A giant planet that is evaporating because of its star. So far only small planets have been observed to meet this destiny and no one would have ever suspected that this fate could even touch a planet the size of Neptune, moreover rotating around a dying star, a white dwarf that is the equivalent of what will remain of our Sun at the end of its evolution. Published in Nature, the discovery is due to researchers coordinated by Boris Gaensicke, from the British university of Warwick.
The discovery, which indicates that even the dying stars can still host planets, happened by chance: while the researchers were studying at 7,000 white dwarfs surveyed by the Sloan Digital Sky Survey, they identified one different from each other due to the subtle variations in its brightness. "We suspected that in this system there could have been something exceptional - notes Gaensicke - and we hypothesized that it could be related to a planetary residue".
The researchers then observed the star, called WDJ0914 + 1914, which is about 1,500 light years from the constellation of Cancer, using the Very Large Telescope of the Southern European Observatory (ESO), in Chile. In this way they identified the traces of hydrogen, oxygen and sulfur in the gas disk surrounding the star, in amounts similar to those found in the atmosphere layers of the giant planets of the Solar System.
If a similar planet orbited near a warm white dwarf, its outer layers would evaporate, accumulating in a disk, and it is just what happens around WDJ0914 + 1914: with a temperature of around 28,000 degrees, the star is evaporating the giant planet , which loses over 3,000 tons of material per second.
