Results 31 to 40 of about 180 (127)
Probing extreme black‐hole outflows on short timescales via high spectral‐resolution x‐ray imagers
Astronomische Nachrichten, Volume 345, Issue 6-7, July-August 2024.Abstract We investigate outflows and the physics of super‐Eddington versus sub‐Eddington regimes in black hole systems. Our focus is on prospective science using next‐generation high‐resolution soft x‐ray instruments. We highlight the properties of black hole ultraluminous x‐ray source (ULX) systems in particular. Owing to scale invariance in accreting
C. Pinto +9 more
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Quantitative spectroscopy of Wolf-Rayet stars [PDF]
International Astronomical Union Colloquium, 1988 Advances in theoretical modeling of rapidly expanding atmospheres in the past few years made it possible to determine the stellar parameters of the Wolf-Rayet stars. This progress is mainly due to the improvement of the models with respect to their spatial extension: The new generation of models treat spherically-symmetric expanding atmospheres, i.e ...
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How Massive the Wolf-Rayet Stars are ? [PDF]
International Astronomical Union Colloquium, 1981 If the Wolf-Rayet stars are produced by the evolution of massive stars with mass loss (Paczynski 1967, Conti 1976) from 0 stars to WN stars and thereafter to WC stars, then we may expect to observe a correlation of decreasing mean masses in the same sense as the evolution.Information about the masses of TO stars are obtained from studies of binary ...
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High energy processes in Wolf‐Rayet stars [PDF]
Astronomische Nachrichten, 2019 Wolf‐Rayet (WR) stars are massive (≥10 M⊙) evolved stars undergoing advanced nuclear burning in their cores, rapidly approaching the end of their lives as supernovae. Their powerful winds enrich the interstellar medium with heavy elements, providing raw material for future generations of stars.
Skinner, S. L. +3 more
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On the Hydrogen Abundance in Wolf-Rayet Stars [PDF]
Symposium - International Astronomical Union, 1984 With a semiempirical NLTE-model in spherical geometry we investigate the hydrogen abundance in Wolf-Rayet stars. We find that the flux contribution of the H-Balmer to the He-Pickering lines lies between the usually applied approximate formulae for the optically thin and optically thick case. This result can be understood with our finding that there are
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Comparison of Star Clusters With and Without Wolf‐Rayet Stars in Wolf‐Rayet Galaxies
The Astrophysical Journal Supplement Series, 2005 We compare the properties of young star clusters with and without Wolf-Rayet (W-R) stars in W-R galaxies using optical, near-infrared imagery and optical spectroscopy. Our work identifies the clusters with W-R stars in these galaxies for the first time. With this information, comparisons of clusters with and without W-R stars are now possible, enabling
Brent A. Buckalew +2 more
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Massive Wolf-Rayet (WR) stars comprise a spectroscopic class characterized by high temperatures (Teff > ~30 kK) and powerful and rapid stellar winds. Hydrogen-rich WR stars represent the most massive stars in existence (M > ~100 Msun), while classical WR stars are hydrogen-depleted, evolved massive stars which probe the final evolutionary stages ...
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, 2015 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
Hamann, Wolf-Rainer (Prof. Dr.) +2 more
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Ultraviolet classification of Wolf-Rayet stars [PDF]
Symposium - International Astronomical Union, 1995 The ultraviolet spectra of 94 WR stars obtained from Vilspa IUE archive are used here to look for classification criteria in the UV region alone. We have tried to select as many single and SB1 type stars as possible in the Galaxy and the LMC to get the complete, flux-calibrated spectra between 1150 and 3250 Å. Altogether 56 (34 of WN and 22 of WC type)
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Rotation and Wolf-Rayet Star Formation [PDF]
International Astronomical Union Colloquium, 1999 AbstractNew results for 60 M⊙ stellar models with different rotation rates are presented. Some effects of rotation on Wolf-Rayet star formation are discussed.
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