Molecular Hydrogen Emission from Young Stellar Outflows in NGC 2264

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Session 44 -- Young Stars, T Tauri Stars, Herbig Haro Objects
Display presentation, Wednesday, 1, 1994, 9:20-6:30

[44.03] Molecular Hydrogen Emission from Young Stellar Outflows in NGC 2264

F. Pich\'e, J. L. Pipher, E. Howard (Univ. of Rochester)

We present near-infrared $H_2$ 1-0S(1) 2.122 $\mu m$ images of the energetic outflow NGC 2264G and the Herbig-Haro object NGC2264/HH124. Observations were carried out at the Mt. Lemmon Observing Facility with the Univ. of Rochester 256x256 InSb infrared imager in March 1994.

In NGC 2264G, the telescope was pointed at the position of the $H_2$ peak as listed in Margulis et al. (1990). Our images reveal the $H_2$ emission to be composed of three components, two bright knots of emission along with more diffuse emission. Presumably, the two knots of emission represent shock interfaces between the outflow material and the surrounding interstellar medium. We compare the position of these bright knots of $H_2$ emission with the clumps seen in the CO maps presented in Margulis et al. (1990). A search for [FeII] 1.644 $\mu m$ returned no detection.

In HH124, we report the detection of a fan shaped reflection nebula originating from the IRAS source 06382+1017. From our improved coordinates, we can infer that IRAS 06382+1017 coincides with HH124D at the geometric center of HH124. This leaves little doubt as to the identity of the driving source of this object. $H_2$ emission is detected in that reflection nebula as well as in each of the components of this HH object (HH124A-F). Walsh, Ogura, \& Reipurth (1992) report a discrepancy between the observed optical spectra of the HH124 knots and model spectra based on the shock velocities of the individual knots. They hypothesize that the discrepancy could be explained by the shock material being predominantly in molecular form. Comparison of the brightness of the $H_2$ emission relative to the strength of the optical emission will be used to prove or disprove that hypothesis.

This work is supported by a travel grant from the National Geographic Society. We also gratefully acknowledge the collaboration of the Univ. of Minnesota and UCSD in letting us perform our observations at the Mt. Lemmon Observing Facility.

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