Poster abstract details
Abell 70 as a Rosetta stone linking post-AGB binaries and PNe
Abstract
More than 40 close binary central stars are known that have passed through a common-envelope stage, but we know essentially nothing about orbital periods in the intermediate range (P=100--1500 days). Such binaries are most likely the long sought-after progeny of post-AGB binaries and chemically peculiar stars whose composition was modified by binary evolution. We have recently discovered the binary nature of the central star of Abell 70 (A70; PN G038.1-25.4) which belongs to the small class of Barium-enhanced central stars (A35, LoTr5, and WeBo1). A70 shows only a cool subgiant with strong
Barium lines in the optical, while GALEX UV imaging confirms the presence of a hot white dwarf. This rules out a `born-again’ scenario and provides impetus for further discoveries to be made. An s-process rich cool star in a nebula ejected by the polluting star is a very transient stage that constitutes a formidable Rosetta stone for advancing multiple poorly understood aspects of stellar evolution. These include the s-process mechanism due to thermal pulses on the AGB, the thermohaline mixing, the mass transfer process in binaries, and the ejection mechanism of the PN envelope.
Barium lines in the optical, while GALEX UV imaging confirms the presence of a hot white dwarf. This rules out a `born-again’ scenario and provides impetus for further discoveries to be made. An s-process rich cool star in a nebula ejected by the polluting star is a very transient stage that constitutes a formidable Rosetta stone for advancing multiple poorly understood aspects of stellar evolution. These include the s-process mechanism due to thermal pulses on the AGB, the thermohaline mixing, the mass transfer process in binaries, and the ejection mechanism of the PN envelope.