论文标题
狼射线系统EZ Canis Majoris中同伴的性质
The nature of the companion in the Wolf-Rayet system EZ Canis Majoris
论文作者
论文摘要
EZ Canis Majoris是一位古典狼射线星，其二元性质数十年来一直在辩论。它最近被建模为偏心二进制，在伴侣附近的休克加热区域的发射区域周期性亮度上进行了定期亮度。本文的重点是进一步测试二进制模型，并通过寻找在冲击加热区域中引起的发射来限制看不见的亲密伴侣的性质。我们分析了超过400个高分辨率的1983年至1995年之间获得的国际紫外线探索者光谱，并在2010年获得的XMM-Newton观测值。光曲线和径向速度（RV）变化与偏心二进制模型拟合，轨道元素构成了构成。我们在1992年和1995年的初级排放线中发现了RV变化，并在1992年和1995年发现了30 km/s的RV变化，第二套具有抗相距RV曲线的排放量为k $ _2 \ sim $ 150 kmm/s。同时拟合RV和光曲线的模型可为每个时期产生轨道元素。采用狼射线质量m $ _1 \ sim $ 20 m $ _ \ odot $导致m $ _2 \ sim $ 3-5 m $ _ $ _ \ odot $，这意味着同伴可以是晚期B型星星。偏心（E = 0.1）二进制模型还解释了XMM-Newton获得的硬X射线光曲线和对这些数据的拟合表明，最大持续时间比典型的暴露时间短。两种发射成分的反相RV变化以及与RVS和光曲线的同时拟合是有利于EZ Canis Majoris二元性质的具体证据。从冲击加热区域的发射紧密痕迹的假设是不确定的，尽管它是可行的，因为伴侣受WR辐射场显着加热并受到WR风的影响。
EZ Canis Majoris is a classical Wolf-Rayet star whose binary nature has been debated for decades. It was recently modeled as an eccentric binary with a periodic brightening at periastron of the emission originating in a shock heated zone near the companion. The focus of this paper is to further test the binary model and to constrain the nature of the unseen close companion by searching for emission arising in the shock-heated region. We analyze over 400 high resolution the International Ultraviolet Explorer spectra obtained between 1983 and 1995 and XMM-Newton observations obtained in 2010. The light curve and radial velocity (RV) variations were fit with the eccentric binary model and the orbital elements were constrained. We find RV variations in the primary emission lines with a semi-amplitude K$_1\sim$30 km/s in 1992 and 1995, and a second set of emissions with an anti-phase RV curve with K$_2\sim$150 km/s. The simultaneous model fit to the RVs and the light curve yields the orbital elements for each epoch. Adopting a Wolf-Rayet mass M$_1\sim$20 M$_\odot$ leads to M$_2\sim$3-5 M$_\odot$, which implies that the companion could be a late B-type star. The eccentric (e=0.1) binary model also explains the hard X-ray light curve obtained by XMM-Newton and the fit to these data indicates that the duration of maximum is shorter than the typical exposure times. The anti-phase RV variations of two emission components and the simultaneous fit to the RVs and the light curve are concrete evidence in favor of the binary nature of EZ Canis Majoris. The assumption that the emission from the shock-heated region closely traces the orbit of the companion is less certain, although it is feasible because the companion is significantly heated by the WR radiation field and impacted by the WR wind.
