Scientists may have found the first “second-generation” planet: a world that formed from the debris of its dead host star. Here is what the discovery means.

When a sun-like star dies, it swells into a red giant, sheds its outer layers and collapses into a hot, dense white dwarf. Any close planets are usually destroyed. But astronomers found chemical traces on the white dwarf HS 0209+0832 suggesting a new gas giant condensed from the ejected material.

The smoking gun is niobium, a heavy element found for the first time on a white dwarf’s surface. Heavy elements sink fast in white dwarfs, so they must have arrived recently, likely stripped from a nearby planet’s atmosphere. A repeating 4.4-day signal in NASA’s TESS data fits a giant planet in a tight orbit.

Why it matters: more than 95 percent of stars will become white dwarfs. If second-generation planets are common, white dwarfs could host far more planets than thought, and our own sun might gain a new planet billions of years from now. The planet is still a candidate, awaiting confirmation from the James Webb Space Telescope.