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
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.