TURATTO, MassimoMassimoTURATTOCAPPELLARO, EnricoEnricoCAPPELLARODanziger, I. J.I. J.DanzigerBENETTI, StefanoStefanoBENETTIGouiffes, C.C.GouiffesDELLA VALLE, MassimoMassimoDELLA VALLE2022-09-292022-09-2919930035-8711http://hdl.handle.net/20.500.12386/32667We present a set of optical observations of SN 1988Z covering a period of 3 yr from the discovery. This relatively bright supernova shows an unusual photometric behaviour, with broad light curves in the B, V and R bands resembling those of SN 1987F. The colour evolution is unique, with a slow blueward evolution in the early months, after which it remains nearly constant. The spectrum is characterized at all epochs by strong Balmer emission, without the usual P Cygni absorption component which is typical of SNeII at early stages. Several He I emission lines are also visible. These lines have a complex structure, with several components evolving with time with respect to both width and intensity. The Hα luminosity decline is exceptionally slow and cannot be explained by a simple radioactive model, so this object is an ideal candidate for a supernova in which there is interaction of the SN ejecta with a circumstellar wind. A number of unresolved, forbidden emission lines of [O III], [N II], [Ne III], [Fe II], [Fe III], [Fe VII], [Fe x] and, tentatively, of [Fe xI], [A x] and [Ca V] have been identified. Their presence and relative strengths suggest the existence of a shock, which gives further support to the theory of an ejecta-wind interaction.STAMPAenArticle10.1093/mnras/262.1.128https://academic.oup.com/mnras/article/262/1/128/10335881993MNRAS.262..128TFIS/05 - ASTRONOMIA E ASTROFISICA