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arXiv 0801.2963astro-ph
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蛇夫座中一颗新的明亮短周期发射线双星

A New, Bright, Short-Period, Emission Line Binary in Ophiuchus

M. A. Stark, Richard A. Wade, John R. Thorstensen, Christopher S. Peters, Horace A. Smith, Robert D. Miller, E. M. Green

摘要:

11等的恒星LS IV-08 3之前在亮星巡天中被归类为OB星,或者是热亚矮星。它实际上是一颗双星。我们目前的光谱学,光谱轨道要素,和时间序列测光,从观察基特峰国家天文台2.1米,斯图尔特天文台2.3米,MDM天文台1.3米和2.4米,霍比-埃伯利9.2米,密歇根州立大学0.6米望远镜。恒星表现出不同强度的H和He I吸收线的核心发射。发射也存在于4686埃(He II)和4640/4650埃(N III/C III)附近。从2005年7月到2007年6月收集的时间序列光谱显示了H-alpha线的相干周期性径向速度变化,我们将其解释为周期为0.1952894(10)天的轨道运动。高分辨率光谱显示,有两个发射分量,一个宽的和一个窄的,反相移动,可能会产生一个吸积盘和辐射面的质量施主星。在类似于轨道周期的时间尺度上,也存在不太连贯、低振幅的光度变化。弥漫的星际带显示出相当大的变红,然而这与~100-200 pc的距离是一致的。这颗恒星可能是弱ROSAT X射线源的对应物,其性质与激变变星(CV)双星系统中的吸积一致。我们将LS IV-08 3归类为CV星UX Uma子类的新成员。

英文摘要:

The 11th magnitude star LS IV -08 3 has been classified previously as an OB star in the Luminous Stars survey, or alternatively as a hot subdwarf. It is actually a binary star. We present spectroscopy, spectroscopic orbital elements, and time series photometry, from observations made at the Kitt Peak National Observatory 2.1m, Steward Observatory 2.3m, MDM Observatory 1.3m and 2.4m, Hobby-Eberly 9.2m, and Michigan State University 0.6m telescopes. The star exhibits emission of varying strength in the cores of H and He I absorption lines. Emission is also present at 4686 Angstroms (He II) and near 4640/4650 Angstroms (N III/C III). Time-series spectroscopy collected from 2005 July to 2007 June shows coherent, periodic radial velocity variations of the H-alpha line, which we interpret as orbital motion with a period of 0.1952894(10) days. High-resolution spectra show that there are two emission components, one broad and one narrow, moving in antiphase, as might arise from an accretion disk and the irradiated face of the mass donor star. Less coherent, low-amplitude photometric variability is also present on a timescale similar to the orbital period. Diffuse interstellar bands indicate considerable reddening, which however is consistent with a distance of ~100-200 pc. The star is the likely counterpart of a weak ROSAT X-ray source, whose properties are consistent with accretion in a cataclysmic variable (CV) binary system. We classify LS IV -08 3 as a new member of the UX UMa subclass of CV stars.

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