Astronomers from the European Southern Observatory have just announced the discovery of an exoplanet orbiting a star whose origins lie outside the Milky Way. This star, HIP 13044, entered the Milky Way via the Helmi Stream, a stream of stars resulting from a collision with a nearby dwarf galaxy.
Title: A Giant Planet Around a Metal-poor Star of Extragalactic Origin Authors: Johny Setiawan (1), Rainer J. Klement (1), Thomas Henning (1), Hans-Walter Rix (1), Boyke Rochau (1), Jens Rodmann (2), Tim Schulze-Hartung (1) (1) MPIA Heidelberg, (2) ESTEC Noordwijk
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 Jupiter masses 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.
An exoplanet orbiting a star that entered our Milky Way from another galaxy has been detected by a European team of astronomers using the MPG/ESO 2.2-metre telescope at ESOs La Silla Observatory in Chile. The Jupiter-like planet is particularly unusual, as it is orbiting a star nearing the end of its life and could be about to be engulfed by it, giving tantalising clues about the fate of our own planetary system in the distant future. Read more
Title: A Giant Planet Around a Metal-Poor Star of Extragalactic Origin Authors: Johny Setiawan1, Rainer J. Klement, Thomas Henning, Hans-Walter Rix, Boyke Rochau, Jens Rodmann and Tim Schulze-Hartung
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 Mjup and its orbital semimajor 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.
The first planet has been found around a star that seems to be an interloper from another galaxy. Curiously, the star also contains fewer heavy elements thought to be needed to build planets than any other planet-hosting star yet discovered. The planet, which is 1.25 times as massive as Jupiter, lies 2300 light years from Earth and orbits a bloated, ageing star slightly less massive than the sun. Johny Setiawan of the Max Planck Institute for Astronomy in Heidelberg, Germany, and colleagues found the planet by the way its gravity caused its host star to wobble. Read more
Astronomers claim to have discovered the first planet originating from outside our galaxy. The Jupiter-like planet, they say, is part of a solar system which once belonged to a dwarf galaxy. This dwarf galaxy was in turn devoured by our own galaxy, the Milky Way, according to a team writing in the academic journal Science. Read more