J/ApJ/931/45ivo://CDS.VizieR/J/ApJ/931/45doi:10.26093/cds/vizier.19310045CDSNunez A.Agueros M.A.Covey K.R.Douglas S.T.Drake J.J.Rampalli R.,Bowsher E.C.Cargile P.A.Kraus A.L.Law N.M.2026-05-29T20:05:03Z2024-05-07T12:00:20ZCDS support team

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

cds-question@unistra.fropen-star-clustersx-ray-sourcesvisible-astronomyinfrared-sourcesX-ray observations of low-mass stars in open clusters are critical to understanding the dependence of magnetic activity on stellar properties and their evolution. Praesepe and the Hyades, two of the nearest, most-studied open clusters, are among the best available laboratories for examining the dependence of magnetic activity on rotation for stars with masses <~1M_{sun}_. We present an updated study of the rotation-X-ray activity relation in the two clusters. We updated membership catalogs that combine pre-Gaia catalogs with new catalogs based on Gaia Data Release 2. The resulting catalogs are the most inclusive ones for both clusters: 1739 Praesepe and 1315 Hyades stars. We collected X-ray detections for cluster members, for which we analyzed, re-analyzed, or collated data from ROSAT, the Chandra X-ray Observatory, the Neil Gehrels Swift Observatory, and XMM-Newton. We have detections for 326 Praesepe and 462 Hyades members, of which 273 and 164, respectively, have rotation periods-an increase of 6x relative to what was previously available. We find that at ~700Myr, only M dwarfs remain saturated in X-rays, with only tentative evidence for supersaturation. We also find a tight relation between the Rossby number and fractional X-ray luminosity L_X_/L_bol_ in unsaturated single members, suggesting a power-law index between -3.2 and -3.9. Lastly, we find no difference in the coronal parameters between binary and single members. These results provide essential insight into the relative efficiency of magnetic heating of the stars' atmospheres, thereby informing the development of robust age-rotation-activity relations.2022ApJ...931...45Nhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/931/45CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toB/chandra : The Chandra Archive Log (CXC, 1999-2014)B/swift : Swift Master Catalog (HEASARC, 2004-)B/xmm : XMM-Newton Obs. Log (XMM-Newton Science Operation Center, 2012)III/198 : Palomar/MSU nearby star spectroscopic survey (Hawley+ 1997)IX/10 : ROSAT All-Sky Bright Source Catalogue (1RXS) (Voges+ 1999)IX/28 : ROSAT HRI Pointed Observations (1RXH) (ROSAT Team, 2000)IX/30 : Second ROSAT PSPC Catalog (ROSAT, 2000)II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)VII/233 : The 2MASS Extended sources (IPAC/UMass, 2003-2006)II/314 : UKIDSS-DR8 LAS, GCS and DXS Surveys (Lawrence+ 2012)II/319 : UKIDSS-DR9 LAS, GCS and DXS Surveys (Lawrence+ 2012)IV/34 : K2 Ecliptic Plane Input Catalog (EPIC) (Huber+, 2017)I/345 : Gaia DR2 (Gaia Collaboration, 2018)IX/57 : The Chandra Source Catalog (CSC), Release 2.0 (Evans+, 2019)IX/58 : 2SXPS; Swift X-ray telescope point source catalogue (Evans+, 2020)I/350 : Gaia EDR3 (Gaia Collaboration, 2020)I/352 : Distances to 1.47 billion stars in Gaia EDR3 (Bailer-Jones+, 2021)IX/65 : XMM-Newton Serendipitous Source Catalogue 4XMM-DR11 (Webb+, 2022)IX/69 : XMM-Newton Serendipitous Source Catalogue 4XMM-DR13 (Webb+, 2023)J/ApJS/91/625 : ROSAT survey of the Pleiades (Stauffer+ 1994)J/A+A/298/115 : ROSAT study of Praesepe (Randish+, 1995)J/ApJ/448/683 : Hyades RASS observations (Stern+ 1995)J/A+A/327/1039 : Structure and evolution of low-mass stars (Chabrier+ 1997)J/A+A/397/147 : Activity-rotation relationship in stars (Pizzolato+ 2003)J/ApJ/646/297 : Spitzer obs. of pre-main-sequence stars (Rebull+, 2006)J/AJ/134/2340 : Membership of Praesepe & Coma Berenices (Kraus+, 2007)J/ApJ/687/1264 : Age estimation for solar-type dwarfs (Mamajek+, 2008)J/A+A/510/A27 : Very low mass stars in Praesepe (Boudreault+, 2010)J/MNRAS/407/465 : Fast-rotating M dwarfs in NGC2516 (Jackson+, 2010)J/MNRAS/404/1817 : 2MASS/SDSS data for 806 ultracool dwarfs (Zhang+, 2010)J/ApJ/731/17 : Var. of low-mass stars in SDSS Stripe 82 (Becker+, 2011)J/MNRAS/411/2099 : Fast-rotating M-dwarf stars in NGC 2547 (Jeffries+, 2011)J/A+A/531/A92 : Deep all-sky census of the Hyades (Roeser+, 2011)J/ApJ/743/48 : Stars with rot. periods & X-ray luminosities (Wright+, 2011)J/A+A/539/A64 : X-ray data for IC 348 young stars (Alexander+, 2012)J/A+A/559/A43 : Pan-STARRS1 (PS1) obs. of the Hyades (Goldman+, 2013)J/ApJS/208/9 : Intrinsic colors & temperatures of PMS stars (Pecaut+, 2013)J/ApJ/784/156 : Parallaxes for nearby mid-to-late M dwarfs (Dittmann+, 2014)J/ApJ/795/161 : Activity & rotation in Praesepe & Hyades (Douglas+, 2014)J/ApJ/809/161 : X-ray obs. & membership probabilities of M37 (Nunez+, 2015)J/A+A/589/A113 : PMS stars in h Per (Argiroffi+, 2016)J/A+A/588/A103 : 2nd ROSAT all-sky survey (2RXS) source cat. (Boller+, 2016)J/ApJ/822/47 : K2 rotation periods for 65 Hyades members (Douglas+, 2016)J/AJ/152/8 : Stellar mult. impact on planetary syst. I. (Kraus+, 2016)J/ApJ/842/83 : Praesepe members rot. periods from K2 LCs (Douglas+, 2017)J/ApJ/845/72 : The factory & the beehive. III. (Kraus+, 2017)J/ApJ/834/176 : Spectroscopic survey of M37 candidate members (Nunez+, 2017)J/A+A/618/A93 : Gaia DR2 open clusters in the MW (Cantat-Gaudin+, 2018)J/A+A/616/A10 : Open clusters GaiaDR2 HR diagrams (Gaia Collaboration, 2018)J/AJ/156/259 : Robo-AO detected close binaries in Gaia DR2 (Ziegler+, 2018)J/ApJ/879/100 : K2 rot. periods for Hyades & Praesepe (Douglas+, 2019)J/A+A/628/A66 : alpha Persei, Pleiades and Praesepe clusters (Lodieu+, 2019)J/A+A/623/A35 : A 3D view of the Hyades population (Lodieu+, 2019)J/A+A/621/L3 : Hyades tidal tails with Gaia DR2 (Meingast+, 2019)J/A+A/627/A4 : Praesepe (NGC 2632) and its tidal tails (Roeser+, 2019)J/A+A/621/L2 : Hyades tidal tails revealed by Gaia DR2 (Roeser+, 2019)J/A+A/640/A66 : Updated X-ray view of the Hyades cluster (Freund+, 2020)J/A+A/638/A20 : M dwarfs X-ray activity & rotation (Magaudda+, 2020)J/AJ/159/19 : SOAR TESS survey. I. (Ziegler+, 2020)J/ApJ/921/167 : Rotators in Praesepe with K2 LCs & Gaia (Rampalli+, 2021)J/A+A/649/A3 : Gaia EDR3 photometric passbands (Riello+, 2021)J/A+A/657/A7 : Stellar & substellar comp. from Gaia EDR3 (Kervella+, 2022)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/931/45https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/931/45http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/931/45https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/931/45https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/931/45http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/931/45GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/931/45/table2 (Praesepe and Hyades membership catalog)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/931/45/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/931/45/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/931/45/table2?GETtext/xml+votable180.050000true130.2687520.249443890.005555555555555556Cone search capability for table J/ApJ/931/45/table3 (X-ray source catalog: basic source properties)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/931/45/table3?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/931/45/table3?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/931/45/table3?GETtext/xml+votable180.050000true2.2145653.215590.005555555555555556Cone search capability for table J/ApJ/931/45/table4 (Log of Chandra and XMM observations of Praesepe and Hyades)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/931/45/table4?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/931/45/table4?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/931/45/table4?GETtext/xml+votable180.050000true67.962517.863333060.0055555555555555563/73 4/301 304 306 1469 1471 5/80-81 84 87 256 261-262 264-265 1069 1071 1081-1084 1086-1087 1130 1158-1159 1165 1167 1200-1201 1203 1248 5851 5869 5873-5875 5880-5881 5883 6050 6052 6054 6058-6059 6/46 60 62 75 78 95 100 107 125 197 211 247 251 260 262 265 272-274 276 278-279 281 287 303 305 309 311 313 315 318 330 333-335 340-342 344-345 352-353 355 357-358 360 363 365-370 373-375 378-379 381-383 401 405 407 422 426-428 438 450 455-456 458 462 464-466 470 472 475 477-478 481 483 488 490 499 501 507 528 540 583 601 608 663 671 701 706 711-712 729 766 770 780 784 795 803 820 823 829 835 837 840 847 879 882 889-890 906 917 922 924 959 968 989 997 1009 1020 1029 1031-1033 1035-1038 1041-1043 1052 1054 1064-1065 1068 1072 1074-1075 1077 1090 1094 1096-1097 1113 1127 1146 1158-1159 1162-1163 1166-1167 1180 1196 1198-1199 1201 1206 1210-1211 1224 1232 1234 1239 1242 1272 1312 1324 1342 1380 1385 1415 1450-1451 1458 1473 1554 1564 1567-1568 1577 1580 1602-1603 1609 1611 1614 1640 1661 1676 1704 1713 1720 1752 1810 1817 1827 1839 1897 2052 2086 2139 2152 2163 2178 2183 2211 2228 2274 2293 2296 2325 2328 2335 2350 2356 2368 2375 2383 2391 2418 2426 2446 2456 2466 2468 2483 2525 2535 2577 2583 2589 2609 2618 2634 2711 2715 2739 2788-2789 2792 2802 2804 2806 2809 2811 2813 2827-2828 2830 2838 2866 2880 2893 2915 2924 2949 2974 2981 2992 2995 3032 3045 3066 3117 3133 3335 3583 3593 3625 4096 4129 4136 4195 4225-4226 4228 4232 4236 4238-4239 4255 4259-4261 4265 4267-4268 4272 4274-4275 4281-4283 4298-4299 4304 4314 4321-4323 4340 4342-4343 4458 4489 4491 4495 4514 4518 4524 4526 4529 4536 4558 4569 4577 4587 4591 4597 4602 4611-4613 4615 4617 4623 4625-4627 4629-4631 4645 4655 4657-4659 4664-4665 4667 4756-4757 4759 4796 4808-4809 4837 4839 4852 4882-4884 4887-4888 4890 4893-4894 4912 4914 4916 4919-4920 4923 4926 4931-4932 4939 4942 4982 4996-4997 5000-5001 5007-5010 5012-5013 5019 5023 5026 5028 5033 5042 5045 5047 5058 5064 5067 5076-5077 5080 5085 5088 5090 5096 5099 5101 5105 5109 5117 5288 5352 5643 5655 5665-5666 5674 5677 5679 5697 5764-5765 5770 5773 5782 5784 5786 5789 5791 5796 5804 5812 5816-5817 5864 5866 5870 5878 6174 6232 6363 6407 6417 6421 6457 6462 6469 6485 6491 6493 6496 6505 6517-6518 6526 6609 6696 6700 6711 6717 6748 6797 6802 6809 6843 6867 7168 7178 7184 7189-7190 7193 7199 7203 7209 7246 7251-7252 7271 7275 7279 7285 7316 7323 7344 7348-7349 7351 7363 7367-7369 7372 7375 7378 7381-7382 7386 7389-7391 7399 7404 7408 7413-7414 7417-7418 7422 7466 7552 7578 7585 7599 7752 7756 7768 7771 7798 7943 7969 7974 7980 7987 12440 12655 12667 12760 12789 13312 13351 13376 13389 13412 13472 13503 13542 13579 13591 13643 13650 13654 13667 13669 13681 13702 13714 13732 13737 13742 13758-13759 13761 13770 13772 13774 13782 13787 13795-13796 13802 13805 13808-13809 13818 13823 13840 13911 13917 13943 14028 14030 14035-14037 14043 14057 14060-14061 14065 14067 14070-14071 14076 14085 14091 14093-14094 14108 14113-14114 14121-14123 14126 14132 14134-14135 14137 14142 14144-14145 14149 14154 14162 14169 14178 14191 14194 14207-14208 14211-14212 14217-14219 14221 14223 14226-14227 14229-14230 14232-14233 14237 14240 14242-14243 14250 14253 14258-14259 14266 14280 14294 15424 15443 15452 17714 17731 17843 17852 17857 17871 18036 18404 18544 19361 19384 19424 19446 19448 19457 19470 19751 19957 20087 20134 20157 20486 20574 20583-20584 20601 20672 20690 20737 20753 20770 20780 20799 20842 20846 20876 20881 20883 20891 20913 20924 20928 20932 20955 20962 20973 20984 20988 21055 21082 21094 21156 21177 21196 21204 21209 21221 21227 21235 21238 21242 21249 21275 21289 21300-21301 21303 21307-21308 21318-21319 21324 21329 21350 21354 21361 21368 21370 21372 21374 21377-21378 21383 21391 21398 21412 21418 21429 21440 21455 21464 21472 21485 21490 21493 21496 21500 21764 21839 21847 21852 21871 21875-21876 21878-21880 21886-21887 21957 21972-21974 21979-21980 22001 22005-22006 22053 22144 22171 22176-22177 22185 22204 22207 22229 22244 22254 22511 22558 22566 22598 22628 22663 22679 22713 22722 22745 22760-22761 22764 22769 22781 22787 22810-22811 22820 22823 22827 22830 22837 22844 22847 22856-22857 22864-22865 22869 22872 22882 22884 22890 22892 22902 22904 22906-22908 22910-22912 22914 22916 22920-22921 22935-22936 22948-22949 22956 22959 22970 22978 22980 23006 23010-23011 23013 23017 23022-23024 23026 23029 23035 23037 23111 23113 23115 23139-23140 23169 23171 23211 23256 23261 23276 23282-23283 23285-23286 23288 23313 23315 23321 23324-23325 23328-23329 23332 23335 23339 23344-23345 23348-23349 23352 23355-23356 23358-23359 23362 23364 23368-23370 23372 23374-23375 23378 23383 23385-23389 23392-23393 23395-23396 23399-23400 23403 23408 23410 23413 23415-23416 23418-23419 23421 23423 23436-23437 23440 23443-23444 23448-23450 23453-23454 23462-23463 23468-23470 23472 23484 23487 23489-23491 23529-23531 23558 23561 23569 23575 23580 23583-23584 23588 23593 23597 23603 23608 23611 23618 23626 23636 23651 23659-23660 23663 23667 23680 23689 23694-23695 23698 23702 23704-23705 23710 23714 23721-23724 23726-23727 23737-23739 23741 23748 23753 23784 23787 23789 23794 23816 23818 23852 23886 23904 23918 23932 23936 23943 23970 24011 24019 24058 24066-24068 24070 24075-24076 24078 24083 24094-24095 24097-24100 24102-24106 24109-24111 24114 24118 24123-24124 24126 24129-24130 24137 24162 24171 24173 24175 24179 24192 24194-24196 24204 24206-24207 24212 24215 24220 24223-24226 24228-24230 24241-24244 24246 24248-24249 24251-24252 24256 24258-24259 24266 24280 24294 24297-24298 24310 24315 24319 24336 24344 24355 24359-24360 24363 24367 24382 24394 24403 24410-24411 24414 24421 24423 24433 24470 24482 24491 24502 24506 24510 24538 24552 24554 24562 34773 36609 36758 36793 36922 38997 39036 39137 39170 39178 39479 39596 39628 39644 39662 39669-39670 39672 39713 39730 39733 39815 39820 39834 39844 39846 39854 39858 39864-39865 40854-40855 40857-40858 40876-40878 40986 45568 48923https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/931/45?format=asciiX-rayOpticalInfrareddefaultJ/ApJ/931/45/table2Praesepe and Hyades membership catalogNameName of starmeta.id;meta.maincharprimarySimbadSimbad column added by the CDSmeta.ref.urlcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordint2MASS2MASS designation (JHHMMSSss+DDMMSSs)meta.id.crosscharGaia? Gaia EDR3 designationmeta.id.crossnullableRAJ2000Right ascension (J2000)degpos.eq.ra;meta.mainDEJ2000[-84.4/77.1] Declination (J2000)degpos.eq.dec;meta.mainClusterCluster to which object belongs ("Praesepe": 3095 sources; or "Hyades": 1410 sources)meta.id.parentcharMm[0/1] Member in our Legacy catalog (1962 occurrences; see Section 2.1)meta.code.memberintMmCG18[0/1] Member in Cantat-Gaudin+ 2018, J/A+A/618/A93meta.code.memberintCG18Display data from Cantat-Gaudin+ 2018, J/A+A/618/A93 within 1.5"meta.ref.urlintnullableMmGaia[0/1] Member in Gaia Coll.+ 2018, J/A+A/616/A10meta.code.memberintG18Display data from Gaia Coll.+ 2018, J/A+A/616/A10 within 1.5"meta.ref.urlintnullableMmL19a[0/1] Member in Lodieu+ 2019, J/A+A/628/A66meta.code.memberintMmL19b[0/1] Member in Lodieu+ 2019, J/A+A/623/A35meta.code.memberintLCatDisplay data from Lodieu+ 2019, J/A+A/628/A66 and J/A+A/623/A35 within 1.5"meta.ref.urlintnullableMmMA19[0/1] Member in Meingast & Alves 2019, J/A+A/621/L3meta.code.memberintMmRS19[0/1] Member in Roser & Schilbach 2019, J/A+A/627/A4meta.code.memberintMmR19[0/1] Member in Roser+ 2019, J/A+A/621/L2meta.code.memberintMCatDisplay data from Meingast+ 2019, J/A+A/621/L3; Roeser+ 2019, J/A+A/627/A4 and J/A+A/621/L2 within 3"meta.ref.urlintnullableUCDw[0/1] Ultracool dwarf in the literaturemeta.codeintDist[12.7/8828] Distance from the Sunpcpos.distance;pos.heliocentricfloate_Dist[0.01/1449] Mean error of distancepcstat.errorfloatr_DistSource of distance (1)meta.ref;pos.framecharKmag[1/19.7]? K magnitudemagphot.mag;em.IR.Kfloatnullablee_Kmag[0/0.3]? Mean error of K magnitudemagstat.error;phot.magfloatnullabler_Kmag? Source of K magnitude (1)meta.ref;pos.framecharGmag[2.67/25.25]? G magnitudemagphot.mag;em.optfloatnullablee_Gmag[0.003/3]? Mean error of G magnitudemagstat.error;phot.magfloatnullabler_GmagSource of G magnitude ("G" or "2M") (1)meta.refcharBP-RP[-0.4/4.8]? Gaia EDR3 BP-RPmagphot.color;em.opt.B;em.opt.RfloatnullableBin[0/2] Binary flag (2)meta.codeintRUWE[0.7/43.3]? Gaia EDR3 RUWE statisticstat.errorfloatnullableProt[0.13/49.4]? Rotation perioddtime.periodfloatnullableXflux[1.7e-16/1.7e-11]? X-ray energy flux in the 0.1-2.4keV bandmW.m**-2phot.flux;em.X-raydoublenullablee_Xflux[1.8e-16/4e-13]? Mean error on XfluxmW.m**-2stat.errordoublenullableMass[0.05/4]? Stellar masssolMassphys.massfloatnullabletau[7.3/163]? Convective turnover timedtime.scalefloatnullableLbol[1.2e+29/1.1e+36]? Bolometric luminosity1e-07Wphys.luminositydoublenullablee_Lbol[1.2e+27/2.7e+35]? Mean error of Lbol1e-07Wstat.errordoublenullableXrayDisplay data from the X-ray catalog (link to Table 3)meta.ref.urlcharJ/ApJ/931/45/table3X-ray source catalog: basic source propertiesQ[mx]? Quality flag (6)meta.code.qualcharNameName of optical counterpartmeta.id;meta.maincharInstInstrument used in the observation (2)instr.setup;obscharRAJ2000Right ascension (J2000)degpos.eq.ra;meta.mainDEJ2000[-31/60.4] Declination (J2000)degpos.eq.dec;meta.mainPosErr[0/15]? X-ray positional uncertaintyarcsecstat.error;posfloatnullableOffAxis[0/48]? Off-axis anglearcmininstr.offsetfloatnullableDet[3.7/557012]? Detection likelihood (3)stat.likelihooddoublenullableCtsBroad[1/110869]? Net counts in the broad bandctphot.count;em.X-rayintnullableVar[0/2]? Variability flag (4)meta.code;src.varintnullablerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintID? Catalog Source IDmeta.idcharSourceProvenance of X-ray information (1)meta.id;meta.datasetcharIAUName? IAU namemeta.idcharObsID? Observation IDmeta.id;obscharCRBroad[7.4e-05/4.4] Net count rate in the broad bandcount.s**-1phot.count;em.X-raydoublee_CRBroad[2.4e-05/0.05] Mean error of CRBroadcount.s**-1stat.errordoubleCRSoft[5.7e-05/4.2]? Net count rate in the soft bandcount.s**-1phot.count;em.X-raydoublenullablee_CRSoft[2.2e-05/0.04]? Mean error of CRSoftcount.s**-1stat.errordoublenullableCRHard[1.3e-10/0.2]? Net count rate in the hard bandcount.s**-1phot.count;em.X-raydoublenullablee_CRHard[1e-05/0.03]? Mean error of CRHardcount.s**-1stat.errordoublenullableBroadDefinition of broad band rangekeVinstr.bandpasscharSoft? Definition of soft band rangekeVinstr.bandpasscharHard? Definition of hard band rangekeVinstr.bandpasscharHR[-1/1]? Hardness ratio: (hard-soft)/(hard+soft)phot.flux;arith.ratiofloatnullableExp[122/218656]? Exposure timestime.duration;obs.exposureintnullableXflux[1.7e-16/1.7e-11] Unabsorbed X-ray energy flux in the 0.1-2.4keV bandmW.m**-2phot.flux;em.X-raydoublee_Xflux[1.8e-16/1.2e-12] Mean error of XfluxmW.m**-2stat.errordoubler_XfluxSource of X-ray energy flux calculation (5)meta.ref;pos.framecharFl[0/1] X-ray flare removed?meta.codeintSep[0/87] Separation between X-ray source and optical counterpartarcsecpos.angDistancefloatFitDisplay the spectral fits (link to Table 5)meta.ref.urlintnullableJ/ApJ/931/45/table4Log of Chandra and XMM observations of Praesepe and HyadesModeFilter or data mode (1)instr.paramcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintClusterCluster in which filed of view falls ("Hyades": 83 sources or "Praesepe": 30 sources)meta.id;meta.maincharInstInstrument used in the observation (XMM's EPIC, or Chandra's ACIS-I, ACIS-S or HRC-1)instr.setup;obscharObsIDObservation ID(s)meta.id;obscharPIPrincipal investigator of observationobs.observercharDateYear and month of start of observationtime.epochcharDur[5000/231180] Total duration of observationstime.duration;obsintRAJ2000[9.1/348.2] Right ascension (J2000)degpos.eq.ra;meta.mainDEJ2000[-8.6/57] Declination (J2000)degpos.eq.dec;meta.mainRollRoll angle of telescopedeginstr.offsetcharJ/ApJ/931/45/table5Spectral fits for the highest X-ray count Chandra, Swift, and XMM sourcesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintID[90868/108431505010001]? Catalog Source IDmeta.idnullableIAUNameIAU namemeta.id;meta.maincharkT[0.4/2.1] Plasma temperature of APEC modelkeVphys.temperature;meta.modelledfloate_kT[0.002/0.3] Mean error on kTkeVstat.error;phys.energyfloatMetal[0.05/0.9] Plasma metal abundance with respect to SolarSunphys.abund.Zfloate_Metal[0.003/0.5] Mean error on MetalSunstat.error;phys.abund.ZfloatNH[0.02/1.1]? Atomic neutral hydrogen column density1e+21cm**-2phys.columnDensityfloatnullablee_NH[0.01/0.4]? Mean error on NH1e+21cm**-2stat.errorfloatnullableXfluxUnabsorbed X-ray energy flux in the 0.1-2.4keV bandmW.m**-2phot.flux;em.X-raydoublee_XfluxMean error of unabsorbed X-ray energy fluxmW.m**-2stat.errordoubleChi2[0.4/2.6] Reduced chi squared statisticstat.fit.chi2floatdof[7/786] Degrees of freedomstat.fit.dofint