A Study of Binary Origin in the Nuclei of Planetary Nebulae

• Main Authors: Chih-Hao Hsia, 夏志浩
• Other Authors: Wing-Huen Ip
• Format: Others
• Language: en_US
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/7k8u97

博士 === 國立中央大學 === 天文研究所 === 96 === Young planetary nebulae play an important role in the stellar evolution of intermediateto low-mass stars (0.8-8 M⊙) 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. We report on our detailed investigation of the young planetary nebula Hubble 12, well-known for its extended hourglass-like envelope. We present evidence (in the form of 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 could be suggestive of the low-mass nature for the secondary component. In addition, we also discuss a series of two-dimensional rings along a common axis aligned with the bipolar lobes found in the planetary nebula Hb 12. The rings have a separation of about 0.3 arcsec, which can be translated into a physical separation of ∼ 1000 AU, or a time separation of the order of 50 yr. We suggest that the existence of the rings is a manifestation of the interaction between a time-variable, collimated fast outflow with the circumstellar envelope created by the stellar wind of an asymptotic giant branch star. We also search for binary candidates using spectroscopic identification and photometric classification. Based on the understanding of the common characteristics of the known binary nuclei of PNe and determined by the photometric selection criteria of V-R > 0 and B-I > -0.5, we found that a significant fraction (83%) of PNe might be of binary origin. We selected about 80 % new binary candidates using the selection criteria. Further observations and more time are needed to confirm these binary candidates.