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Session 40 - Supernova Remnants & SN 1987A.
Display session, Thursday, January 08
Exhibit Hall,

[40.13] STIS Observations of Shock Interaction Around SN 1987A

G. Sonneborn, C. S. J. Pun, S. Maran, T. Gull (NASA/GSFC), E. Michael, R. McCray (U. Colorado), P. Lundqvist (Stockholm Obs.)

Visual and ultraviolet spatially resolved (\sim0\farcs1) spectra of SN\,1987A obtained were with STIS on days 3715 and 3743 (27 Apr. and 25 May 1997) show that high-velocity SN debris is colliding with circumstellar gas. Very broad Ly-\alpha emission with velocities extending to \sim\pm20,000\,km\,s^-1 originates inside the inner circumstellar ring and appears to fill most of the surface area within 0\farcs67 \pm 0\farcs03 (0.14 pc at a distance of 50 kpc) of the ring's center. The observed Ly-\alpha flux from the shocked ejecta is (1.85 \pm 0.53)\times 10^-13 erg^-1 cm^-2\,s^-1 and (1.25 \pm 0.51)\times 10^-12 erg^-1 cm^-2\,s^-1 after correcting for extinction. A spatially unresolved blue-shifted emission feature was discovered in H-\alpha (and other lines) on the inner ring at p.a.\,31^\circ\pm 8^\circ. The H\alpha emission extends to --250 km s^-1 with no corresponding red-shifted emission. This highly localized interaction appears to be the initial contact of the supernova blast wave with an inward protrusion of the inner ring. The broad Ly-\alpha emission and the `hot spot' are separate interaction phemonena associated with the reverse and forward shocks, respectively. STIS spectra also show that the size of the inner ring in [O I] 6300, [O II] 3727, and [O III] 5007 has a dependence on ionization potential, in agreement with photoionization models of the ring. New UV and visual spectra are planned for Dec. 1997.

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