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HST-COS Observations on Hydrogen, Helium, Carbon, and Nitrogen Emission from the SN 1987A Reverse ShockWe present the most sensitive ultraviolet observations of Supernova 1987 A to date. Imaging spectroscopy from the Hubble Space Telescope-Cosmic Origins Spectrograph shows many narrow (Delta v approximates 300 km/s) emission lines from the circumstellar ring, broad Delta v approximates 10-20 x 10(exp 3) km/s) 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(exp 2)S(sub 1/2)-l(exp 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 lambda1640, C IV lambda 1550, and N IV ] lambda1486 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) approximately 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.
Document ID
20120009502
Acquisition Source
Goddard Space Flight Center
Document Type
Reprint (Version printed in journal)
Authors
France, Kevin
(Colorado Univ. Boulder, CO, United States)
McCray, Richard
(Colorado Univ. Boulder, CO, United States)
Penton, Steven V.
(Colorado Univ. Boulder, CO, United States)
Kirshner, Robert P.
(Smithsonian Institution Cambridge, MA, United States)
Challis, Peter
(Smithsonian Institution Cambridge, MA, United States)
Laming, J. Martin
(Naval Research Lab. Washington, DC, United States)
Bouchet, Patrice
(Commissariat a l'Energie Atomique Gif-sur-Yvette, France)
Chevalier, Roger
(Virginia Univ. Charlottesville, VA, United States)
Garnavich, Peter M.
(Notre Dame Univ. IN, United States)
Fransson, Claes
(Stockholm Univ. Sweden)
Heng, Kevin
(Zurich Univ. Switzerland)
Larsson, Josefin
(Stockholm Univ. Sweden)
Lawrence, Stephen
(Hofstra Univ. Hempstead, NY, United States)
Lundqvist, Peter
(Stockholm Univ. Sweden)
Panagia, Nino
(Space Telescope Science Inst. Baltimore, MD, United States)
Pun, Chun S. J.
(Hong Kong Univ. Hong Kong)
Smith, Nathan
(Arizona Univ. Tucson, AZ, United States)
Sollerman, Jesper
(Stockholm Univ. Sweden)
Sonneborn, George
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Sugerman, Ben
(Goucher Coll. Towson, MD, United States)
Wheeler, J. Craig
(Texas Univ. Austin, TX, United States)
Date Acquired
August 25, 2013
Publication Date
December 2, 2011
Publication Information
Publication: The Astrophysical Journal
Publisher: American Astronautical Society
Volume: 743
Issue: 2
Subject Category
Astronomy
Report/Patent Number
GSFC.JA.6150.2012
Funding Number(s)
CONTRACT_GRANT: NAS5-98043
CONTRACT_GRANT: NAS5-26555
CONTRACT_GRANT: NNX08AC146
Distribution Limits
Public
Copyright
Other

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