A pulsar-helium star compact binary system formed by common envelope evolution
Z. L. Yang, J. L. Han, D. J. Zhou, W. C. Jing, Wen‐Cong Chen, Tie‐Gang Wang, Xiang‐Dong Li, Song Wang, Bo Wang, Hongwei Ge, Y. L. Guo, L. H. Li, Yong Shao, Jifeng Liu, W. Q. Su, L. G. Hou, W. J. Huang, Jinchen Jiang, Peng Jiang, Jinghai Sun, Bojun Wang, Chenwei Wang, H. G. Wang, Jingbo Wang, Na Wang, Piao Wang, Shuangqiang Wang, Heng Xu, Jin-Long Xu, Renxin Xu, W. M. Yan, Yi Yan, X. P. You, Daqi Yu, Z. S. Yuan, C. F. Zhang
Abstract
A stellar common envelope occurs in a binary system when the atmosphere of an evolving star expands to encompass an orbiting companion object. Such systems are predicted to evolve rapidly, ejecting the stellar envelope and leaving the companion in a tighter orbit around a stripped star. We used radio timing to identify a pulsar, PSR J1928+1815, with a spin period of 10.55 ms in a compact binary system with an orbital period of 3.60 hours. The companion star has 1.0 to 1.6 solar masses, eclipses the pulsar for about 17% of the orbit, and is undetected at other wavelengths, so it is most likely a stripped helium star. We interpret this system as having recently undergone a common envelope phase, producing a compact binary.