A Three-dimensional View of Molecular Hydrogen in SN 1987A

Abstract

Abstract SN 1987A is the only young supernova (SN) in which H2 has been detected in the ejecta. The properties of H2 are important for understanding the explosion and the ejecta chemistry. Here we present new Very Large Telescope/SINFONI observations of H2 in SN 1987A, focusing on the 2.12 μm (1,0)S(1) line. We find that the 3D emissivity is dominated by a single clump in the southern ejecta, with weaker emission being present in the north along the plane of the circumstellar ring. The lowest observed velocities are in the range of 400–800 , in agreement with previous limits on inward mixing of H. The brightest regions of H2 coincide with faint regions of Hα, which can be explained by Hα being powered by X-ray emission from the ring, while the H2 is powered by 44Ti. A comparison with ALMA observations of other molecules and dust shows that the brightest regions of H2, CO, and SiO occupy different parts of the inner ejecta and that the brightest H2 clump coincides with a region of very weak dust emission. The latter is consistent with theoretical predictions that the H2 should form in the gas phase rather than on dust grains.