Abstract:
A high quality optical spectrum of the 1981 Type I supernova in NGC 4536 at maximum light is well represented by a synthetic spectrum consisting of resonance scattering lines of Ca_II, Si_II, S_II, Mg_II, and O_I, superposed on a continuum. The assumption of LTE at the photosphere leads to relative abundances of Ca, Si, S, Mg, and O that are consistent with solar abundances for a range of continuum temperatures. The spectrum is inconsistent with models such as the "double-detonation" model in which material with v = (12-15) × 10³ km s⁻¹ is burned completely to Ni⁵⁶.
