NGC 4647 is an example of a late-type galaxy believed to be in the early stages of interaction with an early-type system. It appears to be both HI deficient and CO rich. Whilst the HI data indicate the system has a low atomic gas density, the 12CO (J=2-1) flux gives a molecular gas mass of ∼ 6 × 109 Msun corresponding to a surface density of ∼ 20 Msun pc-2, significantly larger than average for a galaxy of this type. The large CO to HI surface density ratio could be explained by enhanced HI to H2 conversion in the system.
- The Neutral ISM in Starburst Galaxies
- Pub Date:
- December 2004