Statistical studies of interstellar absorption
Abstract
A maximum-likelihood function is used for a statistical analysis of interstellar absorption. Four models of the space distribution of dust clouds are considered: a uniform distribution and distributions where the mean cloud density decreases with height above the galactic plane in accordance with the barometric law, the plane of symmetry of the dust layer is inclined by some angle to the galactic plane, and the plane of symmetry of the dust layer is parallel to the galactic plane but displaced from it by a certain distance. It is found that the cloud mean optical depth is 0.24 mag, the number of clouds at a distance of 1 kpc is 7.1, the cloud optical depth increases to a value of 0.40 mag at a distance of 0.6 to 0.8 kpc, and the cloud density decreases while mean absorption increases. The half-thickness of the dust layer is estimated to be 100 to 120 pc, and it is concluded that the dust clouds are apparently not distributed uniformly in space.
- Publication:
-
Physical Processes in Gas-Dust Nebulae
- Pub Date:
- 1978
- Bibcode:
- 1978ppgd.book....3K
- Keywords:
-
- Cosmic Dust;
- Electromagnetic Absorption;
- Interstellar Extinction;
- Nebulae;
- Spatial Distribution;
- Maximum Likelihood Estimates;
- Milky Way Galaxy;
- Optical Thickness;
- Statistical Analysis;
- Astrophysics