— A star's planet-forming dust disk vanished in less than two years.
— The dust grains probably were remnants of two rocky proto-planets that crashed.
— The finding adds a new twist into the story of how planets like Earth may form.
For a long while, it looked like the young star known as TYC 8241 2652 1 was getting ready to make some planets.
The sun-like star, located about 450 light-years from Earth in the constellation Centaurus was encircled by a disk of warm, brightly glowing dust located about as far away from the star as Mercury orbits the sun.
But something strange happened between 2008, when the star was observed by a powerful ground-based infrared telescope in Chile, and 2010 when NASA's WISE infrared space telescope took a look: The dust was gone.
"We said 'Whoa, what's going on here?'" astronomer Ben Zuckerman, with the University of California Los Angeles, told Discovery News.
The discovery has scientists wondering anew about the path from dust to planet.
"It doesn't look like it is quite a monotonic progression from tiny dust grains to full-fledge rocky planets as we and others might have believed. There may be bumps and wiggles and holes along the road," Zuckerman said.
The dust that once orbited around the star likely came from two small rocky bodies that were destroyed when they smashed into each other. Astronomers have found no evidence of any planets around the star.
As far as what happened to the dust, no one knows. One theory is that friction with intervening gas caused the dust to slow and fall onto the star, lured by gravity. Another idea is that the dust grains continued crashing into each other until, too small to remain in orbit, they got blasted out of the system. But whatever happened, happened fast.
"The disappearance … in less than two years is incredibly fast by our current understanding, and the impact of this is difficult to predict," astronomer Margaret Moerchen, with the European Southern Observatory in Chile, wrote in an analysis of the research published in Nature.
Astronomers plan to keep an eye on the star to see if another dust disk forms.
"My guess is that the star can and will make planets in the future because in order to produce so much dust a few decades ago it must have been pretty well along the way," Zuckerman said. "This was just a bit of glitch."
The star most likely has other proto-planets in orbit, similar to what produced the dust in the first place, which could be the source of a new dust disk.
"The best thing we can do at this point is to continue to observe the star and see what happens," said astronomer Carl Melis, with the University of California San Diego.
"If anything changes then that will be useful for trying to diagnose what actually happened here," Melis told Discovery News. "Even if the system doesn't change for a long period of time, that also is going to give some information."
The research appears in this week's Nature.