Magnetic fields and differential rotation on the pre-main sequence - II. The early-G star HD 141943 - coronal magnetic field, Halpha emission and differential rotation

Marsden, S. C. and Jardine, M. M. and Ramirez Velez, J. C. and Alecian, E. and Brown, C. J. and Carter, B. D. and Donati, J.-F. and Dunstone, N. and Hart, R. and Semel, M. and Waite, I. A. (2011) Magnetic fields and differential rotation on the pre-main sequence - II. The early-G star HD 141943 - coronal magnetic field, Halpha emission and differential rotation. Monthly Notices of the Royal Astronomical Society, 413 (3). pp. 1939-1948. ISSN 0035-8711

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Spectropolarimetric observations of the pre-main sequence early-G star HD 141943 were made at three observing epochs (2007, 2009 and 2010). The observations were made using the 3.9-m Anglo-Australian Telescope with the UCLES echelle spectrograph and the SEMPOL spectropolarimeter visitor instrument. The brightness and surface magnetic field topologies (given in Paper I) were used to determine the star's surface differential rotation and reconstruct the coronal magnetic field of the star.

The coronal magnetic field at the three epochs shows on the largest scales that the field structure is dominated by the dipole component with possible evidence for the tilt of the dipole axis shifting between observations. We find very high levels of differential rotation on HD 141943 (˜8 times the solar value for the magnetic features and ˜5 times solar for the brightness features), similar to that evidenced by another young early-G star, HD 171488. These results indicate that a significant increase in the level of differential rotation occurs for young stars around a spectral type of early-G. We also find for the 2010 observations that there is a large difference in the differential rotation measured from the brightness and magnetic features, similar to that seen on early-K stars, but with the difference being much larger. We find only tentative evidence for temporal evolution in the differential rotation of HD 141943.

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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: © 2011 The Authors. Permanent restricted access to published version in accordance with the copyright policy of the publisher. Author version made available.
Faculty / Department / School: Historic - Faculty of Sciences - Department of Biological and Physical Sciences
Date Deposited: 24 Mar 2012 10:30
Last Modified: 11 Feb 2015 05:22
Uncontrolled Keywords: stars activity; imaging; magnetic fields; individual stars; HD 141943
Fields of Research : 02 Physical Sciences > 0201 Astronomical and Space Sciences > 020110 Stellar Astronomy and Planetary Systems
02 Physical Sciences > 0205 Optical Physics > 020503 Nonlinear Optics and Spectroscopy
01 Mathematical Sciences > 0101 Pure Mathematics > 010102 Algebraic and Differential Geometry
Socio-Economic Objective: E Expanding Knowledge > 97 Expanding Knowledge > 970102 Expanding Knowledge in the Physical Sciences
Identification Number or DOI: 10.1111/j.1365-2966.2011.18272.x

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