J/A+A/686/A66ivo://CDS.VizieR/J/A+A/686/A66doi:10.26093/cds/vizier.36860066CDSBellotti S.Morin J.Lehmann L.T.Petit P.Hussain G.A.J.Donati J-F.,Folsom C.P.Carmona A.Martioli E.Klein B.Fouque P.Moutou C.,Alencar S.Artigau E.Boisse I.Bouchy F.Bouvier J.Cook N.J.,Delfosse X.Doyon R.Hebrard G.2024-11-21T20:01:31Z2024-05-29T08:45:30ZCDS support team

CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France

cds-question@unistra.frvariable-starsmagnetic-fieldsvisible-astronomyinfrared-astronomyDynamo models of stellar magnetic fields for partly and fully convective stars are guided by observational constraints. Zeeman-Doppler imaging has revealed a variety of magnetic field geometries and, for fully convective stars in particular, a dichotomy: either strong, mostly axisymmetric, and dipole- dominated or weak, non-axisymmetric, and multipole-dominated. This dichotomy is explained by dynamo bistability or by long-term magnetic cycles, but there is no definite conclusion on the matter. We analysed optical spectropolarimetric data sets collected with ESPaDOnS and Narval between 2005 and 2016, and near-infrared SPIRou data obtained between 2019 and 2022 for three active M dwarfs with masses between 0.1 and 0.6M_{sun}_: EV Lac, DS Leo, and CN Leo. We looked for changes in time series of longitudinal magnetic field, width of unpolarised mean-line profiles, and large-scale field topology as retrieved with principal component analysis and Zeeman-Doppler imaging. We retrieved pulsating (EV Lac), stable (DS Leo), and sine-like (CN Leo) long-term trends in longitudinal field. The width of near-infrared mean-line profiles exhibits rotational modulation only for DS Leo, whereas in the optical it is evident for both EV Lac and DS Leo. The line width variations are not necessarily correlated to those of the longitudinal field, suggesting complex relations between small- and large-scale field. We also recorded topological changes: a reduced axisymmetry for EV Lac and a transition from toroidal- to poloidal-dominated regime for DS Leo. For CN Leo, the topology remained dipolar and axisymmetric, with only an oscillation in field strength. Our results show a peculiar evolution of the magnetic field for each M dwarf, confirming that M dwarfs with distinct masses and rotation periods can undergo magnetic long-term variations, and suggesting a variety of cyclic behaviours of their magnetic fields.2024A&A...686A..66Bhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/686/A66CatalogResearchIsServedByTAP VizieR generic servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/686/A66https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/686/A66http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/686/A66https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/686/A66https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/686/A66http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/686/A66GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticalInfrareddefaultJ/A+A/686/A66/tablee1SPIRou observations of EV LacrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintDateDate of observationtime.epochnullableUTUniversal time of observationstime.epoch;obsnullableHJDHeliocentric Julian date of the observation (HJD-3450000)dtime.epochdoubleNcycCycle number as computed with Eq. 1meta.id;meta.mainfloattexpExposure time of polarimetric sequencestime.duration;obs.exposurecharS/NSignal-to-noise ratio of polarimetric sequence at 650nmstat.snrintsigmaLSDRMS noise level of Stokes V (in 1e-4 unpolarised continuum unit)instr.det.noisefloatJ/A+A/686/A66/tablee2SPIRou observations of DS LeorecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintDateDate of observationtime.epochnullableUTUniversal time of observationstime.epoch;obsnullableHJDHeliocentric Julian date of the observation (HJD-3450000)dtime.epochdoubleNcycCycle number as computed with Eq. 1meta.id;meta.mainfloattexpExposure time of polarimetric sequencestime.duration;obs.exposurecharS/NSignal-to-noise ratio of polarimetric sequence at 650nmstat.snrintsigmaLSDRMS noise level of Stokes V (in 1e-4 unpolarised continuum unit)instr.det.noisefloatJ/A+A/686/A66/tablee3SPIRou observations of CN LeorecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintDateDate of observationtime.epochnullableUTUniversal time of observationstime.epoch;obsnullableHJDHeliocentric Julian date of the observation (HJD-3450000)dtime.epochdoubleNcycCycle number as computed with Eq. 1meta.id;meta.mainfloattexpExposure time of polarimetric sequencestime.duration;obs.exposurecharS/NSignal-to-noise ratio of polarimetric sequence at 650nmstat.snrintsigmaLSDRMS noise level of Stokes V (in 1e-4 unpolarised continuum unit)instr.det.noisefloatJ/A+A/686/A66/tablee4Longitudinal field of EV Lac from ESPaDOnS, Narval and SPIRourecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintHJDHeliocentric Julian date of the observation (HJD-2450000)dtime.epochdoubleBlLongitudinal fieldGphys.magFieldfloate_BlFormal error bar on longitudinal fieldGstat.errorfloatInstInstrumentmeta.id;instrcharJ/A+A/686/A66/tablee5Longitudinal field of DS Leo from ESPaDOnS, Narval and SPIRourecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintHJDHeliocentric Julian date of the observation (HJD-2450000)dtime.epochdoubleBlLongitudinal fieldGphys.magFieldfloate_BlFormal error bar on longitudinal fieldGstat.errorfloatInstInstrumentmeta.id;instrcharJ/A+A/686/A66/tablee6Longitudinal field of CN Leo from ESPaDOnS, Narval and SPIRourecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintHJDHeliocentric Julian date of the observation (HJD-2450000)dtime.epochdoubleBlLongitudinal fieldGphys.magFieldfloate_BlFormal error bar on longitudinal fieldGstat.errorfloatInstInstrumentmeta.id;instrchar