HST-COS OBSERVATIONS OF HYDROGEN, HELIUM, CARBON, AND NITROGEN EMISSION FROM THE SN 1987A REVERSE SHOCK
- Center for Astrophysics and Space Astronomy, University of Colorado, 389 UCB, Boulder, CO 80309 (United States)
- JILA, University of Colorado and NIST, 440 UCB, Boulder, CO 80309 (United States)
- Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, MS-78, Cambridge, MA 02138 (United States)
- Naval Research Laboratory, Code 7674L, Washington, DC 20375 (United States)
- Service d'Astrophysique DSM/IRFU/SAp CEA - Saclay, Orme des Merisiers, F-91191 Gif-sur-Yvette (France)
- Department of Astronomy, University of Virginia, P.O. Box 400325, Charlottesville, VA 22904-4325 (United States)
- 225 Nieuwland Science, University of Notre Dame, Notre Dame, IN 46556-5670 (United States)
- Department of Astronomy, The Oskar Klein Centre, Stockholm University, S-106 91 Stockholm (Sweden)
- ETH Zuerich, Institute for Astronomy, Wolfgang-Pauli-Strasse 27, CH-8093 Zuerich (Switzerland)
- Department of Physics and Astronomy, Hofstra University, Hempstead, NY 11549 (United States)
- Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)
- Department of Physics, University of Hong Kong, Pok Fu Lam Road, Hong Kong (China)
- Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States)
- NASA Goddard Space Flight Center, Code 665, Greenbelt, MD 20771 (United States)
- Department of Physics and Astronomy, Goucher College, 1021 Dulaney Valley Road, Baltimore, MD 21204 (United States)
We present the most sensitive ultraviolet observations of Supernova 1987A to date. Imaging spectroscopy from the Hubble Space Telescope-Cosmic Origins Spectrograph shows many narrow ({Delta}v {approx} 300 km s{sup -1}) emission lines from the circumstellar ring, broad ({Delta}v {approx} 10-20 Multiplication-Sign 10{sup 3} km s{sup -1}) emission lines from the reverse shock, and ultraviolet continuum emission. The high signal-to-noise ratio (>40 per resolution element) broad Ly{alpha} emission is excited by soft X-ray and EUV heating of mostly neutral gas in the circumstellar ring and outer supernova debris. The ultraviolet continuum at {lambda} > 1350 A can be explained by H I two-photon (2s {sup 2} S{sub 1/2}-1s {sup 2} S{sub 1/2}) emission from the same region. We confirm our earlier, tentative detection of N V {lambda}1240 emission from the reverse shock and present the first detections of broad He II {lambda}1640, C IV {lambda}1550, and N IV] {lambda}1486 emission lines from the reverse shock. The helium abundance in the high-velocity material is He/H = 0.14 {+-} 0.06. The N V/H{alpha} line ratio requires partial ion-electron equilibration (T{sub e} /T{sub p} Almost-Equal-To 0.14-0.35). We find that the N/C abundance ratio in the gas crossing the reverse shock is significantly higher than that in the circumstellar ring, a result that may be attributed to chemical stratification in the outer envelope of the supernova progenitor. The N/C abundance may have been stratified prior to the ring expulsion, or this result may indicate continued CNO processing in the progenitor subsequent to the expulsion of the circumstellar ring.
- OSTI ID:
- 22004430
- Journal Information:
- Astrophysical Journal, Vol. 743, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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