A Near Infrared Study of the MonR2 Star Formation Region
Session 75 -- Star Formation II
Oral presentation, Thursday, 2:30-4:00, Zellerbach Playhouse Room

## [75.03] A Near Infrared Study of the MonR2 Star Formation Region

E. M. Howard, J. L. Pipher, W. J. Forrest (Rochester)

We present H (1.65$\mu$m), K (2.23$\mu$m), and L'' (3.81$\mu$m) broadband images as well as Br$\gamma$ (n = 7$\rightarrow$4, 2.166$\mu$m) and Br$\alpha$ (n = 5$\rightarrow$4, 4.052$\mu$m) hydrogen recombination line images, and 3.29$\mu$m, and 3.4$\mu$m unidentified feature emission images of the Monoceros R2 star formation region at a plate scale of $\sim$0.9'' per pixel. The Brackett line images are combined with radio data to map the line of sight dust extinction to the compact HII region on a small spatial scale. This extinction map is then used to de-redden regions of the H and K images interior to the HII region. IRS1$\rm_{SW}$, the ionizing source, is found to be consistent with a B0 star. Comparison of de-reddened H and K images with the Brackett images and recent high resolution HCO$^+$ measurements leads to the development of a torus model for the dense molecular gas surrounding the HII region. The 3.29$\mu$m emission is found to be coincident with the ring of scattered light at 2.2$\mu$m and just outside the Br$\alpha$ and Br$\gamma$ emission. The 3.4$\mu$m image is of too low S/N to determine if any variation in the 3.29 to 3.4$\mu$m emission ratio with distance from the ionizing source is seen, however 3.4$\mu$m emission is detected in a ring coincident with the 3.29$\mu$m emission.