Tony Wong (ATNF)

Atomic and molecular gas in disk galaxies- Dr Tony Wong Colloquium

ATNF Basement Meeting Room

Abstract

Current knowledge of the radial distributions of atomic and molecular
gas in disk galaxies will be briefly reviewed. Almost all of our
knowledge is based on observations of the HI and CO lines at 21 cm and
2.6 mm wavelength, and some of the caveats associated with these methods
are discussed. In nearby spiral galaxies the molecular gas fraction is
observed to decrease with radius, which can be understood in terms of
a decline in hydrostatic disk pressure. However, as observations of
the LMC demonstrate, stochastic effects tend to dominate on sub-kpc
scales, and other sources of external pressure may affect clouds as well.
The implications of these findings for molecular cloud formation, star
formation recipes, and the molecular content of damped Lyman-alpha systems
will be briefly discussed.