Astronomers Discover Comet Factory
Posted on June 11, 2013
Astronomers using the new Atacama Large Millimeter/submillimeter Array (ALMA) have imaged a comet factory. The astronomers imaged a "dust trap" around a young star in a system called Oph-IRS 48 (about 400 light-years from Earth). This region around the young star is where dust particles can grow by clumping together. The astronomers say it solves a mystery about how dust particles in discs eventually grow large enough to form comets, planets and other rocky bodies.
Astronomers were looking for a safe have (a dust trap) where grains can clump without being destroyed before they grow big enough to become comets or planets. Computer models suggest that dust grains grow when they collide and stick together, but when bigger dust balls collide at high speed they would break apart again. Dust traps were proposed as a way the dust clumps could build into large enough sized objects to survive on their own. In the dust trap bigger dust grains get trapped and can grow much larger by colliding and sticking together. This is the first observational proof of their existence in space.
Nienke van der Marel, a PhD student at Leiden Observatory in the Netherlands and lead author of the study says in a statement, "It's likely that we are looking at a kind of comet factory as the conditions are right for the particles to grow from millimetre to comet size. The dust is not likely to form full-sized planets at this distance from the star. But in the near future ALMA will be able to observe dust traps closer to their parent stars, where the same mechanisms are at work. Such dust traps really would be the cradles for new-born planets."
Here is an animation of the disc of dust surrounding the Oph-IRS 48 system. Bigger particles in this dust trap tend to clump together and grow bigger and bigger, eventually forming boulders and comets. Take a look: