We present H (1.65 micron), K (2.23 micron), and L<SUP>double prime</SUP>(3.81 micron) broad-band images as well as Br(gamma) (n = 7 approaches 4, 2.166 micron) and Br(alpha) (n = 5 approaches 4, 4.052 micron) hydrogen recombination line images, and 3.29 micron and 3.4 micron unidentified feature emission images of the Monoceros R2 star formation region at a plate scale of approximately 0.9 sec/pixel. The Brackett line images ar combined with 5 GHz data to map the line-of-sight dust extinction to the compact H II region on a small spatial scale. This extinction map is then used to deredden regions of the H and K imges interior to the H II region. IRS 1<SUB>SW</SUB>, the ionizing source, is found to be consistent with a B0 star. Comparison of dereddened H and K images with the Brackett images and recent high-resolution HCO(+) measurements leads to the development of a torus model for the dense molecular gas surrounding the H II region. The 3.29 micron emission is found to be coincident with the ring of scattered light at 2.2 micron and just outside the Br(alpha) and Br(gamma) emission. The 3.4 micron image is of too low a signal-to-noise ratio to determine if any variation in the 3.29 to 3.4 micron emission ratio with distance from the ionizing source is seen; however, 3.4 micron emission is detected in a ring coincident with the 3.29 micron emission.
Authors: Eric Howard, J. L. Pipher, W. J. Forrest
DOI: https://doi.org/10.1086/174016
Publish Year: 1994
