arXivDaily arXiv每日学术速递 周一至周五更新
arXiv周末暂无论文更新,休息一下吧,周末愉快~~
arXiv 1202.3623astro-ph.EP
收藏

在有近距离太阳系外行星的恒星中色球Ca II H & K发射增强的证据

Evidence for enhanced chromospheric Ca II H & K emission in stars with close-in extrasolar planets

Tereza Krejcova, Jan Budaj

摘要:

行星与恒星的相互作用表现在许多方面。人们发现,一颗靠近的系外行星会在几颗恒星的光谱中的几条线的核心中引起微小但可测量的变化,这与系外行星的轨道周期相对应。有和没有系外行星的恒星可能有不同的性质。我们研究的主要目标是寻找系外行星可能对其宿主恒星的大气层产生的影响。与以前的研究不同,我们不研究宿主恒星光谱的变化或有和没有系外行星的恒星之间的差异。我们的目标是研究大量具有系外行星的恒星,其色球活动的当前水平,并寻找与系外行星性质的可能相关性。为了分析恒星的色球活动,我们利用我们自己的(2.2米ESO/MPG望远镜)和公开可用的档案光谱(凯克天文台档案),测量Ca II H和K线核心的等效宽度,并将它们用作其活动的示踪剂。随后,我们寻找它们的轨道参数和质量的系外行星的依赖。我们发现了一个有统计意义的证据,即主恒星的Ca II K线发射的等效宽度和log R '_{HK}活动参数随系外行星的半长轴和质量而变化。具有半长轴a <= 0.15 AU(P_orb <= 20天)的系外行星的T_eff <= 5500 K的恒星具有宽范围的Ca II K发射,并且通常比具有类似温度但具有更高半长轴值的恒星具有更强的发射。对于质量更大的系外行星,具有近距离系外行星(a <= 0.15 AU)的冷恒星(T_eff <= 5500 K)的Ca II K发射也更明显。恒星色球层活动的总体水平可能会受到它们附近的系外行星的影响。拥有巨大近距离系外行星的恒星可能更加活跃。

英文摘要:

The planet-star interaction is manifested in many ways. It was found out that a close-in exoplanet causes small but measurable variability in the cores of a few lines in the spectra of several stars which corresponds to the orbital period of the exoplanet. Stars with and without exoplanets may have different properties. The main goal of our study is to search for influence which exoplanets might have on atmospheres of their host stars. Unlike the previous studies, we do not study changes in the spectrum of a host star or differences between stars with and without exoplanets. We aim to study a large number of stars with exoplanets, current level of their chromospheric activity and look for a possible correlation with the exoplanetary properties. To analyse the chromospheric activity of stars we exploit our own (2.2m ESO/MPG telescope) and publicly available archival spectra (Keck Observatory Archive), measure the equivalent widths of the cores of Ca II H and K lines and use them as a tracer of their activity. Subsequently, we search for their dependence on the orbital parameters and mass of the exoplanet. We found a statistically significant evidence that the equivalent width of the Ca II K line emission and log R'_{HK} activity parameter of the host star varies with the semi-major axis and mass of the exoplanet. Stars with T_eff <= 5500 K having exoplanets with semi-major axis a <= 0.15 AU (P_orb <= 20 days) have a broad range of Ca II K emissions and much stronger emission in general than stars at similar temperatures but with higher values of semi-major axes. Ca II K emission of cold stars (T_eff <= 5500 K) with close-in exoplanets (a <= 0.15 AU) is also more pronounced for more massive exoplanets. The overall level of the chromospheric activity of stars may be affected by their close-in exoplanets. Stars with massive close-in exoplanets may be more active.

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。

↑