White Dwarf HS 0209+0832 over Time (Artist’s Concept)

In this (not-to-scale) artist’s concept, a lower-mass star like the Sun (1) ages into a puffy red giant star (2) that eventually expels its outer envelope of gas and dust into space, which forms a disk around the bright cinder of its remaining core, called a white dwarf (3). A second-generation planet forms in this disk, orbiting the white dwarf and losing some of its atmosphere back onto the white dwarf’s surface (4).