Technology & Science

This real-life Death Star eats planets, new study suggests

A new study provides evidence that interplanetary violence may not be just for the movies. An international research team discovered a planetary system with a host star similar to Earth’s sun, and the star’s composition suggests it ingested some of its planets.

'Violent histories may be common for planetary systems,' researchers say

HIP68468, a twin star to the sun about 300 light-years away, may have swallowed one or more of its planets, based on lithium and refractory elements recently discovered near its surface. (Gabi Perez/Instituto de Astrofísica de Canarias Illustration)

A new study provides evidence that interplanetary violence may not be just for the movies.

In Star Wars, the Death Star can destroy a planet with a single blast. Now, scientists have discovered a host star with a similar capability, but instead of shooting another planet, this star eats planets for lunch.

An international research team discovered a planetary system with a star similar to Earth's sun. The star's composition suggests it ingested some of its planets, according to a study published in Astronomy & Astrophysics.

"It doesn't mean that the sun will 'eat' the Earth any time soon," co-author Jacob Bean said. "But our discovery provides an indication that violent histories may be common for planetary systems, including our own."

The first planet orbiting a star other than the sun (these worlds are called exoplanets) was discovered in 1995. Astronomers have since found more than two thousand exoplanets, but studying stars that are similar to our sun — called solar twins — and their connections to their planets is rare.

Clues but not conclusions

Although this solar twin provides clues, researchers are careful to point out that conclusions can't be drawn from a single system.

The research team plans "to study more stars like this to see whether this is a common outcome of the planet formation process," co-author Megan Bedell said.

The star's composition points to a history of ingesting planets, the researchers say. It contains four times more lithium and a surplus of refractory elements, which are metals resistant to heat and are abundant in rocky planets.

Scientists explain that stars with hot interiors, like the sun and this star, consume lithium over time. However, planets preserve lithium because their inner temperatures aren't as hot. Therefore, when a star engulfs a planet, the lithium from the planet stands out.

"It's as if we saw a cat sitting next to a bird cage," Debra Fischer, an astronomy professor at Yale who wasn't involved in the study, said. 

"If there are yellow feathers sticking out of the cat's mouth, it's a good bet that the cat swallowed a canary."