Dynamical age of OctansJ/A+A/689/A11ivo://CDS.VizieR/J/A+A/689/A11doi:10.26093/cds/vizier.36890011CDSGalli P.A.B.Miret-Roig N.Bouy H.Olivares J.Barrado D.2024-11-29T20:05:19Z2024-08-29T08:20:03ZCDS support teamCDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, Francecds-question@unistra.frstellar-associationsproper-motionsradial-velocitystellar-agesOctans is one of the most distant (d~150pc) young stellar associations of the solar neighbourhood, and it has not yet been sufficiently explored. Its age is still poorly constrained in the literature and requires further investigation. We take advantage of the state-of-the-art astrometry delivered by the third data release of the Gaia space mission combined with radial velocity measurements obtained from high-resolution spectroscopy to compute the 3D positions and 3D spatial velocities of the stars and derive the dynamical traceback age of the association. We created a clean sample of cluster members by removing potential outliers from our initial list of candidate members. We then performed an extensive traceback analysis using different subsamples of stars, different metrics to define the size of the association, and different models for the Galactic potential to integrate the stellar orbits in the past. We derive a dynamical age of 34^+2^_-2_Myr that is independent from stellar models and represents the most precise age estimate currently available for the Octans association. After correcting the radial velocity of the stars for the effect of gravitational redshift, we obtain a dynamical age of 33^+3^_-1_Myr, which is in very good agreement with our first solution. This shows that the effect of gravitational redshift is small for such a distant young stellar association. Our result is also consistent with the less accurate age estimates obtained in previous studies from lithium depletion (30-40Myr) and isochrones (20-30Myr). By integrating the stellar orbits in time, we show that the members of Octans and Octans-Near had different locations in the past, which indicates that the two associations are unrelated despite the close proximity in the sky. This is the first reliable and precise dynamical age result for the Octans young stellar association. Our results confirm that it is possible to derive precise dynamical ages via the traceback method for ~30 Myr old stellar clusters at about ~150 pc with the same precision level that has been achieved in other studies for young stellar groups within 50 pc of the Sun. This represents one more step towards constructing a self-consistent age scale based on the 3D space motion of the stars in the young stellar clusters of the solar neighbourhood.2024A&A...689A..11Ghttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/689/A11CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toI/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/689/A11https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/689/A11http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/689/A11https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/689/A11https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/689/A11http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/689/A11GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/689/A11/tablea1 (Radial velocities derived in this paper)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/689/A11/tablea1?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/689/A11/tablea1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/689/A11/tablea1?GETtext/xml+votable180.050000true57.62286029-43.61828790.005555555555555556Cone search capability for table J/A+A/689/A11/tablea2 (Properties of Octans stars)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/689/A11/tablea2?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/689/A11/tablea2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/689/A11/tablea2?GETtext/xml+votable180.050000true6.27499723-62.61855340.0055555555555555566/20522 20528 20551 20554 20557 20561 20563-20564 20574 20594 20607 20719 20726 20756 20788 21070 33047 33070 33073 33504 33631 33655 33669 33907 33972 33980 34063 34099 34105 34117 34168 34276 34281 34294 34320 34365 34395 34487 34573 34575 34583 34611 34828 35396 37400 37402 37520 38946 38949 39053 39068 39078 39083 39100 39104 39154 39166 39453 39478 39493 39507 39533-39535 39545 39568 39607 39613 39618 39621-39622 39629 39632 39636 39644 39648 39673 40977 40991 41028 41236 45072 45101 45105 45192 45208 45338 45405 45485 45607 46217 47106 47135 471621.5062136169708525e-19 9.736485774071566e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/689/A11?format=asciidefault
J/A+A/689/A11/tablea1Radial velocities derived in this paperrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintAllDisplay all datameta.ref.urlcharGaiaDR3Source identifier from Gaia-DR3 cataloguemeta.id;meta.mainRA_ICRSRight ascension (ICRS) at Ep=2016.0degpos.eq.ra;meta.mainDE_ICRSDeclination (ICRS) at Ep=2016.0degpos.eq.dec;meta.mainMJDModified Julian datedtime.epochfloatRVRadial velocitykm/sphys.veloc;pos.heliocentricfloate_RVRadial velocity uncertaintykm/sstat.errorfloats_RVRadial velocity scatterkm/sstat.error;spect.dopplerVelocfloatPIDProgramme identifiermeta.code;obscharInstInstrumentmeta.id;instrcharFlag[0/1] Binary flag (0=single; 1=binary)meta.code.errorint
J/A+A/689/A11/tablea2Properties of Octans starsAllDisplay all datameta.ref.urlcharGaiaDR3Source identifier from Gaia-DR3 cataloguemeta.id;meta.mainRA_ICRSRight ascension (ICRS) at Ep=2016.0degpos.eq.ra;meta.mainDE_ICRSDeclination (ICRS) at Ep=2016.0degpos.eq.dec;meta.mainpmRAProper motion in right ascensionmas/yrpos.pm;pos.eq.rafloate_pmRAProper motion uncertainty in right ascensionmas/yrstat.error;pos.pm;pos.eq.rafloatpmDEProper motion in declinationmas/yrpos.pm;pos.eq.decfloate_pmDEProper motion uncertainty in declinationmas/yrstat.error;pos.pm;pos.eq.decfloatplxParallaxmaspos.parallax.trigfloate_plxParallax uncertaintymasstat.error;pos.parallaxfloatRV1? Radial velocity (Gaia-DR3)km/sspect.dopplerVelocfloatnullablee_RV1? Radial velocity uncertainty (Gaia-DR3)km/sstat.errorfloatnullableRV2? Radial velocity (this paper)km/sspect.dopplerVelocfloatnullablee_RV2? Radial velocity uncertainty (this paper)km/sstat.errorfloatnullableFlag1[0/1] Binary flag (0=single; 1=binary)meta.code.errorintFlag2[0/1] Sample flag (0=rejected; 1=accepted)meta.code.errorintFlag3[0/1] Control sample 1 (0=rejected; 1=accepted)meta.code.errorintFlag4[0/1] Control sample 2 (0=rejected; 1=accepted)meta.code.errorint_RA.icrsRight ascension (ICRS) at Epoch=J2000, proper motions taken into accountdegpos.eq.raindexed_DE.icrsDeclination (ICRS) at Epoch=J2000, proper motions taken into accountdegpos.eq.decindexedrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordint
J/A+A/689/A11/tablea3Youth indicators of Octans starsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintAllDisplay all datameta.ref.urlcharGaiaDR3Source identifier from Gaia-DR3 cataloguemeta.id;meta.mainGmagG-band magnitude (Gaia-DR3)magphot.mag;em.optfloatJmag? J-band magnitude (2MASS)magphot.mag;em.IR.JfloatnullableNUV? NUV magnitude (GALEX)magphot.mag;em.UVfloatnullableHR1? Hardness ratio 1 (1)phot.flux;arith.ratiofloatnullableMIR? Mid-infrared excess significance (2)stat.fit.goodnessfloatnullableEWLi? Lithium equivalent width (m{AA})0.1pmspect.line.eqWidthintnullableYouthList of youth indicatorsmeta.codecharFlag[0/1] Final membership (0=rejected; 1=accepted)meta.code.errorint