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Abstract
Spectroscopic and spectropolarimetric observations of the pre-main sequence early-G star HD 141943 were obtained at four observing epochs (in 2006, 2007, 2009 and 2010). The observations were undertaken at the 3.9-m Anglo-Australian Telescope using the UCLES echelle spectrograph and the SEMPOL spectropolarimeter visitor instrument. Brightness and surface magnetic field topologies were reconstructed for the star using the technique of least-squares deconvolution to increase the signal-to-noise ratio of the data.
The reconstructed brightness maps show that HD 141943 had a weak polar spot and a significant amount of low-latitude features, with little change in the latitude distribution of the spots over the 4 yr of observations. The surface magnetic field was reconstructed at three of the epochs from a high-order (l < 30) spherical harmonic expansion of the spectropolarimetric observations. The reconstructed magnetic topologies show that in 2007 and 2010 the surface magnetic field was reasonably balanced between poloidal and toroidal components. However, we find tentative evidence of a change in the poloidal/toroidal ratio in 2009 with the poloidal component becoming more dominant. At all epochs the radial magnetic field is predominantly non-axisymmetric while the azimuthal field is predominantly axisymmetric with a ring of positive azimuthal field around the pole similar to that seen on other active stars.
Original language | English |
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Pages (from-to) | 1922-1938 |
Number of pages | 17 |
Journal | Monthly Notices of the Royal Astronomical Society |
Volume | 413 |
Issue number | 3 |
DOIs | |
Publication status | Published - 21 May 2011 |
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Dive into the research topics of 'Magnetic fields and differential rotation on the pre-main sequence - I. The early-G star HD 141943-brightness and magnetic topologies'. Together they form a unique fingerprint.Projects
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Astrophysics in St Andrews: Astrophysics in St Andrews / SUPA (Continuan of Rolling Grant - XPP089
Bonnell, I. A. (PI), Cameron, A. C. (CoI), Dominik, M. (CoI), Driver, S. P. (CoI), Greaves, J. S. (CoI), Horne, K. D. (CoI), Jardine, M. M. (CoI), Wood, K. (CoI) & Zhao, H. (CoI)
Science & Technology Facilities Council
1/04/09 → 31/03/12
Project: Standard