Name: Kenneth Hinkle

Institution: NOAO

e-mail: hinkle(no-spam)noao.edu

Partner Country: USA

Science Meeting: Yes

User Meeting: Yes

NGO Staff Meeting: Yes

Presentation: Yes

Format: Oral

Title: Post-AGB Circumbinary Shells -- Remnants from Stellar Evolution

Abstract:

High-resolution 2.3-4.6 micron Phoenix/Gemini spectroscopy has been done on binary post-AGB stars with circumbinary shells. The early-type primary stars have severe depletion of refractory elements. The infrared spectrum is from an oxygen-rich circumbinary shell interior to an extended carbon-rich shell. The oxygen-rich shell is a thin Keplerian region near the circumbinary dust. The masses of the stars in the binaries are derived and the binary evolution discussed. A model is described that produces the stellar surface abundances from winnowing of gases through the grains.