Absolute Spectrophotometry of SN 1987A and the Hα Bochum Event

Abstract

AbstractSpectrophotometric optical fluxes of SN 1987A have been measured at high accuracy with the 61cm telescope equipped with a rapid spectrum scanner. This highly homogeneous data set covers the wavelength range 3200-8700Å at 10Å resolution. Selected wavelength regions, e.g. around Hα, have also been measured at 3Å resolution. The Hα line shows an undisturbed P Cygni-type profile until March 15, superimposed by variable fine-structure thereafter, developing within a few days into a blue-shifted, peak-like flux excess and a red-shifted flux deficiency. This fine-structure is intrinsic to Hα. Similar fine-structure is also observed in Na I-D, in Paschen-α and possibly in Hβ. We discuss our observations in terms of the ‘mystery spot’, and of models involving a jet and interactions with surrounding pre-existing material, and we propose density inhomogeneities, or occupation number deficits due to NLTE effects, within the inner regions of the envelope as origin.