J/ApJ/834/176ivo://CDS.VizieR/J/ApJ/834/176doi:10.26093/cds/vizier.18340176CDSNunez A.Agueros M.A.Covey K.R.Lopez-Morales M.2017-09-04T08:35:09Z2017-08-10T14:40:41ZCDS support team

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

cds-question@unistra.fropen-star-clustersinfrared-photometryvisible-astronomybroad-band-photometryline-intensitiesstellar-massesspectroscopyWe present the results of a spectroscopic survey to characterize chromospheric activity, as measured by H{alpha} emission, in low-mass members of the 500Myr old open cluster M37. Combining our new measurements of H{alpha} luminosities (L_H{alpha}_) with previously cataloged stellar properties, we identify saturated and unsaturated regimes in the dependence of the L_H{alpha}_-to-bolometric luminosity ratio, L_H{alpha}_/L_bol_, on the Rossby number R_o_. All rotators with R_o_ smaller than 0.03+/-0.01 converge to an activity level of L_H{alpha}_/L_bol_=(1.27+/-0.02)x10^-4^. This saturation threshold (R_o,sat_=0.03+/-0.01) is statistically smaller than that found in most studies of the rotation-activity relation. In the unsaturated regime, slower rotators have lower levels of chromospheric activity, with L_H{alpha}_/L_bol_(R_o_) following a power-law of index {beta}=-0.51+/-0.02, slightly shallower than that found for a combined ~650Myr old sample of Hyades and Praesepe stars. By comparing this unsaturated behavior to that previously found for coronal activity in M37 (as measured via the X-ray luminosity, L_X_), we confirm that chromospheric activity decays at a much slower rate than coronal activity with increasing R_o_. While a comparison of L_H{alpha}_ and L_X_ for M37 members with measurements of both reveals a nearly 1:1 relation, removing the mass-dependencies by comparing instead L_H{alpha}_/L_bol_ and L_X_/L_bol_ does not provide clear evidence for such a relation. Finally, we find that R_o,sat_ is smaller for our chromospheric than for our coronal indicator of activity (R_o,sat_=0.03+/-0.01 versus 0.09+/-0.01). We interpret this as possible evidence for coronal stripping.2017ApJ...834..176Nhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/834/176CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toVII/233 : The 2MASS Extended sources (IPAC/UMass, 2003-2006)J/AJ/130/873 : Properties of BQS objects in the SDSS DR3 area (Jester+, 2005)J/AJ/134/2340 : Praesepe & Coma Berenices clusters' membership (Kraus+, 2007)J/ApJ/675/1233 : gri photometry in M37 (NGC 2099) (Hartman+, 2008)J/ApJ/675/1254 : M37 variable stars (Hartman+, 2008)J/A+A/483/253 : BV photometry of NGC 2099 variables (Messina+, 2008)J/ApJS/181/444 : X-emitting stars identified from RASS/SDSS (Agueros+, 2009)J/ApJ/691/342 : griBVI photometry in M37 (Hartman+, 2009)J/MNRAS/407/465 : Fast-rotating M dwarfs in NGC2516 (Jackson+, 2010)J/ApJ/743/48 : Stellar rotation periods & X-ray luminosities (Wright+, 2011)J/MNRAS/431/2063 : UV/X-ray activity of M dwarfs within 10pc (Stelzer+, 2013)J/ApJ/809/161 : X-ray obs. and membership probabilities of M37 (Nunez+, 2015)J/A+A/589/A113 : PMS stars in h Per (Argiroffi+, 2016)J/ApJ/829/23 : Stellar flares from Q0-Q17 Kepler LCs (Davenport, 2016)J/ApJ/822/47 : K2 rotation periods for 65 Hyades members (Douglas+, 2016)J/ApJ/830/44 : M37 low-mass stars X-ray luminosity functions (Nunez+, 2016)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/834/176https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/834/176http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/834/176https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/834/176https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/834/176http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/834/176GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/834/176/table2 (M37 members)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/834/176/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/834/176/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/834/176/table2?GETtext/xml+votable180.050000true88.0772080632.530781110.0055555555555555566/24520 245221.5062136169708525e-19 4.653515163505597e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/834/176?format=asciiInfraredOpticaldefaultJ/ApJ/834/176/table2M37 membersrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintOID[2321/360125] Optical ID as in Paper I (Nunez+, 2015, J/ApJ/809/161)meta.id;meta.mainintRAJ2000Right ascension of object (J2000)degpos.eq.ra;meta.mainDEJ2000Declination of object (J2000)degpos.eq.dec;meta.mainPMm[0.2/0.95]? Probability that object is cluster membermeta.id.parent;stat.probabilityfloatnullableBinBinarity flag (0=likely a single member; 1=likely a binary member)meta.codeintgmag[15.8/24.4] Megacam/MMT g magnitude (1)magphot.mag;em.opt.Bfloatimag[15/20.9] Megacam/MMT i magnitude (1)magphot.mag;em.opt.IfloatJmag[13.8/17.2]? 2MASS J magnitudemagphot.mag;em.IR.JfloatnullableMass[0.2/1.3] Stellar mass (2)solMassphys.massfloatRo[0.005/1]? Rossby number R_o_ (3)stat.paramfloatnullableEWHa[-7.6/2.8]? H{alpha} line equivalent width0.1nmspect.line.eqWidthfloatnullablee_EWHa[0/1]? Standard deviation of H{alpha} line equivalent width0.1nmstat.errorfloatnullableEWNII6584[-20.8/-0.06]? [NII]6584-Angstrom line equivalent width0.1nmspect.line.eqWidthfloatnullablee_EWNII6584[0.02/3]? Standard deviation of EWNII65840.1nmstat.errorfloatnullableEWNII6548[-7/0.3]? [NII]6548-Angstrom line equivalent width0.1nmspect.line.eqWidthfloatnullablee_EWNII6548[0/3]? Standard deviation of EWNII65480.1nmstat.errorfloatnullablechi? chi value ({chi}=f_0_/f_bol_) (4)phot.flux;arith.ratiodoublenullableLHa/Lbol[/0.0003]? H{alpha} to bolometric luminosity ratiophys.luminosity;arith.ratiodoublenullablee_LHa/Lbol? Standard deviation of LHa/Lbolstat.errordoublenullableLX/Lbol[/0.004]? X-ray to bolometric luminosity ratiophys.luminosity;arith.ratiodoublenullablee_LX/Lbol? Standard deviation of LX/Lbolstat.errordoublenullableH08Display data from Hartman+, 2008, J/ApJ/675/1233, within 0.5"meta.ref.urlintnullable2MDisplay the 2MASS data (Cutri+ 2003, II/246) within 3"meta.ref.urlchar