The Rotationally Modulated Polarization of ξ Boo A

Cotton, Daniel V. and Evensberget, Dag and Marsden, Stephen C. and Bailey, Jeremy and Zhao, Jinglin and Kedziora-Chudczer, Lucyna and Carter, Bradley D. and Bott, Kimberly and Vidotto, Aline A. and Petit, Pascal and Morin, Julien and Jeffers, Sandra V. (2019) The Rotationally Modulated Polarization of ξ Boo A. Monthly Notices of the Royal Astronomical Society, 483. pp. 1574-1581. ISSN 0035-8711

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Abstract

We have observed the active star ξ Boo A (HD 131156A) with high precision broadband linear polarimetry contemporaneously with circular spectropolarimetry. We find both signals are modulated by the 6.43 d rotation period of ξ Boo A. The signals from the two techniques are 0.25 out of phase, consistent with the broadband linear polarization resulting from differential saturation of spectral lines in the global transverse magnetic field. The mean magnitude of the linear polarization signal is ̃4 ppm G-1 but its structure is complex and the amplitude of the variations suppressed relative to the longitudinal magnetic field. The result has important implications for current attempts to detect polarized light from hot Jupiters orbiting active stars in the combined light of the star and planet. In such work stellar activity will manifest as noise, both on the time-scale of stellar rotation, and on longer time-scales - where changes in activity level will manifest as a baseline shift between observing runs.


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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society © 2018 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
Faculty/School / Institute/Centre: Current - Institute for Advanced Engineering and Space Sciences - Centre for Astrophysics (1 Aug 2018 -)
Faculty/School / Institute/Centre: Current - Faculty of Health, Engineering and Sciences - School of Sciences (6 Sept 2019 -)
Date Deposited: 22 Jan 2020 04:38
Last Modified: 07 Feb 2020 01:52
Uncontrolled Keywords: polarization – stars; activity – stars; individual HD 131156A – stars; magnetic field
Fields of Research : 02 Physical Sciences > 0201 Astronomical and Space Sciences > 020110 Stellar Astronomy and Planetary Systems
Socio-Economic Objective: E Expanding Knowledge > 97 Expanding Knowledge > 970102 Expanding Knowledge in the Physical Sciences
Identification Number or DOI: 10.1093/mnras/sty3180
URI: http://eprints.usq.edu.au/id/eprint/37364

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