The findings foreshadow what might happen to our solar system when the sun dies in about five billion years, astronomers say.

As stars like our sun run out of nuclear fuel, they swell, becoming red giants. Astronomers think that when this happens to our star, its bulging atmosphere will engulf Mercury, Venus, and maybe even Earth.

(See "Red Giant Sun May Not Destroy Earth.")

Eventually, the outer layers of a sunlike star's atmosphere will balloon away to form a nebula, leaving the star's dense core—a white dwarf—shining in the center. (See a white dwarf picture.)

The study authors speculate that any planets not roasted by the star's initial expansion—which takes tens to a few hundred million years—would have their orbits destabilized