Mid-infrared observations of O-type stars: spectral morphology

Autor: D. S. Maia, Jean-Claude Bouret, W. L. F. Marcolino, T. Lanz, Marc Audard
Přispěvatelé: Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Observatoire de la Côte d'Azur (OCA), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Columbia Astrophysics Laboratory (CAL), Columbia University [New York], Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES), Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015 - 2019) (COMUE UCA), Université de Genève (UNIGE)
Jazyk: angličtina
Rok vydání: 2017
Předmět:
010504 meteorology & atmospheric sciences
Astrophysics::High Energy Astrophysical Phenomena
FOS: Physical sciences
Astrophysics
Astrophysics::Cosmology and Extragalactic Astrophysics
Stellar classification
01 natural sciences
Spectral line
Spitzer Space Telescope
0103 physical sciences
Astrophysics::Solar and Stellar Astrophysics
Emission spectrum
010303 astronomy & astrophysics
Solar and Stellar Astrophysics (astro-ph.SR)
Astrophysics::Galaxy Astrophysics
0105 earth and related environmental sciences
Line (formation)
O-type star
Physics
[SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR]
Astronomy and Astrophysics
[PHYS.ASTR.SR]Physics [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR]
Stars
Astrophysics - Solar and Stellar Astrophysics
13. Climate action
Space and Planetary Science
Astrophysics::Earth and Planetary Astrophysics
Supergiant
Zdroj: Monthly Notices of the Royal Astronomical Society
Monthly Notices of the Royal Astronomical Society, Oxford University Press (OUP): Policy P-Oxford Open Option A, 2017, 470 (3), pp.2710-2722. ⟨10.1093/mnras/stx1191⟩
Monthly Notices of the Royal Astronomical Society, 2017, 470 (3), pp.2710-2722. ⟨10.1093/mnras/stx1191⟩
ISSN: 0035-8711
1365-2966
DOI: 10.1093/mnras/stx1191⟩
Popis: We present mid-infrared observations for a sample of 16 O-type stars. The data were acquired with the NASA Spitzer Space Telescope, using the IRS instrument at moderate resolution (R $\sim$ 600), covering the range $\sim 10-37$ microns. Our sample includes early, mid and late O supergiants and dwarfs. We explore for the first time their mid-IR spectral morphology in a quantitative way. We use NLTE expanding atmosphere models to help with line identifications, analyze profile contributions and line-formation regions. The O supergiants present a rich emission line spectra. The most intense features are from hydrogen - $6\alpha$, 7$\alpha$, and $8\alpha$ - which have non-negligible contributions of HeI or HeII lines, depending on the spectral type. The spectrum of early O supergiants is a composite of HI and HeII lines, HeI lines being absent. On the other hand, late O supergiants present features composed mainly by HI and HeI lines. All emission lines are formed throughout the stellar wind. We found that O dwarfs exhibit a featureless mid-IR spectrum. Two stars of our sample exhibit very similar mid-IR features, despite having a very different optical spectral classification. The analysis of O-type stars based on mid-IR spectra alone to infer spectral classes or to estimate physical parameters may thus be prone to substantial errors. Our results may therefore inform spectroscopic observations of massive stars located in heavily obscured regions and help establish an initial framework for observations of massive stars using the Mid-Infrared Instrument on the James Webb Space Telescope.
Comment: 16 pages, 9 figures, accepted for publication in MNRAS
Databáze: OpenAIRE
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