Ultraviolet Opacity and Fluorescence in Supernova Envelopes

Abstract

view Abstract Citations (21) References (30) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Ultraviolet Opacity and Fluorescence in Supernova Envelopes Li, Hongwei ; McCray, Richard Abstract By the time the expanding envelope of a Type II supernova becomes transparent in the optical continuum most of the gamma-ray luminosity produced by radioactive Fe/Co/Ni clumps propagates into the hydrogen/ helium envelope and is deposited there, if at all. The resulting fast electrons excite He I and H I, the two- photon continua of which are the dominant internal sources of ultraviolet radiation. The UV radiation is blocked by scattering in thousands of resonance lines of metals and converted by fluorescence into optical and infrared emission lines that escape freely. We describe results of Monte Carlo calculations that simulate non-LTE scattering and fluorescence in more than five million allowed lines of Ca, Sc, Ti, V, Cr, Mn, Fe, Co, and Ni. For a model approximating conditions in the envelope of SN 1987A, the calculated emergent spectrum resembles the observed one. For the first 2 yr after explosion, the ultraviolet radiation (λ ≲ 3000 Å) is largely blocked and converted into a quasi continuum of many thousands of weak optical and infrared emission lines and some prominent emission features, such as the Ca II λλ8600 triplet. Later, as the envelope cools and expands, it becomes more transparent, and an increasing fraction of the luminosity emerges in the UV band. Publication: The Astrophysical Journal Pub Date: January 1996 DOI: 10.1086/176659 Bibcode: 1996ApJ...456..370L Keywords: RADIATIVE TRANSFER; LINE: FORMATION; STARS: ATMOSPHERES; STARS: SUPERNOVAE: GENERAL; STARS: SUPERNOVAE: INDIVIDUAL ALPHANUMERIC: SN 1987A full text sources ADS | data products NED (2) SIMBAD (1)