FCRAO Observations of M33

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 emissions gathered with the FCRAO 14m telescope (see Figure) and IRAS HiRes images of the 60micron and 100micron emissions. The Schmidt law, Sigma_SFR ~ Sigma_gas^n, is constructed using radial profiles of the HI 21cm, CO, and far infrared emissions. 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, n_mol, is 1.36 +/- 0.08. The star formation rate has a steep dependence on total mass gas surface density, (Sigma_HI+Sigma_H_2), 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.

CO Integrated Intensity

M33 CO J=1-0
FCRAO 14m Telescope
SEQUOIA focal plane array