J/A+A/697/A32ivo://CDS.VizieR/J/A+A/697/A32doi:10.26093/cds/vizier.36970032CDSSpaeth D.Reffert S.Trifonov T.Kaminski A.Albrecht S.Grundahl F.,Fredslund Andersen M.Quirrenbach A.Palle P.2025-06-02T20:01:30Z2025-05-05T08:53:40ZCDS support team

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

cds-question@unistra.frgiant-starsexoplanetsradial-velocityvisible-astronomyspectroscopyFrom a long-term Doppler monitoring campaign of 373 giant stars, we have identified ten giants with periodic radial velocity variations that are challenging to associate with planets. Similar cases in the literature are attributed to poorly understood intrinsic processes. Our goal is to confirm or refute the presence of planets around these ten evolved stars. Additionally, we evaluate the reliability and sensitivity of planet-confirmation metrics when applied to giant stars and present cases of intrinsically induced radial velocity variations, aiming to enhance the physical understanding of the phenomenon. We combined 25 years of radial velocity data from the Hamilton/Lick, SONG, and CARMENES spectrographs. To assess consistency with Keplerian models, we examined the residuals and tracked changes in statistical significance as new data were incorporated. Additionally, we compared radial velocity amplitudes across optical and infrared wavelengths, searched for periodic variations of activity indicators, and examined their correlations with radial velocities. Seven of the ten giants exhibit intrinsically induced radial velocity variations. The strongest arguments against planets orbiting the giants are guided by long-term radial velocity monitoring that detects changing periodicity on long timescales or detects systematics close to the original period in the radial velocity residuals. While activity indicators offer some support, their signals are generally weak. Comparing optical and infrared radial velocity amplitudes also proves insufficient for confirming or refuting planets. We find HIP 64823 remains a promising candidate for hosting a giant exoplanet with orbital period P=7.75yr. For two stars, the evidence remains inconclusive. Long-term radial velocity monitoring is essential for distinguishing planetary companions from intrinsic variations in evolved stars.2025A&A...697A..32Shttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/697/A32CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/A+A/475/1003 : Stellar parameters of G and K giant stars (Hekker+, 2007)J/A+A/574/A116 : G and K giant stars stellar parameters (Reffert+, 2015)J/A+A/647/A160 : Radial velocity data of epsilon Cyg (Heeren+, 2021)J/A+A/661/A63 : Precise radial velocities of giant stars. XVI.https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/697/A32https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/697/A32http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/697/A32https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/697/A32https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/697/A32http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/697/A32GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/697/A32/stars (List of studied stars)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/697/A32/stars?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/697/A32/stars?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/697/A32/stars?GETtext/xml+votable180.050000true24.498291748.62821110.0055555555555555566/1770 2837 4358 8198 11473 18204 21605 26595 29589 32257 32725 40795https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/697/A32?format=asciiOpticaldefaultJ/A+A/697/A32/starsList of studied starsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameStar namemeta.id;meta.maincharRAJ2000Right ascension (J2000)pos.eq.ra;meta.mainDEJ2000Declination (J2000)pos.eq.dec;meta.mainRVLShow the Lick Radial Velocity curvesmeta.ref.urlcharLickIndicates RV data in lick.dat filemeta.id;meta.filecharRVSShow the Lick Radial Velocity curvesmeta.ref.urlcharSONGIndicates RV data in song.dat filemeta.id;meta.filecharRVVShow the CARMENES VIS Radial Velocity curvesmeta.ref.urlcharCarmVISIndicates RV data in carmvis.dat filemeta.id;meta.filecharRVNShow the CARMENES NIR Radial Velocity curvesmeta.ref.urlcharCarmNIRIndicates RV data in carmnir.dat filemeta.id;meta.filecharJ/A+A/697/A32/lickRadial velocities and Halpha measurements measured by the Hamilton Echelle spectrograph at Lick observatory (Vogt, 1987PASP...99.1214V)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameStar namemeta.id;meta.maincharSeqLine sequential numbermeta.recordintJDJulian Datedtime.epochdoubleRVRadial velocitym/sphys.veloc;pos.heliocentricfloate_RVUncertainty in radial velocitym/sstat.errorfloatHalphaHalpha line index measurementspect.index;spect.linedoublee_HalphaUncertainty in Halpha line index measurementstat.error;spect.linedoubleCCD[6/8] Identifier of CCD, used for separating the Halpha data setsmeta.id;instr.setup;instr.detintJ/A+A/697/A32/songRadial velocities measured by the Hertzsprung SONG spectrograph at Teide observatory (Andersen et al., 2014RMxAC..45...83A)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameStar namemeta.id;meta.maincharSeqLine sequential numbermeta.recordintBJDBarycentric Julian Date reduced by pyodine; Heeren et al., 2023A&A...674A.164Hdtime.epochdoubleRVRadial velocity reduced by pyodinem/sphys.veloc;pos.heliocentricdoublee_RVUncertainty in radial velocity reduced by pyodinem/sstat.errorfloatJ/A+A/697/A32/carmvisRadial velocities and activity indicators measured by the VIS channel of the CARMENES spectrograph at Calar Alto Astronomical Observatory (Quirrenbach et al., 2014SPIE.9147E..1FQ)e_CRXUncertainty in chromatic index reduced by SERVAL (in m/s/Np)stat.errorfloatrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameStar namemeta.id;meta.maincharSeqLine sequential numbermeta.recordintBJDBarycentric Julian Date reduced by SERVAL (Zechmeister et al., 2018A&A...609A..12Z)dtime.epochdoubleRVRadial Velocity reduced by SERVALm/sphys.veloc;pos.heliocentricfloate_RVUncertainty in radial velocity reduced by SERVALm/sstat.errorfloatCRXChromatic index reduced by SERVAL (in m/s/Np)spect.indexfloatdLWDifferential linewidth reduced by SERVAL1000m**2.s**-2spect.line.widthfloate_dLWUncertainty in differential linewidth reduced by SERVAL1000m**2.s**-2stat.errorfloatHalphaHalpha line index measurement reduced by SERVALspect.index;spect.linedoublee_HalphaUncertainty in Halpha line index measurement reduced by SERVALstat.error;spect.linedoubleNaD1NaD1 line index measurement reduced by SERVALspect.indexdoublee_NaD1Uncertainty in NaD1 line index measurement reduced by SERVALstat.errordoubleNaD2NaD2 line index measurement reduced by SERVALspect.indexdoublee_NaD2Uncertainty in NaD2 line index measurement reduced by SERVALstat.errordoubleCaIRT1CaIRT1 line index measurement reduced by SERVALspect.indexdoublee_CaIRT1Uncertainty in CaIRT1 line index measurement reduced by SERVALstat.errordoubleCaIRT2CaIRT2 line index measurement reduced by SERVALspect.indexdoublee_CaIRT2Uncertainty in CaIRT2 line index measurement reduced by SERVALstat.errordoubleCaIRT3CaIRT3 line index measurement reduced by SERVALspect.indexdoublee_CaIRT3Uncertainty in CaIRT3 line index measurement reduced by SERVALstat.errordoubleFWHMFull width at half maximum of cross-correlation function reduced by RACCOON (Lafarga et al., 2020A&A...636A..36L)km/sstat.correlationfloate_FWHMUncertainty in full width at half maximum of cross-correlation function reduced by RACCOONkm/sstat.error;phys.angSizefloatContContrast of cross-correlation function reduced by RACCOON%phot.flux;arith.ratiofloate_ContUncertainty in contrast of cross-correlation function reduced by RACCOON%stat.errorfloatBISBisector inverse slop reduced by RACCOONkm/sphys.velocfloate_BISUncertainty in Bisector inverse slop reduced by RACCOONkm/sstat.errorfloatJ/A+A/697/A32/carmnirRadial velocities and activity indicators measured by the NIR channel of the CARMENES spectrograph at Calar Alto Astronomical Observatory (Quirrenbach et al., 2014SPIE.9147E..1FQ)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameStar namemeta.id;meta.maincharSeqLine sequential numbermeta.recordintBJDBarycentric Julian Date reduced by SERVALdtime.epochdoubleRVRadial Velocity reduced by SERVALm/sphys.veloc;pos.heliocentricfloate_RVUncertainty in radial velocity reduced by SERVALm/sstat.errorfloatCRXChromatic index reduced by SERVALspect.indexfloate_CRXUncertainty in chromatic index reduced by SERVALstat.errorfloatdLWDifferential linewidth reduced by SERVAL (in m/s/Np)1000m**2.s**-2spect.line.widthfloate_dLWUncertainty in differential linewidth reduced by SERVAL (in m/s/Np)1000m**2.s**-2stat.errorfloatFWHMFull width at half maximum of cross-correlation function reduced by RACCOONkm/sstat.correlationfloate_FWHMUncertainty in full width at half maximum of cross-correlation function reduced by RACCOONkm/sstat.error;phys.angSizefloatContContrast of cross-correlation function reduced by RACCOON%phot.flux;arith.ratiofloate_ContUncertainty in contrast of cross-correlation function reduced by RACCOON%stat.errorfloatBISBisector inverse slop reduced by RACCOONkm/sphys.velocfloate_BISUncertainty in bisector inverse slop reduced by RACCOONkm/sstat.errorfloat