J/A+A/672/A37ivo://CDS.VizieR/J/A+A/672/A37doi:10.26093/cds/vizier.36720037CDSIbanez Bustos R.V.Buccino A.P.Flores M.Martinez C.F.Mauas P.J.D.2024-11-28T20:03:05Z2023-03-27T10:08:08ZCDS support team

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

cds-question@unistra.frlate-type-starsm-starsvisible-astronomyspectroscopyDifferent approaches have been adopted to study both short- and long-term stellar magnetic activity, and although the mechanisms by which low-mass stars generate large-scale magnetic fields are not well understood, it is known that stellar rotation plays a key role. There are stars that show a cyclical behaviour in their activity studied on the blue side of the visible spectrum, which can be explained by solar dynamo or {alpha}{Omega} dynamo models. However, when studying late-type dwarf stars, they become redder and it is necessary to implement other indicators to analyse their magnetic activity. In the present work, we perform a comparative study between the best-known activity indicators so far defined from the Ca II and H{alpha} lines to analyse M-dwarf stars. We studied a sample of 29 M stars with different chromospheric activity levels and spectral classes ranging from dM0 to dM6. To do so, we employed 1796 spectra from different instruments with a median time span of observations of 21 years. The spectra have a wide spectral range that allowed us to compute the chrosmospheric activity indicators based on CaII and H{alpha}. In addition, we complemented our data with photometric observations from the TESS space mission for better stellar characterisation and short-term analysis. We obtained a good and significant correlation ({rho}=0.91) between the indexes defined from the two lines for the whole set of stars in the sample. However, we found that there is a deviation for faster rotators (with Prot<4-days) and higher flare activity (at least one flare per day). For the individual analysis, we found that the indexes computed individually for each star correlate independently of the level of chromospheric emission and the rotation period. There is an overall positive correlation between CaII and H{alpha} emission in dM stars, except during flare events. In particular, we found that low-energy high-frequency flares could be responsible for the deviation in the linear trend in fast-rotator M dwarfs. This implies that the rotation period could be a fundamental parameter to study the stellar activity and that the rotation could drive the magnetic dynamo in low-mass active stars.2023A&A...672A..37Ihttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/672/A37CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toI/345 : Gaia DR2 (Gaia Collaboration, 2018)J/AcA/62/67 : ASAS photometry of ROSAT sources (Kiraga, 2012)J/MNRAS/443/2561 : CONCH-SHELL catalog of nearby M dwarfs (Gaidos+, 2014)J/A+A/597/A108 : GJ 536 HARPS and HARPS-N data (Suarez Mascareno+, 2017)J/A+A/613/A25 : Radial velocity for Ross 128 (Bonfils+, 2018)J/A+A/621/A126 : CARMENES input catalogue of M dwarfs IV. (Diez Alonso+ 2019)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/672/A37https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/672/A37http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/672/A37https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/672/A37https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/672/A37http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/672/A37GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/672/A37/table1 (Activity indicators in M dwarfs)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/672/A37/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/672/A37/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/672/A37/table1?GETtext/xml+votable180.050000true1.3517853-37.35736330.0055555555555555566/4444 16391 16758 19466 20507 20896 22148 22807 22964 25989 26555 26583 26972 28955 30505 30626 31781 33493 33582 38247 40435 41591 43187 45269 46456 46776 46922 48263 48274https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/672/A37?format=asciiOpticaldefaultJ/A+A/672/A37/table1Activity indicators in M dwarfsSimbadSimbad column added by the CDSmeta.ref.urlcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintStarName of the starmeta.id;meta.maincharSpTypeSpectral typesrc.spTypecharB-V(B-V) colour indexphot.color;em.opt.B;em.opt.VfloatTeff? Effective temperatureKphys.temperature.effectiveintnullablee_Teff? Effective temperature errorKstat.error;phys.temperature.effectiveintnullableM*? Stellar masssolMassphys.massfloatnullableR*? Stellar radiussolRadphys.size.radiusfloatnullable<S>? Mean value of the Mount Wilson indexmeta.code;spect.index;stat.meanfloatnullable<A>? Mean value of the A indexmeta.code;spect.index;stat.meanfloatnullablerhoS-A? Correlation coefficient between indexesstat.fit.paramfloatnullablee_rhoS-A? Correlation coefficient standard errorstat.errorfloatnullableB_rhoS-A? Upper value of 95% confidence levelstat.fit.param;phys.atmol.levelfloatnullableb_rhoS-A? Lower value of 95% confidence levelstat.fit.param;phys.atmol.levelfloatnullablelogR'HKChromospheric emission levelphot.flux;arith.ratiofloate_logR'HKChromospheric emission level errorstat.errorfloatNobsNumber of observationsmeta.numberintProt? Rotation perioddtime.perioddoublenullablee_Prot? Rotation perioddstat.errordoublenullabler_ProtRotation period references (1)meta.ref;pos.framechar_RARight Ascension (J2000) from SIMBAD (not part of the original data)degpos.eq.ra;meta.main_DEDeclination (J2000) from SIMBAD (not part of the original data)degpos.eq.dec;meta.mainJ/A+A/672/A37/listList od fits spectrarecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintStarName of the starmeta.id;meta.maincharNxNumber of pixels along X-axismeta.numberintNyNumber of pixels along Y-axismeta.numberintObs.dateObservation datestime.epoch;obsnullablesizeSize of FITS fileKibytephys.size;meta.fitsintspShow the spectrummeta.ref.urlcharFileNameName of FITS file, in subdirectory spmeta.id;meta.fitscharTitleTitle ofr the filemeta.title;meta.filechar