OPTICAL-SPECTRUM OF THE IR SOURCE IRC-1996(10420 IN 1992)

To understand the evolutionary stage of the peculiar supergiant IRC 10420, we have been taking spectra for several years at the 6-m telesc ope. The optical spectrum of IRC + 10420 in the years from 1992 throug h 1996 points to an increase in the effective temperature: a spectral class A5 instead of the former F8 determined by Humphreys et al. Now i t resembles the spectra of late-type B[e] stars. The spectrum contains both absorptions (mainly of ions) formed in the photosphere, apparent ly stationary with respect to the centre of mass of the star, and emis sions, which can be formed in the fossil expanding envelope as well as partly in its compressing region. Using our spectra and spectral data obtained by Oudmaijer, we estimate the atmospheric parameters T-eff = 8500 K, log g = 1.0, xi(t) = 12 km s(-1) and conclude that the metall icity of IRC + 10420 is solar: the average value [(V, Cr, Fe)/H]. = -0 .03. A combination of results allows us to consider IRC + 10420 as a m assive supergiant evolving to the WR stage.