标题： 天鹅座X-3和消失的沃尔夫-拉耶X射线双星问题 显示英文标题

标题： Cygnus X-3 and the problem of the missing Wolf-Rayet X-ray binaries

摘要： 天鹅座X-3 是一个强X射线源（\(L_X\) 约为 \(10^\{38\}\) 尔格/秒），被认为由一个致密天体和从氦星吸积物质组成。 我们通过分析得出，对于天鹅座X-3的质量损失率和轨道周期导数的估计范围与两种模型一致：i）该系统是分离的，系统的质量损失来源于高光度氦星的恒星风，其中只有允许观测到的X射线亮度的部分被吸积；ii）该系统是半分离的，罗氏瓣溢出的低至中等质量氦供体将物质转移给致密天体，随后系统的超爱丁顿速率过量物质被抛射。 这些分析结果似乎与演化计算一致。 通过种群综合研究，我们发现银河系中可能存在约1个从质量大于～7倍太阳质量的沃尔夫-拉叶星吸积黑洞的X射线双星系统，以及约1个从罗氏瓣溢出的氦星（质量小于～1.5倍太阳质量）吸积中子星的X射线双星系统。 天鹅座X-3 可能是其中之一。 显示英文摘要

摘要： Cygnus X-3 is a strong X-ray source (L_X about 10^38 erg/s) which is thought to consist of a compact object, accreting matter from a helium star. We find analytically that the estimated ranges of mass-loss rate and orbital-period derivative for Cyg X-3 are consistent with two models: i) the system is detached and the mass loss from the system comes from the stellar wind of a massive helium star, of which only a fraction that allows for the observed X-ray luminosity is accreted, or ii) the system is semidetached and a Roche-lobe-overflowing low- or moderate-mass helium donor transfers mass to the compact object, followed by ejection of its excess over the Eddington rate from the system. These analytical results appear to be consistent with evolutionary calculations. By means of population synthesis we find that currently in the Galaxy there may exist ~1 X-ray binary with a black hole that accretes from a >~ 7 MSun Wolf-Rayet star and ~1 X-ray binary in which a neutron star accretes matter from a Roche-lobe-overflowing helium star with mass <~ 1.5 MSun. Cyg X-3 is probably one of these systems.