Stimulated Emission of Recombination Lines in H i Regions
Abstract
Radio-frequency recombination lines arising from ionized atoms in H i regions can have intensities which are greatly strengthened over their equilibrium values as a result of stimulated emission due to a background continuum. It is suggested that the "anomalous" recombination line is formed in this way. In addition, hydrogen and helium recombination lines from H ii regions are expected to have components formed in H i clouds. Recombination lines may also be observable from H i clouds that are in the line of sight to nonthermal continuum sources. Such lines can be used to give a direct measure of the degree of ionization and abundances in the interstellar medium
- Publication:
-
The Astrophysical Journal
- Pub Date:
- October 1969
- DOI:
- 10.1086/180430
- Bibcode:
- 1969ApJ...158L..49D