J/A+A/684/A106ivo://CDS.VizieR/J/A+A/684/A106doi:10.26093/cds/vizier.36840106CDSMeunier N.Mignon L.Kretzschmar M.Delfosse X.2024-11-29T20:01:27Z2024-04-09T10:07:18ZCDS support team

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

cds-question@unistra.frdwarf-starsm-starsspectroscopyThe chromospheric emission estimated in the core of different lines, such as CaII H & K, Na D1 and D2, and Ha, is not always correlated between lines. In particular, the CaII H & K and Ha emission time series are anti-correlated for a few percent of the stars, contrary to what is observed on the Sun. This puzzling result has been observed for both solar-type stars and M stars. Our objective is to characterise these relationships in more detail using complementary criteria, and based on a large set of spectra obtained with HARPS for a large sample of M dwarfs. This should allow to evaluate whether or not additional processes are required to explain the observations. We analysed the time average and variability of the Ca, Na, and H{alpha} emissions for 177 M stars ranging from subspectral types M0 to M8, paying particular attention to their (anti-)correlations on both short and long timescales as well as slopes between indices. We also computed synthetic H{alpha} time series based on different assumptions of plage properties. We compared our findings with observations in order to evaluate whether or not the main observed properties could be reproduced. The statistical properties of our sample, in terms of correlations and slopes between indices at different timescales, differ from what we previously obtained for FGK stars: there are fewer stars with a null correlation, and the correlations we find show a weaker dependence on timescale. However, there can be a large dispersion from one season to another for stars with a well identified low or negative correlation. We also specify the complex relationship between the average activity levels, with a clear indication of a change in the sign of the slope from the relation between Ca and H{alpha} (and between Na and H{alpha}) for the most massive M dwarfs. In addition, we observe a change in slope in the Na-Ca relation at an intermediate activity level. At this stage, we are not able to find simple plage properties that, alone, are sufficient to reproduce the observations. However, the simulations already allow us to point out that it is not straightforward to compare the temporal variability correlation and the integrated indices. Our findings also demonstrate the need for complex activity patterns to explain some of the observations. We conclude that the relation between the three indices examined here exhibits a large diversity in behaviour over the sample studied. More detailed simulations with complex activity patterns are necessary to understand these observations. This will teach us about plage properties for this type of star.2024A&A...684A.106Mhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/684/A106CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/A+A/675/A168 : Stellar properties of 177 M dwarfs (Mignon+, 2023)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/684/A106https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/684/A106http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/684/A106https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/684/A106https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/684/A106http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/684/A106GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/684/A106/tablea1 (Main parameters of the stars in our and activity from our analysis)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/684/A106/tablea1?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/684/A106/tablea1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/684/A106/tablea1?GETtext/xml+votable180.050000true118.5453447-25.30317280.0055555555555555566/115 131 546 4157 4366 4444 4651 8343 8394 8440 8739 10278 12440 16391 16758 16847 16910 17288 17455 17870 18496 18569 18666 18856 19064 19466 20100 20867 20896 21171 21271 21473 21527 21777 21953 22014 22222 22309 22626 22645 22700 22807 22959 22964 23137 23238 23363 23731 23735 24227 24713 24995 25009 25125 25388 25426 25516 25639 25989 26495 26560 26583 26772 26972 27201 27392 27462 27484 27912 28548 28955 29170 29665 29684 30321 30429 30505 30522 30625 30735 30771 30893 30931 31013-31014 31031 31035 31191 31216 31495 31781 32335 33441 33702 33758 33849 33966 34181 34301 34448 34514 34767 34924 34975 35057 35324-35325 35388 35499 35670 36078 36133 36614 36732 36892 36910 37379 37654 37942 38152 38456 38464 38551 38675 38744 38913 39059 39080 39807 39912 40250 40341 40359 40436 40505 40513 40811 41252 41455 41591 42054 42101 42209 42255 42290 42314 42429 42459 42471 42544 42652 42784 42982 43187 43203 43336 43723 43970 44728 44921 45322 45497 46128 46218 46275 46566 46632 46699 47121 47183 47337 47347 47414 47758 48274 48906 49101https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/684/A106?format=asciidefaultJ/A+A/684/A106/tablea1Main parameters of the stars in our and activity from our analysisrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameStar namemeta.id;meta.maincharV-KV-K colour index (1)magphot.color;em.opt.V;em.IR.Kfloatn_V-K[d] d indicates calculate on V-K (1)meta.notecharTeffEffective temperature (2)Kphys.temperature.effectiveintn_Teff[*] * for estimated Teff value (2)meta.notechar[Fe/H]? Metallicity [Fe/H] (3)phys.abund.ZfloatnullableNBNumber of nightsmeta.numberintlogR'HKChromospheric activity index logR'HKphot.flux;arith.ratiofloatSCaAverage chromospheric activity index SCaspect.indexfloate_SCarms of SCastat.errorfloatSNaAverage chromospheric activity index SNaspect.indexfloate_SNarms of SNastat.errorfloatSHalphaAverage chromospheric activity index SHalphaspect.indexfloate_SHalpharms of SHalphastat.errorfloatSeason[S] Flag indicating more than four seasonsmeta.codecharSimbadSimbad column added by the CDSmeta.ref.urlchar_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/684/A106/tablea2Global correlations and slopes between activity indicators for the 177 stars in our sample, with their 1-sigma uncertaintyrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameStar namemeta.id;meta.maincharC-Ca-HaCorrelation Ca-Halphastat.correlationfloate_C-Ca-HaUncertainty on correlation Ca-Halphastat.errorfloatC-Na-CaCorrelation Na-Castat.correlationfloate_C-Na-CaUncertainty on correlation Na-Castat.errorfloatC-Na-HaCorrelation Na-Halphastat.correlationfloate_C-Na-HaUncertainty on correlation Na-Halphastat.errorfloatsl-Ha-CaSlope Halpha vs. Castat.fit.paramfloate_sl-Ha-CaUncertainty on slope Halpha vs. Castat.errorfloatsl-Na-CaSlope Na vs. Castat.fit.paramfloate_sl-Na-CaUncertainty on slope Na vs. Castat.errorfloatsl-Ha-NaSlope NHalpha vs. Nastat.fit.paramfloate_sl-Ha-NaUncertainty on slope Halpha vs. Nastat.errorfloat