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Published February 20, 2015 | Published + Submitted
Journal Article Open

The First Science Results from Sphere: Disproving the Predicted Brown Dwarf Around V471 Tau


Variations of eclipse arrival times have recently been detected in several post-common envelope binaries consisting of a white dwarf and a main-sequence companion star. The generally favored explanation for these timing variations is the gravitational pull of one or more circumbinary substellar objects periodically moving the center of mass of the host binary. Using the new extreme-AO instrument SPHERE, we image the prototype eclipsing post-common envelope binary V471 Tau in search of the brown dwarf that is believed to be responsible for variations in its eclipse arrival times. We report that an unprecedented contrast of ${\Delta }{{m}_{H}}=12.1$ at a separation of 260 mas was achieved, but resulted in a non-detection. This implies that there is no brown dwarf present in the system unless it is 3 mag fainter than predicted by evolutionary track models, and provides damaging evidence against the circumbinary interpretation of eclipse timing variations. In the case of V471 Tau, a more consistent explanation is offered with the Applegate mechanism, in which these variations are prescribed to changes in the quadrupole moment within the main-sequence star.

Additional Information

© 2015 The American Astronomical Society. Received 2014 December 17; Accepted 2015 January 16; Published 2015 February 18. A.H., M.R.S., C.C., H.C., L.C., and A.B. acknowledge support from the Millennium Nucleus RC130007 (Chilean Ministry of Economy). M.R.S., S.P., C.C., L.C., and A.B. also acknowledge support from FONDECYT grants 1141269, 3140585, 3140592, 1440109, and 11140572, respectively. T.R.M. thanks the UK's Science and Technology Facilities Council for support during the course of this work under grant ST/L000733/1.

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Submitted - 1502.05116v1.pdf

Published - apjl_800_2_L24.pdf


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August 22, 2023
August 22, 2023