The Temperature Structure of Be Star Disks in the Small Magellanic Cloud

Abstract

The temperature structure of Be star circumstellar disks at the sub-solar metallicity appropriate to the Small Magellanic Cloud (SMC) is investigated. It is found that for central stars of the same spectral type, Be star disks in the SMC are systematically hotter by several thousand degrees compared to Milky Way (MW) disks with the same density structure. For early spectral types (B0e - B3e), this results in systematically smaller Hα equivalent widths for Be stars in the SMC. The implication of this result on Be star frequency comparisons between MW and SMC clusters is shown to be a 5 - 10% lowering of the detection efficiency of Be stars in SMC clusters. These calculations are also compared to the known Hα equivalent width distributions in the MW and SMC. For the MW, reasonable agreement is found; however, for the SMC, the match is not as good and systematically larger Be star disks may be required.

arXiv comment31 pages, 10 figures, Accepted for publication in the astrophysical Journal

References in corpus (34)

• Mass-loss predictions for O and B stars as a function of metallicity
• A Grid of NLTE Line-Blanketed Model Atmospheres of Early B-type Stars
• Stellar evolution with rotation VII: Low metallicity models and the blue to red supergiant ratio in the SMC
• Be-star rotation: how close to critical?
• The empirical metallicity dependence of the mass-loss rate of O- and early B-type stars
• Effects of gravitational darkening on the determination of fundamental parameters in fast rotating B-type stars
• 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
• Evolution towards the critical limit and the origin of Be stars
• The VLT-FLAMES survey of massive stars: Evolution of surface N abundances and effective temperature scales in the Galaxy and Magellanic Clouds
• The VLT-FLAMES survey of massive stars: Surface chemical compositions of B-type stars in the Magellanic Clouds
• The VLT-FLAMES Survey of Massive Stars: Observations in the Galactic Clusters NGC 3293, NGC 4755 and NGC 6611
• The VLT-FLAMES survey of massive stars: atmospheric parameters and rotational velocity distributions for B-type stars in the Magellanic Clouds
• A Statistical Study of Threshold Rotation Rates for the Formation of Disks around Be Stars
• Effects of metallicity, star-formation conditions, and evolution in B and Be stars. II: Small Magellanic Cloud, field of NGC 330
• The Thermal Structure of the Circumstellar Disk Surrounding the Classical Be Star gamma Cassiopeia
• Mass and angular momentum loss via decretion disks
• CHARA Array K'-band Measurements of the Angular Dimensions of Be Star Disks
• 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
• Effects of metallicity, star formation conditions and evolution in B and Be stars. I: Large Magellanic Cloud, field of NGC 2004
• Be stars in and around young clusters in the Magellanic Clouds
• Be stars and binaries in the field of the SMC open cluster NGC330 with VLT-FLAMES
• Be phenomenon in open clusters: Results from a survey of emission-line stars in young open clusters
• Properties of the H-alpha-emitting Circumstellar Regions of Be Stars
• Constraining the Physical Parameters of the Circumstellar Disk of chi Ophiuchi
• A slitless spectroscopic survey for Halpha emission-line objects in SMC clusters
• A Pulsational Mechanism for Producing Keplerian Disks around Be Stars
• Be Star Disk Models in Consistent Vertical Hydrostatic Equilibrium
• Effects of Metallicity on the Rotation Rates of Massive Stars
• A Parameter Study of Classical Be Star Disk Models Constrained by Optical Interferometry
• VLTI/MIDI observations of 7 classical Be stars
• A non-LTE analysis of the spectra of two narrow lined main sequence stars in the SMC
• The Thermal Structure of Gravitationally-Darkened Classical Be Star Disks
• A Photometric Technique to Search for Be Stars in Open Clusters
• Sub-milliarcsecond precision spectro-astrometry of Be stars

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• Rotational Mixing in Be Stars: Nitrogen Abundances for a Sample of Be Stars from the MiMeS Survey
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• On the Intrinsic Continuum Linear Polarization of Classical Be Stars: The Effects of Metallicity and One-Armed Density Perturbations