Secular changes in the orbits of the quadruple system VW LMi
T. Pribulla, Emil Puha, T. Borkovits, J. Budaj, Z. Garai, E. W. Guenther, Ľ. Hambálek, R. Komžík, E. Kundra, Gy. M. Szabó, M. Vaňko
Abstract
ABSTRACT VW LMi is the tightest known quadruple system with 2 + 2 hierarchy. It consists of a W UMa-type eclipsing binary (P12 = 0.477 55 d) and another detached non-eclipsing binary (P34 = 7.93 d) orbiting around a common centre of mass in about P1234 = 355 d. We present new observations of the system extending the time baseline to study long-term perturbations in the system and to improve orbital elements. The multidataset modelling of the system (four radial-velocity curves for the components and the timing data) clearly showed an apsidal motion in the non-eclipsing binary at a rate of 4.6 deg yr−1, but no other perturbations. This is consistent with the nearly co-planarity of the outer, 355-d orbit, and the 7.93-d orbit of the non-eclipsing binary. Extensive N-body simulations enabled us to constrain the mutual inclination of the non-eclipsing binary and the outer orbits to j34–1234 < 10 deg.