2003/11/10 by M. H. Heyer, E. Corbelli, S. E. Schneider +1 · 1 citation
Physics and Astronomy · #astro-ph
paper · pdf · doi:10.1086/381196
published as Astrophys.J. 602 (2004) 723-729 · 19 pages + 5 figures. Accepted for publication in ApJ
arxiv created 2003/11/10 · arxiv updated 2009/12/01
The relationship between the star formation rate and surface density of neutral gas within the disk of M33 is examined with new imaging observations of CO J=1-0 emission gathered with the FCRAO 14m telescope and IRAS HiRes images of the 60 micron and 100 micron emission. The Schmidt law, SigmaSFR ~ Sigmagasn, is constructed using radial profiles of the HI 21cm, CO, and far infrared emission. A strong correlation is identified between the star formation rate and molecular gas surface density. This suggests that the condensation of giant molecular clouds is the limiting step to star formation within the M33 disk. The corresponding molecular Schmidt index, nmol, is 1.36 +/- 0.08. The star formation rate has a steep dependence on total mass gas surface density, (SigmaHI+SigmaH2), owing to the shallow radial profile of the atomic gas which dominates the total gas surface density for most radii. The disk pressure of the gas is shown to play a prominent role in regulating the molecular gas fraction in M33.