A Sun-Like Star 1,300 Light-Years Away Just Got Caught Eating One of Its Own Planets

When a star eats a planet, the event happens fast — sometimes in just days or weeks. Too fast for any telescope to catch in the act. But the chemical evidence lingers, and a team led by University of Michigan astronomers has now found it around the star TOI-5882, a near-twin of our Sun located about 1,300 light-years away.

The telltale clue was lithium. Stars naturally contain very little lithium — most of it gets consumed in nuclear fusion early in a star's life. Planets, on the other hand, are rich in the element. When TOI-5882 was measured, it showed far more lithium than any normal star of its type should possess. "You are what you eat," said lead researcher Brooke Kotten, a graduate student at U-M. "If a star eats a planet, it takes on a bunch of lithium."

To confirm the signal was unusual, the team compared TOI-5882 against dozens of similar stars. The lithium excess stood out clearly. The researchers estimate the swallowed planet was between a few Earth masses and the size of Neptune. A brown dwarf companion — a gaseous object more than 20 times the mass of Jupiter that orbits TOI-5882 — may have disrupted the planet's orbit and sent it spiraling into the star.

The study, published in The Astrophysical Journal, has implications closer to home. In about 5 billion years, our own Sun will expand into a red giant and engulf Mercury, Venus, and possibly Earth. By studying how stars consume planets now, astronomers are piecing together the final chapter of solar system evolution.