Surface magnetic fields on two accreting T Tauri stars: CV Cha and CR Cha

• Published in: Monthly notices of the Royal Astronomical Society 2009-09, Vol.398 (1), p.189-200
• Main Authors: Hussain, G. A. J., Collier Cameron, A., Jardine, M. M., Dunstone, N., Velez, J. Ramirez, Stempels, H. C., Donati, J.-F., Semel, M., Aulanier, G., Harries, T., Bouvier, J., Dougados, C., Ferreira, J., Carter, B. D., Lawson, W. A.
• Format: Article
• Language: English
• Subjects: Accretion disks; Astronomy; Earth, ocean, space; Exact sciences and technology; Magnetic fields; open clusters and associations: individual: Chamaeleon I; Star & galaxy formation; Stars & galaxies; stars: formation; stars: imaging; stars: individual: CR Cha; stars: individual: CV Cha; stars: magnetic fields
• ISSN: 0035-8711; 1365-2966
• DOI: 10.1111/j.1365-2966.2009.14881.x

We have produced brightness and magnetic field maps of the surfaces of CV Cha and CR Cha: two actively accreting G- and K-type T Tauri stars in the Chamaeleon I star-forming cloud with ages of 3–5 Myr. Our magnetic field maps show evidence for strong, complex multipolar fields similar to those obtained for young rapidly rotating main-sequence stars. Brightness maps indicate the presence of dark polar caps and low-latitude spots – these brightness maps are very similar to those obtained for other pre-main-sequence and rapidly rotating main-sequence stars. Only two other classical T Tauri stars have been studied using similar techniques so far: V2129 Oph and BP Tau. CV Cha and CR Cha show magnetic field patterns that are significantly more complex than those recovered for BP Tau, a fully convective T Tauri star. We discuss possible reasons for this difference and suggest that the complexity of the stellar magnetic field is related to the convection zone; with more complex fields being found in T Tauri stars with radiative cores (V2129 Oph, CV Cha and CR Cha). However, it is clearly necessary to conduct magnetic field studies of T Tauri star systems, exploring a wide range of stellar parameters in order to establish how they affect magnetic field generation, and thus how these magnetic fields are likely to affect the evolution of T Tauri star systems as they approach the main sequence.