Variations in the spectrum of the Seyfert Galaxy AK 120
Abstract
The intensity ratio of the emission lines (OIII) lambda 5007 and H beta decreased strongly within the 13 months between November 1978 and December 1979. Variations of line profiles and equivalent widths have also been observed. The physical conditions in the emission line region and the relevant time scales are discussed. It is concluded that the observed line changes are most likely caused by variations of the photoionizing flux.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- November 1981
- Bibcode:
- 1981A&A...103..216S
- Keywords:
-
- Astronomical Spectroscopy;
- Emission Spectra;
- Line Spectra;
- Periodic Variations;
- Seyfert Galaxies;
- Galactic Nuclei;
- H Beta Line;
- Oxygen Spectra;
- Photoionization;
- Spectral Energy Distribution;
- Astronomy