Stars in their late stage of evolution , such as Horizontal Branch stars , are still largely unexplored for planets .
We report the detection of a planetary companion around HIP 13044 , a very metal-poor star on the red Horizontal Branch , based on radial velocity observations with a high-resolution spectrograph at the 2.2-m MPG/ESO telescope .
The star ’ s periodic radial velocity variation of P = 16.2 days caused by the planet can be distinguished from the periods of the stellar activity indicators .
The minimum mass of the planet is 1.25 M _ { \mathrm { jup } } and its orbital semi-major axis 0.116 AU .
Because HIP 13044 belongs to a group of stars that have been accreted from a disrupted satellite galaxy of the Milky Way , the planet most likely has an extragalactic origin .