The spectroscopic orbit and the geometry of R AquariiM. Gromadzki and J. Mikołajewska
Nicolaus Copernicus Astronomical Center, Bartycka 18, 00-716 Warszawa, Poland
Received 25 April 2008 / Accepted 4 December 2008
Context. R Aqr is one of the closest symbiotic binaries and the only D-type system with radial velocity data suitable for orbital parameter estimation.
Aims. The aims of our study are to derive a reliable spectroscopic orbit of the Mira component, and to establish connections between the orbital motion and other phenomena exhibited by R Aqr .
Methods. We reanalyze and revise the velocity data compiled by McIntosh & Rustan complemented by additional velocities.
Results. We find an eccentric orbit (e = 0.25) with a period 43.6 yr. This solution is in agreement with a resolved VLA observation of this system. We demonstrate that the last increase in extinction towards the Mira variable in 1974–1981 occurred during its superior, spectroscopic conjunction, and can be due to obscuration by a neutral material in the accreting stream. We also show that jet ejection is not connected with the orbital position.
Key words: stars: binaries: symbiotic -- stars: binaries: spectroscopic -- stars: individual: R Aquarii -- stars: fundamental parameters
© ESO 2009