Massive stars at low metallicity - Evolution and surface abundances of O dwarfs in the SMC

  title={Massive stars at low metallicity - Evolution and surface abundances of O dwarfs in the SMC},
  author={J-C. Bouret and Thierry M. Lanz and Fabrice Martins and Wagner L. F. Marcolino and D. John Hillier and {\'E}ric Depagne and Ivan Hubeny},
  journal={Astronomy and Astrophysics},
We study the evolution, rotation, and surface abundances of O-type dwarfs in the Small Magellanic Cloud. We analyzed the UV and optical spectra of twenty-three objects and derived photospheric and wind properties. The observed binary fraction of the sample is ~ 26%, which is compatible with more systematic studies, if one considers that the actual binary fraction is potentially larger owing to low-luminosity companions and that the sample excluded obvious spectroscopic binaries. The location of… 

Massive stars in the Small Magellanic Cloud

Context. The evolution of massive stars depends on several physical processes and parameters. Metallicity and rotation are among the most important, but their quantitative effects are not well

The MiMeS Survey of Magnetism in Massive Stars: CNO surface abundances of Galactic O stars

The evolution of massive stars is still partly unconstrained. Mass, metallicity, mass loss and rotation are the main drivers of stellar evolution. Binarity and magnetic field may also significantly

A study of the effect of rotational mixing on massive stars evolution: surface abundances of Galactic O7-8 giant stars

Context. Massive star evolution remains only partly constrained. In particular, the exact role of rotation has been questioned by puzzling properties of OB stars in the Magellanic Clouds. Aims. Our

Far-ultraviolet Spectra of Main-sequence O Stars at Extremely Low Metallicity

Metal-poor massive stars dominate the light we observe from star-forming dwarf galaxies and may have produced the bulk of energetic photons that reionized the universe at high redshift. Yet, the

A dearth of young and bright massive stars in the Small Magellanic Cloud

Context. Massive star evolution at low metallicity is closely connected to many fields in high-redshift astrophysics, but is poorly understood so far. Because of its metallicity of ∼0.2 Z⊙, its


We present the first quantitative ultraviolet spectroscopic analysis of resolved OB stars in IC 1613. Because of its alleged very low metallicity (≲1/10 Z☉, from H ii regions), studies in this Local

Spectroscopic and physical parameters of Galactic O-type stars. III. Mass discrepancy and rotational mixing

Context. Massive stars play a key role in the evolution of galaxies and our Universe. Aims. Our goal is to compare observed and predicted properties of single Galactic O stars to identify and

No breakdown of the radiatively driven wind theory in low-metallicity environments

We present a spectroscopic analysis of HST/COS observations of three massive stars in the low metallicity dwarf galaxies IC 1613 and WLM. These stars, were previously observed with VLT/X-shooter by

Chemical abundances of fast-rotating massive stars. II. Interpretation and comparison with evolutionary models

Aims: Past observations of fast-rotating massive stars exhibiting normal nitrogen abundances at their surface have raised questions about the rotational mixing paradigm. We revisit this question

Spectroscopic evolution of massive stars near the main sequence at low metallicity

Context. The evolution of massive stars is not fully understood. Several physical processes affect their life and death, with major consequences on the progenitors of core-collapse supernovae,



Properties of Galactic early-type O-supergiants - A combined FUV-UV and optical analysis

We aim to constrain the properties and evolutionary status of early and mid-spectral type supergiants (from O4 to O7.5). These posses the highest mass-loss rates among the O stars, and exhibit


We present projected rotational velocity values for 97 Galactic, 55 SMC, and 106 LMC O-B type stars from archival FUSE observations. The evolved and unevolved samples from each environment are

Observational effects of magnetism in O stars: surface nitrogen abundances ,

Aims. We investigate the surface nitrogen content of the six magnetic O stars known to date as well as of the early B-type star τ Sco. We compare these abundances to predictions of evolutionary

A quantitative study of O stars in NGC 2244 and the Monoceros OB2 association

Aims. Our goal is to determine the stellar and wind properties of seven O stars in the cluster NGC 2244 and three O stars in the OB association Mon OB2. These properties give us insight into the mass

The Physical Properties and Effective Temperature Scale of O-Type Stars as a Function of Metallicity. II. Analysis of 20 More Magellanic Cloud Stars and Results from the Complete Sample

In order to determine the physical properties of the hottest and most luminous stars and understand how these properties change as a function of metallicity, we have analyzed HST/UV and high-S/N

High-mass binaries in the very young open cluster NGC 6231. Implication for cluster and star formation

New radial-velocity observations of 37 O- and B stars in the very young open cluster NGC 6231 confirm the high frequency of short-period spectroscopic binaries on the upper main sequence. Among the

Quantitative Spectroscopy of O Stars at Low Metallicity: O Dwarfs in NGC 346

We present the results of a detailed analysis of the properties of dwarf O-type stars in a metal-poor environment. High-resolution, high-quality ultraviolet and optical spectra of six O-type stars in

Lower mass loss rates in O-type stars: Spectral signatures of dense clumps in the wind of two Galactic O4 stars

We have analyzed the far-ultraviolet spectrum of two Galactic O4 stars, the O4If+ supergiant HD 190429A and the O4V((f)) dwarf HD 96715, using archival FUSE and IUE data. We have conducted a

O stars with weak winds: the Galactic case

We study the stellar and wind properties of a sample of Galactic O dwarfs to track the conditions under which weak winds (i.e mass loss rates lower than � 10 −8 M⊙ yr −1 ) appear. The sample is

The VLT-FLAMES survey of massive stars: constraints on stellar evolution from the chemical compositions of rapidly rotating Galactic and Magellanic Cloud B-type stars

Aims. We have previously analysed the spectra of 135 early B-type stars in the Large Magellanic Cloud (LMC) and found several groups of stars that have chemical compositions that conflict with the