A team of German astronomers has founda Jupiter-like exoplanetorbiting around a very old star of extragalactic origin which the Milky Way “devoured”, in an act ofgalactic cannibalism, between six and nine billion years ago. The finding questions current models of planet formation.
Commonly accepted astrophysical models predict thatthe probability of planets forming increases when a star contains more metals. However, Johny Setiawan and other colleagues from the Max Planck Institute for Astronomy (Germany) have discovered a planet, theHIP 13044 b, orbiting a star that is extremely metal-poor and, furthermore, very old. Specifically, the starHIP 13044it has passed the red giant phase in its stellar evolution. In principle, the newly discovered planet should have been absorbed by part of the star as it expanded.
According to the authors, the information is interesting to predicthow the planets of the Solar System will evolve when the Sun becomes a red giant. “The close orbit of this planet (with a mass slightly greater than that of Jupiter) could be an indication that the giants of our solar system could also end up closer to a” post-red “giant Sun,” suggests Setiawan.
The discovery ofHIP 13044 bwas performed using the 2.2-meter MPG telescope of theEuropean Southern Observatory (ESO)in La Silla (Chile), and during the course of a systematic search project for planets orbiting stars in the last stages of stellar evolution. In the past 15 years, astronomers have detected about 500 planets around stars in our cosmic neighborhood, but so far none have been confirmed to come from outside the Milky Way.
