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arXiv 1306.4334astro-ph.SR
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四重前主序星系统LkCa3:对恒星演化模型的启示

The quadruple pre-main sequence system LkCa3: Implications for stellar evolution models

Guillermo Torres, Dary Ruiz-Rodriguez, Mariona Badenas, L. Prato, G. H. Schaefer, Lawrence H. Wasserman, Robert D. Mathieu, David W. Latham

摘要:

我们发现金牛座-御夫座恒星形成区的前主序天体LkCa 3是一个M星的等级四重系统。它以前被认为是一个近距离(约0.5弧秒)的视双星,其中一个是一个中等偏心的12.94天单线光谱双星。对档案光学光谱的重新分析补充了新的近红外光谱,显示两个视觉组件是双线的,第二个具有4.06天的周期和圆形轨道。除了轨道要素,我们确定的光学和近红外线通量比,有效温度,并预计所有四颗恒星的旋转速度。使用现有的光度监测观测的系统,以前揭示了旋转周期的主要在较长的周期的二进制,我们也检测到旋转信号的主要在4.06天的二进制,这是同步的轨道运动。只有假设的coevality,比较所有这些限制与当前的恒星演化模型从达特茅斯系列点的年龄为140万年和距离为133 pc,与以前的估计该地区,并建议该系统是在金牛座复杂的近侧。LkCa 3和著名的四重前主序系统GG Tau的性质与里昂系列中广泛使用的模型的混合长度参数α_ML = 1.0的类似比较强烈支持达特茅斯模型。

英文摘要:

We report the discovery that the pre-main sequence object LkCa3 in the Taurus-Auriga star-forming region is a hierarchical quadruple system of M stars. It was previously known to be a close (~0.5 arc sec) visual pair, with one component being a moderately eccentric 12.94-day single-lined spectroscopic binary. A re-analysis of archival optical spectra complemented with new near-infrared spectroscopy shows both visual components to be double-lined, the second one having a period of 4.06 days and a circular orbit. In addition to the orbital elements, we determine optical and near-infrared flux ratios, effective temperatures, and projected rotational velocities for all four stars. Using existing photometric monitoring observations of the system that had previously revealed the rotational period of the primary in the longer-period binary, we detect also the rotational signal of the primary in the 4.06-day binary, which is synchronized with the orbital motion. With only the assumption of coevality, a comparison of all of these constraints with current stellar evolution models from the Dartmouth series points to an age of 1.4 Myr and a distance of 133 pc, consistent with previous estimates for the region and suggesting the system is on the near side of the Taurus complex. Similar comparisons of the properties of LkCa3 and of the well-known quadruple pre-main sequence system GG Tau with the widely used models from the Lyon series for a mixing length parameter of alpha_ML = 1.0 strongly favor the Dartmouth models.

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