An eclipsing M-dwarf close to the hydrogen burning limit from NGTS
An eclipsing M-dwarf close to the hydrogen burning limit from NGTS
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DOI：
10.1093/mnras/staa2513
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发表时间：
2020-08
影响因子：
4.8
通讯作者：
J. Acton;M. Goad;S. Casewell;J. Vines;M. Burleigh;P. Eigmüller;L. Nielsen;B. Gänsicke;D. Bayl
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作者：
J. Acton;M. Goad;S. Casewell;J. Vines;M. Burleigh;P. Eigmüller;L. Nielsen;B. Gänsicke;D. Bayl
我们发现了NGTS J0930−18，这是一个质量比极高的M-矮星双星系统，具有早期的M-矮星初级星系和晚期的接近氢燃烧极限的M-矮星次级星系。测光和径向速度的全球模拟表明，二次分量(NGTS J0930−18 B)的质量为M*=$0.0818^0.0040}-0.0015}$M⊙，半径R*=$0.1059^{+0.0023}_-0.0021}$R⊙，是直接测量质量和半径的最小质量恒星之一。NGTSJ0930−18的质量比Q=$0.1407^+0.0065}-0.017}$，是已知的食M矮星双星系统中质量比最低的，这给双星的形成和演化模型提出了有趣的问题。NGTSJ0930−18B的质量和半径与恒星演化模型基本一致。NGTJ0930−18B位于星下边界附近稀疏分布的质量半径参数空间。这种类型的单线食双星系统的质量和半径的精确测量对于限制质量-半径关系的不确定性至关重要-由于在低质量恒星周围发现了越来越多的类地行星，这一关系具有重要意义。
We present the discovery of NGTS J0930−18, an extreme mass ratio eclipsing M-dwarf binary system with an early M-dwarf primary and a late M-dwarf secondary close to the hydrogen burning limit. Global modelling of photometry and radial velocities reveals that the secondary component (NGTS J0930−18 B) has a mass of M* = $0.0818 ^{+0.0040}_{-0.0015}$ M⊙ and radius of R* = $0.1059 ^{+0.0023}_{-0.0021}$ R⊙, making it one of the lowest mass stars with direct mass and radius measurements. With a mass ratio of q = $0.1407 ^{+0.0065}_{-0.017}$, NGTS J0930−18 has the lowest mass ratio of any known eclipsing M-dwarf binary system, posing interesting questions for binary star formation and evolution models. The mass and radius of NGTS J0930−18 B is broadly consistent with stellar evolutionary models. NGTS J0930−18 B lies in the sparsely populated mass radius parameter space close to the substellar boundary. Precise measurements of masses and radii from single lined eclipsing binary systems of this type are vital for constraining the uncertainty in the mass–radius relationship – of importance due to the growing number of terrestrial planets being discovered around low-mass stars.