Image caption This artist's impression shows HIP 13044 b, an exoplanet orbiting a star that entered the Milky Way from another galaxy 
 
 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. 
 
 The star, called HIP 13044, is nearing the end of its life and is 2000 light years from Earth. 
 
 The discovery was made using a telescope in Chile. 
 
 Cosmic cannibalism 
 
 Planet hunters have so far netted nearly 500 so-called "exoplanets" outside our Solar System using various astronomical techniques. 
 
 Media playback is unsupported on your device Media caption A video shows how the distant solar system may appear 
 
 But all of those so far discovered, say the researchers, are indigenous to our own galaxy, the Milky Way. 
 
 This find is different, they say, because the planet circles a sun which belongs to a group of stars called the "Helmi stream" which are known to have once belonged to a separate dwarf galaxy. 
 
 This galaxy was gobbled up by the Milky Way between six and nine billion years ago in an act of intergalactic cannibalism. 
 
 The new planet is thought to have a minimum mass 1.25 times that of Jupiter and circles in close proximity to its parent star, with an orbit lasting just 16.2 days. 
 
 Image caption The exoplanet was detected by a team using the MPG/ESO 2.2-m telescope in Chile 
 
 It sits in the southern constellation of Fornax. 
 
 The planet would have been formed in the early era of its solar system, before the world was incorporated into our own galaxy, say the researchers. 
 
 "This discovery is very exciting," said Rainer Klement of the Max Planck Institute for Astronomy in Heidelberg, Germany, who targetted the stars in the study. 
 
 "For the first time, astronomers have detected a planetary system in a stellar stream of extragalactic origin. This cosmic merger has brought an extragalactic planet within our reach." 
 
 Dr Robert Massey of the UK's Royal Astronomical Society said the paper provided the first "hard evidence" of a planet of extragalactic origin. 
 
 "There's every reason to believe that planets are really quite widespread throughout the Universe, not just in our own galaxy, the Milky Way, but also in the thousands of millions of others there are," he said, "but this is the first time we've got hard evidence of that." 
 
 End Days 
 
 The new find might also offer us a glimpse of what the final days of our own Solar System may look like. 
 
 HIP 13044 is nearing its end. Having consumed all the hydrogen fuel in its core, it expanded massively into a "red giant" and might have eaten up smaller rocky planets like our own Earth in the process, before contracting. 
 
 The new Jupiter-like planet discovered appears to have survived the fireball, for the moment. 
 
 "This discovery is particularly intriguing when we consider the distant future of our own planetary system, as the Sun is also expected to become a red giant in about five billion years," said Dr Johny Setiawan, who also works at the Max Planck Institute for Astronomy, and who led the study. 
 
 "The star is rotating relatively quickly," he said. "One explanation is that HIP 13044 swallowed its inner planets during the red giant phase, which would make the star spin more quickly." 
 
 The new planet was discovered using what is called the "radial velocity method" which involves detecting small wobbles in a star caused by a planet as it tugs on its sun. 
 
 These wobbles were picked up using a ground-based telescope at the European Southern Observatory's La Silla facility in Chile. ||||| Some extrasolar planets are truly out of this world. 
 
 Astronomers have for the first time discovered a planet in the Milky Way that came from another galaxy. The planet, which has a mass of at least 1.25 Jupiters, orbits an elderly star that was ripped from a small satellite galaxy some 6 to 9 billion years ago. 
 
 Johny Setiawan and Rainer Klement of the Max Planck Institute for Astronomy in Heidelberg, Germany, describe the finding online November 18 in Science. 
 
 “The coolness factor is definitely that the planet and star came from another galaxy,” says Sara Seager of MIT, who was not part of the study. “The planet almost certainly formed during the time the star was in the other galaxy.” 
 
 In hunting for extrasolar planets, Setiawan and his colleagues homed in on HIP 13044, about 2,000 light-years from Earth, because it’s part of a stream of stars called Helmi, believed to have originated in another galaxy. The star’s motion could also be monitored for many months each year with a spectrograph at the European Southern Observatory’s La Silla site in Chile, looking for telltale wobbles that would indicate the tiny tug of an unseen, orbiting planet. 
 
 HIP 13044 and the other stars in the Helmi stream stand out in the solar neighborhood because they have elongated orbits that take them about 42,000 light-years above and below the plane of the Milky Way’s disk. Such orbits strongly suggest the stars were part of a group torn from a satellite galaxy and stretched out by gravitational tidal forces into a filament or stream. 
 
 The discovery, notes planet hunter Scott Gaudi of Ohio State University in Columbus, “is doubly weird: It is a weird planet around a weird star.” The star is unusual because it has the lowest abundance of metals — about 1 percent of the sun’s — of any star known to have a planet. (In astronomical parlance, a metal refers to any element heavier than helium.) The vast majority of the roughly 500 extrasolar planets known are found around stars with a much higher metal abundance, and the leading theory of planet formation suggests that stars with high metal contents are those that form giant, Jupiter-like planets. 
 
 Also unusual is that HIP 13044 is old enough to have exhausted its supply of hydrogen fuel and passed through the red giant phase of evolution, in which it mushroomed in size. Since then the star contracted to a diameter about seven times that of the sun and is now burning helium at its core. A star in this phase of evolution, known as the red horizontal branch, has never before been found to have a planet. 
 
 In part, that’s because the enhanced activity of old, evolved stars, including the presence of magnetically driven disturbances known as starspots, makes it more difficult to discern a stellar wobble, says Setiawan. In addition, “there is a high risk that you will not find any planets because they have been engulfed by the star during the [red giant] evolutionary phase,” he adds. 
 
 In order to survive, HIP 13044’s planet, which now resides much closer to the star than Mercury does to the sun, must have originally orbited at a much greater distance, the researchers say. That’s the only way it could have escaped being swallowed during the time the star was a red giant. (In several billion years, the sun will also become a puffed-up red giant and is likely to engulf Earth and the other inner planets.) 
 
 Other planets that resided closer to HIP 13044 would not have been so lucky. One explanation for the star’s relatively rapid rate of rotation is that it has been spun up by the angular momentum of planets it swallowed. Other rapidly rotating, elderly stars that have evolved to the red horizontal branch may have had similar dining habits, researchers have previously noted. 
 
 Even though the newfound planet has dodged one bullet, it will soon face another. In a few million years, when the star exhausts all the helium forged at its core, it will undergo a more rapid and larger expansion in which the planet is likely to be destroyed. 
 
 See Also:
– As planets go, HIP 13044B is one hell of a survivor. Astronomers say the planet—the first one originating from another galaxy ever found in the Milky Way—is part of a solar system that once belonged to a dwarf galaxy that was cannibalized by our own. The planet has already survived its elderly star's red giant phase, which left it with an unusual orbit that drew it to astronomers' attention, Wired reports. The intergalactic immigrant is the first concrete evidence that planets exist in other galaxies. "There's every reason to believe that planets are really quite widespread throughout the universe, not just in our own galaxy, the Milky Way, but also in the thousands of millions of others there are," one astronomer tells the BBC. "This is the first time we've got hard evidence of that." Researchers say the find provides clues about the likely fate of our own solar system.