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B.E.K. Sugerman (Columbia U.), S.S. Lawrence (Hofstra U.), A.P.S. Crotts (Columbia U.), P.M. Garnavich (Notre Dame), R.P. Kirshner (CfA), P. Challis (U. Oklahoma), Supernova INtensive Studies (SINS) Collaboration
Supernova (SN) 1987A in the Large Magellanic Cloud is the first naked-eye SN in over three centuries, and the first SN remnant (SNR) seen to form within a pre-existing circumstellar environment that has been mapped in significant detail. We are now observing a unique period in the formation of SNR~1987A as the high-velocity SN debris overtakes the slowly expanding circumstellar equatorial ring (ER).
We present ground-based near-infrared imaging and {\em HST} optical imaging of the interaction between the ejecta of SN~1987A and its equatorial circumstellar ring. This interaction has made a transition, from emission restricted to a few ``hot spots'' to a collision producing optical emission over a nearly continuous distribution, with most breaks in P.A.\ less than 20 degrees. Recent data suggest that the forward blast is now reaching the bulk of the ER material to the east. The centroids of many spots are measured to move at 2000-3000 km s{-1}, which we interpret as a lower limit of the velocity of the forward blast front. Multi-wavelength light curves of the spots show that they do not evolve uniformly, and change significantly on timescales as short as one month. Implications of observed delays between spots appearances suggest that the early appearance of the first hot spot is explained by its inward radial position and a fairly uniform forward blast wave, rather than extraordinary physical circumstances. This research has been supported by grants from NASA (NAG5-3502) and STScI (GO-8806 and GO-8872).
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Bulletin of the American Astronomical Society, 34
© 2002. The American Astronomical Soceity.