【場所】国立天文台・三鷹 中央棟（北）1階 講義室
【発表者（敬称略）】（総研大 Min Cheul Hong M2・三鷹、指導教員 : 本間 希樹）
Orbit determination for R Aquarii
R Aqr is one of the closest symbiotic systems and the only D-type system with radial velocity data suitable for orbital parameter estimation. The aims of our study are to determine reliable orbital parameters of R Aqr, and to establish connections between the orbital motion and other phenomena exhibited in this system.
R Aquarii (R Aqr) is a symbiotic system composed of a mass losing Mira long period variable and hot white dwarf companion which is believed to have an accretion disk. Interesting thing in this system is presence of a jet. A lot of orbital solutions were published, but came up with different results had wide range. Though observations of the system have not yielded consistent values of the orbital parameters, the binary parameters of the orbit determine whether or not Roche lobe outflow of the long period variable is a possibility or if interacting stellar winds are necessary to the jet and formation of accretion disk. Futermore, R Aqr is one of the only two symbiotics to have circumstellar masers asscoiated with the Mira so that VLBI observation gives us a great chance for studying symbiotic system beyond AGB stars.
In this presentation, we introduce the symbiotic system, R Aqr, expected orbital model from radial velocity data, and the VERA observation results so far achieved.