Chugai, N. N.N. N.ChugaiDanziger, I. J.I. J.DanzigerDELLA VALLE, MassimoMassimoDELLA VALLE2022-10-042022-10-0419950035-8711http://hdl.handle.net/20.500.12386/32686An optical spectrum of SN 1978K (NGC 1313) in the range of 4000-7200 A was obtained on 1992 October 22, i.e. 14.4 yr after the outburst. The spectrum is still dominated by the narrow (FWHM<=560 km s^-1) Hα line having a luminosity 2.2x10^38 erg s^-1 (D=3.7 Mpc, A_V=0.64 mag), 1.5-2 times lower than the values derived from published data for 1989 December and 1990 October. There is no evidence for a broad Hα component (HWZI~3000-10000 km s^-1) with an upper limit of luminosity ~3x10^36 erg s^-1. We suggest that the optical emission of SN 1978K originates from radiative shock waves propagating in the dense (~4x10^6 cm^-3) clouds of a circumstellar wind. The cloud shock waves are driven by the expanding low-mass (<e1>M<=</e1>2M_solar) supernova ejecta with the present radius ~(2-3)x10^17 cm. The mass of circumstellar material involved in the dynamical interaction is ~=1M_solar and the corresponding mass-loss rate of pre-SN wind is ~2x10^-4 M_solar yr^-1. The observed X-ray emission is attributed to the shock waves in the boundary layer of the same population of clouds. Alternatively, however, the X-ray emission might emanate from the shock waves in a different cloud population with a lower density.STAMPAenArticle10.1093/mnras/276.2.530https://academic.oup.com/mnras/article/276/2/530/9988881995MNRAS.276..530CFIS/05 - ASTRONOMIA E ASTROFISICA