1999/11/05 by D. Branch, David Branch, David J. Jeffery +5 · 41 citations
Physics and Astronomy · #Absorption (acoustics) #Astronomy and Astrophysical Research #Astrophysics and Cosmic Phenomena #Emission spectrum #Gamma-ray bursts and supernovae #Intensity (physics) #Line (geometry) #Line width #Scattering #Spectral line #Supernova #Wavelength #astro-ph
paper · pdf · doi:10.1086/316510
published in Publications of the Astronomical Society of the Pacific 112(768), 217-223 (Institute of Physics) · accepted for publication in PASP
arxiv created 1999/11/05 · openalex publication_date 2000/02/01 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We discuss a simple model for the formation of a supernova spectral line by resonance scattering in the presence of external illumination of the line‐forming region by light from circumstellar interaction (toplighting). The simple model provides a clear understanding of the most conspicuous toplighting effect: a rescaling or, as we prefer, a "muting" of the line profile relative to the continuum. This effect would be present in more realistic models, but would be harder to isolate. An analytic expression for a muting factor for a P Cygni line is derived that depends on the ratio E of the toplighting specific intensity to the specific intensity from the supernova photosphere. If E<1, the line profile is reduced in scale or "muted." If E = 1, the line profile vanishes altogether. If E>1, the line profile flips vertically: then having an absorption component near the observer‐frame line‐center wavelength and a blueshifted emission component.