Shock Excited $\bf{\rm H_2}$ Emission in the L1448 Outflow.

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Session 81 -- Stellar Winds and Outflows
Display presentation, Friday, January 14, 9:30-6:45, Salons I/II Room (Crystal Gateway)

[81.05] Shock Excited $\bf{\rm H_2}$ Emission in the L1448 Outflow.

F. Pich\'e, J. L. Pipher, S. N. Raines (U. Rochester), K. L. Thompson (NRL), T. Hodge, C. E. Woodward (WIRO), H. A. Smith (SI-NASM)

We present near-infrared imaging of the young outflow L1448 in both 2.122 $\mu m$ $1 - 0 S(1)$ and 2.223 $\mu m$ $1 - 0 S(0)$ lines of molecular hydrogen. The observations were performed, at the WIRO 2.3 m telescope, with the University of Rochester 256 x 256 InSb imager. A 1.5\% CVF filter was used for the $1 -0 S(1)$ imaging and the Naval Research Lab K-band Fabry-Perot ($\Delta\lambda/\lambda = 850$) was used for the $1 - 0 S(0)$ observations. The 2.223 $\mu m$ emission closely parallels the highly collimated and knotty structures previously observed at 2.122 $\mu m$ (Bally, Lada, \& Lane, 1993). The predicted theoretical line ratio [$1 - 0 S(0)/1 - 0 S(1)$] is expected to be 0.45 for fluorescence and ranges from 0.21 to 0.22 for shock excited emission (Wolfire \& K\"onigl, 1991). The observed line ratio of $0.22 \pm 0.04$ confirms the shock excitation origin of the molecular hydrogen emission in L1448.

This work was supported in part by the Smithsonian Institution Scholarly Studies Program and the Office of Naval Research. Infrared Astronomy at WIRO is supported by a grant from the NSF (AST91-16644).

Bally, J., Lada, E. A., \& Lane, A. P. 1993, Ap. J. in press

Wolfire, M. G., \& K\"onigl, A. 1991, Ap. J. 383, 205

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