J/A+A/707/A242ivo://CDS.VizieR/J/A+A/707/A242CDSBerni L.Palla M.Magrini L.Spina L.2026-04-02T06:28:33Z2026-03-17T08:09:53ZCDS support team

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

cds-question@unistra.frinfrared-sourceschemical-abundancesradial-velocityThe accretion of Gaia-Enceladus/Sausage (GES) onto the Milky Way is one of the most prominent features of the Galactic halo revealed by the combination of the Gaia satellite and large spectroscopic surveys. This massive accretion is responsible for a notable amount of the Milky Way stellar mass and was significant enough to alter the formation history and the morphology of the MW. In this work, we aim to analyse the selection of stars identified in Berni et al. (2025A&A...700A.160B) in GES with different kinematics and chemical properties to test the hypothesis of a two-phase accretion event. We apply several statistical tests to assess the significance of the separation between the two populations in GES. We then employ Galactic chemical evolution models to investigate the origin of the chemical differences encountered in the analysis. We confirm the presence of two distinct populations, with consistently different dynamical and chemical properties. The low-energy population seems to show higher overall abundances, whereas the high-energy one may be more metal-poor. We attribute this difference to the presence of at least two separate populations of stars within Gaia-Enceladus, likely associated with the innermost (low-energy) and outermost (high-energy) regions of the progenitor. The models successfully reproduce the patterns in metallicity and [alpha/M] distributions in an inside-out scenario. Our analysis supports the presence of a former metallicity gradient in Gaia-Enceladus, and reinforces the interpretation of its accretion as a multi-passage event through the Milky Way disc.2026A&A...707A.242Bhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/707/A242CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toIII/286 : APOGEE-2 DR17 final allStar catalog (Abdurro'uf+, 2022)J/A+A/691/A333 : Gaia-Sausage-Enceladus abundances (Ernandes+, 2024)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/707/A242https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/707/A242http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/707/A242https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/707/A242https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/707/A242http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/707/A242GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/707/A242/table1 (Population 1)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/707/A242/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/707/A242/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/707/A242/table1?GETtext/xml+votable180.050000true331.5670305740143-34.71367802820960.005555555555555556Cone search capability for table J/A+A/707/A242/table2 (Population 2)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/707/A242/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/707/A242/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/707/A242/table2?GETtext/xml+votable180.050000true203.494249766036944.17684959550130.0055555555555555566/357 460 527 550-551 1067 2157 2547 4073 4161 4279 4340 4681 4749 4772 4799 4801 4847 4880 4883 4923 4933 4970 5016 5108 5139 5336-5338 5437 5553-5554 5557 5561 5566 5575 5609 5630 5681 5739 5755 5757 5800 5840 5843 5860 5867 5888 5913 5915 5919 5923 5940-5941 5964-5965 5975 6175 6408 6451 6536 6543 6559 6561 6595 6630 6646 7339 7916 7950 8234 8275-8276 8284 8288 8292 8375 8440 8443 8448 8657 8659 8691 8695 8699 8784-8785 8866-8868 8942 8962 8964 8966 8969 8972 8987 8990-8991 9015 9029 9031 9044 9051 9059 9067 9070-9071 9154 9157 9182 9203 9230 9253-9256 9258-9259 9261-9262 9266-9267 9273 9277 9281 9290 9302 9312 9329 9334 9347 9352 9357-9360 9364 9369 9375 9378 9384 9389 9397 9431 9434 9436 9463 9471 9473-9474 9482 9505 9510 9516 9601 9641 9644 9666 9707 9785 9804 9819 9836 9838 9850 9856 9862 9872 9875 9877-9878 9884-9886 9894 9914 9923 9928 9938 9943 9957 9962 10016 10024-10026 10061 10099 10123 10181 10184 10200 10205 10211 10215 10234 10245 10252 10261 10294 10297 10300 10323 10369 10371-10372 10375 10377 10390-10391 10404-10405 10431 10434 10443 10449 10488 10543 10571 10579 10583 10598 10600 10604 10620 10632-10633 10636 10668 10702 10706 10712 10714 10742 10747-10748 10810 10855 10866 10872 10895 10904 10913 10916 10925 10935 10940 10954-10955 10978 10992-10993 11012 11022 11039 11047 11058 11060 11062 11066 11093 11108 11110 11131 11169 11203 11267 11269 11296-11298 11303 11312 11314 11327 11357-11358 11407-11408 11433-11434 11447 11460 11717 11749 11986 12114 12254 12274 12358 12390 12398 13162 13340 13378 14587 15109 15121 15146 15171 15279 15315 15340 15354 15798 15933 16647 16803 16808 16942-16943 16981 17210 17289 17296 17316 17327 17602 17763 17799 17818 18039 18044 18096 18130 18142 18179 18222 18227 18309 18317 18335 18426 18448 18474 18494 18532 18565 18574 18585 18649 18746 18769 18777 18835 19025 19031 19037 19228 19279 19373 19775 19796 19975 19981 19998 20010 20382 22380 23056 23072 23191 24842-24843 25350 25356 25387 25403 25489-25490 25548 25590 25642 25693 25713 25843 25851 25853-25854 25878 25945 25983 26012 26041 26043 26047 26058 26100 26118 26161 26166 26169 26177 26193 26252 26266 26283 26346 26595 26722 26915 26921 26958 26987 26997 27007-27008 27014 27017 27068 27077 27093 27120 27236-27237 27351-27352 27452 27492 27494 27508 27538 27628-27629 27641 27668 27676-27677 27687 27704 27894 27900 27941 27946 27975 28030-28032 28072 28078 28123 28127 28149 28245-28247 28291 28327 28420 28462 28483 28551 28555 28630 28644 28648 28745 28946 28973 29350-29351 30774 30967 31019 31105 31113 31115 31374 31410 31416-31417 31447 31603 31606 31618 31660-31661 31706 32429 32432 32435 32440 32458 32463 32508 32680 32875 32878 32893 32961 32981 33041 33044 33050 33058 33063 33081 33089-33090 33138 33141 33149 33151 33169-33170 33172 33181 33217 33228-33229 33294 33318 33330 33794 33797 33808 33812 33827-33828 33836 33847 33864 33921 33925-33926 34240 35331 36351 36525 36772 36808 36816 36886 36900 37006 37038 37383 37408 37419 37426 37430 37437 37452 37515 37517 37544 37557-37558 37600 37602 37849 38604 38921 38923 38948 38953 39048 39050 39080 40290 40296 42976 42984 42997 44305 44362 44364 44728 44770 44777 45000 45024 45895 46194 46846 46976 47021 47034 47060 47827 48488 48500 49128https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/707/A242?format=asciiInfrareddefaultJ/A+A/707/A242/table1Population 1recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordinte_[Ca/Fe]? Error on [Ca/Fe]stat.error;phys.abunddoublenullable[Fe/H]Abundance [Fe/H]phys.abund.Fedoublee_[Fe/H]Error on [Fe/H]stat.error;phys.abund.Fedouble[Ce/Fe]? Abundance [Ce/Fe]phys.abunddoublenullablee_[Ce/Fe]? Error on [Ce/Fe]stat.error;phys.abunddoublenullableSimbadSimbad column added by the CDSmeta.ref.urlcharAPOGEEAPOGEE name (2MHHMMSSss+DDMMSSs)meta.id;meta.maincharRAJ2000Right ascension (J2000)degpos.eq.ra;meta.maine_RAJ2000Error on right ascensiondegstat.error;pos.eq.radoubleDEJ2000Declination (J2000)degpos.eq.dec;meta.maine_DEJ2000Error on declinationdegstat.error;pos.eq.decdoubleRV? Radial velocitykm/sphys.veloc;pos.heliocentricdoublenullablee_RV? Error on radial velocitykm/sstat.errordoublenullableEOrbital energykpc.cm**-2.s**-2src.orbitalinte_EError on orbital energykpc.cm**-2.s**-2stat.errorintLzAngular momentumkpc.km/sphys.angMomentumfloate_LzError on angular momentumkpc.km/sstat.errorfloat[M/H]Metallicity [M/H]phys.abund.Zfloate_[M/H]Error on metallicitystat.error;phys.abunddouble[alpha]Alpha element abundancepos.eq.radoublee_[alpha]Error on alpha element abundancestat.error;pos.eq.radouble[C/Fe]? Abundance [C/Fe]phys.abunddoublenullablee_[C/Fe]? Error on [C/Fe]stat.error;phys.abunddoublenullable[N/Fe]? Abundance [N/Fe]phys.abunddoublenullablee_[N/Fe]? Error on [N/Fe]stat.error;phys.abunddoublenullable[O/Fe]Abundance [O/Fe]phys.abunddoublee_[O/Fe]Error on [O/Fe]stat.error;phys.abunddouble[Na/Fe]? Abundance [Na/Fe]phys.abunddoublenullablee_[Na/Fe]? Error on [Na/Fe]stat.error;phys.abunddoublenullable[Mg/Fe]Abundance [Mg/Fe]phys.abunddoublee_[Mg/Fe]Error on [Mg/Fe]stat.error;phys.abunddouble[Al/Fe]? Abundance [Al/Fe]phys.abunddoublenullablee_[Al/Fe]? Error on [Al/Fe]stat.error;phys.abunddoublenullable[Si/Fe]Abundance [Si/Fe]phys.abunddoublee_[Si/Fe]Error on [Si/Fe]stat.error;phys.abunddouble[Ca/Fe]? Abundance [Ca/Fe]phys.abunddoublenullableJ/A+A/707/A242/table2Population 2recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSimbadSimbad column added by the CDSmeta.ref.urlcharAPOGEEAPOGEE name (2MHHMMSSss+DDMMSSs)meta.id;meta.maincharRAJ2000Right ascension (J2000)degpos.eq.ra;meta.maine_RAJ2000Error on right ascensiondegstat.error;pos.eq.radoubleDEJ2000Declination (J2000)degpos.eq.dec;meta.maine_DEJ2000Error on declinationdegstat.error;pos.eq.decdoubleRV? Radial velocitykm/sphys.veloc;pos.heliocentricdoublenullablee_RV? Error on radial velocitykm/sstat.errordoublenullableEOrbital energykpc.cm**-2.s**-2src.orbitalinte_EError on orbital energykpc.cm**-2.s**-2stat.errorintLzAngular momentumkpc.km/sphys.angMomentumfloate_LzError on angular momentumkpc.km/sstat.errorfloat[M/H]Metallicity [M/H]phys.abund.Zfloate_[M/H]Error on metallicitystat.error;phys.abunddouble[alpha]Alpha element abundancepos.eq.radoublee_[alpha]Error on alpha element abundancestat.error;pos.eq.radouble[C/Fe]? Abundance [C/Fe]phys.abunddoublenullablee_[C/Fe]? Error on [C/Fe]stat.error;phys.abunddoublenullable[N/Fe]? Abundance [N/Fe]phys.abunddoublenullablee_[N/Fe]? Error on [N/Fe]stat.error;phys.abunddoublenullable[O/Fe]Abundance [O/Fe]phys.abunddoublee_[O/Fe]Error on [O/Fe]stat.error;phys.abunddouble[Na/Fe]? Abundance [Na/Fe]phys.abunddoublenullablee_[Na/Fe]? Error on [Na/Fe]stat.error;phys.abunddoublenullable[Mg/Fe]Abundance [Mg/Fe]phys.abunddoublee_[Mg/Fe]Error on [Mg/Fe]stat.error;phys.abunddouble[Al/Fe]? Abundance [Al/Fe]phys.abunddoublenullablee_[Al/Fe]? Error on [Al/Fe]stat.error;phys.abunddoublenullable[Si/Fe]Abundance [Si/Fe]phys.abunddoublee_[Si/Fe]Error on [Si/Fe]stat.error;phys.abunddouble[Ca/Fe]? Abundance [Ca/Fe]phys.abunddoublenullablee_[Ca/Fe]? Error on [Ca/Fe]stat.error;phys.abunddoublenullable[Fe/H]Abundance [Fe/H]phys.abund.Fedoublee_[Fe/H]Error on [Fe/H]stat.error;phys.abund.Fedouble[Ce/Fe]? Abundance [Ce/Fe]phys.abunddoublenullablee_[Ce/Fe]? Error on [Ce/Fe]stat.error;phys.abunddoublenullable