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arXiv 0802.3542astro-ph
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中极EI UMa:一个极前激变变星

The Intermediate Polar EI UMa: A Pre-Polar Cataclysmic Variable

Tamara W. Reimer, William F. Welsh, Koji Mukai, F. A. Ringwald

摘要:

我们目前的光学和X射线时间序列测光的EI UMa,揭示调制在746和770秒,我们解释为白矮星自旋和自旋轨道边带。这些检测,结合以前的X射线研究,建立EI UMa作为一个中间极性。我们估计质量吸积速率约为3.6 x 10^{17} g/s^{-1},这接近甚至可能大于临界速率,超过这个速率矮新星不稳定性就会被抑制。我们还估计白矮星有一个大的磁矩μ>(3.4 +/- 0.2)x 10^{33} G cm ^3。高质量的吸积率和磁矩意味着吸积环的存在,而不是一个磁盘,以及相对较长的轨道周期,这些都表明EI UMa是一个罕见的前极激变变星的例子。

英文摘要:

We present optical and X-ray time-series photometry of EI UMa that reveal modulation at 746 and 770 s, which we interpret as the white dwarf spin and spin-orbit sidebands. These detections, combined with previous X-ray studies, establish EI UMa as an intermediate polar. We estimate the mass accretion rate to be ~ 3.6 x 10^{17} g s^{-1}, which is close to, and likely greater than, the critical rate above which dwarf nova instabilities are suppressed. We also estimate the white dwarf to have a large magnetic moment mu > (3.4 +/- 0.2) x 10^{33} G cm^3. The high mass accretion rate and magnetic moment imply the existence of an accretion ring rather than a disk, and along with the relatively long orbital period, these suggest that EI UMa is a rare example of a pre-polar cataclysmic variable.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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