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

光谱型为O的发光热亚矮星是失去了大部分氢包层的主序星的残余物。这些恒星的形成尚不清楚。最近，两个最亮的sdo被发现是x射线双星，它们有像白矮星或中子星这样的大质量致密伴星。虽然这种类型的sdO恒星已经被发现了几十年，但还没有对其近距离的伴星进行系统的搜索。利用安装在2.1m望远镜上的SES光谱仪，我们在麦克唐纳天文台获得了7个晚上对8个明亮sdo进行高分辨率、时间分辨光谱的观测。我们的目标是测量由看不见的近距离伴星引起的径向速度变化，并推导出这种双星的轨道解。看不见的同伴的本性可以通过这种方式受到约束。

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.