室女座Zeta星A3V的一颗微弱伴星的发现和表征
Discovery and Characterization of a Faint Stellar Companion to the A3V Star Zeta Virginis
摘要：
通过高阶自适应光学和日冕照相术的结合，我们发现了A3 V恒星室女座ζ的一个微弱的恒星伴星。在H波段，这颗伴星比它的主星暗7等，在5个历元中，红外线成像显示这颗伴星与它的主星有共同的自行。使用演化模型，我们估计它的质量为0.168+/-.016太阳质量，给出这个系统的质量比q = 0.082。假设这两个天体是同时代的，这个质量表明伴星的光谱类型是M4 V-M7 V，这是通过积分场光谱测量证实的。我们从这颗伴星上看到了轨道运动的明确证据，并且能够将半长轴限制在大于24.9天文单位，周期> 124$ yrs，离心率> 0.16。对更高质量恒星的多重性研究相对较少，而像这颗位于质量比分布极低端的双星伴星是对在如此低的质量比下不完整的调查的有用补充。此外，双星伴星的频率可以帮助区分双星形成的情景，预测大量的低质量伴星形成于大质量的星周盘的早期碎片。像这样的系统可以提供对A星异常X射线发射的洞察，假设是来自看不见的晚型恒星同伴。事实上，我们计算出这颗M矮星伴星的存在很容易解释ROSAT探测到的这颗恒星的X射线发射。
英文摘要：
Through the combination of high-order Adaptive Optics and coronagraphy, we report the discovery of a faint stellar companion to the A3V star zeta Virginis. This companion is ~7 magnitudes fainter than its host star in the H-band, and infrared imaging spanning 4.75 years over five epochs indicates this companion has common proper motion with its host star. Using evolutionary models, we estimate its mass to be 0.168+/-.016 solar masses, giving a mass ratio for this system q = 0.082. Assuming the two objects are coeval, this mass suggests a M4V-M7V spectral type for the companion, which is confirmed through integral field spectroscopic measurements. We see clear evidence for orbital motion from this companion and are able to constrain the semi-major axis to be greater than 24.9 AU, the period > 124$ yrs, and eccentricity > 0.16. Multiplicity studies of higher mass stars are relatively rare, and binary companions such as this one at the extreme low end of the mass ratio distribution are useful additions to surveys incomplete at such a low mass ratio. Moreover, the frequency of binary companions can help to discriminate between binary formation scenarios that predict an abundance of low-mass companions forming from the early fragmentation of a massive circumstellar disk. A system such as this may provide insight into the anomalous X-ray emission from A stars, hypothesized to be from unseen late-type stellar companions. Indeed, we calculate that the presence of this M-dwarf companion easily accounts for the X-ray emission from this star detected by ROSAT.
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。
