Carnegie Institution for Science | 2015 Jun 25
[img3="What Boss’s model disk looks like after 205 years of evolution, courtesy of Alan Boss."]https://carnegiescience.edu/sites/carne ... valPic.jpg[/img3][hr][/hr]New work from Carnegie’s Alan Boss offers a potential solution to a longstanding problem in the prevailing theory of how rocky planets formed in our own Solar System, as well as in others. The snag he’s untangling: how dust grains in the matter orbiting a young protostar avoid getting dragged into the star before they accumulate into bodies large enough that their own gravity allows them to rapidly attract enough material to grow into planets. The study is published by The Astrophysical Journal.
In the early stages of their formation, stars are surrounded by rotating disks of gas and dust. The dust grains in the disk collide and aggregate to form pebbles, which grow into boulders, and so on increasing in size through planetesimals, planetary embryos, and finally rocky terrestrial planets. But there are some difficult outstanding questions raised by this theory. One of these is that the pressure gradient of the gas in the disk would create a headwind that would spiral the pebbles and boulders inward toward the young protostar, where they would be destroyed.
The problem is most acute in bodies that are between 1 and 10 meters in radius, because they would be most susceptible to the gas drag. If too many particles in this size range were lost, there wouldn’t be enough remaining to collide with each other and accumulate into planetesimals and, eventually, planets. ...
Orbital Survival of Meter-size and Larger Bodies During Gravitationally Unstable Phases of Protoplanetary Disk Evolution - Alan P. Boss
- Astrophysical Journal 807(1) 10 (2015 Jun 01) DOI: 10.1088/0004-637X/807/1/10