HIP 13044b

HIP 13044b, first extrasolar planet that was found orbiting a star that originated outside the Milky Way Galaxy. HIP 13044b has a mass at least 1.25 times that of Jupiter and orbits its host star, HIP 13044, every 16.2 days at a distance of 17.4 million km (10.8 million miles). It was discovered in 2010 by astronomers using a 2.2-metre (7.2-foot) telescope at the La Silla Observatory in Chile. HIP 13044 is at a distance of about 2,000 light-years from Earth in the constellation Fornax and is a star in the Helmi stream, the remnant of a dwarf galaxy that was torn apart into a “stream” of stars and captured by the Milky Way Galaxy after a close encounter between six billion and nine billion years ago.

Of all the stars with planets, HIP 13044 has the lowest amount of heavy elements, such as iron. It is thought that planets form around rocky central cores made from heavy elements in the disc of material left over after the formation of the star. Based on HIP13044’s composition, it is possible that HIP 13044b formed in a completely different manner than other planets and thus has no rocky central core.

HIP 13044 is a red giant star, a star late in its life that has expanded to many times its original size because it has exhausted the hydrogen fuel in its core and is shining through the burning of hydrogen in an extremely hot shell surrounding the now helium core. Most previous extrasolar planets have been found around stars that were still young enough to be burning hydrogen in their cores. If any inner planets existed, they were likely swallowed by HIP 13044 as it expanded into a red giant, and HIP 13044b itself may meet such a fate.