LMC中WNL星的光谱观测：一般性质和双星状态
A Spectroscopic Survey of WNL Stars in the LMC: General Properties and Binary Status
摘要：
我们报告的结果，一个激烈的，光谱调查的所有41晚型，富氮沃尔夫-拉叶星（WR）在大麦云（LMC）可观察到的地面望远镜。这次调查结束了蒙特利尔大质量恒星集团长达十年的努力，以监测麦哲伦星云中所有已知的WR恒星，除了R136中的6颗拥挤的WNL恒星，这将在其他地方讨论。我们调查的重点是监测所谓的WNL星的径向速度（RV）的变化，以确定其中的短到中期（$P \la 200$天）的双星。我们的研究结果与其他WR亚型的研究结果一致，并表明LMC WNL星的双星频率与银河系WNL星的双星频率在统计上是一致的。我们已经确定了四个以前未知的二进制文件，使已知的WNL二进制文件在LMC的总数为9。由于很可能只有一个双星是经典的，燃烧氦的WNL恒星，而是超亮的，因此质量极大的，燃烧氢的物体，我们的研究大大增加了已知的含有这种物体的双星的数量，从而为通过独立于模型的开普勒轨道确定它们的质量铺平了道路。预计我们双星中的一些恒星将是已知质量最大的。随着每个WR星的双星状态现在已知，我们还研究了我们的计划星的光度和X射线特性，使用档案CAMO光度以及钱德拉和ROSAT数据。我们发现，我们的一个可能是单一的WNL恒星是已知的X射线最亮的WR源之一。我们还确定了一个二元候选人从其RV的变化和X射线光度，其中窝藏最明亮的WR星在本地组。
英文摘要：
We report the results of an intense, spectroscopic survey of all 41 late-type, nitrogen-rich Wolf-Rayet (WR) stars in the Large Magellanic Cloud (LMC) observable with ground-based telescopes. This survey concludes the decade-long effort of the Montréal Massive Star Group to monitor every known WR star in the Magellanic Clouds except for the 6 crowded WNL stars in R136, which will be discussed elsewhere. The focus of our survey was to monitor the so-called WNL stars for radial-velocity (RV) variability in order to identify the short- to intermediate-period ($P \la 200$ days) binaries among them. Our results are in line with results of previous studies of other WR subtypes, and show that the binary frequency among LMC WNL stars is statistically consistent with that of WNL stars in the Milky Way. We have identified four previously unknown binaries, bringing the total number of known WNL binaries in the LMC to nine. Since it is very likely that none but one of the binaries are classical, helium-burning WNL stars, but rather superluminous, hence extremely massive, hydrogen-burning objects, our study has dramatically increased the number of known binaries harbouring such objects, and thus paved the way to determine their masses through model-independent, Keplerian orbits. It is expected that some of the stars in our binaries will be among the most massive known. With the binary status of each WR star now known, we also studied the photometric and X-ray properties of our program stars using archival MACHO photometry as well as Chandra and ROSAT data. We find that one of our presumably single WNL stars is among the X-ray brightest WR sources known. We also identify a binary candidate from its RV variability and X-ray luminosity which harbours the most luminous WR star known in the Local Group.
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