AI 中文总结
研究超软X射线源WX Cen快速轨道衰减问题，提出由双星与环绕双星盘共振相互作用产生的潮汐扭矩导致，通过恒星演化模型表明带特定质量环绕双星盘的WD双星可演化成类似WX Cen的系统并触发氢燃烧。
AI 中文摘要
WX Cen很可能是致密双星超软X射线源的候选者，由白矮星（WD）和充满洛希瓣的供体恒星组成。最近检测到该源正以\(\dot{P} =-(4.4\pm0.4)\times10^{-7}~ \rm days~\rm{yr}^{-1}\)的速率快速轨道衰减。通过质量函数和光学食可约束供体恒星质量。观测到的轨道周期导数无法由WD吸积时的质量损失、磁制动机制等产生。我们提出WX Cen的快速轨道衰减是由双星与环绕双星盘的共振相互作用产生的潮汐扭矩引起的。详细的恒星演化模型表明，一个带有\(2.5 \times 10^{-7}~M_{\odot}\)环绕双星盘的WD双星可演化为类似WX Cen的系统，其轨道周期导数为\(\dot{P}=-4.0\times10^{-7}~ \rm days~\rm{yr}^{-1}\)，且有较高的质量转移率可触发WD表面稳定的氢燃烧过程。
英文摘要
WX Cen is most likely a candidate of compact binary supersoft X-ray sources, which consists of a white dwarf (WD) and a donor star that fills the Roche lobe. Recently, this source was detected to be experiencing a rapid orbital decay at a rate of $\dot{P} =-(4.4\pm0.4)\times10^{-7}~ \rm days~\rm{yr}^{-1}$. According to the mass function and optical eclipses, the donor-star mass can be constrained to be $0.41-0.44$, $0.47-0.50$, and $0.55-0.59~M_\odot$ when the WD mass is $0.7$, $0.9$, and $1.2~M_\odot$, respectively. The observed orbital period derivative cannot be produced by the angular momentum loss due to mass loss during the accretion of the WD, magnetic braking (MB) mechanisms, including standard MB, convection and rotation-enhanced MB, and anomalous MB prescriptions. We propose that the rapid orbital decay of WX Cen is caused by the tidal torque that originates from the resonant interaction between the binary and a surrounding circumbinary (CB) disk. Detailed stellar evolution models indicate that a WD binary with a $2.5 \times 10^{-7}~M_{\odot}$ CB disk can evolve toward a WX Cen-like system, which has an orbital period derivative of $\dot{P}=-4.0\times10^{-7}~ \rm days~\rm{yr}^{-1}$ and a relatively high mass-transfer rate of $5.3\times10^{-7}~M_\odot\rm yr^{-1}$ that can trigger a stable hydrogen burning process on the surface of the WD.
Comments11 pages, 7 figures, 1 table. ApJ in press
