Physical Properties and Galactic Distribution of Molecular Clouds identified in the Galactic Ring Survey

Details Physical Properties and Galactic Distribution of Molecular Clouds identified in the Galactic Ring Survey Physical Properties and Galactic Distribution of Molecular Clouds identified in the Galactic Ring Survey

2010-10-14

arxiv.org/abs/1010.2798v1

Astrophysical Journal 723 (2010) 492-507

Astronomy and Astrophysics

Astrophysics

Galaxy Astrophysics

Scientific paper

We derive the physical properties of 580 molecular clouds based on their 12CO and 13CO line emission detected in the University of Massachusetts-Stony Brook (UMSB) and Galactic Ring surveys. We provide a range of values of the physical properties of molecular clouds, and find a power-law correlation between their radii and masses, suggesting that the fractal dimension of the ISM is around 2.36. This relation, M = (228 +/- 18) R^{2.36+/-0.04}, allows us to derive masses for an additional 170 GRS molecular clouds not covered by the UMSB survey. We derive the Galactic surface mass density of molecular gas and examine its spatial variations throughout the Galaxy. We find that the azimuthally averaged Galactic surface density of molecular gas peaks between Galactocentric radii of 4 and 5 kpc. Although the Perseus arm is not detected in molecular gas, the Galactic surface density of molecular gas is enhanced along the positions of the Scutum-Crux and Sagittarius arms. This may indicate that molecular clouds form in spiral arms and are disrupted in the inter-arm space. Last, we find that the CO excitation temperature of molecular clouds decreases away from the Galactic center, suggesting a possible decline in the star formation rate with Galactocentric radius. There is a marginally significant enhancement in the CO excitation temperature of molecular clouds at a Galactocentric radius of about 6 kpc, which in the longitude range of the GRS corresponds to the Sagittarius arm. This temperature increase could be associated with massive star formation in the Sagittarius spiral arm.

Affiliated with

Also associated with

No associations

Rating

Physical Properties and Galactic Distribution of Molecular Clouds identified in the Galactic Ring Survey does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Physical Properties and Galactic Distribution of Molecular Clouds identified in the Galactic Ring Survey, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Physical Properties and Galactic Distribution of Molecular Clouds identified in the Galactic Ring Survey will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-284602