Magnetic field evolution of the K2 dwarf V471 Tau

B. Zaire (1) , J. -F. Donati (1) , B. Klein

1 IRAP - Institut de recherche en astrophysique et planétologie

Observations of the eclipsing binary system V471 Tau show that the time of the primary eclipses varies in an apparent periodic way. With growing evidence that the magnetically active K2 dwarf component might be responsible for driving the eclipse timing variations (ETVs), it is necessary to monitor the star throughout the predicted ~35 yr activity cycle that putatively fuels the observed ETVs. We contribute to this goal with this paper by analysing spectropolarimetric data obtained with ESPaDOnS at the Canada-France-Hawaii Telescope in December 2014 and January 2015. Using Zeeman-Doppler Imaging, we reconstruct the distribution of brightness inhomogeneities and large-scale magnetic field at the surface of the K2 dwarf. Compared to previous tomographic reconstructions of the star carried out with the same code, we probe a new phase of the ETVs cycle, offering new constraints for future works exploring whether a magnetic mechanism operating in the K2 dwarf star is indeed able to induce the observed ETVs of V471 Tau.

Mots clés: Magnetic fields; stars: magnetic field; stars: imaging; stars: individual: V471 Tau; binaries: eclipsing; techniques: polarimetric; Astrophysics - Solar and Stellar Astrophysics; Magnetic fields; Magnetic fields; Magnetic fields

Domaines: Planète et Univers [physics]

B. Zaire, J. -F. Donati, B. Klein. Magnetic field evolution of the K2 dwarf V471 Tau. Monthly Notices of the Royal Astronomical Society, 2022, 513 (2), pp.2893-2903. ⟨10.1093/mnras/stac721⟩. ⟨insu-03672036⟩