DIFFERENCES IN THE EMISSION-LINE SPECTRUM AT MAXIMUM AND MINIMUM OF THE NUCLEAR BRIGHTNESS OF THE SEYFERT-GALAXY NGC-7469

Citation
Ii. Pronik et al., DIFFERENCES IN THE EMISSION-LINE SPECTRUM AT MAXIMUM AND MINIMUM OF THE NUCLEAR BRIGHTNESS OF THE SEYFERT-GALAXY NGC-7469, Astrophysics and space science, 239(1), 1996, pp. 97-111
Citations number
72
Categorie Soggetti
Astronomy & Astrophysics
ISSN journal
0004640X
Volume
239
Issue
1
Year of publication
1996
Pages
97 - 111
Database
ISI
SICI code
0004-640X(1996)239:1<97:DITESA>2.0.ZU;2-3
Abstract
We have compiled data on relative intensities, fluxes and profiles of emission lines of the NGC 7469 nuclear spectrum observed in the optica l region by many authors during 1966-1986. The aim of our investigatio n is to reveal differences in the characteristics of the emission line s in maxima and minima of the nuclear brightness. The distinction was revealed for relative intensities, fluxes and profiles. During the ext reme maxima profiles of H-gamma, H-beta and H-alpha lines, colour indi ces of the nucleus and its high level of accretion rate resemble those of QSOs. On the other hand, during the deep minimum 1989 the nucleus had the properties of a Sy2 type. There is a relation between variable fluxes of H-beta and [OIII] lambda 5007 Angstrom lines which is diffe rent for the minima and maxima of the nuclear brightness. The fluxes o f the [OIII] lambda 5007 Angstrom line during the minima of the nuclea r brightness are systematically higher than those in maxima. The above mentioned peculiarities of the emission lines in the NGC 7469 nucleus can be understood in terms of the increase of electron temperature, e lectron density and velocities of the nuclear gas from minimum to maxi mum.