The VLT-FLAMES survey of massive stars: atmospheric parameters and rotational velocity distributions for B-type stars in the Magellanic Clouds

Abstract

We provide atmospheric parameters and rotational velocities of a large sample (~400) of O- and early B-type stars, analysed in a homogeneous and consistent manner, for use in constraining theoretical models. Comparison of the rotational velocities with evolutionary tracks suggest that the end of core hydrogen burning occurs later than currently predicted. We also show that the large number of the luminous blue supergiants observed in the fields are unlikely to have directly evolved from main-sequence massive O-type stars as neither their low rotational velocities or position on the H-R diagram are predicted. We suggest that blue-loops or mass-transfer binary systems may populate the blue supergiant regime. By comparing the rotational velocity distributions of the Magellanic Cloud stars to a similar Galactic sample we find that (at 3sigma confidence level) massive stars (above 8Msun) in the SMC rotate faster than those in the solar neighbourhood. However there appears to be no significant difference between the rotational velocity distributions in the Galaxy and the LMC. We find that the vsini distributions in the SMC and LMC can modelled with an intrinsic rotational velocity distribution which is a Gaussian peaking at 175km/s (SMC) and 100km/s (LMC). We find that in NGC346 in the SMC, the 10-25Msun main-sequence stars appear to rotate faster than their higher mass counterparts. Recently Yoon et al. (2006) have determined rates of GRBs by modelling rapidly rotating massive star progenitors. Our measured rotational velocity distribution for the 10-25Msun stars is peaked at slightly higher velocities than they assume, supporting the idea that GRBs could come from rapid rotators with initial masses as low as 14Msun at low metallicities. (abridged).

25 pages with tables. 11 figures. Submitted to A&A and corrected for referee's comments

References in corpus (3)

• Effects of gravitational darkening on the determination of fundamental parameters in fast rotating B-type stars
• The VLT-FLAMES survey of massive stars: Wind properties and evolution of hot massive stars in the LMC
• Rotational Velocities For B0-B3 Stars in 7 Young Clusters: Further Study of the Relationship between Rotation Speed and Density in Star-Forming Regions

Cited by in corpus (10)

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• Galaxies with Wolf-Rayet signatures in the low-redshift Universe - A survey using the Sloan Digital Sky Survey
• The VLT-FLAMES survey of massive stars: rotation and nitrogen enrichment as the key to understanding massive star evolution
• The Araucaria Project: the Local Group Galaxy WLM--Distance and metallicity from quantitative spectroscopy of blue Supergiants
• A FUSE Survey of the Rotation Rates of Very Massive Stars in the Small and Large Magellanic Clouds
• Properties of WNh stars in the Small Magellanic Cloud: evidence for homogeneous evolution
• Variability of Be Stars in Southern Open Clusters
• The blue supergiant Sher 25 and its intriguing hourglass nebula
• The evolution of massive and very massive stars in clusters