Discovery of molecular hydrogen in SN 1987A

TL;DR

This paper reports the first detection of molecular hydrogen in SN 1987A, revealing insights into molecule formation and excitation mechanisms in supernova ejecta over time.

Contribution

The study presents the first observational detection of H_2 in SN 1987A, confirming molecule formation and suggesting excitation by 44Ti decay.

Findings

H_2 detected in supernova ejecta at late epochs

H_2 emission concentrated in the core, similar to [Si I]/[Fe II]

H_2 luminosity remains nearly constant over time

Abstract

Both CO and SiO have been observed at early and late phases in SN 1987A. H_2 was predicted to form at roughly the same time as these molecules, but was not detected at early epochs. Here we report the detection of NIR lines from H_2 at 2.12 mu and 2.40 mu in VLT/SINFONI spectra obtained between days 6489 and 10,120. The emission is concentrated to the core of the supernova in contrast to H-alpha and approximately coincides with the [Si I]/[Fe II] emission detected previously in the ejecta. Different excitation mechanisms and power sources of the emission are discussed. From the nearly constant H_2 luminosities we favour excitation resulting from the 44Ti decay.