"The stuff we see [in the disk] can't have been there before," said Boris Gansicke, an astrophysicist at the University of Warwick in the United Kingdom and the paper's lead author.
"It must have been brought to this place after the white dwarf formed."
He and his colleagues believe that the gas originated from a 30-mile-wide (50-kilometer-wide) asteroid that they think was kicked out of a stable orbit by an interaction with a large planetlike object.
The larger body forced the asteroid close enough to the white dwarf to be broken up by the star's gravity.
"It was just shredded to pebbles, and the white dwarf is quite hot still, so the material got evaporated to form the disk," Gansicke said.
Solar System Model
In a few billion years, Gansicke and colleagues expect our solar system to look similar to SDSS 1228+1040.
During our sun's red giant phase, the inner planets Mercury, Venus, and probably Earth will be destroyed, Gansicke noted.
But as the sun swells, it will lose about half its mass, and its weakened gravitational pull will allow Mars, the asteroid belt, and the outer planets to escape to wider orbits.
(Related news: "Early Life Fed on Organic Haze, Study Suggests" [November 6, 2006].)
After the dying sun becomes a white dwarf, one of the asteroids in the surviving asteroid belt may be knocked out of orbit by Jupiter's gravity and sent on a course close to the dead star.
That asteroid will eventually meet the same fate as the one that came too close to SDSS 1228+1040.
"We believe in five to eight billion years, the solar system will look very much like the white dwarf" in Virgo, Gansicke said.
"It will mainly have the asteroids going around it and a couple of planets."
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