The well-known multiple star system, Castor, and particularly, the [(Aa, Ab), (Ba, Bb)] subsystem, was studied in detail. After a rigorous analysis of the quality controls, a new solution for the visual orbit yielded new values for the different physical and orbital parameters of the system. In addition, a comprehensive investigation of the orbital configuration of the quadruple system allowed us to provide both accurate individual masses and orbital inclinations of the spectroscopic subcomponents, as well as a new value of its orbital parallax. Finally, by means of a numerical analysis of the long-term dynamics, we obtained the most probable values of the nodal angles of the two spectroscopic subsystems for the first time.
Furthermore, the full characterization of this remarkable system allowed us to discuss some interesting features of its present configuration. In this way, we concluded that the eccentric (Aa, Ab) subsystem is yet undergoing Kozai-Lidov cycles whereas, on the contrary, the circular (Ba, Bb) subsystem has probably already reached a stable stage.
Astrometry Celestial mechanics Binaries: spectroscopic Binaries: visual Stars: fundamental parameters Stars: \(\alpha\) Gem AB (Castor)
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The authors thank W. Hartkopf of USNO for providing the data and other relevant information necessary for this research.
This paper was supported by the Spanish Ministerio de Economía y Competitividad under Project AYA 2011-26469 as well as by the IEMath-Galicia Network (FEDER-Xunta of Galicia).
Docobo, J.A.: In: Arenou, F., Hestroffer, D. (eds.) Proceedings of the Workshop “Orbital Couples: Pas de Deux in the Solar System and the Milky Way”, p. 119. Observatoire de Paris, Paris (2012)