Companions to AGB Stars

We used the Galaxy Evolution Explorer (GALEX) to try to understand the origins of plantary nebulae. Some of the most promising explanations for the broad diversity of shapes seen among planetary nebulae require that the asymptotic giant branch (AGB) star that forms the nebula have a binary companion. Since AGB stars are very luminous in the red or infrared, overwhelming any light from a companion star, we instead used GALEX to observe them in the ultraviolet, where a companion could compete with the AGB star or even dominate the luminosity of the system. We identified several AGB stars with excess ultraviolet flux consistent with a stellar companion.


"Binarity in Cool Asymptotic Giant Branch Stars: a GALEX Search for Ultraviolet Excesses", Sahai, Raghvendra; Findeisen, Krzysztof; Gil de Paz, Armando; Sanchez Contreras, Carmen (2008), The Astrophysical Journal 689, 1274 ADS

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