The First Direct Evidence of a White Dwarf Ripping a Planet Apart
Black holes may be well known for their gluttonous tendencies, but they’re not the only dead stars capable of slurping down passing objects. For years, evidence has been mounting that white dwarf stars also have a penchant for snacking – and on their own planets, no less.
Now, for the first time, astronomers have caught such a Cronian meal in action, betrayed by the flare of X-ray light as material from the planet falls down onto the stellar core.
“We have finally seen material actually entering the star’s atmosphere,” says astrophysicist Tim Cunningham of the University of Warwick in the UK.
“It is the first time we’ve been able to derive an accretion rate that doesn’t depend on detailed models of the white dwarf atmosphere.”
White dwarfs, just like neutron stars and black holes, are the collapsed cores of stars that reached the end of their main sequence life spans when they ran out of fuel for nuclear fusion. What differentiates them is the mass: white dwarfs are the cores of precursor stars up to eight times the mass of the Sun; neutron stars and black holes are from more massive stars.
During the end of its life, a dying star ejects most of its outer material. Nevertheless, exoplanets have been spotted orbiting white dwarfs. And, in recent years, astronomers have spotted signs that white dwarfs may have been accreting (or forming) exoplanets, too.