The CARMENES search for exoplanets around M dwarfs Variability on long timescales as seen in chromospheric indicators

It is clearly established that the Sun has an 11-yr cycle that is caused by its internal magnetic field. Such a cycle is also observed in a sample of M dwarfs. In the framework of exoplanet detection or atmospheric characterisation of exoplanets, the activity status of the host star plays a crucial...

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Detalles Bibliográficos
Autores: Caballero, J. A., Montes Gutiérrez, David, otros, ...
Tipo de recurso: artículo
Fecha de publicación:2023
País:España
Institución:Universidad Complutense de Madrid (UCM)
Repositorio:Docta Complutense
Idioma:inglés
OAI Identifier:oai:docta.ucm.es:20.500.14352/73277
Acceso en línea:https://hdl.handle.net/20.500.14352/73277
Access Level:acceso abierto
Palabra clave:52
Low-Mass stars
Activity cycles
Magnetic cycles
Term activity
H-alpha
Rotation
Planet
Astrofísica
Astronomía (Física)
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spelling The CARMENES search for exoplanets around M dwarfs Variability on long timescales as seen in chromospheric indicatorsCaballero, J. A.Montes Gutiérrez, Davidotros, ...52Low-Mass starsActivity cyclesMagnetic cyclesTerm activityH-alphaRotationPlanetAstrofísicaAstronomía (Física)It is clearly established that the Sun has an 11-yr cycle that is caused by its internal magnetic field. Such a cycle is also observed in a sample of M dwarfs. In the framework of exoplanet detection or atmospheric characterisation of exoplanets, the activity status of the host star plays a crucial role, and inactive states are preferable for such studies. This means that it is important to know the activity cycles of these stars. We study systematic long-term variability in a sample of 211 M dwarfs observed with CARMENES, the high-resolution optical and near-infrared spectrograph at Calar Alto Observatory. In an automatic search using time series of different activity indicators, we identified 26 stars with linear or quadratic trends or with potentially cyclic behaviour. Additionally, we performed an independent search in archival R′_(HK) data collected from different instruments whose time baselines were usually much longer. These data are available for a subset of 186 of our sample stars. Our search revealed 22 cycle candidates in the data. We found that the percentage of stars showing long-term variations drops dramatically to the latest M dwarfs. Moreover, we found that the pseudo-equivalent width (pEW) of the Hα and Ca II infrared triplet more often triggers automatic detections of long-term variations than the TiO index, differential line width, chromatic index, or radial velocity. This is in line with our comparison of the median relative amplitudes of the different indicators. For stars that trigger our automatic detection, this leads to the highest amplitude variation in R′_(HK), followed by pEW(Hα), pEW(Ca II IRT), and the TiO index.EDP ScienciesUniversidad Complutense de Madrid20232023-02-0820232023-02-08journal articlehttp://purl.org/coar/resource_type/c_6501info:eu-repo/semantics/articleapplication/pdfhttps://hdl.handle.net/20.500.14352/73277reponame:Docta Complutenseinstname:Universidad Complutense de Madrid (UCM)Inglésengopen accesshttp://purl.org/coar/access_right/c_abf2Atribución 3.0 Españahttps://creativecommons.org/licenses/by/3.0/es/info:eu-repo/semantics/openAccessoai:docta.ucm.es:20.500.14352/732772026-06-02T12:44:21Z
dc.title.none.fl_str_mv The CARMENES search for exoplanets around M dwarfs Variability on long timescales as seen in chromospheric indicators
title The CARMENES search for exoplanets around M dwarfs Variability on long timescales as seen in chromospheric indicators
spellingShingle The CARMENES search for exoplanets around M dwarfs Variability on long timescales as seen in chromospheric indicators
Caballero, J. A.
52
Low-Mass stars
Activity cycles
Magnetic cycles
Term activity
H-alpha
Rotation
Planet
Astrofísica
Astronomía (Física)
title_short The CARMENES search for exoplanets around M dwarfs Variability on long timescales as seen in chromospheric indicators
title_full The CARMENES search for exoplanets around M dwarfs Variability on long timescales as seen in chromospheric indicators
title_fullStr The CARMENES search for exoplanets around M dwarfs Variability on long timescales as seen in chromospheric indicators
title_full_unstemmed The CARMENES search for exoplanets around M dwarfs Variability on long timescales as seen in chromospheric indicators
title_sort The CARMENES search for exoplanets around M dwarfs Variability on long timescales as seen in chromospheric indicators
dc.creator.none.fl_str_mv Caballero, J. A.
Montes Gutiérrez, David
otros, ...
author Caballero, J. A.
author_facet Caballero, J. A.
Montes Gutiérrez, David
otros, ...
author_role author
author2 Montes Gutiérrez, David
otros, ...
author2_role author
author
dc.contributor.none.fl_str_mv Universidad Complutense de Madrid
dc.subject.none.fl_str_mv 52
Low-Mass stars
Activity cycles
Magnetic cycles
Term activity
H-alpha
Rotation
Planet
Astrofísica
Astronomía (Física)
topic 52
Low-Mass stars
Activity cycles
Magnetic cycles
Term activity
H-alpha
Rotation
Planet
Astrofísica
Astronomía (Física)
description It is clearly established that the Sun has an 11-yr cycle that is caused by its internal magnetic field. Such a cycle is also observed in a sample of M dwarfs. In the framework of exoplanet detection or atmospheric characterisation of exoplanets, the activity status of the host star plays a crucial role, and inactive states are preferable for such studies. This means that it is important to know the activity cycles of these stars. We study systematic long-term variability in a sample of 211 M dwarfs observed with CARMENES, the high-resolution optical and near-infrared spectrograph at Calar Alto Observatory. In an automatic search using time series of different activity indicators, we identified 26 stars with linear or quadratic trends or with potentially cyclic behaviour. Additionally, we performed an independent search in archival R′_(HK) data collected from different instruments whose time baselines were usually much longer. These data are available for a subset of 186 of our sample stars. Our search revealed 22 cycle candidates in the data. We found that the percentage of stars showing long-term variations drops dramatically to the latest M dwarfs. Moreover, we found that the pseudo-equivalent width (pEW) of the Hα and Ca II infrared triplet more often triggers automatic detections of long-term variations than the TiO index, differential line width, chromatic index, or radial velocity. This is in line with our comparison of the median relative amplitudes of the different indicators. For stars that trigger our automatic detection, this leads to the highest amplitude variation in R′_(HK), followed by pEW(Hα), pEW(Ca II IRT), and the TiO index.
publishDate 2023
dc.date.none.fl_str_mv 2023
2023-02-08
2023
2023-02-08
dc.type.none.fl_str_mv journal article
http://purl.org/coar/resource_type/c_6501
dc.type.openaire.fl_str_mv info:eu-repo/semantics/article
format article
dc.identifier.none.fl_str_mv https://hdl.handle.net/20.500.14352/73277
url https://hdl.handle.net/20.500.14352/73277
dc.language.none.fl_str_mv Inglés
eng
language_invalid_str_mv Inglés
language eng
dc.rights.none.fl_str_mv open access
http://purl.org/coar/access_right/c_abf2
Atribución 3.0 España
https://creativecommons.org/licenses/by/3.0/es/
dc.rights.openaire.fl_str_mv info:eu-repo/semantics/openAccess
rights_invalid_str_mv open access
http://purl.org/coar/access_right/c_abf2
Atribución 3.0 España
https://creativecommons.org/licenses/by/3.0/es/
eu_rights_str_mv openAccess
dc.format.none.fl_str_mv application/pdf
dc.publisher.none.fl_str_mv EDP Sciencies
publisher.none.fl_str_mv EDP Sciencies
dc.source.none.fl_str_mv reponame:Docta Complutense
instname:Universidad Complutense de Madrid (UCM)
instname_str Universidad Complutense de Madrid (UCM)
reponame_str Docta Complutense
collection Docta Complutense
repository.name.fl_str_mv
repository.mail.fl_str_mv
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score 15,301603

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