HIGH-SPATIAL-RESOLUTION OBSERVATIONS OF H-2 VIBRATIONAL EMISSION IN NGC-7023

Using the Canada-France-Hawaii telescope to observe the reflection neb ula NGC 7023, we have obtained a 0.8 '' spatial resolution image of vi brationally excited H-2 in the v = 1-0 S(1) line at 2.121 mm and in th e v = 1-0 S(2) line at 2.033 mm. As in earlier observations of Hz IR f luorescence in NGC 2023 (Field et al. 1994), the image shows narrow fi lamentary structure. These structures show spatial correlations, but a lso anti-correlations, with the structure of extended red emission (ER E), with implications for the mechanism of ERE. Spatial variations in the S(1) emission and in the ratio of S(1) to S(2) emission are found in regions lying within a one to a few arcseconds of each other. This is interpreted in terms of small scale structures in the gas in the H- 2 emission zone, on a scale of 0.004 pc or less. Our most recent model s of VUV excitation of H-2 IR fluorescence, by light from a nearby sta r, give a good estimate for the observed peak brightness in the v = 1- 0 S(1) line.