J/MNRAS/431/2063ivo://CDS.VizieR/J/MNRAS/431/2063doi:10.26093/cds/vizier.74312063CDSStelzer B.Marino A.Micela G.Lopez-Santiago J.Liefke C.2024-07-21T20:14:40Z2014-06-16T09:43:00ZCDS support team

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

cds-question@unistra.frdwarf-starsm-starsultraviolet-astronomyx-ray-sourcesM dwarfs are the most numerous stars in the Galaxy. They are characterized by strong magnetic activity. The ensuing high-energy emission is crucial for the evolution of their planets and the eventual presence of life on them. We systematically study the X-ray and ultraviolet emission of a subsample of M dwarfs from a recent proper-motion survey, selecting all M dwarfs within 10pc to obtain a nearly volume-limited sample (~90 percent completeness). Archival ROSAT, XMM-Newton and GALEX data are combined with published spectroscopic studies of H{alpha} emission and rotation to obtain a broad picture of stellar activity on M dwarfs. We make use of synthetic model spectra to determine the relative contributions of photospheric and chromospheric emission to the ultraviolet flux. We also analyse the same diagnostics for a comparison sample of young M dwarfs in the TW Hya association (~10Myr). We find that generally the emission in the GALEX bands is dominated by the chromosphere but the photospheric component is not negligible in early-M field dwarfs. The surface fluxes for the H{alpha}, near-ultraviolet, far-ultraviolet and X-ray emission are connected via a power-law dependence. We present here for the first time such flux-flux relations involving broad-band ultraviolet emission for M dwarfs. Activity indices are defined as flux ratio between the activity diagnostic and the bolometric flux of the star in analogy to the CaII R'HK index. For given spectral type, these indices display a spread of 2-3dex which is largest for M4 stars. Strikingly, at mid-M spectral types, the spread of rotation rates is also at its highest level. The mean activity index for fast rotators, likely representing the saturation level, decreases from X-rays over the FUV to the NUV band and H{alpha}, i.e. the fractional radiation output increases with atmospheric height. The comparison to the ultraviolet and X-ray properties of TWHya members shows a drop of nearly three orders of magnitude for the luminosity in these bands between ~10Myr and few Gyr age. A few young field dwarfs (<1Gyr) in the 10-pc sample bridge the gap indicating that the drop in magnetic activity with age is a continuous process. The slope of the age decay is steeper for the X-ray than for the UV luminosity.2013MNRAS.431.2063Shttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/MNRAS/431/2063CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toV/101 : Nearest stars until 10pc (Zakhozhaj, 1979-1996)J/A+A/325/159 : Companions to M dwarfs within 5pc (Leinert+ 1997)J/A+A/421/643 : New nearby stars in the LEHPMS (Reyle+, 2004)J/AJ/132/866 : New M dwarfs in solar neighborhood (Riaz+, 2006)J/MNRAS/373/705 : New M dwarfs within 10pc (Reyle+, 2006)J/MNRAS/383/831 : New DENIS nearby L and late-M dwarfs (Phan-Bao+, 2008)J/AJ/142/138 : All-sky catalog of bright M dwarfs (Lepine+, 2011)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/MNRAS/431/2063https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/MNRAS/431/2063http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/MNRAS/431/2063https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/MNRAS/431/2063https://vizier.iucaa.in/viz-bin/votable?-source=J/MNRAS/431/2063http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/MNRAS/431/2063GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/MNRAS/431/2063/Mstars (Combined table from original tables)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/MNRAS/431/2063/Mstars?https://vizier.iucaa.in/viz-bin/conesearch/J/MNRAS/431/2063/Mstars?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/MNRAS/431/2063/Mstars?GETtext/xml+votable180.050000true1.35079806-37.357040.0055555555555555566/22 131 250 309 527 546 725 811 2737 3005 3345 3715 3791 4158 4444 4462 4693 5000 5333 5420 5534 5590 6552 6672 6726 6894 6974 7103 7395 7512 8023 8123 8440 8562 9471 9585 9629 9696 10027 10037 10149 10448 11636 12454 12679 12865 13451 13688 13743 14515 14772 15311 15346 15548 15602 15960 16041 16391 16758 16827 17058 17534 18268 18440 18496 18666 18761 19466 20071 20100 20459 20896 21149 21151 21925 21953 22014 22040 22289 22309 22325 22645 23047 23564 23718 23735 23997 24227 24713 25009 26279 26327 26538 26560 26699 26972 27201 27289 27392 27459 27731 27762 28343 28646 28955 29458 29684 30505 30771 30833 31019 31191 31781 32093 32115 32229 32335 32645 33425 33579 34181 35670 36511 36614 36971 37377 37379 38456 38551 39499 40250 40505 42054 42255 42290 42314 42652 42784 43187 43580 43723 44257 44284 44921 44937 45317 45322 46632 46718 48274 48906 48985https://cdsarc.cds.unistra.fr/viz-bin/moc/J/MNRAS/431/2063?format=asciiX-rayUVdefaultJ/MNRAS/431/2063/MstarsCombined table from original tablesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintPMPM name (IHHMMm+DDMM)meta.id;meta.maincharGl/GJGliese designation of starmeta.idchard[1.8/10] Heliocentric distance of starpcpos.distance;pos.heliocentricfloate_drms uncertainty on dpcstat.errorfloatSpTypeMK spectral typesrc.spTypecharTeff[2555/3800] Effective temperatureKphys.temperature.effectiveintlogFb[-9.5/-7.0] Bolometric flux at Earthlog(mW.m**-2)phot.flux.bolfloatl_vsini[<] Limit flag on vsinimeta.code.error;phys.veloc.rotatcharvsini[1/35]? Rotational velocitykm/sphys.veloc.rotatfloatnullablelogFnuv? Near-uv flux from Galex (177-283nm)log(mW.m**-2)phot.flux;em.UVfloatnullableb_logFnuv? Lower value of logFnuv intervallog(mW.m**-2)time.interval;stat.minfloatnullableB_logFnuv? Upper value of logFnuv intervallog(mW.m**-2)time.interval;stat.maxfloatnullablel_logFfuvLimit flag on logFfuvmeta.code.errorcharlogFfuv? Far-UV flux from Galex (134-179nm)log(mW.m**-2)phot.flux;em.UVfloatnullableb_logFfuv? Lower value of logFfuv intervallog(mW.m**-2)time.interval;stat.minfloatnullableB_logFfuv? Upper value of logFfuv intervallog(mW.m**-2)time.interval;stat.maxfloatnullablel_logFxLimit flag on logFxmeta.code.errorcharlogFxX-ray flux (0.2-2.0keV)log(mW.m**-2)phot.flux;em.X-rayfloatb_logFx? Lower value of logFx intervallog(mW.m**-2)time.interval;stat.minfloatnullableB_logFx? Upper value of logFx intervallog(mW.m**-2)time.interval;stat.maxfloatnullableSimbadNameSimbad column added by the CDSmeta.idchar_RAPositions from Lepine and Gaidos (LG11), Cat. J/AJ/142/138 (right ascension part)degpos.eq.ra;meta.main_DEPositions from Lepine and Gaidos (LG11), Cat. J/AJ/142/138 (declination part)degpos.eq.dec;meta.main