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  Long-term spot monitoring of the young solar analogue V889 Herculis

Willamo, T., Hackman, T., Lehtinen, J., Käpylä, M. J., Ilyin, I., Henry, G. W., et al. (2019). Long-term spot monitoring of the young solar analogue V889 Herculis. Astronomy and Astrophysics, 622: A170. doi:10.1051/0004-6361/201834562.

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Item Permalink: http://hdl.handle.net/21.11116/0000-0006-472A-C Version Permalink: http://hdl.handle.net/21.11116/0000-0006-472C-A
Genre: Journal Article

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 Creators:
Willamo, T., Author
Hackman, T., Author
Lehtinen, Jyri1, 2, Author              
Käpylä, Maarit J.1, 2, Author              
Ilyin, I., Author
Henry, G. W., Author
Jetsu, L., Author
Kochukhov, O., Author
Piskunov, N., Author
Affiliations:
1Department Sun and Heliosphere, Max Planck Institute for Solar System Research, Max Planck Society, ou_1832289              
2Max Planck Research Group and ERC Consolidator Grant: Solar and Stellar Dynamos - SOLSTAR, Max Planck Institute for Solar System Research, Max Planck Society, Justus-von-Liebig-Weg 3, 37077 Göttingen, DE, ou_2265638              

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 Abstract: Context. Starspots are important manifestations of stellar magnetic activity. By studying their behaviour in young solar analogues, we can unravel the properties of their magnetic cycles. This gives crucial information of the underlying dynamo process. Comparisons with the solar cycle enable us to infer knowledge about how the solar dynamo has evolved during the Sun’s lifetime. Aims. Here we study the correlation between photometric brightness variations, spottedness, and mean temperature in V889 Her, a young solar analogue. Our data covers 18 years of spectroscopic and 25 years of photometric observations. Methods. We use Doppler imaging to derive temperature maps from high-resolution spectra. We use the Continuous Period Search method to retrieve mean V-magnitudes from photometric data. Results. Our Doppler imaging maps show a persistent polar spot structure varying in strength. This structure is centred slightly off the rotational pole. The mean temperature derived from the maps shows an overall decreasing trend, as does the photometric mean brightness, until it reaches its minimum around 2017. The filling factor of cool spots, however, shows only a weak tendency to anti-correlate with the decreasing mean brightness. Conclusions. We interpret V889 Her to have entered into a grand maximum in its activity. The clear relation between the mean temperature of the Doppler imaging surface maps and the mean magnitude supports the reliability of the Doppler images. The lack of correlation between the mean magnitude and the spottedness may indicate that bright features in the Doppler images are real.

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Language(s): eng - English
 Dates: 2019
 Publication Status: Published in print
 Pages: -
 Publishing info: -
 Table of Contents: -
 Rev. Method: Peer
 Identifiers: DOI: 10.1051/0004-6361/201834562
 Degree: -

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Title: Astronomy and Astrophysics
  Other : Astron. Astrophys.
Source Genre: Journal
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Publ. Info: Les Ulis Cedex A France : EDP Sciences
Pages: 10 Volume / Issue: 622 Sequence Number: A170 Start / End Page: - Identifier: Other: 1432-0746
ISSN: 0004-6361
CoNE: https://pure.mpg.de/cone/journals/resource/954922828219_1