The Destruction of the Circumstellar Ring of SN 1987A

TL;DR

This study tracks the evolution and destruction of SN 1987A's circumstellar ring over 20 years, showing the fading of hotspots and predicting the ring's complete destruction by 2025.

Contribution

First long-term observational analysis of SN 1987A's ring, revealing its gradual destruction and providing predictions for its future evolution.

Findings

Hotspots increased exponentially until ~2009, then faded.

Hotspots are accelerating up to 1000 km/s.

Ring expected to be destroyed by ~2025.

Abstract

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.