Pollux: A weak dynamo-driven dipolar magnetic field and implications for its probable planet
International audience Context. Pollux is considered as an archetype of a giant star hosting a planet since its radial velocity (RV) presents very stable sinusoidal variations with a period of about 590 d. We then discovered a weak magnetic field at its surface using spectropolarimetry, questioning...
Published in: | Astronomy & Astrophysics |
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Main Authors: | , , , , , , , , , |
Other Authors: | , , , , , , , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
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HAL CCSD
2021
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Subjects: | |
Online Access: | https://hal.archives-ouvertes.fr/hal-03146215 https://hal.archives-ouvertes.fr/hal-03146215/document https://hal.archives-ouvertes.fr/hal-03146215/file/aa39573-20.pdf https://doi.org/10.1051/0004-6361/202039573 |
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ftmeteofrance:oai:HAL:hal-03146215v1 |
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openpolar |
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Open Polar |
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Météo-France: HAL |
op_collection_id |
ftmeteofrance |
language |
English |
topic |
stars: late-type stars: individual: Pollux stars: magnetic field stars: rotation planets and satellites: general [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph] |
spellingShingle |
stars: late-type stars: individual: Pollux stars: magnetic field stars: rotation planets and satellites: general [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph] Aurière, M. Petit, P. Mathias, P. Konstantinova-Antova, R. Charbonnel, Corinne Donati, J.-F. Espagnet, O. Folsom, C. P. Roudier, T. Wade, G. A. Pollux: A weak dynamo-driven dipolar magnetic field and implications for its probable planet |
topic_facet |
stars: late-type stars: individual: Pollux stars: magnetic field stars: rotation planets and satellites: general [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph] |
description |
International audience Context. Pollux is considered as an archetype of a giant star hosting a planet since its radial velocity (RV) presents very stable sinusoidal variations with a period of about 590 d. We then discovered a weak magnetic field at its surface using spectropolarimetry, questioning the planetary hypothesis.Aims. We followed up our investigations on Pollux to characterize its magnetic field and to infer the effects of magnetic activity on the RV variations.Methods. We first used ESPaDOnS at CFHT and then Narval at TBL to obtain Stokes I and Stokes V spectra of Pollux to study their variations for a duration of 4.25 years, that is, for more than two periods of the RV variations. We used the least-squares deconvolution profiles to measure the longitudinal magnetic field and to perform a Zeeman Doppler imaging (ZDI) investigation.Results. The longitudinal magnetic field of Pollux is found to vary with a sinusoidal behavior and a period similar to that of the RV variations. From the ZDI investigation a rotation period of Pollux is determined to be equal to 660 ± 15 days and possibly different than the period of variations of the RV. As to the magnetic topology, the poloidal component is dominant and almost purely dipolar with an inclination of 10.5° of the dipole with respect to the rotation axis. The mean strength of the surface magnetic field is 0.44 G. Pollux is found approximately as active as the Sun observed as a star and this activity could induce moderate RV variations.Conclusions. As to the origin of the magnetic field of Pollux, we favor the hypothesis that it is maintained through contemporaneous dynamo action. Pollux appears as the representative of a class of slowly rotating and weakly magnetic G-K red giants. To explain the sinusoidal RV variations of Pollux, two scenarios are proposed. If the RV period is different from the rotation period, the observed periodic RV variations are due to the hosted planet and the contribution of Pollux magnetic activity is not significantly detected. ... |
author2 |
Institut de recherche en astrophysique et planétologie (IRAP) Université Toulouse III - Paul Sabatier (UT3) Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP) Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS)-Université Fédérale Toulouse Midi-Pyrénées-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS) Laboratoire Gemini (LG) Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS) Софийски университет = Sofia University Geneva Observatory Université de Genève = University of Geneva (UNIGE) |
format |
Article in Journal/Newspaper |
author |
Aurière, M. Petit, P. Mathias, P. Konstantinova-Antova, R. Charbonnel, Corinne Donati, J.-F. Espagnet, O. Folsom, C. P. Roudier, T. Wade, G. A. |
author_facet |
Aurière, M. Petit, P. Mathias, P. Konstantinova-Antova, R. Charbonnel, Corinne Donati, J.-F. Espagnet, O. Folsom, C. P. Roudier, T. Wade, G. A. |
author_sort |
Aurière, M. |
title |
Pollux: A weak dynamo-driven dipolar magnetic field and implications for its probable planet |
title_short |
Pollux: A weak dynamo-driven dipolar magnetic field and implications for its probable planet |
title_full |
Pollux: A weak dynamo-driven dipolar magnetic field and implications for its probable planet |
title_fullStr |
Pollux: A weak dynamo-driven dipolar magnetic field and implications for its probable planet |
title_full_unstemmed |
Pollux: A weak dynamo-driven dipolar magnetic field and implications for its probable planet |
title_sort |
pollux: a weak dynamo-driven dipolar magnetic field and implications for its probable planet |
publisher |
HAL CCSD |
publishDate |
2021 |
url |
https://hal.archives-ouvertes.fr/hal-03146215 https://hal.archives-ouvertes.fr/hal-03146215/document https://hal.archives-ouvertes.fr/hal-03146215/file/aa39573-20.pdf https://doi.org/10.1051/0004-6361/202039573 |
long_lat |
ENVELOPE(140.018,140.018,-66.660,-66.660) |
geographic |
Pollux |
geographic_facet |
Pollux |
genre |
narval narval |
genre_facet |
narval narval |
op_source |
ISSN: 0004-6361 EISSN: 1432-0756 Astronomy and Astrophysics - A&A https://hal.archives-ouvertes.fr/hal-03146215 Astronomy and Astrophysics - A&A, EDP Sciences, 2021, 646, pp.A130. ⟨10.1051/0004-6361/202039573⟩ |
op_relation |
info:eu-repo/semantics/altIdentifier/doi/10.1051/0004-6361/202039573 hal-03146215 https://hal.archives-ouvertes.fr/hal-03146215 https://hal.archives-ouvertes.fr/hal-03146215/document https://hal.archives-ouvertes.fr/hal-03146215/file/aa39573-20.pdf doi:10.1051/0004-6361/202039573 |
op_rights |
info:eu-repo/semantics/OpenAccess |
op_doi |
https://doi.org/10.1051/0004-6361/202039573 |
container_title |
Astronomy & Astrophysics |
container_volume |
646 |
container_start_page |
A130 |
_version_ |
1766244620522487808 |
spelling |
ftmeteofrance:oai:HAL:hal-03146215v1 2023-05-15T18:50:52+02:00 Pollux: A weak dynamo-driven dipolar magnetic field and implications for its probable planet Aurière, M. Petit, P. Mathias, P. Konstantinova-Antova, R. Charbonnel, Corinne Donati, J.-F. Espagnet, O. Folsom, C. P. Roudier, T. Wade, G. A. Institut de recherche en astrophysique et planétologie (IRAP) Université Toulouse III - Paul Sabatier (UT3) Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP) Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS)-Université Fédérale Toulouse Midi-Pyrénées-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS) Laboratoire Gemini (LG) Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS) Софийски университет = Sofia University Geneva Observatory Université de Genève = University of Geneva (UNIGE) 2021-02 https://hal.archives-ouvertes.fr/hal-03146215 https://hal.archives-ouvertes.fr/hal-03146215/document https://hal.archives-ouvertes.fr/hal-03146215/file/aa39573-20.pdf https://doi.org/10.1051/0004-6361/202039573 en eng HAL CCSD EDP Sciences info:eu-repo/semantics/altIdentifier/doi/10.1051/0004-6361/202039573 hal-03146215 https://hal.archives-ouvertes.fr/hal-03146215 https://hal.archives-ouvertes.fr/hal-03146215/document https://hal.archives-ouvertes.fr/hal-03146215/file/aa39573-20.pdf doi:10.1051/0004-6361/202039573 info:eu-repo/semantics/OpenAccess ISSN: 0004-6361 EISSN: 1432-0756 Astronomy and Astrophysics - A&A https://hal.archives-ouvertes.fr/hal-03146215 Astronomy and Astrophysics - A&A, EDP Sciences, 2021, 646, pp.A130. ⟨10.1051/0004-6361/202039573⟩ stars: late-type stars: individual: Pollux stars: magnetic field stars: rotation planets and satellites: general [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph] info:eu-repo/semantics/article Journal articles 2021 ftmeteofrance https://doi.org/10.1051/0004-6361/202039573 2022-10-04T22:37:41Z International audience Context. Pollux is considered as an archetype of a giant star hosting a planet since its radial velocity (RV) presents very stable sinusoidal variations with a period of about 590 d. We then discovered a weak magnetic field at its surface using spectropolarimetry, questioning the planetary hypothesis.Aims. We followed up our investigations on Pollux to characterize its magnetic field and to infer the effects of magnetic activity on the RV variations.Methods. We first used ESPaDOnS at CFHT and then Narval at TBL to obtain Stokes I and Stokes V spectra of Pollux to study their variations for a duration of 4.25 years, that is, for more than two periods of the RV variations. We used the least-squares deconvolution profiles to measure the longitudinal magnetic field and to perform a Zeeman Doppler imaging (ZDI) investigation.Results. The longitudinal magnetic field of Pollux is found to vary with a sinusoidal behavior and a period similar to that of the RV variations. From the ZDI investigation a rotation period of Pollux is determined to be equal to 660 ± 15 days and possibly different than the period of variations of the RV. As to the magnetic topology, the poloidal component is dominant and almost purely dipolar with an inclination of 10.5° of the dipole with respect to the rotation axis. The mean strength of the surface magnetic field is 0.44 G. Pollux is found approximately as active as the Sun observed as a star and this activity could induce moderate RV variations.Conclusions. As to the origin of the magnetic field of Pollux, we favor the hypothesis that it is maintained through contemporaneous dynamo action. Pollux appears as the representative of a class of slowly rotating and weakly magnetic G-K red giants. To explain the sinusoidal RV variations of Pollux, two scenarios are proposed. If the RV period is different from the rotation period, the observed periodic RV variations are due to the hosted planet and the contribution of Pollux magnetic activity is not significantly detected. ... Article in Journal/Newspaper narval narval Météo-France: HAL Pollux ENVELOPE(140.018,140.018,-66.660,-66.660) Astronomy & Astrophysics 646 A130 |