Magnetic fields in 292 M dwarfs.

Magnetic fields in 292 M dwarfs.J/A+A/662/A41ivo://CDS.VizieR/J/A+A/662/A41doi:10.26093/cds/vizier.36620041CDSReiners A.Shulyak D.Kaepylae P.J.Ribas I.Nagel E.Zechmeister M.,Caballero J.A.Shan Y.Fuhrmeister B.Quirrenbach A.Amado P.J.,Montes D.Jeffers S.V.Azzaro M.Bejar V.J.S.Chaturvedi P.Henning T.,Kuerster M.Palle E.2025-11-18T20:01:38Z2022-06-10T15:32:50ZCDS support team

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

cds-question@unistra.frb-starsmagnetic-fieldsStellar dynamos generate magnetic fields that are of fundamental importance to the variability and evolution of Sun-like and low-mass stars, and for the development of their planetary systems. As a key to understanding stellar dynamos, empirical relations between stellar parameters and magnetic fields are required for comparison to ab initio predictions from dynamo models. We report measurements of surface-average magnetic fields in 292 M dwarfs from a comparison with radiative transfer calculations; for 260 of them, this is the first measurement of this kind. Our data were obtained from more than 15000 high-resolution spectra taken during the CARMENES project. They reveal a relation between average field strength, , and Rossby number, Ro, resembling the well-studied rotation-activity relation. Among the slowly rotating stars, we find that magnetic flux, {Phi}_B_, is proportional to rotation period, P, and among the rapidly rotating stars that average surface fields do not grow significantly beyond the level set by the available kinetic energy. Furthermore, we find close relations between nonthermal coronal X-ray emission, chromospheric H{alpha} and Ca H&K emission, and magnetic flux. Taken together, these relations demonstrate empirically that the rotation-activity relation can be traced back to a dependence of the magnetic dynamo on rotation. We advocate the picture that the magnetic dynamo generates magnetic flux on the stellar surface proportional to rotation rate with a saturation limit set by the available kinetic energy, and we provide relations for average field strengths and nonthermal emission that are independent of the choice of the convective turnover time. We also find that Ca H&K emission saturates at average field strengths of ~800G while H{alpha} and X-ray emission grow further with stronger fields in the more rapidly rotating stars. This is in conflict with the coronal stripping scenario predicting that in the most rapidly rotating stars coronal plasma would be cooled to chromospheric temperatures.2022A&A...662A..41Rhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/662/A41CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/662/A41https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/662/A41http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/662/A41https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/662/A41https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/662/A41http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/662/A41GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/662/A41/tableb1 (Table with stellar parameters and results from our analysis)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/662/A41/tableb1?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/662/A41/tableb1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/662/A41/tableb1?GETtext/xml+votable180.050000true44.143436455.43725060.0055555555555555566/22 497 1032-1033 1357 1672 1793 1822 1875 1938 3266 3345 3374 3900 4033 4145 4366 4444 4595 4867 5000 5009 5041 5207 5343 5420 5488 5534 5590 5849 6325 6384 6552 6672 6676 6809 6894 6980 7003 7103 7262 7264 7395 7428 7471 7510 7605 7611 7763 7775 7837 7921 7937 7980 8023 8032 8123 8163 8208 8240 8281 8331 8394 8440 8562 8627 8733 8790 8843 8915 9188 9471 9529 9578 9597 9750 10037 10149 10225 10278 10448 10464-10465 10694-10695 10901 10999 11044 11177 11255 11403 11636 11671 11856 11923 11974 12140 12184 12191 12592 12621 12732 12865 13085 13427 13451 13567 13688 13743 13875 13912 14277 14395 14515 14650 14709 14772 14781 14850 14985 14993-14994 15052 15078 15311 15346 15355 15431 15548 15598 15602 15635 15748 15763 15792 15960 16041 17020 17219 17302 18440 18496 18553 18666 18761 18789 18942 19050 19064 19131 19306 19352 19466 20023 20071 20100 20109 20459 20472 20795 20896 21151 21171 21427 21747 21953 21969 21986 22014 22222 22277 22289 22309 22626 22645 22661 22709 22807 22942 22964 23014 23094 23230 23363 23453 23564 23718 23731 23735 23743 23867 23910 23997 24151 24213 24227 24231 24239 24977 24995 25009 25363 25388 25512 25528 25849 25989 26327 26538 26555 26560 26583 26706 26731 26757 26768 26772 26821 26972 27201 27289 27320 27392 27419 27459 27462 27730 27762 27787 27912 28223 28341 28343 28548 28646 28955 29146 29170 29458 29684 30011 30345 30419 30429 30455 30490 30505 30771 30833 30893 31014 31019 31191 31642 31686 31767 31781 31803 31811 32033 32076 32093 32115 32329 32335 32392 32458 32491 32541 32617 32753 34757 36732 40250 40359 40386 40435-40436 40505 40513 40610 40623 40784 40892 40932 40941 44518 44696 44921 44936-44937 44967 48274 48485 48500 48801 48906 48935 48958 49101https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/662/A41?format=asciidefaultJ/A+A/662/A41/tableb1Table with stellar parameters and results from our analysisrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSeqRunning Numbermeta.idintKarmnCARMENCITA Catalogue Numbermeta.idcharNameNamemeta.id;meta.maincharNObs? Number of observationsmeta.numberintnullableS/N? Signal-to-Noise ratio at 8700{AA}stat.snrintnullableMassStellar mass in solar unitssolMassphys.massfloatRadStellar radius in solar unitssolRadphys.size.radiusfloatTeffEffective temperature in KelvinKphys.temperature.effectiveintPer? Rotation Perioddtime.periodfloatnullabler_PerReference for Rotation Period (1)meta.ref;pos.framechartauConvective overturn time in daysdtime.epochintlogLbolBolometric luminosity relative to solar in logarithmic unitslog(solLum)phys.luminosityfloatlogLX/Lbol? X-ray to bolometric luminosity in logarithmic unitsphys.luminosity;arith.ratiofloatnullablelogLHa/Lbol? Halpha to bolometric luminosity in logarithmic unitsphys.luminosity;arith.ratiofloatnullablelogLCa/Lbol? Calcium H&K to bolometric luminosity in logarithmic unitsphys.luminosity;arith.ratiofloatnullablel_Limit flag on meta.code.errorcharAverage magnetic fieldGphys.magFieldinte_? Uncertainty of Gstat.errorintnullablevsini? Value of vsini used for fit in km/skm/sphys.veloc.rotat;instr.setupfloatnullable_RARight Ascension (J2000) from SIMBAD (not part of the original data)degpos.eq.ra;meta.mainnullable_DEDeclination (J2000) from SIMBAD (not part of the original data)degpos.eq.dec;meta.mainnullableSimbadNameSimbad column added by the CDSmeta.idcharnullable