Observing Supernova 1987A with the Refurbished Hubble Space Telescope

TL;DR

This study uses the refurbished Hubble Space Telescope to observe supernova 1987A, revealing ongoing shock emission brightening and complex ion scattering phenomena over six years.

Contribution

First detailed comparison of supernova 1987A observations before and after HST instrument refurbishment, highlighting shock evolution and ion scattering mechanisms.

Findings

Ly-alpha and H-alpha lines continue brightening

Maximum velocities of lines decrease over time

Detection of redshifted NV emission lines

Abstract

Observations with the Hubble Space Telescope (HST), conducted since 1990, now offer an unprecedented glimpse into fast astrophysical shocks in the young remnant of supernova 1987A. Comparing observations taken in 2010 using the refurbished instruments on HST with data taken in 2004, just before the Space Telescope Imaging Spectrograph failed, we find that the Ly-a and H-a lines from shock emission continue to brighten, while their maximum velocities continue to decrease. We observe broad blueshifted Ly-a, which we attribute to resonant scattering of photons emitted from hotspots on the equatorial ring. We also detect NV~\lambda\lambda 1239,1243 A line emission, but only to the red of Ly-A. The profiles of the NV lines differ markedly from that of H-a, suggesting that the N^{4+} ions are scattered and accelerated by turbulent electromagnetic fields that isotropize the ions in the collisionless shock.