Modelling the magnetic activity and filtering radial velocity curves of young Suns : the weak-line T Tauri star LkCa 4

• DOI: 10.1093/mnras/stu1679
• Publication Date: 2014-09-16T07:12:34Z
• Authors: J.- F. Donati; E. Hebrard; G. Hussain; C. Moutou; K. Grankin; I. Boisse; J. Morin; S. G. Gregory; A. A. Vidotto; J. Bouvier; S. H. P. Alencar; X. Delfosse; R. Doyon; M. Takami; M. M. Jardine; R. Fares; A. C. Cameron; F. Menard; C. Dougados; G. Herczeg
• Keywords: Radial velocity; Rotation period

We report results of a spectropolarimetric and photometric monitoring the weak-line T Tauri star LkCa 4 within Magnetic Topologies Young Stars Survival close-in giant Exoplanets (MaTYSSE) programme, involving ESPaDOnS at Canada–France–Hawaii Telescope. Despite an age only 2 Myr similarity with prototypical classical stars, shows no evidence for accretion probes interesting transition stage planet formation. Large profile distortions Zeeman signatures are detected in unpolarized circularly polarized lines using Least-Squares Deconvolution (LSD), indicating presence brightness inhomogeneities magnetic fields surface 4. Using tomographic imaging, we reconstruct maps from sets LSD profiles. The large-scale field is strong mainly axisymmetric, featuring ≃2 kG poloidal component ≃1 toroidal encircling equatorial latitudes – latter making markedly different stars similar mass age. map includes dark spot overlapping pole bright region mid-latitudes providing good match to contemporaneous photometry. also find that differential rotation small, typically ≃5.5 times weaker than Sun, compatible solid-body rotation. our modelling, able filter out activity jitter radial velocity curve (of full amplitude 4.3 km s−1) down rms precision 0.055 s−1. Looking hot Jupiters around young Sun-like thus appears feasible, even though such planets