High Spatial Resolution Infrared Imaging and Spectroscopy of the Supernova Remnant IC443

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Session 2 -- Planetary Nebula and Supernova Remnants
Display presentation, Monday, 9:20-6:30, Pauley Room

[2.16] High Spatial Resolution Infrared Imaging and Spectroscopy of the Supernova Remnant IC443

M. J. Richter, J. R. Graham (UCB), G. S. Wright (JAC)

We present high spatial resolution infrared imaging and long slit spectra of the molecular shock in the supernova remnant IC443. The 1--0 S(1) line of H$_2$ at 2.122 $mu m$ has been imaged at an angular resolution of 0.7'' over an area of 50'' x 65'' in the vicinity of the peak emission near the southeast edge of the supernova remnant. At this resolution the shock excited H$_2$ emission breaks up into a wealth of structure, consisting of features with sizes ranging from 1'' up to scales extending beyond the edges of the image. Unlike the optical emission from supernova remnant shocks, the H$_2$ emission cannot be well described as a filamentary structure, but is better portrayed as a chaotic assemblage of knots.

Long slit spectra of the H$_2$ emission has been obtained to constrain the excitation conditions in the molecular gas. The data include 2, 3, and 4 $\mu$m lines from the 1--0, 2--1, 3--2 vibrational bands together with high-J pure rotational lines. The energy of the upper levels of these lines spans excitation energies from 7000 -- 25,000 K. These data enable us to determine the H$_2$ level population with great precision, for comparison with predictions of C-- and J--shock models, and to look for correlation between spatial variation of excitation and the H$_2$ surface brightness. The spectra show remarkably constant H$_2$ line ratios over the length of the slit (90''). Since C-shock models predict temperature variation on scale lengths comparable to the MHD damping length -- a few arc seconds at the distance of IC443 -- this result tends to suggest that a dissociative J--shock is preferred.

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