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arXiv 1104.0342astro-ph.SR
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重新审视五车二的光谱轨道

The spectroscopic orbit of Capella revisited

Michael Weber, Klaus G. Strassmeier

摘要:

上下文五车二是为数不多的有两个演化成巨星的双星之一。较热的部分是赫茨普龙间隙内的色球活跃恒星,而较冷的部分可能是氦核燃烧。目标。已知的轨道平面倾角结合精确的径向速度将允许非常精确的质量来确定单个五车二恒星。这将限制它们的演化阶段,并可能限制活动恒星的磁场对双星系统动力学演化的作用。方法.在2007-2010年期间,我们总共获得了438个高分辨率埃歇尔光谱,并使用测量的速度重新计算轨道要素。我们的双线轨道解决方案产生的平均残差为64米/秒的冷组件和297米/秒的更快速旋转的热组件。结果冷分量的半振幅比Torres等人根据1996-1999年期间的数据确定的轨道小0.045公里/秒,但精确度高5.5倍,而热分量的半振幅则大0.580公里/秒,精确度高3.6倍。这对应于冷组分和热组分的质量分别为2.573 \pm 0.009 M_sun和2.488 \pm 0.008 M_sun。它们的相对误差分别为0.34%和0.30%,约为Torres等人给出的文献-数据组合解的值的一半,但两个分量的绝对值分别相差4%和2%。因此,系统的质量比为q = M_A/M_B = 0.9673 \pm 0.0020。结论.我们的轨道是最精确的,也可能是有史以来最准确的卡佩拉。

英文摘要:

Context. Capella is among the few binary stars with two evolved giant components. The hotter component is a chromospherically active star within the Hertzsprung gap, while the cooler star is possibly helium-core burning. Aims. The known inclination of the orbital plane from astrometry in combination with precise radial velocities will allow very accurate masses to be determined for the individual Capella stars. This will constrain their evolutionary stage and possibly the role of the active star's magnetic field on the dynamical evolution of the binary system. Methods. We obtained a total of 438 high-resolution échelle spectra during the years 2007-2010 and used the measured velocities to recompute the orbital elements. Our double-lined orbital solution yields average residuals of 64 m/s for the cool component and 297 m/s for the more rapidly rotating hotter component. Results. The semi-amplitude of the cool component is smaller by 0.045 km/s than the orbit determination of Torres et al. from data taken during 1996-1999 but more precise by a factor of 5.5, while for the hotter component it is larger by 0.580 km/s and more precise by a factor of 3.6. This corresponds to masses of 2.573\pm0.009 M_sun and 2.488\pm0.008 M_sun for the cool and hot component, respectively. Their relative errors of 0.34% and 0.30% are about half of the values given in Torres et al. for a combined literature- data solution but with absolute values different by 4% and 2% for the two components, respectively. The mass ratio of the system is therefore q = M_A/M_B = 0.9673 \pm 0.0020. Conclusions. Our orbit is the most precise and also likely to be the most accurate ever obtained for Capella.

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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