1.3 MM emission in the disk of NGC 891 : evidence of cold dust.
Abstract
Using the IRAM 30-m telescope equipped with the MPIfR 7-channel bolometer array, we have mapped the λ 1.3 mm continuum emission of NGC 891, an edge-on Sb galaxy similar to the Milky Way. This emission is 7 times stronger along the major axis than the CO 2-1 line averaged over the 50 GHz bolometer passband, and 9 times stronger than the warm dust emission expected from the IRAS data. The λ 1.3 mm dust emission correlates remarkably well with the CO emission and poorly with HI emission, at least up to +/-7 kpc (150") from the center. It arises mostly from cold dust (T <= 20 K) associated with molecular clouds. The H_2_ mass, calculated using Galactic values of the dust absorption cross section, is ~3 times smaller than the H_2_ mass derived from the CO luminosity and Strong et al's (1988) `standard' Galactic CO to H_2_ conversion factor. It is about equal to the HI mass inside a 7 kpc radius. The mass of gas associated with the cold dust is ~20 times the mass of gas associated with warm dust.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- November 1993
- Bibcode:
- 1993A&A...279L..37G
- Keywords:
-
- Cosmic Dust;
- Interstellar Gas;
- Interstellar Matter;
- Molecular Clouds;
- Molecular Spectra;
- Radio Astronomy;
- Radio Spectra;
- Spiral Galaxies;
- Astronomical Spectroscopy;
- Carbon Monoxide;
- Emission Spectra;
- Hydrogen;
- Hydrogen Compounds;
- Iodides;
- Line Spectra;
- Radio Telescopes;
- Astronomy