trinuclear nickel(II) complex (11) and one [1 + 2] pentanuclear copper(II) complex (12), bearing enantiopure or racemic ligands, different substituent groups in the phenyl rings, and different anionic ligands (Cl(-), Br(-), OAc(-), and SCN(-)), have been obtained in which the chiral carbon atoms in the camphoric backbones are arranged in different ways (RRSS for the enantiopure ligands in 1, 2, 4, 5, and 7-10 and RSRS for the racemic ligands in 3, 6, 11, and 12). The steric hindrance effects of the methyl group bonded to one of the chiral carbon atoms of camphoric diamine units are believed to play important roles in the formation of the acyclic [1 + 1] trinuclear complex 11 and [1 + 2] dinuclear and pentanuclear complexes 6 and 12. In dinuclear cadmium(II), zinc(II), and manganese(II) complexes 1-10, the sequence of separations between the metal centers is consistent with that of the ionic radii shortened from cadmium(II) to manganese(II) to zinc(II) ions. Furthermore, UV-vis, circular dichroism, (1)H NMR, and fluorescence spectra have been used to characterize and compare the structural

  12. Spectroscopic evaluation of Co(II), Ni(II) and Cu(II) complexes derived from thiosemicarbazone and semicarbazone.

    PubMed

    Chandra, Sulekh; Kumar, Anil

    2007-12-31

    Co(II), Ni(II) and Cu(II) complexes were synthesized with thiosemicarbazone (L(1)) and semicarbazone (L(2)) derived from 2-acetyl furan. These complexes were characterized by elemental analysis, molar conductance, magnetic moment, mass, IR, electronic and EPR spectral studies. The molar conductance measurement of the complexes in DMSO corresponds to non-electrolytic nature. All the complexes are of high-spin type. On the basis of different spectral studies six coordinated geometry may be assigned for all the complexes except Co(L)(2)(SO(4)) and Cu(L)(2)(SO(4)) [where L=L(1) and L(2)] which are of five coordinated square pyramidal geometry.

  13. Heterotrimetallic Ru(II)/Pd(II)/Ru(II) complexes: synthesis, crystalstructure, spectral characterization, DFT calculation and antimicrobial study.

    PubMed

    Al-Noaimi, Mousa; Nafady, Ayman; Warad, Ismail; Alshwafy, Rwaida; Husein, Ahmad; Talib, Wamidh H; Hadda, Taibi Ben

    2014-03-25

    New ruthenium(II) mononuclear complexes of the type [RuCl2(PPh3)2(η(2)-triamine)] (2) [RuCl(PPh3)2(η(3)-triamine)]Cl (5) (triemine=N(1)-(2-aminoethyl)-1,2-ethanediamine) have been synthesized by reacting [RuCl2(PPh3)3] (1) with one mole equivalent of N(1)-(2-aminoethyl)-1,2-ethanediamine in dichloromethane. Reaction of (2) with half-equivalent of (PhCN)2PdCl2 or Pd(OAc)2 in dichloromethane as a solvent afforded two novel heterotrimetallic Ru(II)-Pd(II)-Ru(II) complexes, [Ru(II)Cl2(PPh3)2(triamine)]2[Pd(II)X2](X=Cl, OAc) (3 and 4), bearing bioactive ligand. The progress of the undertaken reactions was monitored by (31)P{1H} NMR and FTIR. Crystal structure of complex 2 was confirmed by X-ray diffraction. The absorption spectrum of 2 in dichloromethane was modeled by time-dependent density functional theory (TD-DFT). The in vitro antimicrobial studies of complex 2-5 against an array of microorganisms (bacteria and fungi) were conducted. Complexes 3 and 4 exhibit high dual antibacterial and antifungal activity inhibiting microorganisms possibly via hydrolytic pathway which further evidenced by electrochemical analyses. The complexes 3 and 4 show a high inhibitory activity at 200 μg/ml concentration, suggesting that complexes 3 and 4 are two efficient catalytic inhibitor of microorganisms and further, they should be tested against cancer strains.

  14. From Ultracompact to Extended H II Regions

    NASA Astrophysics Data System (ADS)

    Garcia-Segura, Guillermo; Franco, Jose

    1996-09-01

    The dynamical evolution of H II regions and wind-driven bubbles in dense clouds is studied. In particular, we address two different issues: (1) the conditions under which ultracompact H II (UCHII) regions can reach pressure equilibrium with their surrounding medium (and thereby stall their expansion) and (2) the appearance of a powerful dynamic instability in expanding H II regions. At pressure equilibrium, the ionized regions become static, and as long as the ionization sources and the ambient gas densities remain about constant, the resulting UCHII regions are stable and long-lived. The equilibrium sizes and densities, Rs,eq ˜3 X 10-2F⅓48T⅔H II, 4P-⅔7 pc and ni,eq ˜4 × 104P7T-1H II, 4 cm-3 (where Fβ8 is the photoionizing flux in units of 1048 s-11, P7 is the pressure in units of 10-7 dyne cm-2, and TH II,4 is the ion temperature in units of 104 K), are similar to those actually observed in UCHII regions. Similarly, ultra- compact wind-driven bubbles can reach pressure equilibrium, and the resulting final sizes are similar to those of UCHII'S. The same is true for a combined ultracompact structure consisting of an interior wind- driven cavity and an external H II region. For nonmoving stars in a constant-density medium, the lifetimes for all types of ultracompact objects only depend on the stellar lifetimes. For cases with a density gradient, depending on the core size and slope of the density distribution, some regions never reach the static equilibrium condition. A powerful dynamic instability appears when cooling is included in the neutral gas swept up by an H II region or a combined wind-H II region structure. This instability was first studied by Giuliani and is associated with the thin-shell instability described by Vishniac. The internal ionization front exacerbates the growth of the thin-shell instability, creating a rapid shell fragmentation, and our numerical simulations confirm the linear analysis of Giuliani. The fragments tend to merge as

  15. 20 CFR 226.32 - Spouse tier II.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 20 Employees' Benefits 1 2014-04-01 2012-04-01 true Spouse tier II. 226.32 Section 226.32... Spouse tier II. The spouse tier II benefit is computed as follows: (a) The employee's tier II amount as... before reduction for the railroad retirement family maximum, is multiplied by 45 percent. The spouse...

  16. 20 CFR 226.32 - Spouse tier II.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 20 Employees' Benefits 1 2012-04-01 2012-04-01 false Spouse tier II. 226.32 Section 226.32... Spouse tier II. The spouse tier II benefit is computed as follows: (a) The employee's tier II amount as... before reduction for the railroad retirement family maximum, is multiplied by 45 percent. The spouse...

  17. 20 CFR 226.32 - Spouse tier II.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 20 Employees' Benefits 1 2011-04-01 2011-04-01 false Spouse tier II. 226.32 Section 226.32... Spouse tier II. The spouse tier II benefit is computed as follows: (a) The employee's tier II amount as... before reduction for the railroad retirement family maximum, is multiplied by 45 percent. The spouse...

  18. 20 CFR 226.32 - Spouse tier II.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 20 Employees' Benefits 1 2010-04-01 2010-04-01 false Spouse tier II. 226.32 Section 226.32... Spouse tier II. The spouse tier II benefit is computed as follows: (a) The employee's tier II amount as... before reduction for the railroad retirement family maximum, is multiplied by 45 percent. The spouse...

  19. 20 CFR 226.32 - Spouse tier II.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 20 Employees' Benefits 1 2013-04-01 2012-04-01 true Spouse tier II. 226.32 Section 226.32... Spouse tier II. The spouse tier II benefit is computed as follows: (a) The employee's tier II amount as... before reduction for the railroad retirement family maximum, is multiplied by 45 percent. The spouse...

  20. 10 CFR Appendix II to Part 504 - Fuel Price Computation

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... equations II-1 and II-2. This table contains annual fuel price indices for distillate oil, residual oil... i = MPB where: FPB i = Price of the proposed fuel (distillate oil, residual oil, or natural gas) in... 10 Energy 4 2014-01-01 2014-01-01 false Fuel Price Computation II Appendix II to Part 504...