First sub-mm spectral line observations with the IRAM 30-m telescope : a CO(j=3-2) map of IC 342.
Abstract
During the first sub-mm molecular line observations at the IRAM 30-m telescope, the central region of the galaxy IC 342 was mapped in the J = 3-2 transition of CO (at 345 GHz) with 8.4" angular resolution. The main emission feature is an elongated structure of deconvolved size 15", 22". Strongest emission arises from two peaks, which have a separation of 13". The velocity field could be due to rotation, the rotation axis being inclined with respect to the line-of-sight, and/or mass inflow. The ratio of the source averaged brightness temperatures in the 3-2 and 2-1 line is approximately unity, which is consistent with warm (T_kin_ >= 20K), optically thick emission. The gas must be severely clumped within our 8" beam: the beam filling factor of CO over the peaks is 6 to 12%. A scenario is proposed where infall of matter through a bar, visible in a CO map by Lo et al. (1984), into the nucleus could heat the gas and compress it to high densities critical for star formation.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- July 1990
- Bibcode:
- 1990A&A...233..410S
- Keywords:
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- Astronomical Spectroscopy;
- Carbon Monoxide;
- Line Spectra;
- Spiral Galaxies;
- Telescopes;
- Angular Resolution;
- Brightness Temperature;
- Galactic Nuclei;
- Interstellar Matter;
- Radio Telescopes;
- Rotational Spectra;
- Astrophysics