The Spiral Arms Of Planet Birthing

The Spiral Arms Of Planet Birthing
December 30, 2011
by Adam Frank - NPR

Spiral arms in this disk surrounding a young star may be driven by a young planet.

We are used to seeing spiral arms in galaxies, but the physics of rotating astrophysical disks doesn't care too much about size. Thus one can find spiral arms in galaxies that are tens of thousand light-years wide, the rings around planets like Saturn that are tens of thousand mile and, in between, the billion mile wide disks of gas and dust surrounding young stars.

In each case there is some gravitational tug which gets the spiral pattern started. In the image above the "disk perturber" is probably a newly forming planet. When you gaze at those beautiful arcs you are seeing indirect evidence of a world in the throes of creation.

Sweet!

If you want details you can read the NSF press release. Here are a few choice quotes including comments from Carol Grady one of the lead astronomers of the work

The newly imaged disk surrounds SAO 206462, a star located about 456 light-years away in the constellation Lupus. Astronomers estimate that the system is only about 9 million years old. The gas-rich disk spans some 14 billion miles, which is more than twice the size of Pluto's orbit in our own solar system.

"Detailed computer simulations have shown us that the gravitational pull of a planet inside a circumstellar disk can perturb gas and dust, creating spiral arms. Now, for the first time, we're seeing these features," said Carol Grady, a National Science Foundation (NSF)-supported astronomer with Eureka Scientific, Inc.

"The surprise," said Grady, "was that we caught a glimpse of this stage of planet formation. This is a relatively short-lived phase."

PHOTO: http://www.npr.org/blogs/13.7/