First Second-Generation Planet Found Orbiting Dead Star

Scientists have identified the first known second-generation planet — a world forged from the debris of a dead star rather than a primordial disk. The likely gas giant orbits white dwarf HS 0209+0832, located roughly 250 to 270 light-years from Earth near the constellation Cetus.

Researchers led by Jamie Williams at the University of Warwick spotted unusual heavy elements, notably niobium, on the white dwarf's surface using NASA's Hubble Space Telescope and TESS satellite. They interpret this as planetary material falling onto the stellar remnant, with a composition matching the ashes of the star's final evolutionary stages.

“This planetary material is very rich in an element called niobium. It is the first time this element has been found in a white dwarf, which implies the planetary material is composed of the ashes of the star after its death.”

The planet circles its host every 4.4 days at just 4 percent of the Earth-Sun distance. Extreme ultraviolet radiation from the hot white dwarf is evaporating the planet's outer atmosphere, some of which then rains back onto the star, revealing its chemical makeup.

Unlike first-generation planets that form alongside their stars, this object condensed from material expelled when the original star swelled into a red giant and shed its layers. The discovery, published in Nature Astronomy, opens a new window on planetary formation around stellar corpses.