J/AJ/165/12ivo://CDS.VizieR/J/AJ/165/12doi:10.26093/cds/vizier.51650012CDSDuvvuri G.M.Pineda J.S.Berta-Thompson Z.K.France K.Youngblood A.2024-11-25T09:04:55Z2024-01-10T12:45:07ZCDS support team

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

cds-question@unistra.frm-starsspectroscopyultraviolet-astronomyWe obtained ultraviolet and optical spectra for nine M-dwarfs across a range of rotation periods to determine whether they showed stochastic intrinsic variability distinguishable from flares. The ultraviolet spectra were observed during the Far Ultraviolet M-dwarf Evolution Survey Hubble Space Telescope program using the Space Telescope Imaging Spectrograph. The optical observations were taken from the Apache Point Observatory 3.5m telescope using the Dual Imaging Spectrograph and from the Gemini South Observatory using the Gemini Multi-Object Spectrograph. We used the optical spectra to measure multiple chromospheric lines: the Balmer series from H{alpha} to H10 and the CaII H and K lines. We find that after excising flares, these lines vary on the order of 1%-20% at minute-cadence over the course of an hour. The absolute amplitude of variability was greater for the faster rotating M-dwarfs in our sample. Among the five stars for which we measured the weaker Balmer lines, we note a tentative trend that the fractional amplitude of the variability increases for higher-order Balmer lines. We measured the integrated flux of multiple ultraviolet emission features formed in the transition region: the NV, SiIV, and CIV resonance line doublets, and the CII and HeII multiplets. The signal-to-noise ratio of the UV data was too low for us to detect nonflare variability at the same scale and time cadence as the optical. We consider multiple mechanisms for the observed stochastic variability and propose both observational and theoretical avenues of investigation to determine the physical causes of intrinsic variability in the chromospheres of M-dwarfs.2023AJ....165...12Dhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/AJ/165/12CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/AJ/141/97 : SDSS DR7 M dwarfs (West+, 2011)J/MNRAS/421/3189 : CaII and H{alpha} data for dK5/dM4 stars (Houdebine, 2012)J/ApJS/207/15 : M dwarf flare spectra (Kowalski+, 2013)J/ApJS/211/9 : Variability in UV line emission of F-M stars (Loyd+, 2014)J/ApJ/821/93 : Rotation & Galactic kinematics mid M dwarfs (Newton+, 2016)J/ApJ/837/96 : Rotation-Activity Corr. in K-M dwarfs II. (Houdebine+, 2017)J/ApJ/834/85 : H{alpha} emission in nearby M dwarfs (Newton+, 2017)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/AJ/165/12https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/AJ/165/12http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/AJ/165/12https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/AJ/165/12https://vizier.iucaa.in/viz-bin/votable?-source=J/AJ/165/12http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/AJ/165/12GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/AJ/165/12/table1 (*Stellar parameters for the subset of the FUMES considered in this work)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/AJ/165/12/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/AJ/165/12/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/AJ/165/12/table1?GETtext/xml+votable180.050000true341.2415119-33.25048470.0055555555555555566/989 3439 3443 3715 20505 23094 28341 33850 46922https://cdsarc.cds.unistra.fr/viz-bin/moc/J/AJ/165/12?format=asciiUVdefaultJ/AJ/165/12/table1*Stellar parameters for the subset of the FUMES considered in this workSimbadSimbad column added by the CDSmeta.ref.urlcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameStellar identifiermeta.id;meta.maincharprimaryMass[0.23/0.79] Stellar masssolMassphys.massfloate_Mass[0.002/0.02] Negative error on MsunsolMassstat.error;phys.massfloatE_Mass[0.002/0.02] Positive error on MsunsolMassstat.error;stat.maxfloatRad[0.25/0.94] Stellar radiussolRadphys.size.radiusfloate_Rad[0.003/0.03] Negative error on RadsolRadstat.errorfloatE_Rad[0.003/0.03] Positive error on RadsolRadstat.error;stat.maxfloatTeff[3173/3886] Effective temperatureKphys.temperature.effectiveinte_Teff[6/83] Negative error on TeffKstat.error;phys.temperature.effectiveintE_Teff[8/89] Positive error on TeffKstat.error;stat.maxintProt[1.28/53.5] Rotation perioddtime.periodfloatRo[0.02/1] Rossby Numberstat.paramfloatEW[0.15/0.56] H{alpha} quiescent equivalent widthspect.line.eqWidthfloatObsObservations (table9)meta.ref.urlchar_RAPosition from SIMBAD (right ascension part)degpos.eq.ra;meta.mainnullable_DEPosition from SIMBAD (declination part)degpos.eq.dec;meta.mainnullableJ/AJ/165/12/table9Ultraviolet integrated flux measurements and intrinsic variability fitsNameStellar identifiermeta.id;meta.maincharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintFiltFilter usedinstr.setup;instr.filtercharWavemin[1227/1628] Minimum wavelength in filter (added by VizieR team from table7)0.1nmem.wl;stat.minfloatWavemax[1254/1654] Maximum wavelength in filter (added by VizieR team from table7)0.1nmem.wl;stat.maxfloatFlux[4.32/92.4] Integrated flux (10^-15^erg/s/cm^2^)phot.flux;em.UVfloate_Flux[0.3/15] Negative error on Fluxstat.error;phot.fluxfloatE_Flux[0.5/26] Positive error on Fluxstat.error;stat.maxfloatl_aVar[<] Limit on aVarmeta.code.errorcharaVar[0.67/83.1] Absolute intrinsic variability (10^-15^erg/s/cm^2^)src.var.amplitudefloatl_fVar[<] Limit on fVarmeta.code.errorcharfVar[0.06/0.61] Fractional intrinsic variability (10^-15^erg/s/cm^2^)src.var.amplitudefloate_fVar[0.08/0.2]? Negative error on fVarstat.errorfloatnullableE_fVar[0.1/0.3]? Positive error on fVarstat.error;stat.maxfloatnullableNobs[4/23] Number of measurementmeta.numberint