Spectroscopy and Photometry of Black Hole Binary Stars

软X射线瞬变是一种短周期的X射线双星，其中一颗致密恒星--中子星或黑洞--正在从相对正常的伴星中剥离物质。剥离的物质螺旋向下到达致密恒星，释放出引力势能，形成一个热吸积盘。正是这个过热的吸积盘才是X射线发射源。这样的X射线爆发可能会持续几个月，并可以达到超乎寻常的光度，是太阳光度的10万倍。爆炸是由流经圆盘的质量流量增加引起的。爆发之间的X射线光度很低，因此静止的双星系统不会受到强X射线照射的失真，从而能够可靠地测量系统性质。短周期X射线双星中黑洞的比例很高，它们的吸积流可变，爆发之间的X射线光度很低，这使它们成为研究黑洞和黑洞吸积的极佳实验室。虽然它们通常是在X射线波长上发现的，但要解开它们的性质，需要在光学和X射线波长上进行观察。然而，已知的双星在静止时在光学波长下都是微弱的，因此，揭示它们的秘密的速度很慢。该项目将测量X射线双星黑洞的动力学质量，通过发射线的多普勒层析成像测量吸积盘和其他吸积流的结构和演化，并将利用麦克唐纳天文台8米Hobby-Eberly望远镜的排队操作模式来获得任何进入爆发的北X射线瞬变的光学光谱能量分布的天气测量，首次绘制出它们的全面爆发行为图。

AST-0206029PI RobinsonThe Soft X-Ray Transients are short-period, X-ray binary stars in which a compact star - either a neutron star or a black hole - is stripping matter from a relatively-normal companion star. The stripped matter spirals down to the compact star, releasing gravitational potential energy and forming a hot accretion disk. It is this superheated accretion disk that is the source of the X-ray emission. Such bursts of X-ray emission may last a few months and can reach extraordinary luminosities, 100,000 times the sun's luminosity. The bursts are caused by an increase in the flow of mass through the disk. The X-ray luminosity between outbursts is low, so the quiescent binary system is undistorted by strong X-ray irradiation, allowing reliable measurements of system properties. The high proportion of black holes among the short-period X-ray binaries, their variable accretion flows, and their low X-ray luminosity between outbursts make them superb laboratories for studying black holes and black hole accretion. Although they are generally discovered at X-raywavelengths, disentangling their properties requires observations at optical as well as X-ray wavelengths. The known binaries are, however, all faint at optical wavelengths during quiescence and, thus, have been slow to yield their secrets. This project will measure the dynamical masses of the x-ray binary black holes, measure the structure and evolution of the accretion disk and other accretion flows by Doppler Tomography of the emission lines, and will take advantage of the queue-scheduled operating mode of the 8-meter Hobby-Eberly Telescope of McDonald Observatory to obtain synoptic measurements of the optical spectral energy distribution of any northern x-ray transient that goes into outburst, mapping their full outburst behavior for the first time.