Ultraviolet observations of SN 1987A with IUE and HST

Abstract

The first five years of IUE data of SN 1987A (1987.2 - 1992.5) have been re-analyzed to generate a complete catalog of the continuum emission from the supernova debris and the narrow high-temperature emission lines from the circumstellar gas. Special attention is paid on the correct subtraction of the flux from the neighboring stars in the aperture. The bolometric luminosity of SN 1987A is re-calculated to properly include contribution from the UV flux, which becomes increasingly important in late times (at day 800, L(UV)/L(UVOIR) = 0.07). Also, the narrow line data provide improved measurements of the properties of the emitting circumstellar gas, such as size, inclination, and abundance. Efforts to establish a long term evolution of the UV photometry and spectroscopy of the supernova system with IUE and HST axe described. Recent far-UV STIS observations (1997.5) of the shock interaction between the high-velocity supernova debris and the circumstellar gas, in the form of a high-velcity (v ∼ ±20,000 km s -1) broad Lyα emission and a localized 'hot spot' (v ≲ 250 km s -1), associated with reverse and forward shocks, respectively, are presented.