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Date and Time of the Query: 2019-08-25 T10:39:24 PDT
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For refcode 2005ApJ...622..991F:
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2005ApJ...622..991F Hubble Space Telescope and Ground-based Observations of SN 1993J and SN 1998S: CNO Processing in the Progenitors Claes Fransson, Peter M. Challis, Roger A. Chevalier, Alexei V. Filippenko, Robert P. Kirshner, Cecilia Kozma, Douglas C. Leonard, Thomas Matheson, E. Baron, Peter Garnavich, Saurabh Jha, Bruno Leibundgut, Peter Lundqvist, C. S. J. Pun, Lifan Wang, and J. Craig Wheeler Abstract. Ground-based and Hubble Space Telescope observations are presented for SN 1993J and SN 1998S. SN 1998S shows strong, relatively narrow circumstellar emission lines of N III - v and C III - IV, as well as broad lines from the ejecta. Both the broad ultraviolet and optical lines in SN 1998S indicate an expansion velocity of ~7000 km s^-1^. The broad emission components of Ly{alpha} and Mg II are strongly asymmetrical after day 72 past the explosion and differ in shape from H{alpha}. Different models based on dust extinction from dust in the ejecta or shock region, in combination with H{alpha} from a circumstellar torus, are discussed. It is concluded, however, that the double-peaked line profiles are more likely to arise as a result of optical depth effects in the narrow, cool, dense shell behind the reverse shock than in a torus-like region. The ultraviolet lines of SN 1993J are broad, with a boxlike shape, coming from the ejecta and a cool, dense shell. The shapes of the lines are well fitted by a shell with inner velocity ~7000 km s^-1^ and outer velocity ~10,000 km s^-1^. For both SN 1993J and SN 1998S a strong nitrogen enrichment is found, with N/C~12.4 in SN 1993J and N/C~6.0 in SN 1998S. From a compilation of all supernovae with determined CNO ratios, we discuss the implications of these observations for the structure of the progenitors of Type II supernovae. Keywords: Stars: Circumstellar Matter, Nuclear Reactions, Nucleosynthesis, Abundances, Stars: Evolution, Stars: Mass Loss, Stars: Supernovae: Individual: SN 1993J, Stars: Supernovae: Individual: SN 1998S
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