A solar-like magnetic cycle on the mature K-dwarf 61 Cyg A (HD 201091)
| Autor: | C. P. Folsom, Jeffrey C. Hall, Robert H. Cameron, Ansgar Reiners, Sandra V. Jeffers, Stephen C. Marsden, Aline A. Vidotto, Julien Morin, Pascal Petit, J.-F. Donati, S. Boro Saikia, V. Perdelwitz |
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| Přispěvatelé: | Institut für Astrophysik [Göttingen], Georg-August-University [Göttingen], Laboratoire Univers et Particules de Montpellier (LUPM), Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Montpellier 2 - Sciences et Techniques (UM2), Institut de recherche en astrophysique et planétologie (IRAP), Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Computational Engineering and Science Research Centre, University of Southern Queensland (USQ), Max-Planck-Institut für Sonnensystemforschung (MPS), Max-Planck-Gesellschaft, Lowell Observatory [Flagstaff], Hamburger Sternwarte, Observatoire Astronomique de l'Université de Genève (ObsGE), Université de Genève (UNIGE), Trinity College Dublin, Bcool, Université Montpellier 2 - Sciences et Techniques (UM2)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS) |
| Jazyk: | angličtina |
| Rok vydání: | 2016 |
| Předmět: |
Physics
010504 meteorology & atmospheric sciences Field (physics) dynamo / stars: activity / stars: chromospheres / stars: magnetic field / stars: solar-type [SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR] Phase (waves) FOS: Physical sciences Astronomy and Astrophysics Astrophysics Zeeman–Doppler imaging 01 natural sciences Magnetic field Stars Dipole Astrophysics - Solar and Stellar Astrophysics 13. Climate action Space and Planetary Science 0103 physical sciences Differential rotation Astrophysics::Solar and Stellar Astrophysics Astrophysics::Earth and Planetary Astrophysics 010303 astronomy & astrophysics Solar and Stellar Astrophysics (astro-ph.SR) 0105 earth and related environmental sciences Dynamo |
| Zdroj: | Astronomy and Astrophysics-A&A Astronomy and Astrophysics-A&A, EDP Sciences, 2016, 594, pp.A29. ⟨10.1051/0004-6361/201628262⟩ NASA Astrophysics Data System |
| ISSN: | 0004-6361 |
| Popis: | International audience; The long-term monitoring of magnetic cycles in cool stars is a key diagnostic in understanding how dynamo generation and amplification of magnetic fields occur in stars similar in structure to the Sun. We investigate the temporal evolution of a possible magnetic cycle, determined from its large-scale field, of 61 Cyg A over its activity cycle using spectropolarimetric observations and compare it to the solar case. We use Zeeman Doppler imaging (ZDI) to reconstruct the large-scale magnetic geometry over multiple observational epochs spread over a time span of nine years. We investigate the time evolution of the different components of the large-scale field and compare it with the evolution of its chromospheric activity by measuring the flux in three different chromospheric indicators: Ca II H&K, H-alpha and Ca II infra red triplet lines. We also compare our results with the star's coronal activity using XMM-Newton observations. The large-scale magnetic geometry of 61 Cyg A exhibits polarity reversals in both poloidal and toroidal field components, in phase with the chromospheric activity cycle. We also detect weak solar-like differential rotation with a shear level similar to the Sun. During our observational time span of nine years, 61 Cyg A exhibits solar-like variations in its large-scale field geometry as it evolves from minimum activity to maximum activity and vice versa. During its activity minimum in epoch 2007.59, ZDI reconstructs a simple dipolar geometry which becomes more complex close to activity maximum in epoch 2010.55. The radial field flips polarity and reverts back to a simple geometry in epoch 2013.61. The field is strongly dipolar and the evolution of the dipole component of the field is reminiscent of the solar behaviour. The polarity reversal of the large-scale field indicates a magnetic cycle that is in phase with the chromospheric and coronal cycle. |
| Databáze: | OpenAIRE |
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