Feature
The Star That Ate a Mars
Astronomers study white dwarf pollution for clues to extrasolar planet ingredients
For several years, UCLA astronomers have studied GD 362, a peculiarly dirty white dwarf star 165 light-years away in the constellation Hercules. Now they are pretty sure why the atmosphere of this dense, hot but slowly cooling ghost of a once much larger star is so polluted. It ate a planet.
“We probably have a destroyed world here,” says Michael Jura, coleader of the UCLA team. Apparently a planet with the mass of Mars — a billion trillion metric tons or so of rock, iron, dissociated water and other ingredients — was dismembered and atomized, its remains now bobbing in the thin but dense, 10,000 kelvins atmosphere that GD 362’s powerful gravity holds close around itself.
Like a specimen on the ultimate autopsy table, the supposed planet has its insides spread wide for inspection. It would thus appear to provide science its first look at the composition of an alien, rocky and roughly Earthlike planet in an exosolar planetary system. In
