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B. McCollum (IPAC/Caltech), F.C. Bruhweiler (CUA/GSFC), G.M. Wahlgren, M. Eriksson (Lund Obs.), A. Rosas (CUA), E.M. Verner (CUA/UDC/GSFC)
We present preliminary results of our Spitzer MIPS 24 um and 70 um imagery of several symbiotic stars with observed extended optical nebulosity, including Hen 2-104 and HM Sge, from our Cycle 2 Spitzer program which is collecting data throughout the observing year. Symbiotics are a phenomenologically diverse sample of interactive binaries, which have been linked to all of the major unresolved problems arising in the later stages of binary star evolution. Previous near-IR and ISO results revealed dust signatures in many symbiotics. The presence of extended optical emission in some symbiotics, in addition to theoretical considerations, implies that many, if not all, symbiotics have a history of ejection events. Prior to Spitzer, all relevant existing imagery had been either of optical (H-alpha, [N II], [O III]) or of radio emission, sampling only the surrounding H II regions. Those data provide an incomplete depiction at best. Our MIPS imagery offers a more complete morphology of any surrounding ejecta, since the dust itself is a tracer of both the neutral and ionized gas. MIPS imagery allows one to sample dust surrounding symbiotics which may be much more extended than optical emission studies indicate, permitting an investigation of older ejection events. We discuss the observed dust morphologies and compare them with the optical emission line imagery. Where possible, we discuss implications for evolutionary scenarios.
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Bulletin of the American Astronomical Society, 37 #4
© 2005. The American Astronomical Soceity.