Eclipsing binaries in open clusters – I. V615 Per and V618 Per in h Persei
Eclipsing binaries in open clusters – I. V615 Per and V618 Per in h Persei
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DOI：
10.1111/j.1365-2966.2004.07520.x
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发表时间：
2003-12
影响因子：
4.8
通讯作者：
J. Southworth;P. Maxted;B. Smalley
中科院分区：
文献类型：
--
作者：
J. Southworth;P. Maxted;B. Smalley
本文计算了英仙座疏散星团hPersei（NGC 869）中两个早型主序分离食双星的绝对尺寸。英仙座V615的光谱类型为B7 V，周期为13.7天。V618英仙座是A2 V，周期为6.4天。为这两个系统计算新的星历。使用高分辨率光谱法推导出组成星的质量，V615 Per为4.08 ± 0.06 Mfl和3.18± 0.05 Mfl，V618 Per为2.33± 0.03 Mfl和1.56± 0.02 Mfl。通过使用ebop拟合可用的光变曲线来测量半径，V615 Per的半径为2.29±0.14Rfl和1.90±0.09Rfl，V618 Per的半径为1.64±0.07Rfl和1.32±0.07Rfl。通过比较V615 Per的观测光谱和模型大气的合成光谱，我们发现其主星的有效温度为15000 ± 500 K，次级星的有效温度为11000 ± 500 K。V615 Per的赤道自转速度分别为28 ± 5 kmsi ~ 1和8 ± 5 kmsi ~ 1。V618 Per的两个组件都以10± 5 kms i1的速度旋转。这四颗恒星的赤道同步自转速度约为10 kms i ~ 1。这两个系统的轨道圆化的时间尺度，以及V615 Per的旋转同步的时间尺度，都比hPer的年龄大得多。因此，它们的离心率和赤道自转速度可以忽略不计，这支持了它们是由“延迟分裂”形成的假设（Tohline 2002）。我们比较了这些恒星的半径模型的格拉纳达和帕多瓦集团的恒星相同的质量，但dierent组成。我们得出结论，恒星的金属丰度为Z... 0.01。这似乎是第一次估计的散装金属丰度的hPer。最近的测光研究假设了太阳的金属丰度，因此应该对它们的结果进行审查。
We have derived absolute dimensions for two early-type main sequence detached eclipsing binaries in the young open cluster hPersei (NGC869). V615Persei has a spectral type of B7V and a period of 13.7 days. V618Persei is A2V and has a period of 6.4 days. New ephemerides are calculated for both systems. The masses of the component stars have been derived using high-resolution spectroscopy and are 4.08 ± 0.06Mfl and 3.18±0.05Mfl for V615Per and 2.33±0.03Mfl and 1.56±0.02Mfl for V618Per. The radii have been measured by fitting the available light curves using ebop and are 2.29±0.14Rfl and 1.90±0.09Rfl for V615Per and 1.64±0.07Rfl and 1.32±0.07Rfl for V618Per. By comparing the observed spectra of V615Per to synthetic spectra from model atmospheres we find that the eective temperatures of the stars are 15000 ± 500K for the primary and 11000 ± 500K for the secondary. The equatorial rotational velocities of the primary and secondary components of V615Per are 28 ± 5kms i1 and 8 ± 5kms i1 , respectively. Both components of V618Per rotate at 10±5kms i1 . The equatorial rotational velocities for synchronous rotation are about 10kms i1 for all four stars. The timescales for orbital circularisation for both systems, and the timescale for rotational synchronisation of V615Per, are much greater than the age of hPer. Their negligible eccentricities and equatorial rotational velocities therefore support the hypothesis that they were formed by ‘delayed breakup’ (Tohline 2002). We have compared the radii of these stars to models by the Granada and the Padova groups for stars of the same masses but dierent compositions. We conclude that the metallicity of the stars is Z … 0.01. This appears to be the first estimate of the bulk metallicity of hPer. Recent photometric studies have assumed a solar metallicity so their results should be reviewed.