J/ApJS/99/701ivo://CDS.VizieR/J/ApJS/99/701doi:10.26093/cds/vizier.20990701CDSFleming T.A.Molendi S.Maccacaro T.Wolter A.1997-12-09T20:31:32Z1997-12-09T21:31:29ZCDS support team

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

cds-question@unistra.frx-ray-sourcesWe present X-ray data from the ROSAT all-sky survey for those sources catalogued in the Einstein Extended Medium Sensitivity Survey (EMSS) (Cat. <VII/152>) which have been identified with Galactic stars. This "second epoch" of X-ray data taken 10yr later, is used to study coronal flux variability for the most active examples of late-type stars. About 72% of the EMSS stars have been redetected by ROSAT. While the F-stars appear to have remained constant, we find evidence for a general decrease in X-ray flux for the M and solar-type stars. This is probably due to the fact that an X-ray-selected sample will preferentially detect stars while flaring. In contradiction to this, the RS CVn binaries have been redetected at higher X-ray flux levels for the sample as a whole.1995ApJS...99..701Fhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJS/99/701CatalogResearchIsServedByTAP VizieR generic servicerelated-toIX/11 : ROSAT Source Catalog (Voges+ 1994)VII/152 : EINSTEIN Observatory Extended Medium-Sensitivity Survey (EMSS)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJS/99/701https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJS/99/701http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJS/99/701https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJS/99/701https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJS/99/701http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJS/99/701GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapEinsteinX-raydefaultJ/ApJS/99/701/table1R0SAT PSPC survey data on all stars from the EMSSTypeStellar type (1)src.classcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintEMSSEMSS designation (See cat. <VII/152>)meta.id;meta.maincharl_ExpTimeLimit flag on ExpTimemeta.code.errorcharExpTime? Total survey exposure timestime.duration;obs.exposurefloatn_ExpTime[n] n: Not analysedmeta.notecharl_RateTotLimit flag on RateTotmeta.code.errorcharRateTot? Total corrected PSPC count rate (2)ct/sphot.count;em.X-rayfloatn_RateTot[*] *: Count rate computed manuallymeta.notechare_RateTot? 1-sigma error on RateTotct/sstat.errorfloatl_RateHardLimit flag on RateHardmeta.code.errorcharRateHard? Total corrected PSPC hard (0.5-2.0 keV) count ratect/sphot.count;em.X-rayfloate_RateHard? 1-sigma error on RateHardct/sstat.errorfloatHR? Hardness ratiophot.flux;arith.ratiofloatl_FluxTotLimit flag on FluxTotmeta.code.errorcharFluxTot? Total flux (0.1-2.4 keV) (10^-13^erg/cm2/s)1e-16W.m**-2phot.flux;em.X-rayfloatl_FluxHardLimit flag on FluxHardmeta.code.errorcharFluxHard? Hard flux (0.5-2.0 keV) (10^-13^erg/cm2/s)1e-16W.m**-2phot.flux;em.X-rayfloat