Supernova Shocks in Molecular Clouds: Shocks Driven into Dense Cores in IC 443 and 3C 391

TL;DR

This study observes supernova shocks impacting dense molecular cores in IC 443 and 3C 391, analyzing shock conditions and their effects on molecular gas using infrared data and shock modeling.

Contribution

It provides the first detailed analysis of shock conditions in dense cores affected by supernova remnants using combined infrared observations and shock modeling.

Findings

Shocks into gas with ~2000 cm^-3 density have velocities around 60 km/s.

Shocks into denser gas (~10^5 cm^-3) have velocities around 10 km/s.

Shocked clumps are likely prestellar cores unlikely to form stars soon.

Abstract

Supernova shocks into dense molecular cores in IC 443 (clumps B, C, and G) and 3C 391 were observed using the Stratospheric Observatory for Infrared Astronomy and complemented by archival data from the Herschel Space Observatory. The pure rotational transitions 0-0 S(1) and S(5) of H2, and the ground-state 110-101 transition of H2O, are all broadened, arising from molecules that survive the passage of the shock front. Theoretical models from the Paris-Durham shock code were analyzed to generate synthetic profiles that approximately match the observations. The observations can be fit with two shock conditions, which approximate the range of densities in the pre-shock molecular cloud. The width and brightness of the S(5) lines require shocks into gas with a density of order 2,000 cm-3, into which the IC 443 blast wave drives shocks with speed 60 km/s. The brightness and narrower width of the S(1) lines requires different shocks, into gas with density of order 10^5 cm-3, with shock speeds of 10 km/s. The H2O velocity distribution is also consistent with these shocks. The existence of shocks into dense gas shows that the bright shocked clumps in IC~443 were prestellar cores. It is unlikely that they will form stars soon after the passage of the shock front, given the input of kinetic and thermal energy from the shocks.