Time resolved spectroscopy of luminous sdOs - searching for their massive compact companions

光谱类型为O的发光热亚矮星是失去大部分氢包层的主序星的残余。这些恒星的形成尚不清楚。最近，两个最明亮的sdO被发现是X射线双星，它们有着像白色矮星或中子星这样的大质量致密伴星。虽然这种sdO恒星已经被发现了几十年，但还没有系统地寻找过它的近伴星。我们被授予七个晚上在麦克唐纳天文台采取高分辨率，时间分辨光谱的8个明亮的sdO与SES摄谱仪安装在2.1米望远镜。我们的目标是测量径向速度变化所造成的看不见的，密切的同伴，并得出这样的双星的轨道解决方案。看不见的同伴的性质可以通过这种方式受到限制。

Luminous hot subdwarf stars of spectral type O are the remnants of main sequence stars that lost most of their hydrogen envelopes. The formation of these stars is unclear. Recently, two of the brighest sdOs have been discovered to be X-ray binaries with massive compact companion like white dwarfs or neutron stars. Although this kind of sdO stars is known for decades, no systematic search for close companions has been conducted. We were granted seven nights at McDonald observatory to take high resolution, time resolved spectroscopy of 8 bright sdOs with the SES spectrograph mounted at the 2.1m telescope. Our goal is to measure radial velocity shifts caused by unseen, close companions and derive the orbital solutions of such binaries. The nature of the unseen companions can be constrained in this way.