A multiwavelength study of the hierarchical triple HD 181068: A test bed for studying star-planet-interaction?
A multiwavelength study of the hierarchical triple HD 181068: A test bed for studying star-planet-interaction?
复制标题
DOI：
10.1051/0004-6361/201423879
复制
发表时间：
2014-08
期刊：
影响因子：
--
通讯作者：
S. Czesla;K. Huber;P. Schneider;J. Schmitt
中科院分区：
文献类型：
--
作者：
S. Czesla;K. Huber;P. Schneider;J. Schmitt
HD 181068是迄今已知的唯一一颗包含巨星的紧凑、三次日食、等级三元系统。由于其中心高度活跃的G型巨星被一对接近的主序矮星所环绕，该系统是研究潮汐相互作用的理想系统。我们进行了一项多波长研究，以表征HD 181068系统的磁性。为此，我们用XMM-牛顿获得了日食中和日食外的X射线快照和光谱，并结合开普勒光曲线进行了分析。初级巨星在2e31ergs的水平上显示出强烈的静态X射线发射，S指数为0.41+/-0.01，在开普勒波段有高达6e38erg的显著白光耀斑发射。在第二次X射线观测中，我们发现X射线发射水平增加了三倍，但仍在衰减，这可能是由于X射线耀斑造成的。高水平的磁活动与之前报道的这颗巨星中没有类似太阳的振荡是一致的，然而，它的大气经历了由矮星双星不断变化的构型引起的潮汐诱导的振荡。我们发现，激发这些振荡的驱动力可以与典型的热木星产生的扰动相媲美，使该系统成为研究行星系统中也存在的潮汐相互作用影响的潜在试验台。
HD 181068 is the only compact, triply eclipsing, hierarchical triple system containing a giant star known to date. With its central, highly-active G-type giant orbited by a close pair of main-sequence dwarfs, the system is ideal to study tidal interactions. We carried out a multiwavelength study to characterize the magnetic activity of the HD 181068 system. To this end, we obtained in- and out-of-eclipse X-ray snapshots with XMM-Newton and an optical spectrum, which we analyzed along with the Kepler light-curve. The primary giant shows strong quiescent X-ray emission at a level of 2e31 ergs, an S-index of 0.41 +/- 0.01, and marked white-light flares releasing up to 6e38 erg in the Kepler-band. During the second X-ray observation, we found a three-times elevated -- yet decaying -- level of X-ray emission, which might be due to an X-ray flare. The high level of magnetic activity is compatible with the previously reported absence of solar-like oscillations in the giant, whose atmosphere, however, undergoes tidally-induced oscillations imposed by the changing configuration of the dwarf-binary. We found that the driving force exciting these oscillations is comparable to the disturbances produced by a typical hot Jupiter, making the system a potential test bed to study the effects of tidal interactions also present in planetary systems.