双星分数为76%和NGC 188的蓝色落后者不寻常的轨道参数
Robert D Mathieu1, Aaron M Geller
1Department of Astronomy, University of Wisconsin-Madison, 475 North Charter Street, Madison, Wisconsin 53706, USA. mathieu@astro.wisc.edu
Nature
|December 25, 2009
概括
大多数蓝色滞留恒星都存在于二进制星系中,这表明它们不寻常的亮度和质量增长是多星系内部相互作用的结果. 这一发现有助于解决它们的形成途径.
科学领域:
- 恒星天体物理学 恒星天体物理学
- 双星系统是双星系统.
- 星团动力学 星团动力学
背景情况:
- 蓝色滞留恒星是恒星星团中异常发光的主序恒星.
- 它们的存在挑战了标准的恒星进化模型,因为它们本应该演变成巨星或白矮星.
- 以前的研究表明,二进制相互作用是可能的形成机制,但具体的过程仍然不清楚.
研究的目的:
- 为了研究开放星团NGC 188.8中蓝色滞留恒星的二进制频率.
- 为了确定蓝色落后者是否主要来自多星系.
- 为了限制蓝色滞后者形成机制和进化途径.
主要方法:
- 在NGC 188星团中对蓝色落后恒星进行光度和光谱观测.
- 对已识别的蓝色滞留者双星的轨道参数 (周期,离心率) 的分析.
- 蓝色落后星和正常主序星之间的二进制频率和恒星旋转率的比较.
主要成果:
- 在NGC 188中观察到的蓝色落后星中有76%位于二进制星系中,这个比例是正常恒星的三倍.
- 这些蓝色滞后者二进制星表现出明显的周期偏心分布,大多数有1000天的周期.
- 蓝色滞留者与温度相似的主序星相比,它们的旋转速度更快.
结论:
- 高二进制频率强烈支持蓝色滞后者主要来自多星系.
- 双星中的质量转移,合并和恒星碰撞可能是同时形成的过程.
- 快速旋转可能会对蓝色滞后者施加年龄限制,影响它们的进化轨迹.
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