The First Science Results from SPHERE: Disproving the Predicted Brown Dwarf around V471 Tau

Abstract

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 favoured 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 12.1 magnitudes in the H band 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 three magnitudes 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

References in corpus (6)

• Fundamental limitations of high contrast imaging set by small sample statistics
• ULTRACAM: an ultra-fast, triple-beam CCD camera for high-speed astrophysics
• Post-common-envelope binaries from SDSS. IX: Constraining the common-envelope efficiency
• First versus second generation planet formation in post common envelope binary (PCEB) planetary systems
• Spectroscopy of Hyades L dwarf candidates
• Testing the planetary models of HU Aquarii

Cited by in corpus (13)

• Tatooine's Future: The Eccentric Response of Kepler's Circumbinary Planets to Common-Envelope Evolution of their Host Stars
• BEBOP III. Observations and an independent mass measurement of Kepler-16 (AB) b -- the first circumbinary planet detected with radial velocities
• Is there a circumbinary planet around NSVS 14256825?
• The binary mass ratios of circumbinary planet hosts
• Cyclic period oscillation of the eclipsing dwarf nova DV UMa
• Orbital period variation of KIC 10544976: Applegate mechanism versus light travel time effect
• Magnetic field and activity phenomena of the K2 dwarf V471 Tau
• Eclipse timing variation of GK Vir: evidence of a possible Jupiter-like planet in a circumbinary orbit
• SFADI: the Speckle-Free Angular Differential Imaging method
• Magnetic field evolution of the K2 dwarf V471 Tau
• The orbital ephemeris of the classical nova RR Pictoris: presence of a third body?
• A Speckle-Imaging Search for Close Triple Companions of Cataclysmic Binaries
• Variability of eclipse timing:the case of V471 Tauri