Magnetospheric accretion on the T Tauri star BP Tauri
Article
Article Title | Magnetospheric accretion on the T Tauri star BP Tauri |
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ERA Journal ID | 1074 |
Article Category | Article |
Authors | Donati, J. -F. (Author), Jardine, M. M. (Author), Gregory, S. G. (Author), Petit, P. (Author), Paletou, F. (Author), Bouvier, J. (Author), Dougados, C. (Author), Menard, F. (Author), Cameron, A. C. (Author), Harries, T. J. (Author), Hussain, G. A. J. (Author), Unruh, Y. (Author), Morin, J. (Author), Marsden, S. C. (Author), Manset, N. (Author), Auriere, M. (Author), Catala, C. (Author) and Alecian, E. (Author) |
Journal Title | Monthly Notices of the Royal Astronomical Society |
Journal Citation | 386 (3), pp. 1234-1251 |
Number of Pages | 16 |
Year | 2008 |
Publisher | Oxford University Press |
Place of Publication | United Kingdom |
ISSN | 0035-8711 |
1365-2966 | |
Digital Object Identifier (DOI) | https://doi.org/10.1111/j.1365-2966.2008.13111.x |
Web Address (URL) | https://academic.oup.com/mnras/article/386/3/1234/1057083 |
Abstract | From observations collected with the ESPaDOnS and NARVAL spectropolarimeters, we report the detection of Zeeman signatures on the classical T Tauri star (cTTS) BP Tau. Circular polarization signatures in photospheric lines and in narrow emission lines tracing magnetospheric accretion are monitored throughout most of the rotation cycle of BP Tau at two different epochs in 2006. We observe that rotational modulation dominates the temporal variations of both unpolarized and circularly polarized spectral proxies tracing the photosphere and the footpoints of accretion funnels. From the complete data sets at each epoch, we reconstruct the large-scale magnetic topology and the location of accretion spots at the surface of BP Tau using tomographic imaging. We find that the field of BP Tau involves a 1.2 kG dipole and 1.6 kG octupole, both slightly tilted with respect to the rotation axis. Accretion spots coincide with the two main magnetic poles at high latitudes and overlap with dark photospheric spots; they cover about 2 per cent of the stellar surface. The strong mainly axisymmetric poloidal field of BP Tau is very reminiscent of magnetic topologies of fully convective dwarfs. It suggests that magnetic fields of fully convective cTTSs such as BP Tau are likely not fossil remants, but rather result from vigorous dynamo action operating within the bulk of their convective zones. Preliminary modelling suggests that the magnetosphere of BP Tau extends to distances of at least 4R*f to ensure that accretion spots are located at high latitudes, and is not blown open close to the surface by a putative stellar wind. It apparently succeeds in coupling to the accretion disc as far out as the corotation radius, and could possibly explain the slow rotation of BP Tau. |
Keywords | star formation; individual stars; BP Tau; magnetic fields; pre-main-sequence; rotation; polarimetric |
ANZSRC Field of Research 2020 | 510109. Stellar astronomy and planetary systems |
519999. Other physical sciences not elsewhere classified | |
510903. Mesospheric, thermospheric, ionospheric and magnetospheric physics | |
Public Notes | This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2008 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved. |
Byline Affiliations | University of Toulouse, France |
University of St Andrews, United Kingdom | |
Institute of Planetology and Astrophysics of Grenoble, France | |
University of Chile, Chile | |
University of Exeter, United Kingdom | |
European Southern Observatory (ESO), Germany | |
Imperial College London, United Kingdom | |
Anglo-Australian Observatory, Australia | |
Canada-France-Hawaii Telescope, United States | |
Laboratory of Space Science and Astrophysical Instrumentation, France | |
Institution of Origin | University of Southern Queensland |
https://research.usq.edu.au/item/q2qz9/magnetospheric-accretion-on-the-t-tauri-star-bp-tauri
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