Hβ and continuum variability in the Seyfert galaxy Akn 120 from Crimean observations during 1974-1990
Abstract
Crimean spectroscopic observations of the nucleus of the Seyfert galaxy Akn 120 during 1974-1990 are presented. Observations of the H_beta region are used to show that the flux variations in H_beta follow the flux variations in the continuum near lambda 5100 A with a lag of 34-54 days. The cross-correlation between the H_beta wings and the continuum provides evidence for accretion of the matter that is responsible for the line emission. The reproducibility of the H_beta profiles on time scales of about a year or longer at significant continuum variations suggests that the ionization conditions in the broad-line region are reproducible. The emission of the FeII lines, which form the so-called "red shelf," has been separated from the blend of H_beta with FeII. The flux variations in the lines of ionized iron in this shelf and in the FeII (lambda 4570 A) blend correlate with the H_beta-flux variations, suggesting that the H_beta- and FeII-line regions are close in space. An attempt is made to represent the broad H_beta-line profile by Gaussians. If the line profile is fitted by three Gaussian components, then the flux in the short-wavelength component, which is shifted from the systematic velocity by -750 km/s, correlates best with the continuum.
- Publication:
-
Astronomy Letters
- Pub Date:
- September 1999
- Bibcode:
- 1999AstL...25..569D