Studies of small H II regions. I. Infrared photometry of Sharpless 138, 152, and 270.
Abstract
Multiaperture photometric observations from 1.6 to 3.5 of three small H ii regions, Sharpless 138, 152, and 270, are presented. These three objects are shown to be representative of a distinct class of H ii regions. The spatial and spectral distributions of the flux are similar for the three objects: surface brightnesses and apparent color temperatures generally decrease with increasing distance from the infrared centers. The integrated colors are: [1.6 ] - [2.2 ] 1.0 mag, [2.2 ] - [3.5 ] 2.5 mag, similar to those of NGC 7027. A plausible interpretation of the observations is that the infrared flux arises from a mixture of recombination emission and thermal radiation from dust particles. The 3.5- limb-brightening observed in Sb 152 could indicate the presence of a dust shell with an inner radius of 16".
- Publication:
-
The Astrophysical Journal
- Pub Date:
- December 1972
- DOI:
- 10.1086/151824
- Bibcode:
- 1972ApJ...178..667F