PSR J1641+3627F: A Low-mass He White Dwarf Orbiting a Possible High-mass Neutron Star in the Globular Cluster M13
PSR J1641+3627F: A Low-mass He White Dwarf Orbiting a Possible High-mass Neutron Star in the Globular Cluster M13
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DOI：
10.3847/1538-4357/abc345
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发表时间：
2020-10
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影响因子：
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通讯作者：
M. Cadelano;Jianxing Chen;C. Pallanca;A. Istrate;F. Ferraro;B. Lanzoni;P. Freire;M. Salaris
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作者：
M. Cadelano;Jianxing Chen;C. Pallanca;A. Istrate;F. Ferraro;B. Lanzoni;P. Freire;M. Salaris
本文报道在球状星团M13中发现毫秒脉冲星J1631+ 3627 F的伴星星星。通过哈勃太空望远镜获得的光学和近紫外高分辨率观测的组合，我们确定了射电源位置的对应物。它在色星等图上的位置表明它的伴星星星是一颗微弱的氦核白色矮星。我们将观测到的伴星星等与最先进的双星演化模型预测的星等进行了比较，发现它的质量为，半径为，表面温度为K。将伴星质量与脉冲星质量函数结合起来并不足以确定轨道倾角和中子星星质量;然而，后两个量变得相关：我们发现，要么系统是在低倾角下观测到的，要么中子星星是有质量的。事实上，假设双星是随机排列的，相对于观测者的视线，有一个概率，这个系统的主机中子星星质量比。实际上，中子星星的最大质量和中位质量，对应于轨道倾角为90°和60°，分别为和。另一方面，同样假设一个经验中子星星质量概率分布，我们发现这个系统可以容纳一个质量为1f的中子星星，其轨道倾角约为40°。
We report on the discovery of the companion star to the millisecond pulsar J1631+3627F in the globular cluster M13. By means of a combination of optical and near-UV high-resolution observations obtained with the Hubble Space Telescope, we identified the counterpart at the radio source position. Its location in the color–magnitude diagrams reveals that the companion star is a faint ( ) He-core white dwarf. We compared the observed companion magnitudes with those predicted by state-of-the-art binary evolution models and found out that it has a mass of , a radius of , and a surface temperature of K. Combining the companion mass with the pulsar mass function is not enough to determine the orbital inclination and the neutron star mass; however, the last two quantities become correlated: we found that either the system is observed at a low-inclination angle, or the neutron star is massive. In fact, assuming that binaries are randomly aligned with respect to the observer line of sight, there is a of probability that this system hosts a neutron star more massive than . In fact, the maximum and median mass of the neutron star, corresponding to orbital inclination angles of 90° and 60°, are and , respectively. On the other hand, also assuming an empirical neutron star mass probability distribution, we found that this system could host a neutron star with a mass of if orbiting with a low-inclination angle around 40°.