Dimensions of Diffuse and Planetary Nebulae in the Small Magellanic Cloud.

Abstract

Objects in the Small Magellanic Cloud classified by Lindsay as planetary nebulae or probable planetary nebulae have been photographed in Ha light with the Mount Stromlo 74-inch reflector. Of the fourteen objects brighter than Mpg = -3.0, eleven are clearly resolved. Masses for the clearly resolved objects, derived from the observed radii and Lindsay's red magnitudes, range from 2 0 to 33 solar masses. It therefore seems unlikely that these objects can be considered planetary nebulae. These nebulae are compared with other diffuse nebulae by means of an absolute magnitude-log radius diagram. It is probable that most of the unresolved objects are true planetary nebulae. Our data indicate an upper limit to the photographic absolute magnitudes of planetary nebulae at Mpg = -3.0, in reasonable accord with the data of O'Dell for galactic planetaries It is estimated that the Small Magellanic Cloud contains approximately 300 planetary nebulae.