Determining the orbital parameters of binary systems with an AGB primary. The case of the R Aqr symbiotic system
Alcolea, J.; Bachiller, R.; Santander-García, M.; Bujarrabal, V.; Mikolajewska, J.; Castro-Carrizo, A.; Gómez-Garrido, M.; Desmurs, J. -F.; Ilkiewicz, K.
Spain, Poland, France
Abstract
Binary stars including an AGB star hold the clues for understanding important phenomena in stellar evolution, such as common-envelope events, the formation of SN-Ia, and the origin of aspherical pPNe/PNe. Hydro-dynamical codes simulating the companion's influence on the primary mass loss exist, but we still lack information on the orbital parameters of systems where these models can be tested. The best case where this can be pursued is R Aqr. Here, we present the results of the first-ever determination of the whole set of orbital parameters of the system purely based on observational data. The results agree very well with the observational characteristics of the nebula around the system. Reasonable values for the stellar masses agree with distances from period- and diameter-luminosity relationships for Mira variables, but not with those from VLBI observations of SiO masers or GAIA.