Properties of massive stars in four clusters of the VVV survey |
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| Institution: | 1. Astronomical Institute ASCR, Fri?ova 298, Ond?ejov 251 65, Czech Republic;2. LUPM, Université de Montpellier, CNRS, Place Eugène Bataillon, Montpellier F-34095, France;3. Gemini Observatory, Northern Operations Center, 670 N. A’ohoku Place, Hilo, HI 96720, USA;4. Aix Marseille Université, CNRS, LAM (Laboratoire d’Astrophysique de Marseille) UMR 7326, Marseille 13388, France;5. Instituto de Física y Astronomía, Universidad de Valparaíso, Av. Gran Bretaña 1111, Playa Ancha, Casilla 5030, Chile;6. The Milky Way Millennium Nucleus, Av. Vicuña Mackenna 4860, Macul 782-0436, Santiago, Chile;7. Millenium Institute of Astrophysics, MAS, Av. Gran Bretana 1111, Playa Ancha, Casilla 5030, Valparaiso, Chile;1. Departament de Física Aplicada, Universitat Politècnica de Catalunya, c/Esteve Terrades 5, 08860 Castelldefels, Spain;2. Institut d’Estudis Espacials de Catalunya, c/Gran Capità 2–4, Edif. Nexus 201, 08034 Barcelona, Spain;3. Department of Physics, Technion – Israel Institute of Technology, Haifa 32000, Israel;4. Facultad de Ciencias Astronómicas y Geofísicas, Universidad Nacional de La Plata–IALP-CONICET, Paseo del Bosque s/n, 1900 La Plata, Argentina;5. Institut de Ciències de l’Espai–CSIC, Campus UAB, Facultat de Ciències, Torre C5 – parell – 2a planta 08193 Bellaterra, Spain;1. Department of Physics and Astronomy, Butler University, Indianapolis, IN 46208, USA;2. College of Science/Department of Physics & NAOC-GZU-Sponsored Center for Astronomy Research, Guizhou University, Guiyang 550025, PR China;3. Key Laboratory for the Structure and Evolution of Celestial Objects, Chinese Academy of Sciences, Kunming 650011, PR China;1. School of Studies in Physics, Jiwaji University, Gwalior 474011, India;2. Greater Noida Institute of Technology, Plot No. 7, Knowledge Park-II, Greater Noida 201306, India;3. Department of Physics, Lovely Professional University, Phagwara 144411, India;4. Zentrum für Astronomie und Astrophysik, Technische Universität Berlin, Hardenbergstrasse 36, D-10623 Berlin, Germany;1. Department of Physics, Indian Institute of Technology Ropar, Nangal Road, Rupnagar 140001, Punjab, India;2. Raman Research Institute, C.V. Raman Avenue, Sadashivanagar, Bangalore 560012, India;3. INAF/IASF-Bologna, via Gobetti 101, I-40129 Bologna, Italy;4. Laboratoire AIM, CEA-IRFU/CNRS/Universit e Paris Diderot, Service d’Astrophysique, CEA Saclay, F-91191 Gif sur Yvette, France |
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| Abstract: | The evolution of massive stars is only partly understood. Observational constraints can be obtained from the study of massive stars located in young massive clusters. The ESO Public Survey “VISTA Variables in the Vía Lácteá (VVV)” discovered several new clusters hosting massive stars. We present an analysis of massive stars in four of these new clusters. Our aim is to provide constraints on stellar evolution and to better understand the relation between different types of massive stars. We use the radiative transfer code CMFGEN to analyse K-band spectra of twelve stars with spectral types ranging from O and B to WN and WC. We derive the stellar parameters of all targets as well as surface abundances for a subset of them. In the Hertzsprung–Russell diagram, the Wolf–Rayet stars are more luminous or hotter than the O stars. From the log(C/N)–log(C/He) diagram, we show quantitatively that WN stars are more chemically evolved than O stars, WC stars being more evolved than WN stars. Mass loss rates among Wolf–Rayet stars are a factor of 10 larger than for O stars, in agreement with previous findings. |
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