Vortices arise from dead zones in disks around newly forming stars and help the stars complete their birth process.
A new theory by fluid dynamics experts at the University of California, Berkeley, shows how “zombie vortices” help lead to the birth of a new star.
Reporting earlier this week (August 20, 2013) in the journal Physical Review Letters, a team led by computational physicist Philip Marcus shows how variations in gas density lead to instability, which then generates the whirlpool-like vortices needed for stars to form.
Artist concept of a brown dwarf, spotted by NASA’s Spitzer Space Telescope, surrounded by a spinning protoplanetary disk. UC Berkeley researchers have developed a model that shows how vortices help destabilize the disk so that gas can spiral inward toward a forming star. Image courtesy of NASA/JPL-Caltech
Astronomers accept that in the first steps of a new star’s birth, dense clouds of gas collapse into clumps that, with the aid of angular momentum, spin into one or more Frisbee-like disks where a protostar starts to form. But for the protostar to grow bigger, the spinning disk needs to lose some of its angular momentum so that the gas can slow down and spiral inward onto the protostar. Once the protostar gains enough mass, it can kick off nuclear fusion.
“After this last step, a star is born,” said Marcus, a professor in the Department of Mechanical Engineering.
What has been hazy is exactly how the cloud disk sheds its angular momentum so mass can feed into the protostar.