Effects of Metallicity on the Rotation Rates of Massive Stars

Abstract

Recent theoretical predictions for low metallicity massive stars predict that these stars should have drastically reduced equatorial winds (mass loss) while on the main sequence, and as such should retain most of their angular momentum. Observations of both the Be/(B+Be) ratio and the blue-to-red supergiant ratio appear to have a metallicity dependence that may be caused by high rotational velocities. We have analyzed 39 archival Hubble Space Telescope Imaging Spectrograph (STIS), high resolution, ultraviolet spectra of O-type stars in the Magellanic Clouds to determine their projected rotational velocities V sin i. Our methodology is based on a previous study of the projected rotational velocities of Galactic O-type stars using International Ultraviolet Explorer (IUE) Short Wavelength Prime (SWP) Camera high dispersion spectra, which resulted in a catalog of V sin i values for 177 O stars. Here we present complementary V sin i values for 21 Large Magellanic Cloud and 22 Small Magellanic Cloud O-type stars based on STIS and IUE UV spectroscopy. The distribution of V sin i values for O type stars in the Magellanic Clouds is compared to that of Galactic O type stars. Despite the theoretical predictions and indirect observational evidence for high rotation, the O type stars in the Magellanic Clouds do not appear to rotate faster than their Galactic counterparts.

arXiv commentaccepted by ApJ, to appear 20 December 2004 edition

References in corpus (6)

• Collapsars - Gamma-Ray Bursts and Explosions in "Failed Supernovae"
• Presupernova Evolution of Rotating Massive Stars II: -- Evolution of the Surface Properties
• Stellar evolution with rotation VII: Low metallicity models and the blue to red supergiant ratio in the SMC
• A Galactic O-Star Catalog
• New Periodic Variables from the Hipparcos Epoch Photometry
• Be stars in and around young clusters in the Magellanic Clouds

Cited by in corpus (23)

• Evolution towards the critical limit and the origin of Be stars
• Fourier method in the determination of rotational velocities in OB stars
• The VLT-FLAMES survey of massive stars: Mass loss and rotation of early-type stars in the SMC
• A Statistical Study of Threshold Rotation Rates for the Formation of Disks around Be Stars
• The Role of Evolutionary Age and Metallicity in the Formation of Classical Be Circumstellar Disks I. New Candidate Be Stars in the LMC, SMC, and Milky Way
• A quantitative study of O stars in NGC2244 and the Mon OB2 association
• Effects of metallicity, star formation conditions and evolution in B and Be stars. I: Large Magellanic Cloud, field of NGC 2004
• The Massive Progenitor of the Possible Type II-Linear Supernova 2009hd in Messier 66
• A FUSE Survey of the Rotation Rates of Very Massive Stars in the Small and Large Magellanic Clouds
• On the metallicity dependence of HMXBs
• X-Shooting ULLYSES: massive stars at low metallicity. I. Project Description
• A census of massive stars in NGC 346. Stellar parameters and rotational velocities
• The Single Star Path to Be Stars
• Beta Cephei stars in the ASAS-3 data. II. 103 new Beta Cephei stars and a discussion of low-frequency modes
• On Rapidly Rotating Magnetic Core-Collapse Supernovae
• Spectroscopic and physical parameters of Galactic O-type stars. I. Effects of rotation and spectral resolving power in the spectral classification of dwarfs and giants
• Turbulent transport by diffusive stratified shear flows: from local to global models. Part II: Limitations of local models
• Radial Velocities of Galactic O-Type Stars. II. Single-lined Spectroscopic Binaries
• Exploring the stellar rotation of early-type stars in the LAMOST Medium-Resolution Survey. II. Statistics
• The Temperature Structure of Be Star Disks in the Small Magellanic Cloud
• Implications of Elemental Abundances in Dwarf Spheroidal Galaxies
• Nucleosynthesis from massive stars 50 years after B2FH
• Astrophysics in 2005