Evidence for a binary origin of the young planetary nebula hubble 12

Abstract

Young planetary nebulae play an important role in stellar evolution when intermediate- to low-mass stars (0.8-8 M⊙) evolve from the proto-planetary nebula phase to the planetary nebula phase. Many young planetary nebulae display distinct bipolar structures as they evolve away from the proto-planetary nebula phase. One possible cause of their bipolarity could be a binary origin for their energy source. Here we report on our detailed investigation of the young planetary nebula Hubble 12, which is well known for its extended hourglass-like envelope. We present evidence with time-series photometric observations for the existence of an eclipsing binary at the center of Hubble 12. In addition, low-resolution spectra of the central source show absorption features such as CN, G band, and Mg b, which can be suggestive of a low-mass nature for the secondary component. © 2006. The American Astronomical Society. All rights reserved.