Precise Age for the Binary Star System 12 Com in the Coma Berenices Cluster
Precise Age for the Binary Star System 12 Com in the Coma Berenices Cluster
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DOI：
10.3847/1538-3881/accddb
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发表时间：
2023-04
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通讯作者：
Rex K Lam;E. Sandquist;G. Schaefer;C. Farrington;J. Monnier;N. Anugu;C. Lanthermann;R. Klement;J. Ennis;B. Setterholm;T. Gardner;S. Kraus;C. Davies;J. Orosz
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作者：
Rex K Lam;E. Sandquist;G. Schaefer;C. Farrington;J. Monnier;N. Anugu;C. Lanthermann;R. Klement;J. Ennis;B. Setterholm;T. Gardner;S. Kraus;C. Davies;J. Orosz
我们目前的测量干涉分辨双星系统12 Com和单巨星星星31 Com的后发座星系团的星星。12 Com是一个双线分光双星系统，由一颗G7巨星和一颗A3矮星组成。利用帕洛玛试验台干涉仪和高角分辨率天文学中心阵列的大量径向速度数据集和干涉测量，我们测量了质量M1 = 2.64 ± 0.07 M <$和M2 = 2.10 ± 0.03 M <$。干涉测量还使我们能够解析这颗巨星并测量其大小为R1 = 9.12 ± 0.12 ± 0.01R ⊙。根据测量的质量和半径，我们发现年龄为5.33 ± 4.1 ± 4.2亿年。为了比较，我们测量31 Com的半径为8.36 ± 0.15 R。根据光度测量和半径测量，12 Com A可能是星团中演化最明亮的星星，大到足以进入红巨星阶段，但太小了，核心氦燃烧。同时知识12 Com A的质量和光度学提出了强有力的约束对流核心过冲在主序阶段，这反过来又减少了系统的不确定性的年龄。测量该系统的精度提高也提高了我们对星团白色矮星WD 1216 +260的祖先的了解。
We present measurements of the interferometrically resolved binary star system 12 Com and the single giant star 31 Com in the cluster Coma Berenices. 12 Com is a double-lined spectroscopic binary system consisting of a G7 giant and an A3 dwarf at the cluster turnoff. Using an extensive radial velocity data set and interferometric measurements from the Palomar Testbed Interferometer and the Center for High Angular Resolution Astronomy array, we measured masses M 1 = 2.64 ± 0.07M ⊙ and M 2 = 2.10 ± 0.03M ⊙. Interferometry also allows us to resolve the giant and measure its size as R 1 = 9.12 ± 0.12 ± 0.01R ⊙. With the measured masses and radii, we find an age of 533 ± 41 ± 42 Myr. For comparison, we measure the radius of 31 Com to be 8.36 ± 0.15 R ⊙. Based on the photometry and radius measurements, 12 Com A is likely the most evolved bright star in the cluster, large enough to be in the red giant phase, but too small to have core helium burning. Simultaneous knowledge of 12 Com A’s mass and photometry puts strong constraints on convective core overshooting during the main-sequence phase, which in turn reduces systematic uncertainties in the age. Increased precision in measuring this system also improves our knowledge of the progenitor of the cluster white dwarf WD1216+260.