The Destruction of the Circumstellar Ring of SN 1987A

Claes Fransson, Josefin Larsson, Katia Migotto, Dominic Pesce, Peter Challis, Roger A. Chevalier, Kevin France, Robert P. Kirshner, Bruno Leibundgut, Peter Lundqvist, Richard McCray, Jason Spyromilio, Francesco Taddia, Anders Jerkstrand, Seppo Mattila, Nathan Smith, Jesper Sollerman, J. Craig Wheeler, Arlin Crotts, Peter Garnavich, Kevin Heng, Stephen S. Lawrence, Nino Panagia, Chun S. J. Pun, George Sonneborn, Ben Sugerman

Published 2015-05-25Version 1

We present imaging and spectroscopic observations with HST and VLT of the ring of SN 1987A from 1994 to 2014. After an almost exponential increase of the shocked emission from the hotspots up to day ~8,000 (~2009), both this and the unshocked emission are now fading. From the radial positions of the hotspots we see an acceleration of these up to 500-1000 km/s, consistent with the highest spectroscopic shock velocities from the radiative shocks. In the most recent observations (2013 and 2014), we find several new hotspots outside the inner ring, excited by either X-rays from the shocks or by direct shock interaction. All of these observations indicate that the interaction with the supernova ejecta is now gradually dissolving the hotspots. We predict, based on the observed decay, that the inner ring will be destroyed by ~2025.