J/A+A/701/A17ivo://CDS.VizieR/J/A+A/701/A17doi:10.26093/cds/vizier/bc-nx/lbhCDSCharpentier P.Moutou C.Donati J.-F.Cristofari P.I.Larue P.,Marion S.Hood T.Ould-Elhkim M.Artigau E.Cadieux C.Boisse I.,Carmona A.Cook N.J.Delfosse X.Doyon R.Morin J.the SLS Consortium2026-08-03T06:57:04Z2025-08-28T08:05:44ZCDS support team

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

cds-question@unistra.fratomic-physicsspectroscopyvisible-astronomyRecent instruments have extended radial velocity observations from the optical domain to the near-infrared range. In particular, this has allowed to study M dwarfs more extensively, which are known to host rocky planets more frequently. However, these stars also have on average stronger magnetic activity than solar-type stars. Therefore, investigating this magnetic activity is key to uncovering planets around such stars. This paper aims to extensively test a new reliable magnetic activity indicator, named W_1_, and confirm it as a proxy for the small-scale magnetic field for M dwarf stars. W_1_ is derived from a Principal Component Analysis (PCA) applied on the per-line differential Line Width (dLW). However, the PCA is highly sensitive to contamination from telluric residuals in the spectra. Therefore, we employ a filtering technique based on machine learning tools such as unsupervised Dimensional Reduction (DR) algorithm and Support Vector Machine (SVM) to remove faulty lines. We assess the performances of this filtering method using a simulation of observations of the per-line $dLW$ variations before applying it on near-infrared (nIR) high resolution spectroscopic observations using SPIRou at the Canada-France-Hawaii Telescope (CFHT) on five targets, with various levels of stellar magnetic activity, spectral types and rotation periods, from the SPIRou Legacy Survey, namely AU Mic, EV Lac, GJ1286, GJ1289 and Gl 410. The filtered W_1_ signal is modulated with a period consistent with the rotation period retrieved from activity indicators, corresponding to the magnetic activity for all the stars studied. It also correlates with the small- scale magnetic field for all the five stars, with a direct Pearson correlation coefficient greater than 0.80. Additionally, we identified 201 stellar lines that are particularly sensitive to magnetic activity that could be valuable for studying of magnetic fields.2025A&A...701A..17Chttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/701/A17CatalogResearchIsServedByTAP VizieR generic servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/701/A17https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/701/A17http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/701/A17https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/701/A17https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/701/A17http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/701/A17GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticaldefaultJ/A+A/701/A17/linesComplete list of lines isolated from the activity clusters of AU Mic, EV Lac and GJ1289recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintLineIDLine IDmeta.idintWaveStartWavelenth Start of the linenmem.wldoubleWaveEndWavelenth End of the linenmem.wldoubleDepthDepth of the linephys.absorption.opticalDepth;spect.linefloatdLWAmpAmplitude of the dLW variations for that linekm/ssrc.var.amplitudefloatStarStar from which this line is derivedmeta.id;meta.maincharLineID1? Line ID 1meta.idintnullableLineID2? Line ID 2meta.idintnullableLineID3? Line ID 3meta.idintnullableCommentComment on the identification (1)meta.idcharGuess1? Possible Guess IDmeta.idintnullableGuess2? Possible Guess IDmeta.idintnullableGuess3? Possible Guess IDmeta.idintnullableGuess4? Possible Guess IDmeta.idintnullableJ/A+A/701/A17/guessGuess linesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintGuessIDGuess IDmeta.idintWaveGuessedWavelenth of the line in the masknmem.wldoubleSpeciesSpecies of the linemeta.notecharLandeG? Lande Factor of the linephys.atmol.lande;spect.linefloatnullableMaskDepthDepth of the line in the maskphot.flux.density;arith.ratiofloat