The Two States of Star Forming Clouds

Details The Two States of Star Forming Clouds The Two States of Star Forming Clouds

2012-02-13

arxiv.org/abs/1202.2594v1

Astronomy and Astrophysics

Astrophysics

Solar and Stellar Astrophysics

19 pages, 20 figures

Scientific paper

We examine the effects of self-gravity and magnetic fields on supersonic turbulence in isothermal molecular clouds with high resolution simulations and adaptive mesh refinement. These simulations use large root grids (512^3) to capture turbulence and four levels of refinement to capture high density, for an effective resolution of 8,196^3. Three Mach 9 simulations are performed, two super-Alfv\'enic and one trans-Alfv\'enic. We find that gravity splits the clouds into two populations, one low density turbulent state and one high density collapsing state. The low density state exhibits properties similar to non-self-gravitating in this regime, and we examine the effects of varied magnetic field strength on statistical properties: the density probability distribution function is approximately lognormal; velocity power spectral slopes decrease with field strength; alignment between velocity and magnetic field increases with field; the magnetic field probability distribution can be fit to a stretched exponential. The high density state is characterized by self-similar spheres; the density PDF is a power-law; collapse rate decreases with increasing mean field; density power spectra have positive slopes, P({\rho},k) \propto k; thermal-to-magnetic pressure ratios are unity for all simulations; dynamic-to-magnetic pressure ratios are larger than unity for all simulations; magnetic field distribution is a power-law. The high Alfv\'en Mach numbers in collapsing regions explain recent observations of magnetic influence decreasing with density. We also find that the high density state is found in filaments formed by converging flows, consistent with recent Herschel observations. Possible modifications to existing star formation theories are explored.

Affiliated with

Also associated with

No associations

Rating

The Two States of Star Forming Clouds 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 The Two States of Star Forming Clouds, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The Two States of Star Forming Clouds will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-680620