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arXiv 0708.2065astro-ph
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光谱双星系统G1375。I.轨道参数和色球活动

The spectroscopic binary system Gl 375. I. Orbital parameters and chromospheric activity

Rodrigo F. Díaz, Jorge F. González, Carolina Cincunegui, Pablo J. D. Mauas

摘要:

我们研究了光谱双星系统Gl375。我们采用中分辨率阶梯光谱获得的2.15米望远镜在阿根廷天文台CASLEO和光度观测ASAS数据库。我们将复合光谱分成对应于两个分量的光谱。分离的光谱使我们能够确认两个分量的光谱类型相似(dMe3.5),并获得轨道周期(P = 1.87844天)、最小质量(M_1 sin^3 i = 0.35 M_sun和M_2 sin^3 i =0.33 M_sun)和其他轨道参数的精确测量值。光度观测呈现出与轨道周期相同的正弦变化。我们解释这是一个潮汐同步系统中的旋转进行的活动区域的迹象,并研究在较长的时间尺度的调制幅度的演变。与平均震级一起,调制表现出大约800天的周期性变化。这种周期性也被发现在流量的Ca II K线的两个组件,这似乎是在相位。这三个观测值的周期性变化被解释为恒星活动周期的标志。这两个分量似乎是同相的,这意味着它们是磁性连接的。测得的大约2.2年(800天)的活动周期与以前类似恒星的活动周期一致。

英文摘要:

We study the spectroscopic binary system Gl 375. We employ medium resolution echelle spectra obtained at the 2.15 m telescope at the Argentinian observatory CASLEO and photometric observations obtained from the ASAS database. We separate the composite spectra into those corresponding to both components. The separated spectra allow us to confirm that the spectral types of both components are similar (dMe3.5) and to obtain precise measurements of the orbital period (P = 1.87844 days), minimum masses (M_1 sin^3 i = 0.35 M_sun and M_2 sin^3 i =0.33 M_sun) and other orbital parameters. The photometric observations exhibit a sinusoidal variation with the same period as the orbital period. We interpret this as signs of active regions carried along with rotation in a tidally synchronized system, and study the evolution of the amplitude of the modulation in longer timescales. Together with the mean magnitude, the modulation exhibits a roughly cyclic variation with a period of around 800 days. This periodicity is also found in the flux of the Ca II K lines of both components, which seem to be in phase. The periodic changes in the three observables are interpreted as a sign of a stellar activity cycle. Both components appear to be in phase, which implies that they are magnetically connected. The measured cycle of approximately 2.2 years (800 days) is consistent with previous determinations of activity cycles in similar stars.

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