Infrared images of southern HII regions.

The mapping of HII regions in the 2.2-micron continuum is found to be an effective way to establish the distribution of ionized gas and to locate the underlying stars. The present investigation provides 2.2-micron maps of four southern regions. Although each of these objects has been extensively studied at radio wavelenths with low spatial resolution, they have so far (with the exception of G333.6-0.2) received little attention in the infrared. The current study represents the first step towards understanding the structure of the objects. The images were obtained in May 1982 with a recently developed infrared imaging system. The infrared photometer consists of a 1/4mm InSb detector cooled by solid nitrogen, used with the charge integrating electronics described by Barton and Allen (1980). The imaging software scans the telescope across a rectangular area of sky in synchronization with the integrations of the infrared detector. Attention is given to the NGC 3576 (RCW 57), the RCW 38 (CTB 31), the NGC 3603 (RCW 57 II), and the G333.6-0.2.