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Spectroscopic analyses of massive stars at different metallicities

Published online by Cambridge University Press:  29 August 2024

Wolf-Rainer Hamann Open the ORCID record for Wolf-Rainer Hamann [Opens in a new window]
Wolf-Rainer Hamann*
Affiliation:
Institute for Physics and Astronomy, University Potsdam, D-14476 Potsdam, Germany
*
email: wrh@astro.physik.uni-potsdam.de
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Abstract

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Adequate stellar atmosphere models are prerequisite to derive robust stellar parameters from spectroscopic analyses. I will briefly review recent results obtained with the Potdam Wolf-Rayet (PoWR) model atmosphere code, which is applicable to all types of hot stars. Using multi-wavelength observations including the UV, we analyzed large samples of massive stars at various metallicities, gaining important insights on their cosmic role and the feedback to their environment.

A recent extension of PoWR allows to compose the model atmosphere from two zones. A rapidly rotating star, e.g., might possess a cooler equatorial region with a slow wind, and two polar cones with higher photospheric temperature and fast wind. For two examples of rapidly rotating O-type stars, we demonstrate that such model can reproduce wind-line profiles which otherwise would stay inconsistent. Fast rotation, which prevails in particular at low metallicities, thus might bias empirically derived parameters, having implications for feedback as well as for angular-momentum losses of SN and GRB progenitors.

Keywords

stars: atmospheresstars: windsoutflows
Type
Contributed Paper
Information
Proceedings of the International Astronomical Union , Volume 18 , Symposium S361: Massive Stars Near and Far , May 2022 , pp. 139 - 144
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Creative Commons
Creative Common License - CCCreative Common License - BY
This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted re-use, distribution, and reproduction in any medium, provided the original work is properly cited.
Copyright
© The Author(s), 2024. Published by Cambridge University Press on behalf of International Astronomical Union

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