Revisiting the proposed planetary system orbiting the eclipsing polar HU Aquarii

This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society © 2011 RAS © 2011 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.It has recently been proposed, on the basis of eclipse-timing data, that the eclipsing polar cataclysmic variable HU Aquarii is host to at least two giant planets. However, that result has been called into question based upon the dynamical stability of the proposed planets. In this work, we present a detailed re-analysis of all eclipse-timing data available for the HU Aquarii system, making use of standard techniques used to fit orbits to radial-velocity data. We find that the eclipse timings can be used to obtain a two-planet solution that does not require the presence of additional bodies within the system. We then perform a highly detailed dynamical analysis of the proposed planetary system. We show that the improved orbital parameters we have derived correspond to planets that are dynamically unstable on unfeasibly short time-scales (of the order of 10 4 yr or less). Given these results, we discuss briefly how the observed signal might in fact be the result of the intrinsic properties of the eclipsing polar, rather than being evidence of dynamically improbable planets. Taken in concert, our results highlight the need for caution in interpreting such timing variations as being planetary in natureJH and CGT gratefully acknowledge the financial support of the Australian government through ARC Grant DP0774000. RAW is supported by a UNSW Vice-Chancellor’s Fellowship. JPM is partly supported by Spanish grant AYA 2008/01727, thanks Eva Villaver for constructive discussions of planet survivability and gratefully acknowledgesMaria Cunningham for funding his collaborative visit to UNS