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Paper: The Formation, Evolution and Parameters of Short-period Low-mass X-ray Binaries and Black-hole Components
Volume: 404, The Eighth Pacific Rim Conference on Stellar Astrophysics: A Tribute to Kam Ching Leung
Page: 171
Authors: Yungelson, L.R.; Lasota, J.P.
Abstract: We discuss the formation, evolution and observational parameters of the population of short-period (<~10 hr) low-mass black-hole binaries (LMBHB). Their evolution is determined by the orbital angular momentum loss and/or nuclear evolution of the donors. All observed semidetached LMBHB are observed as soft X-ray transients (SXTs). The absence of observed short-period stable luminous X-ray sources with black holes and low-mass optical components suggests that upon RLOF by the donor, the angular-momentum losses are substantially reduced. The model with reduced angular-momentum loss reasonably well reproduces the masses and effective temperatures of the observed secondaries of SXTs. Theoretical mass-transfer rates in SXTs are consistent with those deduced from observations only if the accretion discs in LMBHB are truncated. The population of short-period LMBHB is formed mainly by systems which at RLOF had unevolved or slightly evolved donors (abundance of hydrogen in the center Xc >~ 0.35). Our models suggest that a very high efficiency of common envelopes ejection is necessary to form LMBHB.
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