# The Magnetic Fields at the Surface of Active Single G-K Giants

@article{Aurire2014TheMF,
title={The Magnetic Fields at the Surface of Active Single G-K Giants},
author={Michel Auri{\e}re and Renada Konstantinova-Antova and Corinne Charbonnel and Gregg A. Wade and Svetla Tsvetkova and Pascal Petit and Boris Dintrans and Natalia A. Drake and Thibaut Decressin and Nad{\e}ge Lagarde and Jean-François Donati and T. Roudier and François Lignières and Klaus-Peter Schroder and John D. Landstreet and A. L{\e}bre and Werner W. Weiss and J-P. Zahn},
journal={arXiv: Solar and Stellar Astrophysics},
year={2014}
}`
• Published 23 November 2014
• Physics
• arXiv: Solar and Stellar Astrophysics
We investigate the magnetic field at the surface of 48 red giants selected as promising for detection of Stokes V Zeeman signatures in their spectral lines. We use the spectropolarimeters Narval and ESPaDOnS to detect circular polarization within the photospheric absorption lines of our targets and use the least-squares deconvolution (LSD) method. We also measure the classical S-index activity indicator, and the stellar radial velocity. To infer the evolutionary status of our giants and to…
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## References

SHOWING 1-10 OF 135 REFERENCES
Direct detection of a magnetic field at the surface of V390 Aurigae – an effectively single active giant
• Physics
• 2008
Aims. We have studied the active giant V390 Aur using spectropolarimetry to obtain direct and simultaneous measurements of the magnetic field and the activity indicators in order to infer the origin
Discovery of a weak magnetic field in the photosphere of the single giant Pollux
• Physics, Geology
• 2009
Aims. We observe the nearby, weakly-active single giant, Pollux, in order to directly study and infer the nature of its magnetic field. Methods. We used the new generation spectropolarimeters
Magnetic fields in single late-type giants in the Solar vicinity: How common is magnetic activity on the giant branches?
• Physics
Proceedings of the International Astronomical Union
• 2013
Abstract We present our first results on a new sample containing all single G, K and M giants down to V = 4 mag in the Solar vicinity, suitable for spectropolarimetric (Stokes V) observations with
Magnetic field structure in single late-type giants: the effectively single giant V390 Aurigae
• Physics
• 2012
Aims. We have studied the active giant V390 Aur using spectropolarimetry to obtain direct and simultaneous measurements of the magnetic field and the activity indicators to obtain a precise insight
First detection of a weak magnetic field on the giant Arcturus: remnants of a solar dynamo?
• Physics
• 2011
Context. Arcturus is the second closest K giant and among the brightest stars in the sky. It has not been found to have a magnetic field, even though Ca II H&K lines as activity indicators imply that
Long-term magnetic field monitoring of the Sun-like star ξ Bootis A
• Physics
• 2010
Aims. We aim to investigate the long-term temporal evolution of the magnetic field of the solar-type star ξ Bootis A, both from direct magnetic field measurements and from the simultaneous estimate
A dominant magnetic dipole for the evolved Ap star candidate EK Eridani
• Physics
• 2011
Context. EK Eri is one of the most slowly rotating active giants known, and has been proposed to be the descendant of a strongly magnetic Ap star. Aims: We have performed a spectropolarimetric study
EK Eridani: the tip of the iceberg of giants which have evolved from magnetic Ap stars
Aims. We observe the slowly-rotating, active, single giant, EK Eri, to study and infer the nature of its magnetic field directly. Methods. We used the spectropolarimeter NARVAL at the Telescope
Lithium and magnetic fields in giant stars - HD 232 862: a magnetic and lithium-rich giant
• Physics
• 2009
Aims. We report the detection of an unusually high lithium content in HD 232 862, a field giant classified as a G8II star, and hosting a magnetic field. Methods. With the spectropolarimeters ESPaDOnS
Magnetic fields at the surfaces of stars
SummaryMagnetic fields have now been detected in stars in several parts of the Hertzsprung-Russell diagram. Roughly dipolar fields ranging in strength between 3× 102 and 3×104 G are found in many