2M17091769+3127589: A Mass-transfer Binary with an Extreme Mass Ratio
2M17091769+3127589: A Mass-transfer Binary with an Extreme Mass Ratio
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DOI：
10.3847/1538-3881/ac1788
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发表时间：
2021-07
期刊：
影响因子：
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通讯作者：
A. Miller;M. Kounkel;M. Sun 孙;Don M. Dixon;Chase Boggio;K. Covey;K. Stassun;R. Mathieu
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文献类型：
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作者：
A. Miller;M. Kounkel;M. Sun 孙;Don M. Dixon;Chase Boggio;K. Covey;K. Stassun;R. Mathieu
我们提出了一个奇特的双线光谱食双星系统2M17091769+3127589的轨道解。该解决方案是通过同时拟合 APOGEE 径向速度和 TESS 和 ASAS-SN 光变曲线来确定质量和半径而获得的。该系统由一颗 M=0.256−0.006+0.010 M ⊙, R=3.961−0.032+0.049 R ⊙ 红巨星和一颗更热的 M=1.518−0.031+0.057 M ⊙, R=2.608−0.321+0.034 R ⊙ 亚巨星组成。使用 MESA 演化代码进行的建模表明，该系统可能形成于 5.26 吉尔前，其中 M = 1.2 M ⊙ 主恒星现在是该系统的红巨星，M = 1.11 M ⊙ 次恒星现在是质量更大的亚巨星。由于主星上升红巨星分支时的洛希瓣溢出，进化程度较高的“主星”（即最初是这对恒星中质量较大的恒星）现在的质量仅为“副星”的六分之一。初始质量比和当前质量比之间的这种差异是迄今为止检测到的最极端的差异之一。进化模型表明该系统仍在以Ṁ∼10−9 M ⊙/年的速度进行质量转移，并且它为一些由白矮星和蓝离散星组成的系统提供了一个进化程度较低的前身的例子。
We present the orbital solution of a peculiar double-lined spectroscopic and eclipsing binary system, 2M17091769+3127589. This solution was obtained by a simultaneous fit of both APOGEE radial velocities and TESS and ASAS-SN light curves to determine masses and radii. This system consists of an M=0.256−0.006+0.010 M ⊙, R=3.961−0.032+0.049 R ⊙ red giant and a hotter M=1.518−0.031+0.057 M ⊙, R=2.608−0.321+0.034 R ⊙ subgiant. Modeling with the MESA evolutionary codes indicates that the system likely formed 5.26 Gyrs ago, with a M = 1.2 M ⊙ primary that is now the system’s red giant and a M = 1.11 M ⊙ secondary that is now a more massive subgiant. Due to Roche-lobe overflow as the primary ascends the red giant branch, the more evolved “primary” (i.e., originally the more massive star of the pair) is now only one sixth as massive as the “secondary.” Such a difference between the initial and the current mass ratio is one of the most extreme detected so far. Evolutionary modeling suggests the system is still engaged in mass transfer, at a rate of Ṁ∼10−9 M ⊙/yr, and it provides an example of a less evolved precursor to some of the systems that consist of white dwarfs and blue stragglers.