论文标题
六个原型HMXB的恒星和风参数及其进化状态
The stellar and wind parameters of six prototypical HMXBs and their evolutionary status
论文作者
论文摘要
高质量X射线二进制文件(HMXB)是杰出的天体实验室,可以罕见地瞥见物理过程,这些过程控制着紧凑型物体,大型星形风和恒星进化。在HMXB的子集中,紧凑的物体仅来自大型供体星的风。这些所谓的风馈HMXB根据其X射线属性持续的HMXB和超级快速X射线瞬变(SFXT)。尽管已经提出这种二分法取决于恒星风的特征,但对它们的研究很差。通过这项研究,我们的目标是通过系统地分析紫外线中可观察到的风馈HMXB的供体星来纠正这种情况,并集中于中子星(NS)伴侣的人。我们为所有目标获得了Swift X射线数据,HST紫外光谱和其他光谱。我们的多波长方法使我们能够为六个供体星(四个风馈系统和两个OBE X射线二进制文件)提供恒星和风参数。风能与线驱动风理论的预测一致。三个供体星处于晚期进化阶段,而对于某些恒星,丰度模式表明可能已经积聚了加工的材料。当通过NS在其紧密轨道上经过NS时,供体星风还没有达到其末端速度,但仍然较慢。它的速度与NS伴侣的轨道速度相当。相对于供体星,两种类型的风馈HMXB(持久性与瞬态)之间没有系统的差异。对于我们样品中的SFXT,轨道偏心率对它们的瞬态X射线性质是决定性的。基于轨道参数和供体恒星的进一步演变,研究的HMXB可能会在将来形成索恩 - Ytkow对象。
High-mass X-ray binaries (HMXBs) are exceptional astrophysical laboratories that offer a rare glimpse into the physical processes that govern accretion on compact objects, massive-star winds, and stellar evolution. In a subset of the HMXBs, the compact objects accrete matter solely from winds of massive donor stars. These so-called wind-fed HMXBs are divided in persistent HMXBs and supergiant fast X-ray transients (SFXTs) according to their X-ray properties. While it has been suggested that this dichotomy depends on the characteristics of stellar winds, they have been poorly studied. With this investigation, we aim to remedy this situation by systematically analyzing donor stars of wind-fed HMXBs that are observable in the UV, concentrating on those with neutron star (NS) companions. We obtained Swift X-ray data, HST UV spectra, and additional optical spectra for all our targets. Our multi-wavelength approach allows us to provide stellar and wind parameters for six donor stars (four wind-fed systems and two OBe X-ray binaries). The wind properties are in line with the predictions of the line-driven wind theory. Three of the donor stars are in an advanced evolutionary stage, while for some of the stars, the abundance pattern indicates that processed material might have been accreted. When passing by the NS in its tight orbit, the donor star wind has not yet reached its terminal velocity but it is still significantly slower; its speed is comparable with the orbital velocity of the NS companion. There are no systematic differences between the two types of wind-fed HMXBs (persistent versus transients) with respect to the donor stars. For the SFXTs in our sample, the orbital eccentricity is decisive for their transient X-ray nature. Based on the orbital parameters and the further evolution of the donor stars, the investigated HMXBs will presumably form Thorne-Żytkow objects in the future.