UNUSUAL STRUCTURE IN THE PLANETARY NEBULAE ABELL 30 AND ABELL 78.

Abstract

ABSTRACT Both Abell 30 and Abell 78 have infrared colors suggesting the existence of cool (140 K) and warm (1000 K) dust in a volume surrounding the central stars and extending to a diameter of about 25 arc sec. Cohen et al. (1977) can explain the high temperature of the warm dust if it has an exceptionally low radiation efficiency. The photographic observations presented here reveal the presence of bright central nebulosities in both objects. If these new features have high densities, they may be responsible for the high dust temperatures by trapping Lyman-alpha photons (Krishna Swamy and O'Dell, 1968).