色球活跃双星EI波江座I。绝对尺寸
The chromospherically active binary star EI Eridani I. Absolute dimensions
摘要：
我们提出了一个详细的测定的色球活动双星EI波江座的天体物理参数。我们新的径向速度允许改进的轨道要素集，并揭示长期变化的重心速度。提出了一个周期约为19年的可能的第三体轨道。结合依巴谷视差确定绝对参数。EI Eri的旋转轴倾角被限制在56.0 ± 4.5度，它的光度等级IV由它的半径2.37 ± 0.12 R_Sun确定。与理论恒星演化轨迹的比较表明，它的质量为1.09 ± 0.05 M太阳，年龄约为6.15 Gyr。目前的调查是我们的长期多普勒成像研究的恒星表面的基础。
英文摘要：
We present a detailed determination of the astrophysical parameters of the chromospherically active binary star EI Eridani. Our new radial velocities allow to improve the set of orbital elements and reveal long-term variations of the barycentric velocity. A possible third-body orbit with a period of approximately 19 years is presented. Absolute parameters are determined in combination with the Hipparcos parallax. EI Eri's inclination angle of the rotational axis is confined to 56.0 plus/minus 4.5 degrees, its luminosity class IV is confirmed by its radius of 2.37 plus/minus 0.12 R_Sun. A comparison to theoretical stellar evolutionary tracks suggests a mass of 1.09 plus/minus 0.05 M_Sun and an age of approximately 6.15 Gyr. The present investigation is the basis of our long-term Doppler imaging study of its stellar surface.
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