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arXiv 1105.2162astro-ph.SR
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V2368 Oph:一颗食双星,是Oph U的光度比较星

V2368 Oph: An eclipsing and double-lined spectroscopic binary used as a photometric comparison star for U Oph

P. Harmanec, H. Božić, P. Mayer, P. Eenens, M. Brož, M. Wolf, S. Yang, M. Šlechta, D. Ruždjak, D. Sudar, H. Ak

摘要:

A型星HR 6412 = V2368 Oph被几个研究者用作已知食双星U Oph的光度比较星,但被三个独立的群体发现是可变的,包括我们。通过分析一系列新的光谱和光度观测以及对现有径向速度的关键汇编,我们能够找到光和径向速度变化的正确周期,并证明该物体是一个在高度偏心轨道上移动的食和双线光谱双星。我们导出了该双星的线性星历Tmin.I = HJD(2454294.67 +/- 0.01)+(38.32712 +/- 0.00004)d × E,并初步估算了该双星的基本物理性质。根据我们的光和速度曲线解,初级和次级的去红UBV幅度和有效温度导致了与依巴谷距离在误差范围内一致的距离估计。我们发现,质量比必须接近1,但有限的数量和波长范围内,我们目前的光谱不允许一个真正精确的测定的二进制质量。然而,我们的研究结果令人信服地表明,这两个二元成分都是从主序演化而来的,这使得这个系统在天体物理学上非常重要。在已知的食双星中,只有少数类似演化的A型恒星。未来的系统观测和细致分析可以为恒星演化理论提供非常严格的检验。

英文摘要:

The A-type star HR 6412 = V2368 Oph was used by several investigators as a photometric comparison star for the known eclipsing binary U Oph but was found to be variable by three independent groups, including us. By analysing series of new spectral and photometric observations and a critical compilation of available radial velocities, we were able to find the correct period of light and radial-velocity variations and demonstrate that the object is an eclipsing and double-lined spectroscopic binary moving in a highly eccentric orbit. We derived a linear ephemeris T min.I = HJD (2454294.67 +/- 0.01) + (38.32712 +/- 0.00004)d x E and estimated preliminary basic physical properties of the binary. The dereddened UBV magnitudes and effective temperatures of the primary and secondary, based on our light- and velocity-curve solutions, led to distance estimates that agree with the Hipparcos distance within the errors. We find that the mass ratio must be close to one, but the limited number and wavelength range of our current spectra does not allow a truly precise determination of the binary masses. Nevertheless, our results show convincingly that both binary components are evolved away from the main sequence, which makes this system astrophysically very important. There are only a few similarly evolved A-type stars among known eclipsing binaries. Future systematic observations and careful analyses can provide very stringent tests for the stellar evolutionary theory.

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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