@article{FigerNajarroMorisetal.1998, author = {Figer, Donald F. and Najarro, F. and Moris, Mark and Mclean, Ian S. and Geballe, T. R. and Ghez, A. M. and Langer, Norbert}, title = {The Pistol star}, year = {1998}, language = {en} } @article{FigerNajarroLanger2000, author = {Figer, Donald F. and Najarro, F. and Langer, Norbert}, title = {The pistol star and massive stars in the galactic center}, year = {2000}, language = {en} } @article{EvansSmarttLeeetal.2005, author = {Evans, C. J. and Smartt, S. J. and Lee, J. K. and Lennon, D. J. and Kaufer, A. and Dufton, P. L. and Trundle, C. and Herrero, A. and Simon D{\´i}az, Sergio and de Koter, A. and Hamann, Wolf-Rainer and Hendry, M. A. and Hunter, I. and Irwin, M. J. and Korn, A. J. and Kudritzki, R. P. and Langer, Norbert and Mokiem, M. R. and Najarro, F. and Pauldrach, A. W. A. and Przybilla, Norbert and Puls, J. and Ryans, R. S. I. and Urbaneja, M. A. and Venn, K. A. and Villamariz, M. R.}, title = {The VLT-FLAMES survey of massive stars : Observations in the Galactic clusters NGC3293, NGC4755 and NGC6611}, year = {2005}, abstract = {We introduce a new survey of massive stars in the Galaxy and the Magellanic Clouds using the Fibre Large Array Multi- Element Spectrograph ( FLAMES) instrument at the Very Large Telescope ( VLT). Here we present observations of 269 Galactic stars with the FLAMES- Giraffe Spectrograph ( R similar or equal to 25 000), in fields centered on the open clusters NGC3293, NGC4755 and NGC6611. These data are supplemented by a further 50 targets observed with the Fibre- Fed Extended Range Optical Spectrograph ( FEROS, R = 48 000). Following a description of our scientific motivations and target selection criteria, the data reduction methods are described; of critical importance the FLAMES reduction pipeline is found to yield spectra that are in excellent agreement with less automated methods. Spectral classifications and radial velocity measurements are presented for each star, with particular attention paid to morphological peculiarities and evidence of binarity. These observations represent a significant increase in the known spectral content of NGC3293 and NGC4755, and will serve as standards against which our subsequent FLAMES observations in the Magellanic Clouds will be compared}, language = {en} } @inproceedings{PulsMarkovaNajarroetal.2007, author = {Puls, Joachim and Markova, N. and Najarro, F. and Hanson, M. M.}, title = {Clumping in O-star winds}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17683}, year = {2007}, abstract = {We review various diagnostics of clumping in O-star winds, with special emphasis on its radial stratification. Implications and problems are discussed, and promising NIR methods are presented.}, language = {en} } @inproceedings{NajarroPulsHerreroetal.2007, author = {Najarro, F. and Puls, Joachim and Herrero, A. and Hanson, M. M. and Mart{\´i}n-Pintado, J. and Hillier, D. J.}, title = {Tracking the Clumping in OB Stars from UV to radio}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17701}, year = {2007}, abstract = {We review different line and continua diagnostics from the UV to radio, which can be utilized to simultaneously constrain the clumping structure throughout the stellar wind of massive OB stars.}, language = {en} } @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{NajarrodelaFuenteGeballeetal.2015, author = {Najarro, F. and de la Fuente, D. and Geballe, T. R. and Figer, D. F. and Hillier, D. J.}, title = {The WR population in the Galactic Center}, series = {Wolf-Rayet Stars : Proceedings of an International Workshop held in Potsdam, Germany, 1.-5. June 2015}, journal = {Wolf-Rayet Stars : Proceedings of an International Workshop held in Potsdam, Germany, 1.-5. June 2015}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-87794}, pages = {113 -- 116}, year = {2015}, abstract = {The Galactic Center (GC) hosts three of the most massive WR rich, resolved young clusters in the Local Group as well as a large number of apparently isolated massive stars. Therefore, it constitutes a test bed to study the star formation history of the region, to probe a possible top-heavy scenario and to address massive star formation (clusters vs isolation) in such a dense and harsh environment. We present results from our ongoing infrared spectroscopic studies of WRs and other massive stars at the Center of the Milky Way.}, language = {en} } @article{KourniotisBonanosNajarro2015, author = {Kourniotis, M. and Bonanos, A. and Najarro, F.}, title = {Accurate parameters of massive binaries in the Danks clusters}, series = {Wolf-Rayet Stars : Proceedings of an International Workshop held in Potsdam, Germany, 1.-5. June 2015}, journal = {Wolf-Rayet Stars : Proceedings of an International Workshop held in Potsdam, Germany, 1.-5. June 2015}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-87819}, pages = {121 -- 124}, year = {2015}, abstract = {We present results from our near-infrared spectroscopy with VLT/ISAAC of four, massive eclipsing binary systems in the young, heavily reddened, massive Danks clusters. We derive accurate fundamental parameters and the distance to these massive systems, which comprise of OIf+, WR and O-type stars. Our goal is to increase the sample of well-studied WR stars and constrain their physics by comparison with evolutionary models.}, language = {en} }