Young Star Makes Scientists Rethink Their Planet Formation Theories

A new collaborative study has challenged scientists understanding of the planet formation and now suggests that planets might form much faster than previously thought or, stars harbouring planets could be far more numerous.

This study involved scientists from the University of Georgia; the University of California, San Diego; the University of California, Los Angeles; California State Polytechnic University and the Australian National University.

In 1983, the researchers had spotted the cloud of dust circling the young star in the Scorpius-Centaurus stellar nursery. This dust was thought to be some raw material that helps in planet formation.  The same star was observed in 2008 using a mid-infrared imager at the Gemini South Observatory in Chile and again with the same ground-based telescope in 2009. But 2008 observation showed an infrared emission pattern similar to the 1983 dimension, but 2009 observation triggered curiosity amongst the scientists. The infrared emission dropped by nearly two-thirds. By 2010, when NASA's Wide-field Infrared Survey Explorer (WISE) glimpsed the celestial body, the dust was almost gone.

According to study co-author Inseok Song, assistant professor of physics and astronomy in the UGA Franklin College of Arts and Sciences, "The most commonly accepted time scale for the removal of this much dust is in the hundreds of thousands of years, sometimes millions. What we saw was far more rapid and has never been observed or even predicted. It tells us that we have a lot more to learn about planet formation."

Lead author Carl Melis, a postdoctoral fellow at UC San Diego, said, "It's like the classic magician's trick: Now you see it, now you don't. Only in this case we're talking about enough dust to fill an inner solar system, and it really is gone."

The three potential mechanism offered by scientists are 'Runaway Planetary Accretion", 'Collisional Avalanche', the third explanation might be that the dust particles are so small that the constant stream of light from the star has ejected them all into space, where they have cooled off.

The researchers explored several different explanations for how such a large quantity of dust could disappear so rapidly, and each of their explanations challenges conventional thinking about planet formation.