2000/02/01 by Charles Danforth, Charles W. Danforth, R. H. Cornett +5 · 2 citations
Physics and Astronomy · #Astrophysics and Cosmic Phenomena #Ionosphere and magnetosphere dynamics #Solar and Space Plasma Dynamics #astro-ph
paper · pdf · doi:10.1086/301365
published as Astron.J. 119 (2000) 2319D · 21 pages with 10 figures. See http://www.pha.jhu.edu/~danforth/uit/ for full-resolution figures
arxiv created 2000/02/01 · openalex publication_date 2000/05/01 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/31
During the Astro-1 and Astro-2 space shuttle missions in 1990 and 1995, far ultraviolet (FUV) images of five 40' diameter fields around the rim of the Cygnus Loop supernova remnant were observed with the Ultraviolet Imaging Telescope (UIT). These fields sampled a broad range of conditions, including both radiative and nonradiative shocks in various geometries and physical scales. In these shocks, the UIT B5-band samples predominantly C IV λ1550 and the hydrogen two-photon recombination continuum. Smaller contributions are made by emission lines of [He II] λ1640 and O III] λ1665. We present these new FUV images and compare them with optical Hα and [O III] images and ROSAT HRI X-ray images. Comparing the UIT images with those from the other bands provides new insights into the spatial variations and locations of these different types of emission. By comparing with shock-model calculations and published FUV spectroscopy at select locations, we surmise that resonance scattering in the strong FUV permitted lines is widespread in the Cygnus Loop, especially in the bright optical filaments typically selected for observation in most previous studies.