The magnetic propeller accretion regime of LkCa 15

J. -F. Donati, J. Bouvier, S. H. Alencar, C. Hill, Andrès Carmona, C. P. Folsom, F. Ménard, S. G. Gregory, G. A. Hussain, K. Grankin, C. Moutou, L. Malo, M. Takami, G. J. Herczeg

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Abstract

We present a spectropolarimetric study of the classical T Tauri star (cTTS) LkCa 15 investigating the large-scale magnetic topology of the central star and the way the field connects to the inner regions of the accretion disc. We find that the star hosts a strong poloidal field with a mainly axisymmetric dipole component of 1.35 kG, whereas the mass accretion rate at the surface of the star is 10-9.2 M yr-1. It implies that the magnetic field of LkCa 15 is able to evacuate the central regions of the disc up to a distance of 0.07 au at which the Keplerian orbital period equals the stellar rotation period. Our results suggest that LkCa 15, like the lower mass cTTS AA Tau, interacts with its disc in a propeller mode, a regime supposedly very efficient at slowing down the rotation of cTTSs hosting strong dipolar fields....
Original languageEnglish
Pages (from-to)L1-L5
JournalMonthly Notices of the Royal Astronomical Society: Letters
Volume483
Issue number1
DOIs
Publication statusPublished - 11 Feb 2019

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Keywords

  • stars: formation
  • stars: imaging
  • stars: individual: LkCa 15
  • stars: magnetic fields
  • techniques: polarimetric

Cite this

Donati, J. -F., Bouvier, J., Alencar, S. H., Hill, C., Carmona, A., Folsom, C. P., Ménard, F., Gregory, S. G., Hussain, G. A., Grankin, K., Moutou, C., Malo, L., Takami, M., & Herczeg, G. J. (2019). The magnetic propeller accretion regime of LkCa 15. Monthly Notices of the Royal Astronomical Society: Letters, 483(1), L1-L5. https://doi.org/10.1093/mnrasl/sly207