IRAS OBSERVATIONS OF YOUNG STELLAR OBJECTS IN THE CORONA AUSTRALIS DARK CLOUD

We present an analysis of IRAS data for a 57 pc2 area of the nearby Corona Australis dark cloud complex. A total of 79 far-infrared sources are detected at 12 mum or in at least three IRAS bands. Combining these data with both newly obtained and previously published optical/infrared data, a total of 16 IRAS sources are identified with young stellar objects which are in close proximity to the R Coronae Australis cloud or Rossano Cloud B. Among these objects is a cold, heavily obscured young stellar object, IRAS 32, which radiates only in the 25-100 mum bands and is found to be associated with an extended near-infrared nebula. The majority of the remaining 63 IRAS sources in our sample appear to be related to field stars. A total of 24 young stellar objects are now known to be associated with the Cr A cloud and we investigate their collective properties through analysis of their spectral energy distributions. As observed for embedded populations in other dark clouds, the shapes of the spectral energy distributions constitute a nearly continuous sequence from cold, heavily obscured objects (extreme Class I) to T Tauri stars (Class II), with about equal numbers of Class I and Class II sources. There is a hint of a segregation of the shapes of the spectral energy distributions with source luminosity: eight of nine sources with L > 1.8 L. display Class I or flat energy distributions. We conclude that star formation in the Cr A cloud has proceeded in a manner similar to that in the rho Ophiuchi cloud in terms of duration and efficiency. We attribute the relatively low number of young stellar objects in Cr A to its lower mass of both low-density and high-density molecular gas. The luminosity function of the Cr A sources is unique only by the presence of six intermediate-luminosity (approximately 100 L.) objects. Either the cloud has formed intermediate-mass stars more efficiently than lower mass objects relative to other dark clouds or several of these objects are interlopers.