Ancient planets around Kapteyn’s star

Image source: Planetary Habitability Laboratory; modified July 8, 2014

Typical planetary systems detected by NASA’s Kepler mission are hundreds of light-years away. In contrast, Kapteyn’s star is the 25th nearest star to the sun and it is only 13 light years away from Earth. What makes this discovery different however, is the peculiar story of the star. Kapteyn’s star was born in a dwarf galaxy absorbed and disrupted by the early Milky Way. Such galactic disruption event put the star in its fast halo orbit. The likely remnant core of the original dwarf galaxy is omega Centauri, an enigmatic globular cluster 16, 000 light years from earth which contains hundreds of thousands of similarly old suns. This sets the most likely age of the planets at 11.5 billion years; which is 2.5 times older than Earth and ‘only’ 2 billion years younger than the universe itself (around 13.7 billion years). Dr Anglada-Escude adds: β€œIt does make you wonder what kind of life could have evolved on those planets over such a long time.”

Professor Richard Nelson, leader of the Astronomy Unit at QMUL, who didn’t participate in the research, commented: “This discovery is very exciting. It suggests that many potentially habitable worlds will be found in the next years around nearby stars by ground-based and space-based observatories such as ESA’s PLATO mission. Until we have detected a larger number of them, the properties and possible habitability of the near-most planetary systems will remain mysterious.”

Text taken from the QMUL press release which also contains a short fiction by Alistair Reynolds. The star itself has long been studied and its age and kinematic history would suggest planets were unlikely to exist there. The discovery of planets at Kapteyn’s star gives us the vital insight that planet formation was occurring very early in the history of our Galaxy.


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