Enshrouded exoplanetary systems
Enshrouded exoplanetary systems
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被笼罩的系外行星系统
DOI：
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发表时间：
2018
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影响因子：
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通讯作者：
D. Staab
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文献类型：
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作者：
D. Staab
本论文基于这样的假设：拥有短周期行星的恒星可以显示出异常低的视恒星活动值，这是由覆盖该系统的行星质量损失引起的。由此产生的星周吸收会抑制 Ca II H&K 线的核心，在此测量活动指数 log(R'HK)。我在约 2700 颗恒星的样本中搜索了这种效应，识别出 39 个 log(R'HK) 低于主序基底极限的天体，以及 6 颗毕星团和昴宿星的活动水平远低于星团分布。我描述了一个径向速度程序来寻找绕这些恒星运行的短周期行星。由于附近的明亮恒星成为目标，它们质量损失的伴星将为通过透射光谱探测行星成分提供重要机会。我介绍了通过该计划发现的四颗围绕 HD11231 和 HD38677 运行的候选行星。前者是一个 γ-剑鱼座脉动器，在 6 天的轨道上托管着一颗土星质量的行星，后者是一个紧凑的系统，包含质量约为 18、13 和 3 个地球的行星，周期在 20 至 1.7 天之间。
此外，罗伯特·斯托比摄谱仪经过校准可以测量
log(R'HK) 值。测量了已知热木星宿主WASP-43、WASP-51/HAT-P-30、WASP-72和WASP-103的活动指数，以寻找由伴星引起的异常值。 WASP-43 的活性水平无论从绝对值还是相对于其年龄和 X 射线发射而言都极高。 WASP-103 的活动略高于系统时代的预期。在这两种情况下，恒星与行星的相互作用可能会增强 Ca II H 和 K 的发射。 WASP-51/HAT-P-30 和 WASP-72 显示出异常低的活性；后者落在主序和演化恒星的基底包层以下。我强调指出，四分之一的凌日、短周期行星宿主的活动数据已公布，表现出异常低的活动。这 22 个系统包括热木星和低质量伴星。
This thesis is based on the hypothesis that stars hosting short period planets can show anomalously low apparent stellar activity values caused by planetary mass-loss enshrouding the system. The resulting circumstellar absorption depresses the cores of the Ca II H&K lines, where the activity index log(R'HK) is measured. I searched for this effect in a sample of ∼2700 stars, identifying 39 objects with log(R'HK) below the main sequence basal limit, and 6 Hyades and Pleiades stars with activity levels well below the cluster distributions. I describe a radial velocity programme to search for short period planets orbiting these stars. Because nearby bright stars are targeted, their mass-losing companions will offer key opportunities to probe planetary composition through transmission spectroscopy. I present four planet candidates discovered through this programme orbiting HD11231 and HD38677. The former is a γ-Doradus pulsator hosting a Saturn-mass planet in a 6 day orbit, and the latter is a compact system containing planets with ∼18, 13 and 3 Earth masses and periods between 20 and 1.7 days.
In addition, the Robert Stobie Spectrograph was calibrated to measure
log(R'HK) values. The activity index of the known Hot Jupiter hosts WASP-43, WASP-51/HAT-P-30, WASP-72 & WASP-103 was measured to search for anomalous values caused by the companions. The activity level of WASP-43 is extremely high in absolute terms and relative to its age and X-ray emission. The activity of WASP-103 is marginally higher than expected from the system age. In both cases, star-planet interactions may enhance Ca II H & K emission. WASP-51/HAT-P-30 and WASP-72 show anomalously low activity; the latter falls below the basal envelopes of main sequence and evolved stars. I highlight that a quarter of transiting, short period planets hosts with published activity data exhibit anomalously low activity. These 22 systems include Hot Jupiters and low mass companions.