PHOTOMETRY OF TWO POORLY STUDIED PLANETARY NEBULAE WITH BINARY CENTRAL STARS

ABSTRACT We have observed the central stars of two planetary nebulae, Abell 65 and Hubble 12, both of which are claimed to be close binary systems. We looked at the differential photometry from these systems in hopes of confirming previous reports of variability caused by close binaries. Binary interaction in a planetary nebula is a possible source of the structure of bi-polar or butterfly PN. We determined that one of the two systems, Abell 65, most likely exhibits variability due to irradiation of a cool companion or deformation of one companion caused by it filing a significant fraction of its Roche Lobe. We cannot confirm the binary classification until a complete light curve is obtained. With Hubble 12, which was claimed to be an eclipsing binary system with an irradiation effect, we found no clear variability indicative of a binary system and recommend that it be removed from the list of known binary central stars