J/other/AstL/50.ivo://CDS.VizieR/J/other/AstL/50.780CDSKhamitov I.M.Bikmaev I.F.Gilfanov M.R.Sunyaev R.A.Medvedev P.S.2025-08-01T08:20:05Z2025-07-29T06:55:23ZCDS support team

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

cds-question@unistra.fropen-star-clustersx-ray-sourcesvisible-astronomyUsing SRG/eROSITA X-ray sky survey data and the optical catalog of 2209 Pleiades cluster members constructed from Gaia data, we have found 850 X-ray sources associated with cluster stars. More than 650 of them have been detected in X-rays for the first time. At the distance of the Pleiades the nominal sensitivity of eROSITA in this sky region corresponds to a 0.3-2.3keV luminosity L_X_~1.6x10^28^erg/s. The eROSITA sources associated with the Pleiades radiate with a total luminosity L_X,total_~1.3x10^22^erg/s, which exceeds the X-ray luminosity of the quiet Sun by a million times. A strong, more than a factor of 10, X-ray variability has been recorded for 27 sources. Most of them are known as eruptive optical variable dM stars. R_X_=log(L_X_/L_bol_) for Pleiades stars increases with decreasing effective stellar temperature from R_X_~-5 to R_X_~-2 . The R_X_ distribution of stars is bimodal. The left peak at R_X_~-.43 is formed by FGK stars, while the right peak at R_X_~-3.1 is mostly populated by M stars. The dependence of R_X_ on the Rossby number R_o_ is different for different spectral types. At small Rossby numbers for K and M stars R_X_~-3 and depends weakly on R_o_. At R_o_>~0.25 a rapid decrease in R_X_ is observed for K stars, while there are no M stars with large Rossby numbers in our sample. Most of the F and G stars lie in the range of lower values, R_X_~-4.5, but the size of our sample is not enough to characterize in more detail the R_X_-R_o_ relation for them.2024AstL...50..780Khttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/other/AstL/50.780CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toI/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)J/ApJS/102/75 : ROSAT observations of the Pleiades (Micela+ 1996)J/A+A/682/A34 : SRG/eROSITA all-sky survey catalogs (eRASS1) (Merloni+, 2024)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/other/AstL/50.780https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/other/AstL/50.780http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/other/AstL/50.780https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/other/AstL/50.780https://vizier.iucaa.in/viz-bin/votable?-source=J/other/AstL/50.780http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/other/AstL/50.780GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/other/AstL/50.780/table1 (eROSITA X-ray sources in the Pleiades)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/other/AstL/50.780/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/other/AstL/50.780/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/other/AstL/50.780/table1?GETtext/xml+votable180.050000true46.70929517.692916110.0055555555555555564/28 5/90-91 94 116-118 120-121 123-124 126 209 212 6/247 292 302 319 324 329 332-334 353 357-359 368-369 373 381-382 405 407 414 424 437 439 441 443 446-447 476 478-479 489-491 500 509-511 771 785 788 793 797 832 834-835 840 843 856 859 866-868 870 872 961 967 979 1037 1059 1079 1122 1154 1160 1164 1172 1177 1212 1218 1227-1228 1541 1545 1547 1569 1601 23532 23534 23549-235501.9867573869263685e-19 3.916500758235022e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/other/AstL/50.780?format=asciiX-rayOpticaldefaultJ/other/AstL/50.780/table1eROSITA X-ray sources in the PleiadesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSRGeSRGe name (SRGeJHHMMSS.s+DDMMSS)meta.id;meta.maincharn_SRGe[*] Note on SRGe (1)meta.notecharGaiaDR3Gaia DR3 source_id (2)meta.idRAJ2000Gaia DR3 Right Ascension (J2000) (2)degpos.eq.ra;meta.mainDEJ2000Gaia DR3 Declination (J2000) (2)degpos.eq.dec;meta.mainGmagGaia DR3 G-band mean magnitude (2)magphot.mag;em.optfloatr98eROSITA source position errorarcsecstat.error;posfloatsepSeparation between X-ray (eROSITA) and optical (Gaia DR3) positions of sourcearcsecpos.angDistancefloatN[1/2] Number of Pleiades stars within r98meta.numberintLXX-ray luminosity in 0.3-2.3keV band according to 5 eROSITA surveys (in 10+29erg/s unit)1e+22Wphys.luminosity;em.X-rayfloatSimbadSimbad column added by the CDSmeta.ref.urlcharlogRXLog of ratio X-ray in 0.3-2.3keV to bolometric luminosities (3)phot.flux;arith.ratiofloate_LX1-sigma error of X-ray luminosity in 0.3-2.3keV band according to 5 eROSITA surveys (in 10+29erg/s unit)1e+22Wstat.errorfloatf_Xvar[0/2] Flag on Xvar (4)meta.codeintXvar? Factor of X-ray variability (5)phot.flux;arith.ratiofloatnullableSpTypeSpectral type (3)src.spTypecharJ/other/AstL/50.780/table3Pleiades coincidences of eROSITA and ROSAT sourcesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintIDIdentification number in Michela et al., 1996ApJS..102...75M (1)meta.idintSRGeSRGe name (SRGeJHHMMSS.s+DDMMSS)meta.id;meta.maincharDeltaROSAT and eROSITA X-ray coordinates separationarcsecpos.angDistancefloatoffaxisROSAT off-axis value (1)arcminstat.value;instr.offsetfloatlogLX-ROSATLog of ROSAT X-ray luminosity in 0.1-2.1keV band (in log(erg/s) unit) (1)log(1e-07W)phys.luminosity;em.X-rayfloatlogLX-eROSITALog of X-ray luminosity in 0.3-2.3keV band according to 5 eROSITA surveys (in log(erg/s) unit)log(1e-07W)phys.luminosity;em.X-rayfloatNero[1/2] multiple eROSITA counterpart (2)meta.numberintNgaia[1/2] multiple GAIA DR3 counterpart (3)meta.numberint