Department of Astronomy, The Ohio State University, 140 W. 18th Ave., Columbus, OH 43210, USA.
Center for Cosmology and AstroParticle Physics, The Ohio State University, 191 W. Woodruff Ave., Columbus, OH 43210, USA.
Science. 2019 Nov 1;366(6465):637-640. doi: 10.1126/science.aau4005.
Black hole binary systems with companion stars are typically found via their x-ray emission, generated by interaction and accretion. Noninteracting binaries are expected to be plentiful in the Galaxy but must be observed using other methods. We combine radial velocity and photometric variability data to show that the bright, rapidly rotating giant star 2MASS J05215658+4359220 is in a binary system with a massive unseen companion. The system has an orbital period of ~83 days and near-zero eccentricity. The photometric variability period of the giant is consistent with the orbital period, indicating star spots and tidal synchronization. Constraints on the giant's mass and radius imply that the unseen companion is [Formula: see text] solar masses, indicating that it is a noninteracting low-mass black hole or an unexpectedly massive neutron star.
带有伴星的黑洞双星系统通常通过其 X 射线发射来发现，这些发射是由相互作用和吸积产生的。非相互作用的双星预计在银河系中很丰富，但必须通过其他方法来观测。我们结合径向速度和光度变化数据，表明明亮、快速旋转的巨星 2MASS J05215658+4359220 处于一个双星系统中，伴星是一个看不见的大质量物体。该系统的轨道周期约为 83 天，近于零的偏心率。巨星的光度变化周期与轨道周期一致，表明存在星斑和潮汐同步。对巨星质量和半径的限制表明，看不见的伴星质量约为[公式：见文本]个太阳质量，这表明它是一个非相互作用的低质量黑洞或一个出乎意料的大质量中子星。
