AI 中文总结
研究在银河系中心发现对人马座A*自旋敏感的暗主序星S301，其轨道周期8.7年，近日点距离小，峰值速度高，运动对自旋直接敏感，高偏心率显示它是被俘获成分，为相关研究提供新对象。
AI 中文摘要
位于银河系中心的人马座A*是距离最近的大质量黑洞。其附近区域使得能够测量围绕它的单个恒星轨道。恒星充当测试粒子，探测这个430万个太阳质量黑洞周围的引力势。这些观测已将中心质量精确到亚百分比精度，恒星的轻度相对论运动揭示了主要的相对论修正、引力红移、横向多普勒效应以及由该势的史瓦西度规性质引起的顺行进动。这些效应为β²量级。旋转黑洞的克尔度规会导致β³量级的修正。本文报告发现一颗暗主序星（m_K = 19.3）S301，其轨道周期为8.年，近日点距离足够小，峰值速度达25000千米/秒。在当前近红外干涉测量和未来极大望远镜光谱测量能力范围内，S301的运动对人马座A*的自旋直接敏感。S301的高偏心率表明它是通过希尔斯机制被撕裂的双星的被俘获成分。
英文摘要
Residing in the center of the Milky Way, Sgr A* is the closest massive black hole (MBH). Its vicinity has allowed measuring individual stellar orbits around it. The stars act as test particles and probe the gravitational potential around the $4.3 \times 10^6 M_\odot$ MBH. These observations have determined the central mass to sub-percent precision, and the mildly relativistic motions of stars have given access to the dominant relativistic corrections, the gravitational redshift, the transverse Doppler effect, and the prograde precession imposed by the Schwarzschild metric nature of the potential. These effects are of order $β^2 = (v/c)^2$ (for velocity $v$ and speed of light $c$). The Kerr metric for a rotating black hole leads to corrections of order $β^3$. Here, we report the discovery of a faint main-sequence star ($m_K = 19.3$), S301, on a 8.7-year orbit and with small enough a pericenter distance, such that the star's peak velocity reaches $25000\,$km/s. Within the measurement capabilities of current near-infrared interferometry and future spectroscopy on an extremely large telescope, S301's motion is directly sensitive to the spin of Sgr A*. The high eccentricity of S301 suggests that it is the captured component of a binary that was torn apart via the Hills mechanism.
Commentsaccepted for publication in Nature
