J/ApJS/281/61ivo://CDS.VizieR/J/ApJS/281/61CDSLoaiza-Tacuri V.Souto D.Quispe-Huaynasi F.Cunha K.Daflon S.,Costa-Almeida E.Smith V.V.Ghezzi L.2026-08-13T05:11:09Z2026-08-13T05:59:21ZCDS support team

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

cds-question@unistra.frmultiple-starsexoplanetsvisible-astronomyspectroscopychemical-abundancesstellar-massesstellar-radiiWe present a homogeneous spectroscopic analysis of confirmed Kepler's extended mission (K2) exoplanet-hosting stars, comprising 301 targets with high-resolution optical spectra from HIRES and TRES taken from ExoFOP. We derived effective temperatures, surface gravities, and iron and magnesium abundances in local thermodynamic equilibrium by measuring the equivalent widths of Fe I, Fe II, and Mg I lines. Three estimates of stellar masses and radii were obtained via the Stefan-Boltzmann and isochrone methods using the codes PARAM and isochrones. These were used to derive exoplanetary radii reaching internal precisions of 2.5%, 2.6%, and 6.6%, respectively, and the radius gap was consistently detected near 1.9R_{Earth}_. We measured chromospheric activity from the CaII H and K and H{alpha} lines. Within the low-activity range (logR'_HK_{<}-4.75), stellar activity appears to decrease with increasing planetary radius from super-Earths, sub-Neptunes, sub-Saturns, into the Jupiter regime. According to the [Mg/Fe] measurements, most of our K2 planet hosts belong to the Galactic thin disk, but our sample has a population from the thick disk (high-alpha sequence). Most stars show consistent chemodynamical behavior. We find that the [Mg/Fe] ratios are indistinguishable between systems containing large or small exoplanets, as well as single- or multi-exoplanetary systems. Both the [Fe/H] and [Mg/H] distributions reveal that stars hosting large planets are more iron and magnesium enhanced than those having only small planets, further confirming the link between stellar abundances and exoplanetary size, but no significant differences are found between the single-versus multi-exoplanetary systems.2025ApJS..281...61Lhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJS/281/61CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toIII/159 : Ca II H and K Measurements Made at MWO (Duncan+ 1991)II/335 : Catalog of GALEX UV sources (GUVcat_AIS GR6+7) (Bianchi+ 2017)IV/34 : K2 Ecliptic Plane Input Catalog (EPIC) (Huber+, 2017)I/350 : Gaia EDR3 (Gaia Collaboration, 2020)I/352 : Distances to 1.47 billion stars in Gaia EDR3 (Bailer-Jones+, 2021)III/286 : APOGEE-2 DR17 final allStar catalog (Abdurro'uf+, 2022)VII/233 : 2MASS All-Sky Extended Source Catalog (XSC) (IPAC/UMass, 2003-2006)J/AJ/111/439 : Chromospheric emission in late-type stars. (Henry+ 1996)J/ApJ/622/1102 : The planet-metallicity correlation. (Fischer+, 2005)J/MNRAS/367/1329 : Elemental abundances for 176 stars (Reddy+, 2006)J/A+A/469/309 : Activity in late-type stars (Cincunegui+, 2007)J/MNRAS/384/1178 : 2MASS, SDSS and BVRI photometry for 825 stars (Bilir+, 2008)J/A+A/495/959 : Radial velocity curve of HD 189733 (Boisse+, 2009)J/ApJ/709/447 : Chemical composition of OGLE-2007-BLG-514S (Epstein+, 2010)J/ApJ/725/875 : Chromospheric activity for CPS stars (Isaacson+, 2010)J/A+A/511/A54 : Magnetic cycles and RVel for 8 stars (Santos+, 2010)J/ApJ/771/40 : Main-sequence A, F, G & K stars photometry (Boyajian+, 2013)J/A+A/562/A71 : Abundances of solar neighbourhood dwarfs (Bensby+, 2014)J/A+A/566/A66 : Correlation of logR'HK with logIHa (Gomes da Silva+, 2014)J/A+A/594/A100 : K2 new planetary and EB candidates (Barros+, 2016)J/ApJS/225/32 : Extended abundance analysis of cool stars (Brewer+, 2016)J/ApJS/226/7 : Planet cand. using K2's 1st yr (Crossfield+, 2016)J/ApJ/829/23 : Stellar flares from Q0-Q17 Kepler LCs (Davenport, 2016)J/ApJS/224/2 : K2 EPIC stellar properties for 138600 targets (Huber+, 2016)J/ApJS/222/14 : Planetary cand. from 1st yr K2 mission (Vanderburg+, 2016)J/AJ/154/109 : California-Kepler Survey (CKS). III. Radii (Fulton+, 2017)J/ApJ/844/102 : KIC star plxs from asteroseismology vs Gaia (Huber+, 2017)J/AJ/154/108 : California-Kepler Survey (CKS). II. (Johnson+, 2017)J/ApJ/836/77 : High-S/N optical spectra of FGKM stars (Yee+, 2017)J/A+A/616/A108 : Cool stars chromospheric activity cat. (Boro Saikia+, 2018)J/ApJS/237/38 : Extended abundance analysis of KOIs (Brewer+, 2018)J/AJ/156/264 : California-Kepler Survey. VII. Radius gap (Fulton+, 2018)J/ApJ/860/109 : Keck HIRES sp of subgiants (retired A stars) (Ghezzi+, 2018)J/ApJ/852/49 : Properties of metal-poor stars in APOGEE DR13 (Hayes+, 2018)J/AJ/156/277 : Planets from K2 campaigns 5-8 (Livingston+, 2018)J/AJ/155/136 : Planets orbiting bright stars in K2 C0-10 (Mayo+, 2018)J/AJ/155/21 : Planet candidates from K2 campaigns 5-8 (Petigura+, 2018)J/AJ/156/254 : California-Kepler Survey.VI. Multis & singles (Weiss+, 2018)J/AJ/157/169 : Exoplanets with deep learning in K2 (Dattilo+, 2019)J/AJ/157/100 : RVel & bisector spans for K2-287 (Jordan+, 2019)J/ApJS/244/11 : Planet candidates and EBs in K2 campaigns 0-8 (Kruse+, 2019)J/A+A/623/A114 : Light curve of K2-292 (HD 119130) (Luque+, 2019)J/ApJ/875/29 : Sp. analysis of the CKS sample. I. (Martinez+, 2019)J/AJ/159/280 : Gaia-Kepler stellar properties cat. I. (Berger+, 2020)J/AJ/159/211 : Exoplanets parameters from Kepler and K2 (Cloutier+, 2020)J/ApJS/247/28 : K2 stars with Gaia & LAMOST data (Hardegree-Ullman+, 2020)J/A+A/638/A76 : StarHorse data for 5 surveys (Queiroz+, 2020)J/A+A/635/A43 : Stellar rot. periods from K2 C0-18 (Reinhold+, 2020)J/ApJ/895/52 : EW and abundances in 211 stars with HARPS (Spina+, 2020)J/ApJ/920/19 : Sp. analysis of CKS. II. Metallicities (Ghezzi+, 2021)J/A+A/646/A77 : Activity from AMBRE-HARPS (Gomes da Silva+, 2021)J/ApJS/254/39 : Exoplanets from TESS first 2yr obs (Guerrero+, 2021)J/AJ/161/277 : Sample of 45 H{alpha}EW outliers (Kiman+, 2021)J/AJ/162/238 : Radial velocity follow up of Wolf 503 (Polanski+, 2021)J/AJ/161/82 : Phot. & sp. obs. of TOI-954 and K2-329 (Sha+, 2021)J/MNRAS/510/3449 : KOI planets and KIC stars from Kepler DR25 (Bashi+, 2022)J/other/Sci/377.1211 : RV and LC of 8 M dwarf stars with planets (Luque+, 2022)J/A+A/658/A57 : F-G-K stars activity indicators (Meunier+, 2022)J/AJ/163/179 : The California-Kepler Survey. X. (Petigura+, 2022)J/A+A/672/A37 : Activity indicators in M dwarfs (Ibanez Bustos+, 2023)J/ApJS/265/4 : ExoClock project. III. Ephemerides (Kokori+, 2023)J/ApJ/946/61 : Hydra sp. of K2 planet-host stars (Loaiza-Tacuri+, 2023)J/AJ/165/262 : Scaling K2. VI. HIRES stellar param. (Zink+, 2023)J/ApJ/961/85 : The California-Kepler Survey. XI. Activity (Isaacson+, 2024)J/MNRAS/532/563 : Solar-type stars Halpha line (Souza dos Santos+, 2024)J/ApJS/278/52 : Planet masses, radii & orbits from K2 (Howard+, 2025)J/ApJ/993/233 : Stellar & planetary param. of M-dwarfs (Wanderley+ 2025)http://exoplanetarchive.ipac.caltech.edu/ : NASA exoplanet archive homepagehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJS/281/61https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJS/281/61http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJS/281/61https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJS/281/61https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJS/281/61http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJS/281/61GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJS/281/61/table1 (K2 stars)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJS/281/61/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJS/281/61/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJS/281/61/table1?GETtext/xml+votable180.050000true174.011661-2.52093380.005555555555555556Cone search capability for table J/ApJS/281/61/table3 (Stellar parameters)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJS/281/61/table3?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJS/281/61/table3?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJS/281/61/table3?GETtext/xml+votable180.050000trueCone search capability for table J/ApJS/281/61/table4 (Stellar masses and radii)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJS/281/61/table4?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJS/281/61/table4?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJS/281/61/table4?GETtext/xml+votable180.050000true182.700205-6.29421080.005555555555555556Cone search capability for table J/ApJS/281/61/table5 (Planetary radii)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJS/281/61/table5?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJS/281/61/table5?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJS/281/61/table5?GETtext/xml+votable180.050000true174.0116325-2.52088060.0055555555555555566/267 270 275 279 282 285 313 318 328 340 353-354 368 376 391 397 413 437 450 464 467 1024 1032 1036 1052 1064 1066 4247 4268-4269 4271-4273 4279-4280 4285 4296 4309 4315 4319 4321-4322 4330 4340 4345 4351 4495 4521 4622 4624 4629 4632 4659-4660 4673 4675 4677 4682 4687-4688 4696 4698-4700 4704 4716 4720 4730 4733 4816 4867-4868 4872 4875 4897 4902 4904 17149 17291 17306 17327 17331-17332 17999 18007 18018 18022-18023 18029 18033 18039 18112 18130 18132 18147 18163-18164 18184 18208 18222-18223 18313 18338 18344-18345 18350 18352 18361 18434-18435 18451 18453 18459 18462 18469-18470 18473 18481 18490-18491 18496 18510 18536 18539 18542 18561 18565 18567 18569 18572 18574 18578 18585 18588 18593 18628 18696 18704 18707 18785-18786 18837 18880 23519 24057 24115 24122 24199 24202 24205 24223 24256 24260 24340 25423 25427-25428 25433-25434 25443 25446 25454 25463 25468 25551-25553 25562 25565 25585 25604 25614 25624 25627 25631 25650 25673 25675 25696-25697 25699 25710 25723 25725 25756-25757 25783 25794-25795 25810 25829 26114 26124 26168 26170 26252-26253 26256 26275 26278 26290 26292 26297-26298 26928 26935 26940 26953 26959 26961 26977 26982 26986 26990-26992 26999 27001 27025 27056 27064 27075-27076 27078-27079 27083-27085 27393 27398 27401 27464 27482 27511 27548 27684 27690 27704 27787 28933 28981 28999 29002 29012 29014 29017-29018 29022 29121 29349 29730 42865 42984 42986 42989 44159 44317 44334-44335 44370 44377-44378 44384 44431 44436 44463 44474 44512 44816 48098 48113-48114 48121 48501 48503 48597https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJS/281/61?format=asciiOpticaldefaultJ/ApJS/281/61/table1K2 starsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintEPIC[201110617/251319382] EPIC identifiermeta.id;meta.mainlongHostHost namemeta.idcharRAJ2000[8.7/356.3] Right Ascension (J2000)degpos.eq.ra;meta.mainDEJ2000[-28.8/27.3] Declination (J2000)degpos.eq.dec;meta.mainBmag[8.77/18.43] Apparent B band magnitude (1)magphot.mag;em.opt.BfloatVmag[8.24/17.24] Apparent V band magnitude (1)magphot.mag;em.opt.VfloatSimbadSimbad column added by the CDSmeta.ref.urlcharCampK2 observing campaign number(s)meta.id;obscharInstSpectrograph identifier (HIRES or TRES)meta.id;instrcharNsp[1/260] Number of spectrameta.numberintNpNumber of planets for this star (link to Table 5)meta.ref.urlintnullableAllDisplay all data in this catalog for this star (Tables 1, 3 and 4)meta.ref.urlcharJ/ApJS/281/61/table2Line listrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintlambda[4571/6862] Wavelength; Angstroms0.1nmem.wldoubleIon[12/26.1] Species identifier (1)phys.atmol.ionStagefloatExPot[0/5.11] Excitation potentialeVphys.atmol.excitationfloatlog(gf)[-5.63/-0.22] log oscillator strengthphys.atmol.oscStrengthfloatJ/ApJS/281/61/table3Stellar parametersTeff[4474/6539]? Effective temperatureKphys.temperature.effectiveintnullableAllDisplay all data in this catalog for this star (Tables 1, 3 and 4)meta.ref.urlcharSimbadNameSimbad column added by the CDSmeta.idcharnullable_RARight Ascension (J2000) from SIMBAD (not part of the original data)degpos.eq.ra;meta.mainnullable_DEDeclination (J2000) from SIMBAD (not part of the original data)degpos.eq.dec;meta.mainnullablerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintIDIdentifier (Host name or EPIC)meta.id;meta.maincharSHK[0.097/3.8]? Mount Wilson CaII H & K S-indexspect.indexfloatnullablee_SHK[0.001/0.3]? Uncertainty in SHKstat.error;spect.indexfloatnullablelogRHK[-6.25/-3.89]? log R'_HK_ activity indexphot.flux;arith.ratiofloatnullablee_logRHK[0.006/0.3]? Uncertainty in logR'HKstat.error;phot.flux;arith.ratiofloatnullableHa[0.026/0.17]? The H{alpha} indexspect.index;em.line.Halphafloatnullablee_Ha[0/0.003]? Uncertainty in Hastat.errorfloatnullablelogIHa[-1.62/-0.77]? The log I_H{alpha}_ indexspect.index;em.line.Halphafloatnullablee_logIHa[0/0.03]? Uncertainty in logIHastat.error;spect.index;em.line.Halphafloatnullablee_Teff[4/190]? Uncertainty in TeffKstat.error;phys.temperature.effectiveintnullablelog(g)[2.54/4.94]? log surface gravitylog(cm.s**-2)phys.gravityfloatnullablee_log(g)[0.01/0.6]? Uncertainty in log(g)log(cm.s**-2)stat.error;phys.gravityfloatnullableA(Fe)[6.5/8.11]? log final iron abundancephys.abund.Fefloatnullablee_A(Fe)[0.004/0.2]? Uncertainty in A(Fe)stat.error;phys.abund.FefloatnullableVTurb[0.15/16.5]? Microtrubulent velocitykm/sphys.veloc.microTurbfloatnullablee_VTurb[0.02/35]? Uncertainty in VTurbkm/sstat.error;phys.veloc.microTurbfloatnullableA(Mg)[6.57/8.3]? log final magnesium abundancephys.abundfloatnullablee_A(Mg)[0/0.14]? Uncertainty in A(Mg)stat.error;phys.abundfloatnullableJ/ApJS/281/61/table4Stellar masses and radiirecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintIDIdentifier (Host name or EPIC)meta.id;meta.maincharRsSB[0.5/8.4] Stefan-Boltzmann law derived stellar radiussolRadphys.size.radiusfloate_RsSB[0.005/1.7] Uncertainty in RsSBsolRadstat.error;phys.size.radiusfloatRsPARAM[0.39/3.7]? PARAM code derived stellar radiussolRadphys.size.radiusfloatnullablee_RsPARAM[0/0.3]? Uncertainty in RsPARAMsolRadstat.error;phys.size.radiusfloatnullableMsPARAM[0.45/1.5]? PARAM code derived stellar masssolMassphys.massfloatnullablee_MsPARAM[0/0.06]? Uncertainty in MsPARAMsolMassstat.error;phys.massfloatnullableSimbadNameSimbad column added by the CDSmeta.idcharnullableRsiso[0.53/10.5] Isochrones code derived stellar radiussolRadphys.size.radiusfloatE_Rsiso[0.007/3.5] Upper uncertainty in RsisosolRadstat.error;stat.max;phys.size.radiusfloate_Rsiso[0.007/4.7] Lower uncertainty in RsisosolRadstat.error;stat.min;phys.size.radiusfloatMsiso[0.56/3.1] Isochrones code derived stellar masssolMassphys.massfloatE_Msiso[0.004/0.7] Upper uncertainty in MsisosolMassstat.error;stat.max;phys.massfloate_Msiso[0.006/0.9] Lower uncertainty in MsisosolMassstat.error;stat.min;phys.massfloatAllDisplay all data in this catalog for this star (Tables 1, 3 and 4)meta.ref.urlchar_RARight Ascension (J2000) from SIMBAD (not part of the original data)degpos.eq.ra;meta.main_DEDeclination (J2000) from SIMBAD (not part of the original data)degpos.eq.dec;meta.mainJ/ApJS/281/61/table5Planetary radiiPlanetPlanet identifiermeta.id;meta.mainchare_RpPARAM[0.001/2.4]? Uncertainty in PARAM-Rp(6.3781x10+6m)stat.error;phys.size.radiusfloatnullableSimbadSimbad column added by the CDSmeta.ref.urlcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintDeltaF[73/28460] Transit depth in parts per million(10-6)phot.flux.density;arith.diffdoubleRpSB[0.7/79] Stefan-Boltzmann law derived planetary radius(6.3781x10+6m)phys.size.radiusfloate_RpSB[0.009/16]? Uncertainty in SB-Rp(6.3781x10+6m)stat.error;phys.size.radiusfloatnullableRpPARAM[0.7/23]? PARAM code derived planetary radius(6.3781x10+6m)phys.size.radiusfloatnullableRpiso[0.7/99]? Isochrones code derived planetary radius(6.3781x10+6m)phys.size.radiusfloatnullableE_Rpiso[0.015/33]? Upper uncertainty in iso-Rp(6.3781x10+6m)stat.error;stat.max;phys.size.radiusfloatnullablee_Rpiso[0.014/44]? Lower uncertainty in iso-Rp(6.3781x10+6m)stat.error;stat.min;phys.size.radiusfloatnullable_RARight Ascension (J2000) from SIMBAD (not part of the original data)degpos.eq.ra;meta.main_DEDeclination (J2000) from SIMBAD (not part of the original data)degpos.eq.dec;meta.main