Spiral shocks, triggering of star formation and the velocity dispersion in Giant Molecular Clouds

Details Spiral shocks, triggering of star formation and the velocity dispersion in Giant Molecular Clouds Spiral shocks, triggering of star formation and the velocity dispersion in Giant Molecular Clouds

2005-09-27

arxiv.org/abs/astro-ph/0509809v1

Mon.Not.Roy.Astron.Soc. 365 (2006) 37-45

Astronomy and Astrophysics

Astrophysics

9 pages, 6 figures, accepted for publication in MNRAS

Scientific paper

We present numerical simulations of the passage of clumpy gas through a galactic spiral shock and the subsequent formation of giant molecular clouds (GMCs). The spiral shock forms dense clouds while dissipating kinetic energy, producing regions that are locally gravitationally bound and collapse to form stars. The effect of the clumpiness of gas as it passes through the shock is to generate chaotic internal motions in the gas. The kinematics of these motions are found to agree with the observed velocity-dispersion/size relation found in star-forming regions. In contrast to the standard picture where continuously driven turbulence generates the density inhomogeneities in star-forming clouds, we find here that it is the clumpiness of the interstellar gas that produces the chaotic motions as it passes through the spiral shock and initiates the star formation process. The velocity dispersion can be understood as being due to the random mass loading of clumps as they converge in the spiral shock. In this model there is no need for any internal or external continuous driving mechanism for the 'turbulence'. The coupling of the clouds' internal kinematics to their externally triggered formation removes the need for the clouds to be self-gravitating. Indeed, while clearly some parts of the clouds are self-gravitating and able to form stars, most of the molecular material remains gravitationally unbound. This can provide a simple explanation for the low efficiency of star formation.

Affiliated with

Also associated with

No associations

Rating

Spiral shocks, triggering of star formation and the velocity dispersion in Giant Molecular 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 Spiral shocks, triggering of star formation and the velocity dispersion in Giant Molecular Clouds, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Spiral shocks, triggering of star formation and the velocity dispersion in Giant Molecular Clouds will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-225314