Detection of the excited carbon lines at decametric waves in some galactic objects.
Abstract
Observations of the 25-MHz C-recombination absorption lines C638(alpha)-C641(alpha) toward l = 75 deg b = 0 deg in the Galaxy and toward NGC 2024, obtained using the north-south antenna of the Ukrainian UKR-2 radio telescope with beam size 30 arcmin x 15 deg and resolution 1.4 kHz during summer 1983, are reported. The data are presented graphically and analyzed with reference to hydrogenic and low-temperature dielectronic models of recombination. In the Galaxy field, a dielectronic model of recombination in a large region with Te = 50-100 K, Ne = 0.01-0.001/cu cm, effective scale 20-2 pc, hydrogen-atom number density 3-30/cu cm, and C ionization by diffuse Galactic UV radiation is found to be consistent with the observations. Near NGC 2024, the observations correspond best to the extended C II region identified by Kurtz et al. (1983) at 157 microns, with Ne = 0.3/cu cm, Te = 100 K, and effective scale 1 pc.
- Publication:
-
Pisma v Astronomicheskii Zhurnal
- Pub Date:
- December 1984
- Bibcode:
- 1984PAZh...10..912K
- Keywords:
-
- Astronomical Spectroscopy;
- Carbon;
- Line Spectra;
- Nebulae;
- Radio Astronomy;
- Absorption Spectra;
- Decametric Waves;
- Doppler Effect;
- Milky Way Galaxy;
- Resonance Lines;
- Astrophysics