Doppler images and the underlying dynamo: the case of AF Leporis

Jarvinen, S. P. and Arlt, R. and Hackman, T. and Marsden, S. C. and Kuker, M. and Ilyin, I. V. and Berdyugina, S. V. and Strassmeier, K. G. and Waite, I. A. (2015) Doppler images and the underlying dynamo: the case of AF Leporis. Astronomy & Astrophysics, 574 (A25). pp. 1-18. ISSN 0004-6361

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Abstract

Context: The (Zeeman-)Doppler imaging studies of solar-type stars very often reveal large high-latitude spots. This also includes F stars that possess relatively shallow convection zones, indicating that the dynamo operating in these stars differs from the solar dynamo.

Aims: We aim to determine whether mean-field dynamo models of late-F type dwarf stars can reproduce the surface features recovered in Doppler maps. In particular, we wish to test whether the models can reproduce the high-latitude spots observed on some F dwarfs.

Methods: The photometric inversions and the surface temperature maps of AF Lep were obtained using the Occamian-approach inversion technique. Low signal-to-noise spectroscopic data were improved by applying the least-squares deconvolution method. The locations of strong magnetic flux in the stellar tachocline as well as the surface fields obtained from mean-field dynamo solutions were compared with the observed surface temperature maps.

Results: The photometric record of AF Lep reveals both long- and short-term variability. However, the current data set is too short for cycle-length estimates. From the photometry, we have determined the rotation period of the star to be 0.9660 ± 0.0023 days. The surface temperature maps show a dominant, but evolving, high-latitude (around +65°) spot. Detailed study of the photometry reveals that sometimes the spot coverage varies only marginally over a long time, and at other times it varies rapidly. Of a suite of dynamo models, the model with a radiative interior rotating as fast as the convection zone at the equator delivered the highest compatibility with the obtained Doppler images.


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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: Access to published version in accordance with the copyright policy of the publisher.
Faculty / Department / School: Current - Faculty of Health, Engineering and Sciences - School of Agricultural, Computational and Environmental Sciences
Date Deposited: 03 Jun 2016 04:56
Last Modified: 01 Aug 2016 01:58
Uncontrolled Keywords: stars: imaging; stars: activity; starspots; stars: individual: AF Leb; dynamo
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: 10.1051/0004-6361/201424229
URI: http://eprints.usq.edu.au/id/eprint/28582

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