J/A+A/704/A154ivo://CDS.VizieR/J/A+A/704/A154CDSRajpurohit A.S.Kumar V.Srivastava M.K.Labadie L.Rajpurohit K.,Fernandez-Trincado J.G2026-03-02T06:25:50Z2025-12-12T09:24:45ZCDS support team

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

cds-question@unistra.frm-starsphotometryvisible-astronomyline-intensitieseffective-temperatureMost M dwarfs present high chromospheric activity that can exceed the solar magnetic activity. This can substantially influence planetary, atmospheric, and biological processes, impacting the habitability of orbiting planets. Therefore, characterizing the magnetic activity of M dwarfs is very important for understanding the physical mechanisms responsible for it, which are the primary targets in the search for exoplanets within the habitable zone. This study aims to characterize the stellar activity of active M dwarfs by understanding the relations between magnetic activities, stellar parameters, and flare properties. We analyzed TESS photometric data combined with spectroscopic observations of active M dwarfs. We examined the relationship between the flare occurrence rate, flare energies, rotation period, filling factor, and chromospheric activity indicators. Furthermore, the correlation between flare amplitude and duration and cumulative flare energy frequency distributions was investigated to probe the underlying mechanisms driving magnetic activity in flaring M dwarfs. We find that the flare occurrence rate displays a flat distribution across spectral types M0-M4 (T_eff_~3200K) and declines for later types. Faster rotators with P_rot_<1day exhibit a higher flare occurrence rate and flare activity. M dwarfs with a higher flare occurrence rate tend to exhibit lower flare amplitudes, indicating that frequent flares in these M dwarfs are generally less energetic. Within the mass range of 0.15-0.76M_{sun}_, the median of L_{Halpha_/L_bol_ in evenly divided mass bins of ~0.1M_{sun}_ varies by a factor of ~2.5, while {Delta}EW decreases by 92% across the sample. We derive power-law indexes of the cumulative flare frequency distribution for M dwarf subgroups, indicating a decreasing trend from M0 to M5 dwarfs with a value of alpha from 1.68 to 1.95, respectively. We characterized the stellar activity in M dwarfs through chromospheric indicators like H{alpha} emission, star-spot coverage, flare occurrence rates, flare energies, and flare duration. Our results suggest a stellar activity transition near M4, with stronger H{alpha} emission linked to higher flare occurrence. Rapid rotators (P_rot_<1day) exhibit significantly higher flare occurrence rate, supporting the idea that strong magnetic dynamos in fast-rotating M dwarfs sustain frequent flaring activity. Our analysis confirms that highly active stars dissipate magnetic energy through numerous low-energy flares rather than fewer high-energy events. We also show that chromospheric activity and flare activity follow a power-law relationship.2025A&A...704A.154Rhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/704/A154CatalogResearchIsServedByTAP VizieR generic servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/704/A154https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/704/A154http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/704/A154https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/704/A154https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/704/A154http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/704/A154GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticaldefaultJ/A+A/704/A154/tablea1Summary of TESS observations of flaring targetsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameSource namemeta.id;meta.maincharn_Name[+] Note on Name (1)meta.notecharTICTESS Input Catalog IDmeta.idlongTmag? TESS magnitudemagphot.mag;em.optfloatnullableDist? Distancepcpos.distancefloatnullableSectorsObserved TESS sectors (comma-separated)obs.fieldcharYearsObserving years (comma-separated)time.epochcharPipelinePipeline(s) used (SPOC, TESS-SPOC)meta.id;instrcharCadenceCadence(s) in seconds (20, 120, 200, 600)sinstr.paramcharSimbadNameSimbad column added by the CDSmeta.idcharnullableJ/A+A/704/A154/tablea2Summary of TESS observations of targets for non-flaring sourcesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameSource namemeta.id;meta.maincharn_Name[+] Note on Name (1)meta.notecharTICTESS Input Catalog IDmeta.idlongTmag? TESS magnitudemagphot.mag;em.optfloatnullableDist? Distancepcpos.distancefloatnullableSectorsObserved TESS sectors (comma-separated)obs.fieldcharYearsObserving years (comma-separated)time.epochcharSimbadNameSimbad column added by the CDSmeta.idcharnullablePipelinePipeline(s) used (SPOC, TESS-SPOC)meta.id;instrcharCadenceCadence(s) in seconds (20, 120, 200, 600)sinstr.paramcharJ/A+A/704/A154/tableb1Stellar properties and derived parametersAmed-pct? Median flare amplitude%meta.numberfloatnullablerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameSource identifiermeta.id;meta.maincharSpTypeSpectral typesrc.spTypefloatEWHaMedMedian Halpha equivalent width0.1nmspect.line.eqWidth;stat.medianfloate_EWHaMedUncertainty on EW_Ha_Med0.1nmstat.errorfloatlog(LHa/Lbol)? log10 Halpha to bolometric luminosity ratiophys.luminosity;arith.ratiofloatnullableTeffEffective temperatureKphys.temperature.effectiveintProt? Rotation perioddtime.periodfloatnullablefspot-pct? Spot covering fraction%meta.numberfloatnullableMass? Stellar mass (solar units)solMassphys.massfloatnullableRadius? Stellar radius (solar units)solRadphys.angSize;srcfloatnullableFOR-pct? Flare occurrence rate%meta.numberfloatnullableLflare/Lbol? Flare to bolometric luminosity ratiophys.luminosity;arith.ratiofloatnullableEflare? Mean flare energy (in 10^32^erg unit)1e+25Jphys.energyfloatnullable