The properties and origins of molecular gas in the lenticular galaxiesNGC 404, 4710 and 5195.
Abstract
The recent detection of far infrared and CO emission from a sample of S0 galaxies prompted this study, a closer examination of the properties of the molecular interstellar medium in three S0s. ^12^CO 2 -> 1 and ^13^CO 1 -> 0 spectra were obtained and compared to ^12^CO 1 -> 0 spectra. The resultant line ratios are used to compare the molecular properties of the three S0s with those of normal spiral galaxies. Two of the galaxies, NGC 404 and NGC 4710, apparently have molecular clouds similar to those observed in normal spirals while the clouds in NGC 5195 are different. The molecular clouds in NGC 5195 are probably warmer and may be less dense or more clumpy, on average, than those seen in typical spiral galaxies. This may be related to the strong interaction evident between NGC 5194 and 5195. The calculated star formation rates in NGC 404, 4710 and 5195 can all be supported via return of gas to the interstellar medium from evolved stars. There is no evidence to suggest that the H_2_ in NGC 404 and 4710 is of external origin. A ^12^CO 1 -> 0 map of NGC 5195 is also presented. Two components of emission are present over much of the galaxy. The low velocity component, attributed to the overlying apiral arm of NGC 5194, is strongest to the southeast and south of the center of NGC 5195. The high velocity component, attributed to gas inside NGC 5195, is strongest at the center but is not symmetrically distributed over the galaxy. The CO velocity field is very confused, with several regions of high velocity gas present. This high velocity gas may be H_2_ captured from NGC 5194 during the recent interaction and now falling into NGC 5195.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- November 1990
- Bibcode:
- 1990A&A...239..125S
- Keywords:
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- Galactic Structure;
- Interstellar Gas;
- Molecular Clouds;
- Spiral Galaxies;
- Carbon;
- Emission Spectra;
- Molecular Gases;
- Astrophysics