On the formation of Be stars through binary interaction

Abstract

Be stars are rapidly rotating B type stars. The origin of their rapid rotation is not certain, but binary interaction remains to be a possibility. In this work we investigate the formation of Be stars resulting from mass transfer in binaries in the Galaxy. We calculate the binary evolution with both stars evolving simultaneously and consider different possible mass accretion histories for the accretor. From the calculated results we obtain the critical mass ratios $q_{\mathrm{cr}}$ that determine the stability of mass transfer. We also numerically calculate the parameter $\lambda$ in common envelope evolution, and then incorporate both $q_{\mathrm{cr}}$ and $\lambda$ into the population synthesis calculations. We present the predicted numbers and characteristics of Be stars in binary systems with different types of companions, including helium stars, white dwarfs, neutron stars, and black holes. We find that in Be/neutron star binaries the Be stars can have a lower limit of mass $\sim 8M_{\odot }$ if they are formed by stable (i.e., without the occurrence of common envelope evolution) and nonconservative mass transfer. We demonstrate that isolated Be stars may originate from both mergers of two main-sequence stars and disrupted Be binaries during the supernova explosions of the primary stars, but mergers seem to play a much more important role. Finally the fraction of Be stars which have involved binary interactions in all B type stars can be as high as $\sim 13$, implying that most of Be stars may result from binary interaction.

38 pages, 14 figures, 1 table, accepted for publication in ApJ

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Cited by in corpus (38)

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• Population Synthesis of Black Hole Binaries with Normal-Star Companions: I. Detached Systems
• A Population of Ultraluminous X-ray Sources with An Accreting Neutron Star
• Electron Capture Supernovae From Close Binary Systems
• The Single Star Path to Be Stars
• Combined analysis of neutron star natal kicks using proper motions and parallax measurements for radio pulsars and Be X-ray binaries
• Population Synthesis of Black Hole X-Ray Binaries
• Population Synthesis of Galactic Be-star Binaries with A Helium-star Companion
• The orbital and physical properties of five southern Be+sdO binary systems
• Nonconservative Mass Transfer in Massive Binaries and the Formation of Wolf-Rayet+O Binaries
• Discovery of Rapidly Moving Partial X-ray Absorbers within gamma Cassiopeiae
• Interferometric detections of sdO companions orbiting three classical Be stars
• Dynamical masses of the primary Be star and the secondary sdB star in the single-lined binary kappa Dra (B6 IIIe)
• The X-ray emission of Be+stripped star binaries
• Stable mass transfer can explain massive binary black hole mergers with a high spin component
• The IACOB project VIII. Searching for empirical signatures of binarity in fast-rotating O-type stars
• Is there a propeller neutron star in $\gamma$ Cas?
• On the Neutron Star/Black Hole Mass Gap and Black Hole Searches
• Formation and Destiny of White Dwarf and Be Star Binaries
• Classical OBe Stars as Post-Supernova Runaways: Confirming Binary Origins
• $\nu$ Gem: a hierarchical triple system with an outer Be star
• Centrifugally Driven Mass Loss and Outbursts of Massive Stars
• A Population of Neutron Star Ultraluminous X-ray Sources with A Helium Star Companion
• Properties of the Be-type stars in 30 Doradus
• Constraining the overcontact phase in massive binary evolution -- II. Period stability of known O+O overcontact systems
• The spins of stripped B stars support magnetic internal angular momentum transport
• Effects of the core-collapse supernova ejecta impact on a rapidly rotating massive companion star
• Mass-stream trajectories with non-synchronously rotating donors
• The spin-up of a star gaining mass in a close binary system on the thermal time scale
• On the Formation of SS433
• Population Synthesis of Black Hole Binaries with Compact Star Companions
• GG Carinae: orbital parameters and accretion indicators from phase-resolved spectroscopy and photometry
• Study of a Sample of Faint Be Stars in the Exofield of CoRoT. Part III. Global Spectroscopic Characterization and Astrophysical Parameters of the Central Stars
• A stringent upper limit on Be star fractions produced by binary interaction
• Population synthesis of neutron star X-ray binaries associated with supernova remnants