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| Title: | The magnetic field of the planet-hosting star τ Bootis | |
| Authors: | Catala, C.; Donati, J.-F.; Shkolnik, E.; Bohlender, D.; Alecian, E. | |
| Affiliation: | AA(Observatoire de Paris, LESIA, 5 place Jules Janssen, 92195 Meudon Cedex, France), AB(Observatoire Midi-Pyrénées, LATT, 14 avenue Edouard Belin, 31400 Toulouse, France), AC(NASA Astrobiology Institute, University of Hawaii at Manoa, 2680 Woodlawn Drive, Honolulu, HI 96822, USA), AD(National Research Council of Canada, Herzberg Institute of Astrophysics, 5071 West Saanich Road, Victoria, BC V9E 2E7, Canada), AE(Observatoire de Paris, LESIA, 5 place Jules Janssen, 92195 Meudon Cedex, France) | |
| Publication: | Monthly Notices of the Royal Astronomical Society: Letters, Volume 374, Issue 1, pp. L42-L46. (MNRAS Homepage) | |
| Publication Date: | 01/2007 | |
| Origin: | MNRAS | |
| MNRAS Keywords: | stars: magnetic fields , stars: planetary systems | |
| Abstract Copyright: | (c) 2006 The Authors. Journal compilation © 2006 RAS | |
| DOI: | 10.1111/j.1745-3933.2006.00261.x | |
| Bibliographic Code: | 2007MNRAS.374L..42C |
The analysis of the photospheric lines of τ Boo at ultra-high signal-to-noise ratio reveals the presence of an 18 per cent relative differential rotation. Tentative Zeeman-Doppler imaging, using our spectropolarimetric observations covering only a fraction of the star's rotational phase, indicates a magnetic field with a dominant potential field component. The data are best fitted when a 3.1-d period of modulation and an intermediate inclination are assumed. Considering the level of differential rotation of τ Boo, this implies a rotation period of 3.0 d at the equator and of 3.7 d at the pole, and a topology of the magnetic field where its main non-axisymmetric part is located at low latitudes.
The planet is probably synchronized with the star's rotation at intermediate latitudes, while the non-axisymmetric part of the magnetic field seems located at lower latitudes. Our limited data do not provide sufficient constraints on the magnetic field to study a possible interaction of the planet with the star's magnetosphere. Investigating this issue will require data with much better phase coverage. Similar studies should also be performed for other stars hosting close-in giant planets.
Based on observations obtained at the Canada-France-Hawaii Telescope (CFHT) which is operated by the National Research Council of Canada, the Institut National des Sciences de l'Univers of the Centre National de la Recherche Scientifique of France, and the University of Hawaii.
E-mail: Claude.Catala@obspm.fr (CC); Jean-Francois.Donati@obs-mip.fr (J-FD); shkolnik@ifa.hawaii.edu (ES); david.bohlender@nrc-cnrc.gc.ca (DB); Evelyne.Alecian@obspm.fr (EA)
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