Observations of formaldehyde along the galactic plane.
Abstract
Observations of the 4.83 GHz line of formaldehyde along the galactic plane between 8 and 60 degrees galactic longitude are presented. Spectra and longitude-velocity maps of optical depth are used to determine the radial distribution of formaldehyde. The distribution is found to have a peak at about 5.0 kpc from the galactic center, with a decline at longer radii, and a trough at about 3.5 kpc. The molecular hydrogen density inferred from these observations is in agreement with densities determined from observations of CO (0.15/cu cm at the radius of the sun), increasing exponentially towards the galactic center until a radius of 5 kpc. Observed formaldehyde column densities in the directions of strong H II regions are found to be incompatible with the radial distributions determined and observed distributions are consistent with a model in which formaldehyde is concentrated in the spiral arms.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- April 1979
- DOI:
- 10.1093/mnras/187.2.161
- Bibcode:
- 1979MNRAS.187..161F
- Keywords:
-
- Astronomical Spectroscopy;
- Formaldehyde;
- Interstellar Matter;
- Milky Way Galaxy;
- Molecular Spectra;
- Radial Distribution;
- Absorption Spectra;
- Carbon Monoxide;
- Density Distribution;
- Gas Density;
- H Ii Regions;
- Microwave Spectra;
- Optical Thickness;
- Radio Spectra;
- Spiral Galaxies;
- Astrophysics;
- Formaldehyde:Galactic Plane;
- Formaldehyde:Interstellar Molecules;
- Galactic Structure