A Planetary Companion around a Metal-Poor Star with Extragalactic Origin

J. Setiawan; R. Klement; T. Henning; H. -W. Rix; B. Rochau; T. Schulze-Hartung; J. Rodmann

doi:10.1063/1.3570972

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arXiv · 1102.0503

A Planetary Companion around a Metal-Poor Star with Extragalactic Origin

J. Setiawan·R. Klement·T. Henning·H. -W. Rix·B. Rochau·T. Schulze-Hartung·J. Rodmann

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Abstract

We report the detection of a planetary companion around HIP 13044, a metal-poor star on the red Horizontal Branch. The detection is based on radial velocity observations with FEROS, a high-resolution spectrograph at the 2.2-m MPG/ESO telescope, located at ESO La Silla observatory in Chile. The periodic radial velocity variation of P = 16.2 days can be distinguished from the periods of the stellar activity indicators. We computed a minimum planetary mass 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 planet detection around a star with a metallicity much lower than few percent of the solar value; second, the planet host star resides in a stellar evolutionary stage that is still unexplored in the exoplanet surveys; third, the star HIP 13044 belongs to one of the most significant stellar halo streams in the solar neighborhood, implying an extragalactic origin of the planetary system HIP 13044 in a disrupted former satellite of the Milky Way.

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J. Setiawan, R. Klement, T. Henning, H. -W. Rix, B. Rochau, T. Schulze-Hartung, J. Rodmann. 2011-02-02. A Planetary Companion around a Metal-Poor Star with Extragalactic Origin. https://doi.org/10.1063/1.3570972

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