J/A+A/652/A28ivo://CDS.VizieR/J/A+A/652/A28doi:10.26093/cds/vizier.36520028CDSLafarga M.Ribas I.Reiners A.Quirrenbach A.Amado P.J.,Caballero J.A.Azzaro M.Bejar V.J.S.Cortes-Contreras M.Dreizler S.,Hatzes A.P.Henning T.Jeffers S.V.Kaminski A.Kuerster M.Montes D.,Morales J.C.Oshagh M.Rodriguez-Lopez C.Schoefer P.Schweitzer A.,Zechmeister M.2022-07-07T18:03:44Z2021-08-05T09:08:45ZCDS support team

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

cds-question@unistra.frm-starsstellar-massesline-intensitiesStellar activity poses one of the main obstacles for the detection and characterisation of small exoplanets around cool stars, as it can induce radial velocity (RV) signals that can hide or mimic the presence of planetary companions. Several indicators of stellar activity are routinely used to identify activity-related signals in RVs, but not all indicators trace exactly the same activity effects, nor are any of them always effective in all stars. We evaluate the performance of a set of spectroscopic activity indicators for M dwarf stars with different masses and activity levels with the aim of finding a relation between the indicators and stellar properties. In a sample of 98 M dwarfs observed with CARMENES, we analyse the temporal behaviour of RVs and nine spectroscopic activity indicators: cross-correlation function (CCF) full-width-at-half-maximum (FWHM), CCF contrast, CCF bisector inverse slope (BIS), RV chromatic index (CRX), differential line width (dLW), and indices of the chromospheric lines H{alpha} and calcium infrared triplet. A total of 56 stars of the initial sample show periodic signals related to activity in at least one of these ten parameters. RV is the parameter for which most of the targets show an activity-related signal. CRX and BIS are effective activity tracers for the most active stars in the sample, especially stars with a relatively high mass, while for less active stars, chromospheric lines perform best. FWHM and dLW show a similar behaviour in all mass and activity regimes, with the highest number of activity detections in the low-mass, high-activity regime. Most of the targets for which we cannot identify any activity-related signals are stars at the low-mass end of the sample (i.e. with the latest spectral types). These low-mass stars also show the lowest RV scatter, which indicates that ultracool M dwarfs could be better candidates for planet searches than earlier types, which show larger RV jitter. Our results show that the spectroscopic activity indicators analysed behave differently, depending on the mass and activity level of the target star. This underlines the importance of considering different indicators of stellar activity when studying the variability of RV measurements. Therefore, when assessing the origin of an RV signal, it is critical to take into account a large set of indicators, or at least the most effective ones considering the characteristics of the star, as failing to do so may lead to false planet claims.2021A&A...652A..28Lhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/652/A28CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/652/A28https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/652/A28http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/652/A28https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/652/A28https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/652/A28http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/652/A28GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/652/A28/tablea1 (Properties of the stellar sample)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/652/A28/tablea1?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/652/A28/tablea1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/652/A28/tablea1?GETtext/xml+votable180.050000true1.6799883-7.53806220.0055555555555555566/22 250 497 546 811 1033 1822 1938 2515 2737 3715 3791 4444 5488 5534 7103 7264 7395 7471 8023 8123 8331 8627 8915 11671 12621 12732 13688 13743 13912 14993 15078 15431 15548 15598 15602 15635 15763 15960 16758 17020 17302 17348 18666 18761 19064 19131 19352 19466 20023 20100 20896 21953 22289 22309 22709 22807 22942 23731 23735 23867 24227 26538 26560 26583 26699 26706 26972 27201 27392 27462 27730 27787 28341 28343 28646 28955 29684 30345 30429 30455 30490 30505 30771 30833 31191 31781 32335 32491 40623 44967 48274 485001.398457827073138e-19 1.7798557115773645e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/652/A28?format=asciidefaultJ/A+A/652/A28/tablea1Properties of the stellar samples_RVRadial velocity standard deviationm/sstat.stdev;spect.dopplerVelocfloatrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintKarmnCARMENES identifiermeta.id;meta.maincharNameName(s) of the starmeta.idcharSpTypeSpectral typesrc.spTypecharr_SpTypeSpectral type reference (1)meta.ref;pos.framecharMassStellar mass (2)solMassphys.massdoublee_MassStellar mass uncertaintysolMassstat.error;phys.massfloatJmagJ band magnitude (3)magphot.mag;em.IR.Jfloate_JmagJ band magnitude uncertaintymagstat.error;phot.magfloatl_vsiniUpper limit flag on vsinimeta.code.error;phys.veloc.rotatcharvsiniProjected rotational velocitykm/sphys.veloc.rotatfloate_vsini? Projected rotational velocity uncertaintykm/sstat.error;phys.veloc.rotatfloatnullabler_vsiniProjected rotational velocity reference (4)meta.refcharProt? Rotational perioddtime.perioddoublenullablee_Prot? Rotational period uncertaintydstat.errordoublenullabler_ProtRotational period reference (5)meta.ref;pos.framecharpEW'HaHalpha pseudoequivalent width (6)0.1nmspect.line.eqWidthfloate_pEW'Ha? Halpha pseudoequivalent width uncertainty0.1nmstat.errorfloatnullablelog(LHa/Lbol)? Log ratio of Halpha and bolometric luminosities (6)phys.luminosity;arith.ratiofloatnullablee_log(LHa/Lbol)? Log ratio of Halpha and bolometric luminosities uncertaintystat.errorfloatnullablePlanetPlanetary companionsmeta.code.multipcharNobsNumber of observationsmeta.numberintSpanObservations time spandtime.interval;obsintSimbadNameSimbad column added by the CDSmeta.idchar_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.main