Doppler images and the underlying dynamo: the case of AF Leporis
Article
Article Title | Doppler images and the underlying dynamo: the case of AF Leporis |
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ERA Journal ID | 1050 |
Article Category | Article |
Authors | Jarvinen, S. P. (Author), Arlt, R. (Author), Hackman, T. (Author), Marsden, S. C. (Author), Kuker, M. (Author), Ilyin, I. V. (Author), Berdyugina, S. V. (Author), Strassmeier, K. G. (Author) and Waite, I. A. (Author) |
Journal Title | Astronomy and Astrophysics: a European journal |
Journal Citation | 574 (A25), pp. 1-18 |
Number of Pages | 18 |
Year | 2015 |
Publisher | EDP Sciences |
Place of Publication | France |
ISSN | 0004-6361 |
1432-0746 | |
Digital Object Identifier (DOI) | https://doi.org/10.1051/0004-6361/201424229 |
Web Address (URL) | http://www.aanda.org/articles/aa/abs/2015/02/aa24229-14/aa24229-14.html |
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. |
Keywords | stars: imaging; stars: activity; starspots; stars: individual: AF Leb; dynamo |
ANZSRC Field of Research 2020 | 510109. Stellar astronomy and planetary systems |
Public Notes | File reproduced in accordance with the copyright policy of the publisher/author. |
Byline Affiliations | Leibniz Institute for Astrophysics, Germany |
University of Helsinki, Finland | |
Computational Engineering and Science Research Centre | |
Leibniz Institute for Solar Physics, Germany | |
Institution of Origin | University of Southern Queensland |
https://research.usq.edu.au/item/q34w5/doppler-images-and-the-underlying-dynamo-the-case-of-af-leporis
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