An artist’s impression of a Neptune-like ice giant planet orbiting a white dwarf. Because it orbits the stellar remnant at close range, much of the planet’s atmosphere has been stripped away by intense ultraviolet radiation, forming a disc around the star. Image: ESO/M. Kornmesser
In the first observation of its kind, astronomers using the Very Large Telescope in Chile have found evidence of a Neptune-size planet orbiting a white dwarf, the collapsed remnant of a Sun-like star that has run out of nuclear fuel. The planet orbits so close to the dwarf that its atmosphere has been stripped away by intense ultraviolet radiation, forming a disc around the star.
“It was one of those chance discoveries,” said Boris Gänsicke, a researcher at the University of Warwick who led the study. The team was tipped off by finding traces of elements not seen in the spectra of some 7,000 other white dwarf stars observed by the Sloan Digital Sky Survey.
“We knew that there had to be something exceptional going on in this system, and speculated that it may be related to some type of planetary remnant,” he said.
Using the X-shooter instrument with the European Southern Observatory’s VLT, the team ...