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arXiv 1102.3363astro-ph.SR
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高质量X射线双星OAO 1657-415中子星和施主星的演化和质量

The evolution and masses of the neutron star and donor star in the high mass X-ray binary OAO 1657-415

A. B. Mason, J. S. Clark, A. J. Norton, P. A. Crowther, T. M. Tauris, N. Langer, I. Negueruela, P. Roche

摘要:

本文报道了在VLT上利用ISAAC在H波段对最近发现的高质量X射线双星系统OAO 1657-415中的施主星进行的近红外径向速度测量。采用互相关方法构造径向速度曲线,其半振幅为$22.1 \pm 3.5$ km s $^{-1}$。结合该系统的其他测量参数,这提供了一个动态确定的中子星质量的$1.42 \pm 0.26 M$ _{ \odot } $ and a mass of $ 14.3 \pm 0.8 M $_{\odot}$的Ofpe/WN 9高度演化的施主星。OAO 1657-415是一颗高质量X射线脉冲双星,在同级别中具有最大的离心率和轨道周期。在已知的10颗食X射线双星中,OAO 1657-415是第九颗有动态确定的中子星质量解的双星,也是第二颗有偏心系统的双星。此外,OAO 1657-415中的施主星比其他大质量X射线双星(HMXB)中的大多数超巨星施主更高度演化,加入了一个小但不断增长的HMXB施主名单,具有广泛的氢耗尽大气。考虑到OAO 1657-415的进化发展,我们估计了质量供体的包层的结合能,发现通过螺旋进入去除供体的包层的能量不足,排除了共同包层进化的情况。由于OAO 1657 -415的非零离心率和相对较大的轨道周期,确定OAO 1657 -415的最终演化路径仍然存在问题,我们最后提出了两种可能解释OAO 1657 -415当前轨道配置的情景。

英文摘要:

We report near-infrared radial velocity measurements of the recently identified donor star in the high mass X-ray binary system OAO 1657-415 obtained in the H band using ISAAC on the VLT. Cross-correlation methods were employed to construct a radial velocity curve with a semi-amplitude of $22.1 \pm 3.5$ km s$^{-1}$. Combined with other measured parameters of this system this provides a dynamically determined neutron star mass of $1.42 \pm 0.26 M$_{\odot}$ and a mass of $14.3 \pm 0.8 M$_{\odot}$ for the Ofpe/WN9 highly evolved donor star. OAO 1657-415 is an eclipsing High Mass X-ray binary pulsar with the largest eccentricity and orbital period of any within its class. Of the ten known eclipsing X-ray binary pulsars OAO 1657-415 becomes the ninth with a dynamically determined neutron star mass solution and only the second in an eccentric system. Furthermore, the donor star in OAO 1657-415 is much more highly evolved than the majority of the supergiant donors in other High Mass X-ray binaries (HMXBs), joining a small but growing list of HMXBs donors with extensive hydrogen depleted atmospheres. Considering the evolutionary development of OAO 1657-415, we have estimated the binding energy of the envelope of the mass donor and find that there is insufficient energy for the removal of the donor's envelope via spiral-in, ruling out a Common Envelope evolutionary scenario. With its non-zero eccentricity and relatively large orbital period the identification of a definitive evolutionary pathway for OAO1657-415 remains problematic, we conclude by proposing two scenarios which may account for OAO1657-415 current orbital configuration.

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