HST/COS Spectra of the Wind Lines of VFTS 102 and 285

Abstract

Rapid rotation in massive stars imposes a latitudinal variation in the mass loss from radiatively driven winds that can lead to enhanced mass loss at the poles (with little angular momentum loss) and/or equator (with maximal angular momentum loss). Here we present an examination of the stellar wind lines of the two O-type stars with the fastest known equatorial velocities, VFTS 102 ($V\sin i=610\pm 30$ km/s; O9:Vnnne+) and VFTS 285 ($V\sin i=609\pm 29$ km/s; O7.5 Vnnn) in the Large Magellanic Cloud. Ultraviolet spectra of both stars were obtained with the Hubble Space Telescope Cosmic Origins Spectrograph. The spectrum of VFTS 285 displays a fast outflow in N V and a much slower wind in Si IV, and we argue that there is a two-wind regime in which mass loss is strong at the poles (fast and tenuous wind) but dominant at the equator (slow and dense winds). These ions and wind lines are not present in the spectrum of the cooler star VFTS 102, but the double-peaked H$\alpha$ emission in its spectrum implies equatorial mass loss into a circumstellar disk. The results suggest that in the fastest rotating O-stars, most mass is lost as an equatorial outflow, promoting angular momentum loss that contributes to a spin down over time.

arXiv commentAccepted for publication in ApJ. 17 pages, 5 figures

References in corpus (40)

• X-shooter, the new wide band intermediate resolution spectrograph at the ESO Very Large Telescope
• The Fourth US Naval Observatory CCD Astrograph Catalog (UCAC4)
• Mass loss from hot massive stars
• Classical Be Stars: Rapidly Rotating B Stars with Viscous Keplerian Decretion Disks
• The VLT-FLAMES Tarantula Survey VIII. Multiplicity properties of the O-type star population
• The Cosmic Origins Spectrograph
• The Magellanic Clouds Photometric Survey: The Large Magellanic Cloud Stellar Catalog and Extinction Map
• The incidence of stellar mergers and mass gainers among massive stars
• A UBVR CCD Survey of the Magellanic Clouds
• The VLT-FLAMES Tarantula Survey I: Introduction and observational overview
• Gravity darkening in rotating stars
• The R136 star cluster dissected with Hubble Space Telescope/STIS. I. Far-ultraviolet spectroscopic census and the origin of HeII 1640 in young star clusters
• The VLT-FLAMES Tarantula Survey XII. Rotational velocities of the single O-type stars
• The MiMeS survey of magnetism in massive stars: Magnetic analysis of the O-type stars
• Spitzer SAGE Infrared Photometry of Massive Stars in the Large Magellanic Cloud
• HST/COS Observations of the Ly alpha Forest toward the BL Lac Object 1ES1553+113
• The Progenitor Masses of Wolf-Rayet Stars and Luminous Blue Variables Determined from Cluster Turn-offs. I. Results from 19 OB Associations in the Magellanic Clouds
• A Reanalysis of theUltraviolet Extinction from Interstellar Dust in the Large Magellanic Cloud
• The VLT-FLAMES Tarantula Survey XIV. The O-Type Stellar Content of 30 Doradus
• Direct measurement of the size and shape of the present-day stellar wind of Eta Carinae
• Estimating Be Star Disk Radii using H-alpha Emission Equivalent Widths
• The Physical Properties and Effective Temperature Scale of O-type Stars as a Function of Metallicity. III. More Results from the Magellanic Clouds
• Constraints on the Ionization Balance of Hot-Star Winds from FUSE Observations of O Stars in the Large Magellanic Cloud
• The VLT-FLAMES Tarantula Survey XVIII. Classifications and radial velocities of the B-type stars
• A Modern Search for Wolf-Rayet Stars in the Magellanic Clouds. IV. A Final Census
• The VLT-FLAMES Tarantula Survey: The fastest rotating O-type star and shortest period LMC pulsar - remnants of a supernova disrupted binary?
• Rotating massive O stars with non-spherical 2D winds
• On the class of Oe stars
• The VLT-FLAMES Tarantula Survey XXVI: Properties of the O-dwarf population in 30 Doradus
• Line-driven ablation of circumstellar disks: I. Optically thin decretion disks of classical Oe/Be stars
• The Onfp Class in the Magellanic Clouds
• A spectroscopic investigation of the O-type star population in four Cygnus OB associations. I. Determination of the binary fraction
• Clues on the Origin and Evolution of Massive Contact Binaries: Atmosphere Analysis of VFTS 352
• Critical angular velocity and anisotropic mass loss of rotating stars with radiation-driven winds
• Evolution of rotation in rapidly rotating early-type stars during the main sequence with 2D models
• 3D radiative transfer: Continuum and line scattering in non-spherical winds from OB stars
• A Nozzle Analysis of Slow-Acceleration Solutions in One-Dimensional Models of Rotating Hot-Star Winds
• Optical spectroscopy of the blue supergiant Sk-69 279 and its circumstellar shell with SALT
• Radial Velocities of Six OB Stars
• The binary merger channel for the progenitor of the fastest rotating O-type star VFTS102

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