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HD 63021: Chromospheric Activity and Mass Transfer in a Close Binary
The Astronomical Journal ( IF 5.3 ) Pub Date : 2021-01-14 , DOI: 10.3847/1538-3881/abceb4
David G. Whelan 1 , S. Drew Chojnowski 2, 3 , Jonathan Labadie-Bartz 4 , James Daglen 5 , Ken Hudson 6 , Gary M. Casey 1, 7 , Guy S. Stringfellow 8 , Kathryn V. Lester 9 , John Barry 10 , Joshua Heinerikson 10 , Dan Pankratz 10 , Mary Schreffler 10 , Ryan Maderak 10 , Nick Lotspeich 11 , Molly Vitale-Sullivan 11 , Micah Woodard 11
Affiliation  

Prompted by X-ray detections from multiple surveys, we investigated the A-type star HD 63021 and found that it is a double-lined spectroscopic binary with highly variable emission associated with the primary star. Analysis of our multi-epoch spectroscopic observations, the majority of which were carried out on small aperture telescopes, indicates a very short orbital period of just $2.9$ days, and a mass ratio M$_2$/M$_1$ of $0.23$. The A1 V star is a slow rotator, with a rotational speed of $\sim34$ km/s. Assuming its mass is $2.3$ M$_{\odot}$, the present-day secondary is an evolved star of $\sim0.5$ M$_{\odot}$ that nearly fills its Roche lobe. This secondary star rotates comparatively rapidly at $\sim44$ km/s, and we see evidence that it is chromospherically active. Analysis of a photometric lightcurve from TESS reveals two strong periods, one at the orbital period for the system and another at half the orbital period. These findings suggest that HD 63021 is a close binary system undergoing mass transfer from the secondary star onto the primary star -- in all ways like an Algol eclipsing binary system, except without the eclipse. We discuss the system's mass transfer, which is not steady but seems to run in fits and bursts, and infer the system's basic physical properties from an orbital parameter study, the Roche lobe geometry, and its extant X-ray emission.

中文翻译:

HD 63021:紧密二元中的色层活动和传质

在多次巡天的 X 射线探测的提示下,我们调查了 A 型恒星 HD 63021,发现它是双线光谱双星,具有与主星相关的高度可变发射。对我们的多历元光谱观测(其中大部分是在小孔径望远镜上进行的)的分析表明,轨道周期非常短,仅为 2.9 美元天,质量比 M$_2$/M$_1$ 为 $0.23$。A1 V 星是一个慢速旋转器,旋转速度为 $\sim34 $ km/s。假设它的质量是 $2.3$ M$_{\odot}$,那么现在的次级是一颗演化出的 $\sim0.5$ M$_{\odot}$ 恒星,几乎充满了它的罗氏瓣。这颗次级恒星以 $\sim44$ km/s 的速度自转相对较快,我们看到了它在色球层上活跃的证据。对来自 TESS 的光度曲线的分析揭示了两个强烈的时期,一个在系统的轨道周期,另一个在轨道周期的一半。这些发现表明,HD 63021 是一个紧密的双星系统,正在经历从二级星到一级星的质量转移——在所有方面都类似于大陵五食双星系统,除了没有日食。我们讨论了系统的传质,它不是稳定的,但似乎是间歇性和爆发性的,并从轨道参数研究、罗氏瓣几何结构及其现有的 X 射线发射推断系统的基本物理特性。
更新日期:2021-01-14
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