CO(1-0), CO(2-1) and Neutral Gas in NGC 6946: Molecular Gas in a Late-Type, Gas Rich, Spiral Galaxy

Understand

We present "On The Fly" maps of the CO(1-0) and CO(2-1) emission covering a 10' X 10' region of the NGC 6946.

• Using our CO maps and archival VLA HI observations we create a total gas surface density map, Sigma_gas, for NGC 6946.
• The predominantly molecular inner gas disk transitions smoothly into an atomic outer gas disk, with equivalent atomic and molecular gas surface densities at R = 3.5' (6 kpc).
• We estimate that the total H2 mass is 3 X 10^9 Mo, roughly 1/3 of the interstellar hydrogen gas mass, and about 2% of the dynamical mass of the galaxy at our assumed distance of 6 Mpc.