J/A+A/644/A83ivo://CDS.VizieR/J/A+A/644/A83doi:10.26093/cds/vizier.36440083CDSFernandez-Trincado J.G.Beers T.C.Minniti D.2022-09-19T12:28:10Z2020-12-02T08:06:19ZCDS support team

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

cds-question@unistra.frchemically-peculiar-starsglobular-star-clustersradial-velocityinfrared-astronomyspectroscopypeculiar-variable-starsDetailed elemental-abundance patterns of giant stars in the Galactic halo measured by the Apache Point Observatory Galactic Evolution Experiment (APOGEE-2) have revealed the existence of a unique and significant stellar subpopulation of silicon-enhanced ([Si/Fe]>+0.5) metal-poor stars, spanning a wide range of metallicities (-1.5<[Fe/H]<-0.8). Stars with over-abundances in [Si/Fe] are of great interest because these have very strong silicon (^28^Si) spectral features for stars of their metallicity and evolutionary stage, offering clues about rare nucleosynthetic pathways in globular clusters (GCs). Si-rich field stars have been conjectured to have been evaporated from GCs, however, the origin of their abundances remains unclear, and several scenarios have been offered to explain the anomalous abundance ratios. These include the hypothesis that some of them were born from a cloud of gas previously polluted by a progenitor that underwent a specific and peculiar nucleosynthesis event or, alternatively, that they were due to mass transfer from a previous evolved companion. However, those scenarios do not simultaneously explain the wide gamut of chemical species that are found in Si-rich stars. Instead, we show that the present inventory of such unusual stars, as well as their relation to known halo substructures (including the in situ halo, Gaia-Enceladus, the Helmi Stream(s), and Sequoia, among others), is still incomplete. We report the chemical abundances of the iron-peak (Fe), the light- (C and N), the alpha- (O and Mg), the odd-Z (Na and Al), and the s-process (Ce and Nd) elements of 55 newly identified Si-rich field stars (among more than ~600000 APOGEE-2 targets), which exhibit over-abundances of [Si/Fe] as extreme as those observed in some Galactic GCs, and they are relatively well distinguished from other stars in the [Si/Fe]-[Fe/H] plane. This new census confirms the presence of a statistically significant and chemically-anomalous structure in the inner halo: Jurassic. The chemo-dynamical properties of the Jurassic structure is consistent with it being the tidally disrupted remains of GCs, which are easily distinguished by an over-abundance of [Si/Fe] among Milky Way (MW) populations or satellites.2020A&A...644A..83Fhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/644/A83CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toIII/284 : APOGEE-2 data from DR16 (Johnsson+, 2020)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/644/A83https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/644/A83http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/644/A83https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/644/A83https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/644/A83http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/644/A83GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/644/A83/tablea1 (Basic parameters of stars in the Jurassic structure)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/644/A83/tablea1?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/644/A83/tablea1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/644/A83/tablea1?GETtext/xml+votable180.050000true138.396083322.81608330.0055555555555555566/4881 8891 9037 9664 9883 9892 10102 10294 10676 10911 11012 11275 11286 14470 18437 18569 18668 19412 25694 26112 28715 28726 28734 28778 28782 28842 28849 29184 29194 29238 29283 29351 29404 29754 31018 31115 31604 31624 33000 33057 42417 42449 42705 42887 43003 44717 45025 47658 47756 47793 47796 47801 47871 48028 49077https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/644/A83?format=asciiInfrareddefaultJ/A+A/644/A83/tablea1Basic parameters of stars in the Jurassic structureAPOGEEAPOGEE identifier (APOGEE_ID)meta.id;meta.maincharSimbadSimbad column added by the CDSmeta.ref.urlcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintJ-Ks2MASS J-Ks color index (JKs)magphot.color;em.IR.J;em.IR.KfloatE(B-V)? E(B-V) SFD reddening (EBV)magphot.color.excessdoublenullableAKsWISE? WISE all-sky K-band extinction (AKs_WISE)magobs.atmos.extinctiondoublenullableAKsTARG? K-band extinction adopted for targetting (AKs_TARG)magobs.atmos.extinctiondoublenullable[M/H]Uncalibrated [M/H] from ASPCAP analysis of combined spectrum (MH)phys.abund.FefloatTeffASPCAPUncalibrated ASPCAP Effective Temperature (Teff_ASPCAP)Kphys.temperature.effective;stat.uncalibintloggASPCAPUncalibrated ASPCAP Surface Gravity (log_g_ASPCAP)log(cm.s**-2)phys.gravity;stat.uncalibfloatTeffph? Photometric Effective Temperature (Teff_pho)Kphys.temperature.effectivefloatnullableloggiso? 10Gyr PARSEC isochrone Surface Gravity (log_g_iso)log(cm.s**-2)phys.gravityfloatnullableNvisitsNumber of visits for this star (Nvisits)meta.numberintSNRSignal-to-Noise Ratio of spectrum per pixel in APOGEE DR16 (SNR)stat.snr;instr.pixelintRVscatter? Radial velocity variation (RV_SCATTER)km/sphys.veloc;arith.difffloatnullableRVpost DR16 Heliocentric radial velocity (RV) (1)km/sspect.dopplerVeloc;pos.heliocentricfloatpmRA*Proper motion in Right Ascension, pmRA*cosDEC (mu_alpha_cos_delta)mas/yrpos.pm;pos.eq.rafloate_pmRA*Uncertainty in mu_alpha_cos_delta (e_mu_alpha_cos_delta)mas/yrstat.error;pos.pm;pos.eq.rafloatpmDEProper motion in Declination (mu_delta)mas/yrpos.pm;pos.eq.decfloate_pmDEUncertainty in mu_delta (e_mu_delta)mas/yrstat.error;pos.pm;pos.eq.decfloatHdist? Heliocentric distance (dsun)kpcpos.distance;pos.heliocentricfloatnullablee_Hdist? Uncertainty in Dist (e_dsun)kpcstat.errorfloatnullableTelOrigins of the spectroscopic observations (Telescope) (2)pos.parallax.spect;obscharRUWERenormalised Unit Weight Error (RUWE)stat.errorfloat_RAPositions from APOGEE name (right ascension part)degpos.eq.ra;meta.main_DEPositions from APOGEE name (declination part)degpos.eq.dec;meta.mainJ/A+A/644/A83/tablea2Elemental abundances of stars in the Jurassic structurerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintAPOGEEAPOGEE identifier (APOGEE_ID)meta.id;meta.mainchar[C/Fe]sp? [C/Fe] from BACCHUS analysis of combined spectrum (CFe_spectroscopy) (1)phys.abundfloatnullable[N/Fe]sp? [N/Fe] from BACCHUS analysis of combined spectrum (NFe_spectroscopy) (1)phys.abundfloatnullable[O/Fe]sp? [O/Fe] from BACCHUS analysis of combined spectrum (OFe_spectroscopy) (1)phys.abundfloatnullable[Na/Fe]sp? [Na/Fe] from BACCHUS analysis of combined spectrum (NaFe_spectroscopy) (1)phys.abundfloatnullable[Mg/Fe]sp? [Mg/Fe] from BACCHUS analysis of combined spectrum (MgFe_spectroscopy) (1)phys.abundfloatnullable[Al/Fe]sp? [Al/Fe] from BACCHUS analysis of combined spectrum (AlFe_spectroscopy) (1)phys.abundfloatnullable[Si/Fe]sp? [Si/Fe] from BACCHUS analysis of combined spectrum (SiFe_spectroscopy) (1)phys.abundfloatnullable[Fe/H]sp? [Fe/H] from BACCHUS analysis of combined spectrum (FeH_spectroscopy) (1)phys.abund.Fefloatnullable[Ce/Fe]sp? [Ce/Fe] from BACCHUS analysis of combined spectrum (CeFe_spectroscopy) (1)phys.abundfloatnullable[Nd/Fe]sp? [Nd/Fe] from BACCHUS analysis of combined spectrum (NdFe_spectroscopy) (1)phys.abundfloatnullable[C/Fe]ph? [C/Fe] from BACCHUS analysis of combined spectrum (CFe_photometry) (1)phys.abundfloatnullable[N/Fe]ph? [N/Fe] from BACCHUS analysis of combined spectrum (NFe_photometry) (1)phys.abundfloatnullable[O/Fe]ph? [O/Fe] from BACCHUS analysis of combined spectrum (OFe_photometry) (1)phys.abundfloatnullable[Na/Fe]ph? [Na/Fe] from BACCHUS analysis of combined spectrum (NaFe_photometry) (1)phys.abundfloatnullable[Mg/Fe]ph? [Mg/Fe] from BACCHUS analysis of combined spectrum (MgFe_photometry) (1)phys.abundfloatnullable[Al/Fe]ph? [Al/Fe] from BACCHUS analysis of combined spectrum (AlFe_photometry) (1)phys.abundfloatnullable[Si/Fe]ph? [Si/Fe] from BACCHUS analysis of combined spectrum (SiFe_photometry) (1)phys.abundfloatnullable[Fe/H]ph? [Fe/H] from BACCHUS analysis of combined spectrum (FeH_photometry) (1)phys.abund.Fefloatnullable[Ce/Fe]ph? [Ce/Fe] from BACCHUS analysis of combined spectrum (CeFe_photometry) (1)phys.abundfloatnullable[Nd/Fe]ph? [Nd/Fe] from BACCHUS analysis of combined spectrum (NdFe_photometry) (1)phys.abundfloatnullableJ/A+A/644/A83/tablea3Uncertainties in the chemical abundancesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintAPOGEEAPOGEE identifier (APOGEE_ID)meta.id;meta.maincharErrorsType of error (Errors) (1)meta.notechare_[Fe/H]Uncertainties in [Fe/H] from BACCHUS analysis (FeH)stat.error;phys.abund.Fefloate_[C/Fe]? Uncertainties in [C/Fe] from BACCHUS analysis (CFe)stat.error;phys.abunddoublenullablee_[N/Fe]? Uncertainties in [N/Fe] from BACCHUS analysis (NFe)stat.error;phys.abunddoublenullablee_[O/Fe]? Uncertainties in [O/Fe] from BACCHUS analysis (OFe)stat.error;phys.abunddoublenullablee_[Mg/Fe]Uncertainties in [Mg/Fe] from BACCHUS analysis (MgFe)stat.error;phys.abundfloate_[Al/Fe]? Uncertainties in [Al/Fe] from BACCHUS analysis AlFe)stat.error;phys.abunddoublenullablee_[Si/Fe]Uncertainties in [Si/Fe] from BACCHUS analysis SiFe)stat.error;phys.abundfloate_[Na/Fe]? Uncertainties in [Na/Fe] from BACCHUS analysis NaFe)stat.error;phys.abunddoublenullablee_[Ce/Fe]? Uncertainties in [Ce/Fe] from BACCHUS analysis (CeFe)stat.error;phys.abunddoublenullablee_[Nd/Fe]? Uncertainties in [Nd/Fe] from BACCHUS analysis (NdFe)stat.error;phys.abunddoublenullableJ/A+A/644/A83/tablea4Orbital elements of Si-rich starseccOrbital eccentricity (ecc)src.orbital.eccentricityfloate_eccUncertainty in ecc (e_ecc)stat.errorfloatrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintZmaxMaximum height to the Galactic plane (Zmax)kpcpos.cartesian.z;stat.maxfloate_ZmaxUncertainty in Zmax (e_Zmax)kpcstat.errorfloats_ZmaxStandard deviation between Zmax variation to the bar pattern speed (std_Zmax)kpcstat.stdev;phys.veloc;src.morph.paramfloatrperiPerigalactocentric distance (rperi)kpcpos.distancedoublee_rperiUncertainty in rperi (e_rperi)kpcstat.errorfloats_rperiStandard deviation between rperi variation to the bar pattern speed (std_rperi)kpcstat.stdev;phys.veloc;src.morph.paramfloatrapoApogalactocentric distance (rapo)kpcpos.distancefloate_rapoUncertainty in rapo (e_rapo)kpcstat.errorfloats_rapoStandard deviation between rapo variation to the bar pattern speed (std_rapo)kpcstat.stdev;phys.veloc;src.morph.paramfloats_eccStandard deviation between ecc variation to the bar pattern speed (std_ecc)stat.stdev;phys.veloc;src.morph.paramfloatLzMINMinimum z-component of the angular momentum in the inertial frame (LzMIN)kpc.km/sphys.angMomentum;stat.mindoublee_LzMINUncertainty in LzMIN (e_LzMIN)kpc.km/sstat.errorfloats_LzMINStandard deviation between LzMIN variation to the bar pattern speed (std_LzMIN)kpc.km/sstat.stdev;phys.veloc;src.morph.paramfloatLzMAXMaximum z-component of the angular momentum in the inertial frame (LzMAX)kpc.km/sphys.angMomentum;stat.maxdoublee_LzMAXUncertainty in LzMAX (e_LzMAX)kpc.km/sstat.errorfloats_LzMAXStandard deviation between LzMAX variation to the bar pattern speed (std_LzMAX)kpc.km/sstat.stdev;phys.veloc;src.morph.paramfloatOrbJcstOrbital Jacobi constant (Orbital_Jacobi_constant)km**2.s**-2src.orbitaldoublee_OrbJcstUncertainty in Orbital_Jacobi_constant (e_Orbital_Jacobi_constant)km**2.s**-2stat.errorfloatChaOrbECharacteristic Orbital Energy (Characteristic_orbital_energy)km**2.s**-2phys.energydoublee_ChaOrbEUncertainty in Characteristic_orbital_energy (e_Characteristic_orbital_energy)km**2.s**-2stat.errorfloatOrbSenseOrbital Sense (Orbital_Sense) (1)meta.codecharAPOGEEAPOGEE identifier(APOGEEID)meta.id;meta.mainchar