We report the detection of a planetary companion around HIP 13044, ametal-poor star on the red Horizontal Branch. The detection is based on radialvelocity observations with FEROS, a high-resolution spectrograph at the 2.2-mMPG/ESO telescope, located at ESO La Silla observatory in Chile. The periodicradial velocity variation of P = 16.2 days can be distinguished from theperiods of the stellar activity indicators. We computed a minimum planetarymass of 1.25 MJup and an orbital semi-major axis of 0.116 AU for the planet.This discovery is unique in three aspects: First, it is the first planetdetection around a star with a metallicity much lower than few percent of thesolar value; second, the planet host star resides in a stellar evolutionarystage that is still unexplored in the exoplanet surveys; third, the star HIP13044 belongs to one of the most significant stellar halo streams in the solarneighborhood, implying an extragalactic origin of the planetary system HIP13044 in a disrupted former satellite of the Milky Way.
展开▼
机译：我们报告发现在HIP 13044附近检测到行星伴星，HIP 13044是红色水平分支上的贫金属星。探测是基于FEROS的径向速度观测，FEROS是位于智利ESO La Silla天文台的2.2-mMPG / ESO望远镜的高分辨率光谱仪。 P = 16.2天的径向速度变化可以与恒星活动指标的周期区分开。我们计算出该行星的最小行星质量为1.25 MJup，轨道半长轴为0.116 AU，这一发现在三个方面是独特的：首先，这是首次探测到一颗围绕金属的恒星，其金属度远低于太阳光的百分之几值;其次，行星寄主恒星处于恒星的演化阶段，系外行星的调查仍未对此进行探索。第三，恒星HIP13044属于太阳系中最重要的恒星晕流之一，这暗示着行星系统HIP13044的银河系起源是一颗被破坏的银河系前卫星。
展开▼
