In a few billion years the Sun will destroy the solar system’s inner planets – and if it’s lucky it might get a big cool scar to brag about. That’s what happened to a white dwarf that astronomers have just found, which seems to have a bizarre metal scar on its surface, unlike anything ever seen before.
The white dwarf in question is named WD 0816-310, which at first feels like a classic example of astronomy’s uncreative naming processes, but if we want to stick to the theme it kind of sounds like a prison inmate number. Fittingly, this dying star bears a unique scar from its violent past.
White dwarfs are born among chaos – when a star of a certain mass exhausts its fuel supply, it chokes on its own waste and bursts outwards, leaving behind a dense core that then cools to the background temperature of the universe over trillions of years. And that usually spells doom for any planets that may have orbited the original star, whose shredded remains end up raining down onto the white dwarf.
Astronomers have previously spotted the telltale metallic signatures of these destroyed worlds on white dwarfs, but usually they cover the whole surface fairly evenly. But WD 0816-310 has somehow gathered all of its metals into one spot that it wears like a scar, a move so badass it’s never been seen before.
The discovery was made when astronomers using the Very Large Telescope noticed that the metallic signatures were changing as the white dwarf rotated, indicating higher concentrations in one spot. Intriguingly, the changes synced up with changes in the magnetic field, meaning the scar is located at one of its magnetic poles. That suggests that the planetary material falling towards the surface was guided by the magnetic field to the pole and then held there.
“We have demonstrated that these metals originate from a planetary fragment as large as or possibly larger than Vesta, which is about 500 km (310 mi) across and the second-largest asteroid in the Solar System,” said Jay Farihi, co-author of the study.
Never let anyone tell you space isn’t metal.
The research was published in the Astrophysical Journal Letters. The find is described in the video below.
Source: ESO
