October 3, 2013
A Hostile ‘Cosmic Weather Balloon’ At The Heart Of The Milky Way
John P. Millis, PhD for redOrbit.com - Your Universe Online
We live in relative safety, far away from immense explosions, extreme weather, and chaotic interactions. Of course, I speak of our little corner of the Milky Way, nearly two-thirds of the way out from the galactic center, nestled between two spiral arms. This relatively sparse section of the cosmos stands in stark contracts to the center of the galaxy, where star formation, supernovae and intense space-weather would make life as we know it nearly impossible.But as much as we know about this region, there are still some puzzling observations. For one, there seems to be significant star formation in a region where it wouldn’t necessarily be expected. In an attempt to better understand this, researchers are examining a dense gas cloud near the galactic center, one that they describe as a particularly “inhospitable place."
“In keeping with the metaphor, no one would ever build a ‘vacation home’ somewhere with such harsh conditions. Construction appears to be taking place nonetheless: there are gas clouds near the Galactic Centre where young stars appear to be forming,” says Dr. Paul Clark, a member of Prof. Dr. Ralf Klessen's team at the Centre for Astronomy of Heidelberg University (ZAH).
Normally, cool gas begins to contract, initiated by some outside force – like a passing star or a nearby supernova. Eventually, the gravitational collapse ceases as the heat produced by the collapse and the eventual nuclear fusion in the core sustains the object, creating a star.
“Near the Galactic Centre, this gas is much hotter than at the edges of the Galaxy due to the strength of the radiation field, leading us to believe that star formation at the center of the Milky Way differs from how we understand the process at its edges,” explains Clark.
Clark and his team examined the dense cloud G0.253+0.016 as a type of “cosmic weather balloon." Observations were used to measure the temperature of the system, and from this they derived the radiation intensity in the field. The simulations indicated that the radiation fields at the center of the Milky Way are at least 1,000 times stronger than in the area around our Sun.
"Carbon monoxide plays a key role in most star-forming regions, as it helps to regulate the cloud temperatures. The lower CO content in the Galactic Centre clouds will have strong implications for their evolution," according to Clark.
The team hopes to soon be able to zero in on the mechanism for star formation in this region and better understand the process in regions of high radiation.
A report of the team's study appeared in a recent edition of the Astrophysical Journal Letters.