GMC Origins and Turbulent Motions in Spiral and Dwarf Galaxies

Abstract

CO clouds can be non-self-gravitating in high pressure environments, while most should be strongly self-gravitating at low metallicities and ambient pressures. In the LMC, which is HI-rich, GMC formation and destruction should generally include molecule formation and destruction. In M51, which is CO-rich, GMCs grow by coalescence. The Milky Way is between these two situations. In all cases, large clouds form by accretion of gas and smaller clouds independently of the presence of molecules. GMCs in the Milky Way are analogous to dust lanes and spurs in other galaxies. The virial parameter alpha usually decreases monotonically with increasing cloud mass in surveys, which implies that small scale structure is formed by turbulence. Hierarchies of sequences with decreasing alpha should be present in cloud complexes from sub-solar masses up to the ambient Jeans mass (10^7 Msun).

4 pages, IAU Symposium 292, Beijing, August 2012

References in corpus (7)

• CO Isotopologues in the Perseus Molecular Cloud Complex: the X-Factor and Regional Variations
• The Magellanic Mopra Assessment (MAGMA). I. The Molecular Cloud Population of the Large Magellanic Cloud
• The Nature of the Dense Core Population in the Pipe Nebula: Thermal Cores Under Pressure
• The Atomic to Molecular Transition in Galaxies. I: An Analytic Approximation for Photodissociation Fronts in Finite Clouds
• Dynamically Driven Evolution of the Interstellar Medium in M51
• A High Resolution Study of the HI-H2 Transition across the Perseus Molecular Cloud
• The "Carina Flare" Supershell: Probing the Atomic and Molecular ISM in a Galactic Chimney