@misc{VinkHegerKrumholzetal.2012, author = {Vink, Jorick Sandor and Heger, Alexander and Krumholz, Mark R. and Puls, Joachim and Banerjee, Shiladitya and Castro, Norberto and Chen, K.-J. and Chen{\`e}, A.-N. and Crowther, P. A. and Daminelli, A. and Gr{\"a}fener, G. and Groh, J. H. and Hamann, Wolf-Rainer and Heap, S. and Herrero, A. and Kaper, L. and Najarro, F. and Oskinova, Lida and Roman-Lopes, A. and Rosen, A. and Sander, A. and Shirazi, M. and Sugawara, Y. and Tramper, F. and Vanbeveren, D. and Voss, R. and Wofford, A. and Zhang, Y.}, title = {Very massive stars in the local universe}, series = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, journal = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, number = {601}, issn = {1866-8372}, doi = {10.25932/publishup-41522}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-415220}, pages = {29}, year = {2012}, abstract = {Recent studies have claimed the existence of very massive stars (VMS) up to 300 M⊙ in the local Universe. As this finding may represent a paradigm shift for the canonical stellar upper-mass limit of 150 M⊙, it is timely to discuss the status of the data, as well as the far-reaching implications of such objects. We held a Joint Discussion at the General Assembly in Beijing to discuss (i) the determination of the current masses of the most massive stars, (ii) the formation of VMS, (iii) their mass loss, and (iv) their evolution and final fate. The prime aim was to reach broad consensus between observers and theorists on how to identify and quantify the dominant physical processes.}, language = {en} } @article{FryerLangerHegeretal.2002, author = {Fryer, C. L. and Langer, Norbert and Heger, Alexander and Wellstein, Stephan}, title = {The limiting stellar initial mass for black hole formation in close binary}, year = {2002}, abstract = {We present models for the complete life and death of a 60 Msolar star evolving in a close binary system, from the main-sequence phase to the formation of a compact remnant and fallback of supernova debris. After core hydrogen exhaustion, the star expands, loses most of its envelope by Roche lobe overflow, and becomes a Wolf-Rayet star. We study its post-mass transfer evolution as a function of the Wolf-Rayet wind mass-loss rate (which is currently not well constrained and will probably vary with the initial metallicity of the star). Varying this mass-loss rate by a factor of 6 leads to stellar masses at collapse that range from 3.1 up to 10.7 Msolar. Because of different carbon abundances left by core helium burning and nonmonotonic effects of the late shell-burning stages as function of the stellar mass, we find that, although the iron core masses at collapse are generally larger for stars with larger final masses, they do not depend monotonically on the final stellar mass or even the C/O core mass. We then compute the evolution of all models through collapse and bounce. The results range from strong supernova explosions (Ekin>1051ergs) for the lower final masses to the direct collapse of the star into a black hole for the largest final mass. Correspondingly, the final remnant masses, which were computed by following the supernova evolution and fallback of material for a timescale of about one year, are between 1.2 and 10 Msolar. We discuss the remaining uncertainties of this result and outline the consequences of our results for the understanding of the progenitor evolution of X-ray binaries and gamma-ray burst models.}, language = {en} } @article{HegerWoosleyLanger2000, author = {Heger, Alexander and Woosley, S. E. and Langer, Norbert}, title = {Stellar models including pre-SN/SN phases}, year = {2000}, language = {en} } @article{HegerLangerWoosley2000, author = {Heger, Alexander and Langer, Norbert and Woosley, S. E.}, title = {Presupernova evolution of rotating massive stars I : numerical method and evolution of the internal stellar structure}, year = {2000}, language = {en} } @article{LangerHeger1999, author = {Langer, Norbert and Heger, Alexander}, title = {Massive star evolution}, year = {1999}, language = {en} } @article{LangerHegerWellensteinetal.1999, author = {Langer, Norbert and Heger, Alexander and Wellenstein, Stephan and Herwig, Falk}, title = {Mixing and nucleosynthesis in rotating TP-AGB stars}, year = {1999}, language = {en} } @article{LangerHeger1999, author = {Langer, Norbert and Heger, Alexander}, title = {Evolution and explosion of Wolf-Rayet stars}, year = {1999}, language = {en} } @article{LangerHegerGarciaSegura1998, author = {Langer, Norbert and Heger, Alexander and Garcia-Segura, Guillermo}, title = {Massive stars : the pre-supernova evolution of internal and circumstellar structure}, year = {1998}, language = {en} } @article{HegerLangerWoosley1998, author = {Heger, Alexander and Langer, Norbert and Woosley, S. E.}, title = {Nucleosynthesis in rotating massive stars}, year = {1998}, language = {en} } @article{LangerHegerBraun1998, author = {Langer, Norbert and Heger, Alexander and Braun, H.}, title = {Nucleosynthesis in massive stars}, year = {1998}, language = {en} } @article{LangerHeger1998, author = {Langer, Norbert and Heger, Alexander}, title = {B[e] supergiants : what is their evolutionary status?}, year = {1998}, language = {en} } @article{HegerLanger1998, author = {Heger, Alexander and Langer, Norbert}, title = {The spin-up of contracting red supergiants}, year = {1998}, language = {en} } @article{LangerFliegnerHegeretal.1997, author = {Langer, Norbert and Fliegner, J. and Heger, Alexander and Woosley, S. E.}, title = {Nucleosynthesis in rotating massive stars}, year = {1997}, language = {en} } @article{HegerJeanninLangeretal.1997, author = {Heger, Alexander and Jeannin, Laurent and Langer, Norbert and Baraffe, Isabelle}, title = {Pulsations in red supergiants with high L/M ratio : implications for the stellar and circumstellar structure of supernova progenitors}, year = {1997}, language = {en} }