AAS Meeting #193 - Austin, Texas, January 1999
Session 16. HII Regions
Display, Wednesday, January 6, 1999, 9:20am-6:30pm, Exhibit Hall 1

[Previous] | [Session 16] | [Next]

[16.08] Analysis of Narrow Band Mid-Infrared Images of the HII Complex G34.26+0.15

C. A. Garland, M. F. Campbell (Colby C.), L. K. Deutsch (Boston U.), J. L. Hora, G. G. Fazio (SAO), A. Dayal (CalTech), W. F. Hoffmann (U. Arizona)

We present analysis of mid-ir emission from the ultracompact HII (UCHII) complex G34.26+0.15. The observations were obtained with MIRACII on the IRTF using a 1.8% CVF at 8.0, 9.7, 11.2, 12.8, and 13.2 microns, and a 6.8% filter at 20.6 microns. Previously we presented large area images which included emission from G34D (Garland et al. 1997). In this paper we present and analyze photometric flux densities from the UCHII sources. The flux densities are determined for sources at the radio continuum peaks G34A and G34C, and for an extension of G34C to the south at 20.6 microns, G34CS. The silicate absorption is so deep in this region that there was no detection at 9.7 microns and the 11.2 micron sources are quite faint. At the other wavelengths, the three sources are marginally resolved spatially, indicating true source sizes on the order of 1" FWHM. Simple uniform temperature dust cloud models fit to the photometric data allow us to estimate source temperatures, the column densities of dust seen in emission, and the amount of cold absorbing dust. Model temperatures are on the order of several hundred K, as is common for mid-ir sources. The low level of emission at 9.7 and 11.2 microns places constraints on the column density of the absorping layer to be on the order of 0.5-1.0 x 1024 H cm-2. The column densities of emitting regions are only constrained to give lower limits because we cannot rule out the possibility that the emitting regions are optically thick.

Garland et al. 1997, BAAS, 29, 1216

[Previous] | [Session 16] | [Next]