Chemical characterization of the globular cluster NGC 5634 associated to the Sagittarius dwarf spheroidal galaxy

0.44 MB·

by  Eugenio Carretta

Astronomy&Astrophysicsmanuscriptno.carretta (cid:13)c ESO2017
January13,2017
Chemical characterization of the globular cluster NGC 5634
⋆,⋆⋆
associated to the Sagittarius dwarf spheroidal galaxy
E.Carretta1,A.Bragaglia1,S.Lucatello2,V.D’Orazi2,3,4,R.G.Gratton2,P.Donati1,5,A.Sollima1,andC.Sneden6
1 INAF-OsservatorioAstronomicodiBologna,ViaRanzani1,I-40127Bologna,Italy
2 INAF-OsservatorioAstronomicodiPadova,Vicolodell’Osservatorio5,I-35122Padova,Italy
3 DepartmentofPhysicsandAstronomy,MacquarieUniversity,Sydney,NSW2109,Australia
4 MonashCentreforAstrophysics,SchoolofPhysicsandAstronomy,MonashUniversity,Melbourne,VIC3800,Australia
7 5 DipartimentodiFisicaeAstronomia,Universita`diBologna,vialeBertiPichat6,I-40127Bologna,Italy
1 6 DepartmentofAstronomyandMcDonaldObservatory,TheUniversityofTexas,Austin,TX78712,USA
0
2
ABSTRACT
n
a Aspart of our on-going project on the homogeneous chemical characterization of multiplestellar populations in globular clusters
J
(GCs),westudiedNGC5634,associatedtotheSagittariusdwarfspheroidalgalaxy,usinghigh-resolutionspectroscopyofredgiant

1 stars collected with FLAMES@VLT. We present here the radial velocity distribution of the 45 observed stars, 43 of which are
1 member, thedetailedchemical abundance of 22species fortheseven starsobserved withUVES-FLAMES,and theabundance of
sixelementsforstarsobservedwithGIRAFFE.OnourhomogeneousUVESmetallicityscalewederivedalowmetallicity[Fe/H]=

] −1.867±0.019±0.065 dex (±statistical±systematic error) withσ = 0.050 dex (7 stars). Wefound the normal anti-correlations
R
betweenlightelements(NaandO,MgandAl),signatureofmultiplepopulationstypicalofmassiveandoldGCs.Weconfirmthe
S associationsofNGC5634totheSgrdSph,fromwhichtheclusterwaslostafewGyrago,onthebasisofitsvelocityandposition
. andtheabundanceratiosofαandneutroncaptureelements.
h
p Keywords.Stars:abundances–Stars:atmospheres–Stars:PopulationII–Galaxy:globularclusters–Galaxy:globularclusters:
- individual:NGC5634
o
r
t
s
1. Introduction arebelievedtobethelong-livedpartofthefirstgeneration(FG)
a
[ ofstarsformedinthecluster.Theothertwothirdshaveamod-
Once considered good examples of simple stellar populations,
ified composition(increasedNa,depletedO)andbelongto the
1 Galactic globular clusters (GCs) are currently thought to have
second generation (SG) of stars, polluted by the most massive
v formedinacomplexchainofevents,whichleftafossilrecordin
starsoftheFG(Grattonetal.2001)withejectafromHburning
6 theirchemicalcomposition(seethereviewbyGratton,Carretta
at hightemperature(Denisenkov& Denisenkova1989,Langer
1 &Bragaglia2012).OurhomogeneousFLAMESsurveyofmore
etal.1993).Unfortunately,whatweretheFGstarsthatproduced
1
than 25 GCs (see updated references in Carretta 2015 and
3 thegasofmodifiedcompositionisstillanunsettledquestion,see
Bragaglia et al. 2015) combined with literature data, demon-
0 e.g.Venturaetal.(2001),Decressinetal.(2007),deMinketal.
stratedthatmost,perhapsall,GCshostmultiplestellarpopula-
. (2009),Maccarone&Zureck(2012),Denissenkov&Hartwick
1 tionsthatcanbetracedbytheanticorrelatedvariationsofNaand
(2014),andBastianetal.(2015).
0 OabundancesdiscoveredbytheLick-Texasgroup(asreviewed
7
byKraft1994andSneden2000).Photometrically,GCsexhibit
1 We found that the extension of the Na-O anticorrelation
spread, split and even multiple sequences, especially when the
: tends to be larger for higher mass GCs and that, apparently,
v rightcombinationoffiltersareused.Thesevariationscanbeex-
there is an observed minimum cluster mass for appearance of
i plained in large part by different chemical composition among
X theNa-Oanticorrelation(Carrettaetal.2010a).Thisisanother
clusterstars,inparticularoflightelementslikeHe,C,N,O(e.g.,
importantconstraintforclusterformationmechanisms,because
r Sbordoneetal.2011;Miloneetal.2012).
a itindicatesthemassatwhichweexpectthataclusterisableto
Ourlargeandhomogeneousdatabaseallowedusforthefirst
retainpartoftheejectaoftheFG,hencetoshowtheNa-Osigna-
time a quantitativestudy of the Na-O anticorrelation.In all the
ture(themassesoftheoriginalclustersareexpectedtobemuch
analyzed GCs we found about one third of stars of primordial
higherthanthepresentones,since theSG hastobe formedby
composition, similar to that of field stars of similar metallic-
theejecta ofonlypartoftheFG). Itis importanttounderstand
ity (only showing a trace of type II Supernovae nucleosynthe-
if this limit is real or is due to the small statistics (fewer low-
sis,i.e.lowNa,highO).Accordingtothemostwidelyaccepted
mass clusters have been studied, and only a few stars in each
paradigmofGCformation(e.g.,D’Ercoleetal.2008)thesestars
were observed). After studying the high-mass clusters, we be-
gunasystematicstudyoflow-massGCsandhigh-massandold
Sendoffprintrequeststo:E.Carretta,[email protected]
⋆ Based on observations collected at ESO telescopes under pro- openclusters(OCs)toempiricallyfindthemasslimitfortheap-
gramme093.B-0583 pearanceoftheNa-Oanticorrelationandto understandifthere
⋆⋆ Tables 2 is only available in electronic form at the CDS via aredifferencesbetweenhigh-massandlow-massclusterproper-
anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via ties,e.g.intherelativefractionofFGandSGstars(Bragagliaet
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/???/??? al.2012,2014,Carrettaetal.2014a).
1
E.Carrettaetal.:ChemistryofNGC5634
For a better understanding of multiple stellar populations Table1.LogofFLAMESobservations.
in GCs it is also fundamental to study clusters in other galax-
ies, a challenging task. While a promising approach seems to Setup UTDate UT exptime airmass seeing
init
use abundance-sensitivecolour indexes(see Larsen et al. 2014 (yyyy-mm-dd) (hh:mm:ss) (s) (arcsec)
for GCs in Fornax), only a few GCs (in Fornax and in the HR11 2014-07-21 01:44:19.162 3600 1.302 0.74
HR11 2014-07-28 23:50:50.195 3600 1.096 0.77
Magellanic Clouds) have their abundancesderived using high-
resolutionspectroscopy1.TheseGCsalsoseemtohosttwopop- HR11 2014-07-29 00:57:20.020 3600 1.244 0.65
HR11 2014-08-29 00:13:15.317 3600 1.581 0.71
ulations(Letarteetal.2006forFornax;Johnsonetal.2006and
Mucciarellietal.2009foroldGCsinLMC)butthefractionsof
FG andSG starsinFornaxandLMCGCs seemto bedifferent
morethan4Gyrsago.Thisdeductionstemsfromthelargedis-
withrespecttoclustersofsimilarmassintheMilkyWay(MW).
tance(151kpc)fromthemainbodyofSgr,alagalongthestream
Isthisagainaproblemoflowstatisticsoristhegalacticenviron-
thatimpliesaratherlargeintervalsincephysicalassociation.
ment(adwarfspheroidalandadwarfirregularvsalargespiral)
Very recently S15 analyzed high resolution spectra taken
influencingtheGCformationmechanism?
with the HDS spectrograph at the Subaru telescope (Noguchi
To gain a deeper insight on this problem,we also included
et al. 2002)of two coolgiantsin NGC 5634,obtainingthe de-
in our sample GCs commonly associated to the disrupting
tailedabundancesofabout20species.Theysuggestedtheexis-
Sagittarius dwarf spheroidal to understand if there is a signifi-
tence of multiple populationsin the cluster from the anticorre-
cant difference amongst GCs formed in different environments
lated abundancesof O, Na in the two stars, since the observed
(theMWanddwarfgalaxies).Infact,GCsborninadSphmay
differencesexceedanyspreadduetotheuncertaintiesassociated
have retained a larger fraction of their original mass. After the
totheabundanceanalysis.Atthelowmetallicitytheyderivedfor
very massive GCs M54 (Carretta et al. 2010b) and NGC4590
NGC5634(about[Fe/H]=−1.98dex)theoverallchemicalpat-
(M68:Carrettaetal.2009a,b;althoughthislatterisnotuniver-
ternofstarsindwarfgalaxiesisnotsodifferentfromthatofthe
sallyacceptedasamemberoftheSgrfamily),anotherSgrGCof
field starsof theMilkyWay atthesame metallicity,the largest
ourprojectisTerzan8.Inthisclusterweseesomeindicationof
differencesoccurringathighermetallicity.Therefore,S15were
aSG,atvariancewithotherlow-massSgrGCs(Ter7,Sbordone
notabletoprovideaclearcutchemicalassociationofNGC5634
etal.2007;Pal12,Cohen2004).However,theSGseemstorep-
toSgrdSph,althoughtheyconcludedthatanoriginofthisclus-
resentasmallminority,contrarytowhathappensforhigh-mass
terintheSgrsystemisfavouredbytheirdata.
GCs(Carrettaetal.2014a).
Finally, Dias et al. (2016) analyzed spectra of nine stars in
In the present paper we focus on the chemical characteri-
thewavelengthrange4560-5860Å,ataresolutionabout2000.
zation of NGC 5634, a poorly studied cluster considered to be
They measured radial velocities (RV) and found that eight of
associated to the Sgr dSph (Bellazzini et al. 2002, hereinafter
thestarsarememberofthecluster;theyalsodeterminedatmo-
B02). NGC 5634 is a relatively massive and metal-poor GC
sphericparameters,ironandMg(oralpha)abundanceratiosus-
(M = −7.69, [Fe/H]=-1.88;both values come from the 2010
V ing a comparison with stellar libraries. They found an average
webupdateoftheGalacticGCcatalogue,Harris1996).
RVofabout−30kms−1,withalargedispersion(rms39kms−1),
Thepaperisorganizedasfollows:in§2wepresentliterature
averagemetallicity[Fe/H]=−1.75dex(rms=0.13dex),average
information on the cluster, in §3 we describe the photometric
[Mg/Fe]=0.43 dex (rms= 0.02 dex), and average [α/Fe]=0.20
data,thespectroscopicobservations,andthederivationofatmo-
dex(rms=0.04)dex.Theydidnotcommentonanythingpecu-
spericparameters.Theabundanceanalysisispresentedin§4,a
liarforthecluster,theysimplyuseditaspartoftheirhomoge-
discussion on the light-element abundances is given in §5, the
noeussample.
connectionwithSgrdSphisdiscussedin§6,andasummaryis
presentedin§7.
3. Observationsandanalysis
2. NGC5634intheliterature We used the photometry by B02 to select our targets for
FLAMES; the V,V − I CMD is shown in Fig. 1, lower panel.
The main studies on NGC 5634 were essentially focussed on We converted the x,y positions given in the catalogue to RA
verifyingwhetherthisGCisassociatedtotheSagittariusgalaxy, andDecusingstarsintheTwoMicronAllSkySurvey(2MASS,
usingeitherphotometry(B02)orspectroscopy(Sbordoneatel. Skrutskie et al. 2006)for the astrometric conversion.2 We then
2015, hereinafter S15). NGC 5634 is also part of the study by selectedstarsontheredgiantbranch(RGB)andasymptoticgi-
Dias et al. (2016): they obtained FORS2@VLT spectra of 51 antbranch(AGB)andallocatedtargetsusingtheESOpositioner
MW GCs and determinedmetallicity and alpha elements (Mg, fposs.Giventhecrowdedfieldandthelimitationsoftheinstru-
inparticular)onahomogeneousscale. ment,only45targetswereobserved;theyareindicatedonaclus-
B02observedthisclusterwithbroadbandV,IJohnsonfilters, termapinFig.1,upperpanel.
andusingtheluminositydifferenceoftheturnoffpointwithre-
specttotheHBleveltheyconcludedthatNGC5634isasoldas
3.1.FLAMESspectra
M68andTer8.Thelatterisstillenclosedinthemainbodyof
SgrandisconsideredoneofthefiveconfirmedGCsbelonging
NGC 5634 was observed with the multi-object spectrograph
withhighprobabilitytothisdwarfgalaxy(seee.g.Bellazziniet
FLAMES@VLT (Pasquini et al. 2002) in the ESO program
al.2003,Law&Majewski2010a).Fromtheliteratureradialve-
093.B-0583(PI A. Bragaglia). The observations, in priority B,
locityandGalactocentricpositionB02suggestedthatNGC5634
were performedin service mode;a log is presentedin Table 1.
was a former memberof the Sgr galaxythat becameunbound
2 We used the code cataxcorr, developed by Paolo Montegriffo
1 Ofcoursethisdoesnotincludetheknownclustersassociatedwith at the INAF - Osservatorio Astronomico di Bologna, see
theSgrdSphandnowphysicallywithintheMilkyWay. http://www.bo.astro.it/∼paolo/Main/CataPack.htm
2
E.Carrettaetal.:ChemistryofNGC5634
Fig.2. Histogram of heliocentric RVs (the filled red histogram
indicates the seven UVES stars). The cluster stars are easily
identified,withRVnear−16kms−1.
ThereducedGIRAFFEspectrawereobtainedfromtheESO
archive(request168411),aspartoftheAdvancedDataProducts
(ADP). The UVES spectra were reduced by us using the ESO
pipeline for UVES-FIBRE data, which takes care of bias and
flatfieldcorrection,ordertracing,extraction,fibretransmission,
scatteredlight,andwavelengthcalibration.WethenusedIRAF3
routinesonthe1-d,wavelength-calibratedindividualspectrato
subtractthe(average)sky,measuretheheliocentricRV, shiftto
zeroRV,andcombinealltheexposuresforeachstar.
WeshowinFig.2thehistogramoftheRVs;theclustersig-
natureisevidentandweidentitied43ofthe45observedtargets
asclustermembersonthebasisoftheirRV.Onestarhasnomea-
suredRV,onehasadiscrepantRVandwaslabelledasnonclus-
termember.Star151,initiallyconsideredmemberofthecluster
due to its RV, was afterward classified non-member following
the abundance analysis and then disregarded.The average, he-
Fig.1. Upper panel: a 15′ ×15′ DSS map of NGC 5634, with liocentricRVforeachstarisgiveninTable2,togetherwithits
NorthupandEastleft.Ourtargetsarecolour-codedasobserved rms.FormemberstarswefoundanaverageRVof−16.07kms−1
withGIRAFFE(inred),andUVES(inblue).Nonmemberstars (with σ = 3.98).This value is in excellentagreementwith the
areindicatedingreen.Lowerpanel:V,V −I CMD (fromB02) average RV (−16.7 km s−1, σ = 5.5) found by S15 from two
with FLAMES targets indicated by larger, coloured symbols stars,butnotwiththeolderliteraturevalue(−45.1kms−1)listed
(subsample UVES: filled blue dots and subsample GIRAFFE inHarris(1996,2010webupdate),asalreadydiscussedinS15,
filled and open red squares for RGB and AGB stars, respec- orwiththevalueof−29.6(σ=39.1)kms−1inDiasetal.(2016),
tively.).Greencrossesrepresentnonmemberstars. thatwashoweverobtainedonmuchlowerresolutionspectra.
3.2.Atmosphericparameters
We retrievedthe2MASSmagnitudes(Skrutskieet al.2006)of
Unfortunately, only less than half of the planned observations
the43RV-memberstars; K magnitudes,2MASSidentification,
wasactuallycompleted.Weonlyhavefourexposures(outofthe
andqualityflagaregiveninTable2.Followingourwelltested
six requested) taken with the GIRAFFE high-resolution setup
procedure(foradetaileddescription,seeCarrettaetal.2009a,b),
HR11 (R=24200), containing the 5682-88Å Na i doublet; no
effective temperatures T were derived using an average rela-
exposureswith the HR13 setup, containingthe forbidden[O i] eff
tion between apparent magnitudes and first-pass temperatures
lines,areavailable.TheGIRAFFEobservationsof38starswere
coupledwith the spectra of sevenstars obtainedwith the high-
3 IRAF is distributed by the National Optical Astronomical
resolution(R=47000)UVES(Dekkeretal.2000)580nmsetup
Observatory, which are operated by the Association of Universities
(λλ ≃ 4800−6800Å).Informationonthe45stars(ID,coordi- for Research in Astronomy, under contract withthe National Science
nates,magnitudesandRVs)isgiveninTable2. Foundation.
3
E.Carrettaetal.:ChemistryofNGC5634
fromV −K coloursandthecalibrationsofAlonsoetal.(1999,
2001).Thismethodallowedustodecreasethestar-to-starerrors
inabundancesduetouncertaintiesintemperature.Theadopted
reddeningE(B−V)=0.05,distancemodulus(m−M) =17.16,
V
andinputmetallicity[Fe/H]=−1.88aretakenfromHarris(1996,
2010webupdate).Gravitieswereobtainedfromapparentmag-
nitudesanddistancemodulus,assumingthe bolometriccorrec-
tionsfromAlonsoetal.(1999).Weadoptedamassof0.85M
⊙
forall starsand M = 4.75asthe bolometricmagnitudefor
bol,⊙
theSun,asinourpreviousstudies.
Since only one of the two requested GIRAFFE setups was
done,onlyalimitednumberofFetransitionsfromourhomoge-
neouslinelist(fromGrattonetal.2003)wereavailableforstars
withGIRAFFEspectra,andthisaffectedtheabundanceanalysis.
Fortunately,thesevenstarswithspectratakenwithUVESwere
chosen among those in the brightest magnitude range, close to
the RGB tip (see Fig. 1) and did not suffer excessively for the
lackofallplannedobservations.TheS/Nvaluesperpixelrange
from 90 to 40 from the brightest down to the faintest of our Fig.3.Runoftheironabundancesasafunctionoftheeffective
UVES sample stars. The median S/N for the 35 member stars temperature for the seven UVES stars (blue circles) and stars
with GIRAFFE spectra is 58 at λ ∼ 5600 Å. Literature high- with GIRAFFE spectra (red circles). Abundances from singly
ionized Fe lines are shown in the lower panel, for UVES stars
resolutionspectraareavailableonlyfortwostarsinthiscluster
only.Internalerrorbarsarealsodisplayed(fortheUVESsample
(S15), therefore even such a small sample represents a signifi-
ontheleftcorner,fortheGIRAFFEsampleintherightcorner).
cantimprovement.
ThedottedlineistheaverageabundancederivedfromtheUVES
We measuredthe equivalentwidths(EW) of ironand other
spectra.
elements using the code ROSA (Gratton 1988) as described in
detailinBragagliaetal.(2001).Weemployedspectrumsynthe-
sisfora fewelements(seeSec. 4.3).FortheUVESspectrawe
eliminatedtrendsinthe relationbetweenabundancesfromFe i capture element (Na), three α−capture elements (Mg, Si, and
linesandexpectedlinestrength(Magain1984)toobtainvalues Ca), and three elements of the iron-group(Sc, V, and Ni). The
ofthemicroturbulentvelocityv4.Finallyweinterpolatedwithin abundances were derived using EWs for all species except Cu
t
the Kurucz(1993)grid ofmodelatmospheres(with overshoot- andneutron-captureelements.Theatomicdataforthelinesand
ingon)toderivethefinalabundances,adoptingforeachstarthe thesolarreferencevaluescomefromGrattonetal.(2003).The
modelwith the appropriateatmospheric parametersand whose Naabundanceswerecorrectedfordeparturefromlocalthermo-
abundancesmatchedthosederivedfromFeilines.Theadopted dynamicalequilibriumaccordingto Grattonetal. (1999),as in
atmosphericparameters(T , logg, [A/H], and v) are listed in all the otherpapersof our FLAMESsurvey.Correctionsto ac-
eff t
Table3togetherwithironabundances.Figure3showstherunof countforthehyperfinestructurewereappliedtoSc,V,andMn
[Fe/H]fromneutralandionisedtransitionsas a functionofthe (referencesareinGrattonetal.2003),andY.
effectivetemperature;notrendisvisibleineithercase.Wefind Toestimatetheerrorbudgetwecloselyfollowedtheproce-
for NGC 5634 an average metallicity [Fe/H]= −1.867±0.019 duredescribedinCarrettaetal.(2009a,b).Table4providesthe
dex(rms=0.050dex)and−1.903±0.009dex(rms=0.025dex) sensitivitiesofabundanceratiostouncertaintiesinatmospheric
fromthesevenstarswithUVESspectra,respectivelyforneutral parametersandEWsandtheinternalandsystematicerrorsrela-
and ionised lines. The average difference −0.036± 0.015 dex tivetotheabundancesfromUVESspectra.Thesamequantities
(rms=0.040)dexisnotsignificant. arelistedinTable5forabundancesfromGIRAFFEspectra.In
Theaveragevalueisinverygoodagreementwiththemean thissecondcase,tohaveaconservativeestimateoftheinternal
metallicity we derived from the analysis of the 35 stars with error in vt we adopted the quadratic sum of the GIRAFFE in-
GIRAFFE spectra: [Fe/H]= −1.869 ± 0.016 dex (σ = 0.093 ternal errors for the metal-poor GCs in our FLAMES survey:
dex).Thelargerdispersionis ultimatelymostly duetothe lim- NGC 4590, NGC 6397, NGC 6805, NGC 7078, NGC 7099
ited number of Fe lines available in the spectral range of the (Carretta et al. 2009a), NGC 6093 (Carretta et al. 2015), and
HR11setup,hamperingabetterderivationoftheparameters(see NGC4833(Carrettaetal.2014b).
alsoSection§4). The sensitivities were obtainedby repeatingthe abundance
analysisforallstars,whilechangingoneatmosphericparameter
atthetime,thentakingtheaverage.Theamountofthevariation
4. Abundances in the input parameters used in the sensitivity computations is
giveninthetableheaders.
BesideFe,wepresenthereabundancesofO,Na,Mg,Al,Si,Ca,
OnourUVESmetallicityscale(seeCarrettaetal.2009c)the
Sc, Ti (both from neutraland singly ionized transitions), V, Cr
average metal abundance for NGC 5634 is therefore [Fe/H]=
(frombothCriandCr iilines),Mn,Co, Ni,Zn,Cu, Y,Zr,Ba,
−1.867± 0.019± 0.065 dex (σ = 0.050 dex, 7 stars), where
La,Ce,Nd,andEu,obtainedfromUVESspectra.Forstarsinthe
thefirstandseconderrorbarsrefertostatisticalandsystematic
GIRAFFE sample we derived only abundances of one proton-
errors,respectively.
4 Forthe35memberstarswithGIRAFFEHR11spectratoofewFe Theabundanceratiosforproton-captureelementsaregiven
lineswereavailableandwegenerallyadoptedarelationwiththestar’s inTable6forUVESspectra,togetherwithnumberoflinesused
gravity:v = −0.31logg+2.19,apartfromafewcases,derivedfrom andrmsscatter.AllOabundancesaredetections;nomeasureof
t
ourpreviousanalyses. Oabundanceinstar5634-13waspossiblebecausetheforbidden
4
E.Carrettaetal.:ChemistryofNGC5634
Table3.Adoptedatmosphericparametersandderivedmetallicity.
ID T logg [A/H] v nr [Fe/H]i rms nr [Fe/Hii rms
eff t
(K) (dex) (dex) (kms−1) (dex) (dex)
UVESsample
2 4137 0.61 -1.91 2.11 80 -1.913 0.126 15 -1.933 0.077
5 4221 0.76 -1.86 2.10 73 -1.862 0.095 12 -1.887 0.100
7 4376 1.06 -1.89 1.84 73 -1.892 0.130 18 -1.915 0.104
9 4376 1.04 -1.79 2.00 78 -1.791 0.101 14 -1.877 0.069
10 4374 1.04 -1.82 1.88 73 -1.821 0.110 12 -1.876 0.075
12 4413 1.12 -1.93 1.66 55 -1.932 0.112 14 -1.901 0.087
13 4415 1.11 -1.86 1.91 60 -1.858 0.167 6 -1.933 0.090
GIRAFFEsample
100 4854 1.89 -1.87 1.60 11 -1.872 0.184
103 4904 2.01 -1.82 1.57 8 -1.816 0.163
113 4898 1.98 -1.93 1.38 8 -1.925 0.131
125 4930 2.06 -1.91 1.55 5 -1.910 0.041
132 5023 2.24 -1.81 1.50 5 -1.813 0.172
135 5013 2.21 -1.71 1.50 4 -1.722 0.091
142 5002 2.18 -1.81 1.90 6 -1.809 0.135
146 5038 2.26 -1.79 1.49 3 -1.787 0.259
152 4978 2.14 -1.92 1.53 5 -1.920 0.151
163 5081 2.33 -1.63 1.47 5 -1.629 0.047
167 5111 2.38 -1.83 1.45 4 -1.826 0.127
169 5130 2.42 -1.77 1.81 4 -1.774 0.048
173 5115 2.39 -1.81 1.76 5 -1.811 0.142
182 5128 2.41 -1.91 1.44 3 -1.909 0.407
189 5136 2.43 -1.82 1.44 4 -1.823 0.120
194 5145 2.45 -1.91 1.43 4 -1.911 0.129
19 4555 1.37 -1.90 1.77 8 -1.895 0.098
22 4565 1.39 -1.96 1.76 7 -1.957 0.103
30 4820 1.62 -1.86 1.69 5 -1.859 0.204
35 4624 1.49 -1.85 1.73 9 -1.854 0.145
3 4140 0.62 -1.93 2.00 10 -1.933 0.098
45 4725 1.68 -1.88 1.67 6 -1.877 0.115
46 4722 1.67 -1.93 1.67 8 -1.933 0.207
54 4741 1.70 -1.87 1.66 6 -1.865 0.119
58 4755 1.73 -1.85 1.65 6 -1.850 0.099
60 4738 1.69 -2.00 1.67 4 -1.998 0.110
62 4773 1.76 -1.87 1.64 6 -1.875 0.147
64 4937 1.90 -1.88 1.60 7 -1.883 0.177
70 4834 1.89 -1.82 1.60 5 -1.819 0.128
72 4880 1.96 -2.05 1.23 4 -2.047 0.018
78 4837 1.88 -2.11 0.37 6 -2.107 0.188
82 4917 1.93 -2.03 0.83 3 -2.028 0.018
87 4822 1.84 -1.81 1.62 6 -1.814 0.157
93 4895 2.00 -1.88 1.57 5 -1.754 0.132
97 5370 2.21 -1.80 1.50 4 -1.796 0.117
line[OI]6300.31Åwasaffectedbyskycontamination.Forstars withintheerrorbarsandtheirMg abundanceand[α/Fe]arein
5634-2and5634-9onlyupperlimitscouldbemeasuredforAl. verygoodaccord.
WealsohavethreestarsincommonwiththeAPOGEEsur-
Abundancesofα−capture,iron-peakandneutron-captureel-
vey(Holtzmanetal.2015);howeverparameterswerepresented
ementsfortheindividualstarsarelistedinTable7,Table8,and
onlyfortwoofthestarsinDR12.Furthermore,astraightforward
Table 9, respectively, for the seven stars with UVES spectra.
comparisonisdifficult,becauseofdifferentmodelatmospheres,
Except for iron, all the abundances derived for stars observed
spectralrangesandlinelist,andadoptedmethods.
with GIRAFFE are listed in Table 10. For these 35 stars all
the element ratios are referred to the average iron abundance Limiting the comparison to the optical range, ours is the
[Fe/H]= −1.87 dex. Finally, in Table 11 the mean abundances secondhigh-resolutionopticalspectroscopicstudyof thisclus-
inNGC5634aresummarized. ter. S15 used a full spectroscopic parameter determination for
the two stars they analyzed in NGC 5634. Had we used their
We cross-matchedourstarswiththenineobjectsinDiaset atmospheric parameters for star 5634-2, in common with that
al.(2016)andfoundonlythreeincommon.Stars#9,54,87in studyandobservedwithsimilarresolutionandwavelengthcov-
oursamplearewithin1′′ofstars#11,8,7intheirlistandhave erage, we would have obtained on average higher abundances
reasonably similar V magnitudes (theirs are instrumental val- by0.003±0.016dex(σ = 0.060dex)from14 neutralspecies
ues)andatmosphericparameters.Wedonotdwellonthecom- and lower by −0.049 ± 0.022 dex (σ = 0.058 dex) from 7
parison since their results are based on lower resolution spec- singlyionisedspecies,onceoursolarreferenceabundancesfrom
tra. However,their cluster average metallicity agreeswith ours Grattonetal.(2003)arehomogeneouslyadopted.
5
E.Carrettaetal.:ChemistryofNGC5634
NGC 5634 seems to be an homogeneous cluster, as far as NGC 5634, supporting previous findings by S15 based on the
most elements are concerned. By comparing the expected ob- Naabundancesoftheirtwostars,photometricallyverysimilar.
servational uncertainty due to errors affecting the analysis (the The impression is supported by the upper-right and lower-
internalerrorsinTable4)withtheobserveddispersion(thestan- leftpanelsinFig.4:nosignificantstar-to-starvariationisobser
darddeviationaboutthemeanvaluesinTable11)wecaneval- ved for Mg, while the Al abundances cover a relatively large
uate whether there is an intrinsic or cosmic scatter for a given rangewhichisonlyalowerlimitsincefortwoPstarsonlyupper
elementamongstarsinNGC5634.Thisexercisewasmadeus- limitstotheAlabundancescouldbemeasured.
ingthemoreaccurateabundancesfromUVESspectra;itis es- The lack of any extreme abundance variation in Mg is
sentiallyequivalenttocomputethe“spreadratio”introducedby stronglyconfirmedbythelower-rightpanel,wherewecompare
Cohen(2004)anditshowsthatthereisevidenceforanintrinsic abundancesof Ca and Mg in NGC 5634with the valuesfound
spread only for O, Na, Al, and for a possible spread for Fe, Y, in our homogeneous survey in 25 GCs. The stars analyzed in
andEu. NGC5634followthetrendofclusterstarswithnoextremeMg
However, we do not consider the spread in Fe to be real, depletion(seealsoS15).
sinceinthiscasetheobservationaluncertaintyisverysmalldue To have a more robust estimate of the fraction of first and
tothelargenumberofmeasuredlinesinUVESspectra.Onthe second generation stars in NGC 5634 we may resort to the
otherextreme,whentheabundanceofagivenspecieisbasedon large statistics provided by Na abundances of the combined
a very limited number of lines, the spread ratio may be biased UVES+GIRAFFE semple. We cannot distinguish second gen-
high(seeCohen2004foradiscussion),asinthecaseofYand eration stars with intermediate and extreme composition (this
Eu. Moreover, all five determinations of Eu abundances from would require knowledge also of O abundances), but the defi-
thelineat6437Åareupperlimits.Hadweconsideredonlythe nition of the primordialP fraction in a GC simply rests on Na
detections(fromtheEu6645Åline),thespreadratiowouldbe abundances(Carrettaetal.2009a).
<1,implyingnointrinsicspreadforEuinNGC5634. Usingthetotalsampleandseparatingat[Na/Fe] +0.3dex,
min
thefractionofPstarsinNGC5634is38±10%,whilethefrac-
In conclusion,the overallpatternof the chemicalcomposi-
tionofthesecondgenerationstarsis62±12%,wheretheasso-
tionshowsthatNGC5634isanormalGC,wheremostelements
ciatederrorsareduetoPoissonstatistics.Thesefractionarenot
donotpresentanyintrinsicstar-to-starvariation,exceptforthose
verydifferentfromtheaverageofwhatfoundinmostGCs(see
involved in proton-capturereactions in H burning at high tem-
e.g.Carrettaetal.2009a,2010a).
perature,suchasO,Na,Al,andascommonlyobservedinGCs
(seeGrattonetal.2012).
4.2.Elementsuptoiron-peak
4.1.Thelightelements InFig.6wesummarizethechemicalcompositionofNGC5634
as far as α−elements and iron-peak elements are concerned,
The relations among proton-capture elements in stars of using the individual values derived for stars with UVES spec-
NGC 5634 are summarized in Fig. 4 for the UVES sample. tra, as a function of the metallicity. As a comparison, we also
Abundances of Na are anticorrelated with O abundances also plot the average value relative to the Sgr nucleus ([Fe/H]=-
inNGC5634(upperleftpanel),confirmingthefindingsbyS15 0.74 dex, Carretta et al. 2010b) and to the five GCs confirmed
with a sample three time larger. This cluster shares the typical members of the Sgr dwarf galaxy: M 54 ([Fe/H]=-1.51 dex,
Na-Oanticorrelation,thewidespreadchemicalsignatureofmul- Carretta et al. 2010b), Terzan 8 ([Fe/H]=-2.27 dex, Carretta et
tiplestellarpopulationsinMWGCs.Withintheimportantlimi- al.2014a),Arp2([Fe/H]=-1.80dex,Mottinietal.2008),Pal12
tationsofsmallnumberstatistics,twostarshavedistinctlylarger ([Fe/H]=-0.82 dex, Cohen 2004), and Terzan 7 ([Fe/H]=-0.61
NacontentandlowerOabundancethantheotherfourstars. dex, Sbordone et al. 2007). In the last three cases, the values
Accordingtothehomogeneouscriteriausedbyourgroupto were corrected to the scale of solar abundancespresently used
definestellargenerationsinGCs(seeCarrettaetal.2009a),the (Grattonetal.2003).
twostarswiththehighestNa abundancewouldbesecondgen- AbundancesofstarsinNGC5634seemtobeingoodagree-
eration stars of the intermediate I component, while the other ment with the metal-poor GCs associated to Sgr. Of course,
four giants belong to the first generationin NGC 5634 and re- by itself this cannot be a clearcut proof of the membership of
flecttheprimordialPfraction,withthetypicalpurenucleosyn- NGC 5634 to Sgr rather than to the Milky Way, since at this
thesis by type II SNe (the average abundances for these stars lowmetalabundancetheoverallchemicalpatternoftheα−and
are [Na/Fe]=0.017dex, σ = 0.151dex and [O/Fe]=0.361dex, iron-peak elements simply reflects the typical floor of elemen-
σ = 0.102 dex). The star with only an Na abundance would talabundancesestablishedbytheinterplayofcore-collapseand
be also classified as a first generation star, due to its low ratio typeIasupernovae(seee.g.Wheeleretal.1989).Thispatternis
[Na/Fe]=+0.052dex. supportedalsobytheabundancesderivedfromGIRAFFEspec-
tra(Table11).InSect.5wewilldiscussfurtherelementstosup-
WenotethatthetwostarsanalyzedbyS15show(anticorre-
porttheconnectionwithSgrdSph.
lated)spreadsinOandNaexceedingtheestimatedobservational
uncertainties,anevidencethatpromptedtheauthorstoclaiman
Na-O anticorrelation in NGC 5634. Yet both stars would fall
4.3.Neutron-captureelements
amongourfirstgenerationstars,eitheriftheoriginalabundances
orthosecorrectedfordifferentsolarabundancesareadopted.In Abundancesforsixneutron-captureelementsintheUVESsam-
our data, the observed spread in O for the stars of the P com- plearelistedinTable9andtheirclustermeansareinTable11.
ponent is comparable with the expected uncertainty due to the Ba ii and Nd ii lines could be treated as single unblended ab-
analysis,whereasthespreadinNaformallycorrespondsto1.7σ. sorbers, so they were treated with EW analyses. Transitionsof
We cannot totally exclude a certain amount of intrinsic spread the other four neutron-captureelementshad complicationsdue
among proton-capture elements in the first generation stars in toblending,hyperfine,orisotopicsubstructureandsoweresub-
6
E.Carrettaetal.:ChemistryofNGC5634
Fig.4.Relationsamongproton-captureelementsinstarsofNGC5634observedwithUVES(filledbluecircles).Emptysquaresin
thelower-rightpanelarestarsin24GCsfromCarrettaetal.(2009a,b),Carrettaetal.(2010b,c),Carrettaetal.(2011),Carrettaet
al.(2013),Carrettaetal.(2014b),Carrettaetal.(2015),andasterisksarestarsinNGC2808fromCarretta(2015).Ineachpanelthe
errorbarsrepresentinternalerrors.
Fig.5.Left-handpanel:[Na/Fe]ratiosasafunctionofthetemperatureinstarsobservedwithUVES(bluesquares)andGIRAFFE
(redcircles).Right-handpanel:histogramofthe[Na/Fe]ratios,wherethelineindicatesthedivisionbetweenPandIstars,based
onourusualseparationat[Na/Fe] +0.3.
min
jectedtosyntheticspectrumanalyses.Theelementalmeansap- is overabundantby nearly a factor of three. Here we comment
peartobestraightforward:thelightn-captureelementYandZr onafewaspectsofourderivedn-captureabundances.
areslightlyunder-andover-abundant,respectively,withrespect
to Fe, the traditional s-process rare-earth elements Ba and La OurderivedBaandEuabundancesareinreasonableaccord
havesolar abundances,the r-processdominantEu is overabun- with those reportedby S15. Barium is notthe optimalelement
dantbyaboutafactoroffour,andther-/s-transitionelementNd toassesstheabundancesofthelow-Zendoftherareearths,be-
cause all Ba ii lines are strong and thus less sensitive to abun-
dance than are weaker lines. Fortunately, abundances derived
7
E.Carrettaetal.:ChemistryofNGC5634
Fig.7.SyntheticspectrafortheYiiline5200.4Å.Filledcircles
indicatetheobservedspectrumofstar5634-2.
Fig.6.Abundanceratiosof α− andiron-peakelementsderived
fromUVESspectrainNGC5634asafunctionofthemetallic-
ity(filledbluecircles).Alsoplottedaretheaveragevaluesfrom
Table 11 of Carretta et al. (2014a) relative to the Sgr nucleus
(blackasterisk,Carrettaetal.2010b),toM54(blackemptycir-
cle,Carrettaetal.2010b),Pal12(redfilledsquare,Cohen2004),
Terzan 7 (orange filled star, Sbordone et al. 2007), Terzan 8
(filledlight-bluetriangle,Carrettaetal.2014a),andArp2(green
emptysquare,Mottinietal.2008).Internalerrorbarsrefertoour
UVESsample.
fromweakLaiitransitionsarenotinseveredisagreementwith
theBavalues.
WedeterminedYabundancesforourUVESsamplefromthe
Yiilineat5200.4Å,forhomogeneitywithwhatwedidforTer8
and other GCs in our sample (e.g., Carretta et al. 2014a). The
clustermeanabundancefromthistransitionis[Y/Fe]=−0.083
(σ = 0.119,7stars;seeTable9).Thestar-to-starscatterisrela-
tivelylarge,butalmostallstarshave[Y/Fe].0.Sbordoneetal.
(2015)reportedmuchlowerYabundanceinNGC5634:[Y/Fe]
Fig.8.Abundanceratiosofneutron-captureelementsYandBa
=−0.40fromStar2and−0.33fromStar3.
asafunctionofmetallicity.GreyfilledcirclesareGalacticfield
Star 2 in our study yielded [Y/Fe] = −0.077 from the syn-
starsfromthecompilationbyVennetal.(2004).Theothersym-
thesis of the 5200 Å line. To investigate this +0.32 dex offset
bols are as in Fig. 6: Pal 12 (red filled squares, Cohen 2004),
in [Y/Fe] with respect to S15, we synthesized other Y ii lines
Terzan 7 (orange filled stars, Sbordone et al. 2007), Terzan 8
in Star 2 with the line analysis code MOOG (Sneden 1973).
(filled light-blue triangles, Carretta et al. 2014a), and Arp 2
Using the transition probabilities of Hannaford et al. (1982)
(greenemptysquares,Mottinietal.2008).
and Bie´mont et al. (2011), we used 10 Y ii lines to derive
<[logǫ(Y)]>=+0.25±0.03(σ=0.08dex).Adoptinglogǫ(Y)
⊙
= 2.21(Asplundetal. 2009)leadsto a meanvalueof [Y/H] = tedthemwithourcodeandlinelist.Weobtainedveryconsistent
−1.96or[Y/Fe]=−0.09(withtheclustermean[Fe/H]=−1.87), abundances from these four lines (logǫ = +0.21 ± 0.04 dex,
ingoodagreementwiththevaluederivedfromthe5200Åline σ = 0.09dexandlogǫ = +0.28±0.03dex,σ= 0.06dex,with
alone. andwithoutcontinuumscattering).Thisexercisewouldgivean
ForStar2wedisplayoursynthetic/observedspectrummatch offset0.43-0.50dexwithrespecttothevalueofS15.Atpresent,
in Fig. 7. From this line ourbest estimate is log ǫ(Y) = +0.30. wecannotprovideanexplanationforthedifference.
Weconcludethatthespectrumsynthesisoftheline5200Åalone Derived Ba and Y abundances in NGC 5634 are in good
allows us to derive a fairly good estimate of the Y content. In agreementwiththetrenddefinedbyGalacticfieldstarsofsimi-
general,wedonotfindsubstantialYdeficienciesforanyofour lar(low)metalabundances,asshowninFig.8.Again,themetal-
UVESsampleinNGC5634. rich GCs associated to the Sgr dwarf stand out with respect to
Assuggestedbythereferee,weusedthelineprofileforeach theGalacticfieldstars,whileNGC5634cannotbedistinguished
synthesizedline of Y ii publishedby S15 forstar 2 and we fit- fromitschemicalcompositionalone,asalsooccursforTerzan8,
8
E.Carrettaetal.:ChemistryofNGC5634
Fig.9.PositionandvelocityofNGC5634(largefilledreddot) Fig.10.SystemicrotationofNGC5634:thebest-fitsolutionis
comparedtoaSgrmodel(seetextfordetails). compatiblewithnegligiblerotation.
theclassicalmetal-poorglobularclusterofthefamilyofGCsin ofsystemicrotation.Forthispurpose,inFig.10theRVsofthe
Sgr. 42 bonafide membersare plottedagainsttheir position angles.
The best-fit sinusoidal curve indicates a rotation amplitude of
HerewearecomparingourNGC5634abundanceratioswith
A sini = 1.08±1.34 km s−1, compatiblewith no significant
thoseofotherSgrclusters.Inthenextsectionwewillconsider rot
rotation.
thekinematicsofthisclusterinordertomorefirmlyestablishits
WethenusedourRVdatasettoestimatethedynamicalmass
membershipintheSgrfamily.
ofthesystem.ForthispurposewefittedthedistributionofRVs
with a set of single and multimass King-Michie models (King
5. ConnectionwiththeSagittariusdSphand 1966; Gunn & Griffin 1979). In particular, for each model we
internalkinematics tunedthemodelmasstomaximizethelog-likelihood
AsintroducedinSect.1,NGC5634issuggestedtohaveformed N (v −hvi)2
iinngththeeSsgurbdseSqpuheanntdtidhaalvdeisthruepntiaocncroefteitdsbhyostthgeaMlaxilyky(BWelalyazdzuinr-i L=−Xi=1 (σi2i +ǫi2) +ln(σ2i +ǫi2)
et al. 2002;Law & Majewski2010a).In this scenario,this GC whereN(=42)isthe numberofavailableRVs, v andǫ arethe
i i
isexpectedtofollowanorbitwhichissimilartothatofitspar- radialvelocityofthei-thstaranditsassociateduncertaintyand
ent galaxy and to be embedded in its stream. We checked this σ istheline-of-sightvelocitydispersionpredictedbythemodel
i
hypothesis by comparing the position and systemic motion of atthedistancefromtheclustercentreofthei-thstar.Thebest-fit
NGC5634withthepredictionoftheSagittariusmodelbyLaw singlemassmodelprovidesatotalmassof1.64×105M .This
⊙
&Majewski(2010b).Amongthethreemodelspresentedinthat quantityhastobeconsideredhoweveralowerlimittotheactual
paperweusedtheoneassumingaprolate(q=1.25)Galactichalo totalmassbecauseoftheeffectoftwo-bodyrelaxationaffecting
whichprovidesabetterfittotheobservationalconstraintsonthe this estimate. Indeed, RGB stars (i.e. those for whom RVs are
locationandkinematicsoftheSagittariusstreamstars.Thedis- available)areonaveragemoremassivethantypicalclusterstars
tributionintheheliocentricdistance-radialvelocityplaneofpar- and are thereforeexpectedto becomekinematicallycolder and
ticles within 5degfrom the present-dayposition of NGC 5634 more concentrated than the latter after a timescale comparable
isshowninFig.9.ItisapparentthatinthisdiagramNGC5634 to the half-mass relaxation time. To account for this effect we
lieswellwithinaclumpofSagittariusparticles.Theseparticles performedthesameanalysisadoptingasetofmultimassmodels
belongtothetrailingarmofitsstreamwhichhavebeenlostby withvariouschoicesofthepresent-daymassfunction.Inpartic-
the satellite between 3 and 7 Gyr ago. This is consistent with ular,weadoptedapower-lawmassfunctionwithindicesranging
whatfoundby B02 and Law & Majewski(2010a)even if they from -2.35 (i.e. Salpeter 1955) to 0. We adopted the prescrip-
usedaslightlydifferentsystemicradialvelocityforthiscluster tionsfordarkremnantsandbinariesofSollimaetal.(2012)as-
(-44.4kms−1). sumingabinaryfractionof10%andaflatdistributionofmass-
ratios. The derived masses turn out to be 1.72, 1.82, 2.04 and
1.93×105M formassfunctionslopesofα=0,-1,-2and-2.35,
5.1.Internalkinematics ⊙
respectively,withatypicaluncertaintyof∼4.5×104M .Byas-
⊙
Thepresentdata representsthemostextensiveset ofradialve- sumingtheabsolutemagnitudeM =−7.69listedforthisclus-
V
locities for NGC 5634 and can be useful to study the internal terintheHarriscatalog(1996,2010edition)thecorresponding
kinematics of this cluster. As a first step, we test the presence M/Lratioare1.68,1.79,2.01and1.90.SignificantlylargerM/L
9
E.Carrettaetal.:ChemistryofNGC5634
ratios (by a factor 1.24) are instead obtained if the integrated Table11.MeanabundancesinNGC5634.
magnitudebyMcLaughlin&vanderMarel(2005)isadopted.
Element stars mean rms Note stars mean rms
UVES GIRAFFE
6. Summaryandconclusions [O/Fe]i 6 +0.292 0.134 EW
[Na/Fe]i 7 +0.168 0.271 EW 35 +0.252 0.287
As part of our homogeneous study of GCs, we obtained [Mg/Fe]i 7 +0.519 0.035 EW 35 +0.498 0.064
FLAMESspectraof42memberstarsintheclusterNGC5634, [Al/Fe]i 5 +0.498 0.293 EW
associated to the Sgr dSph, in particular to one of the arms if [Si/Fe]i 7 +0.295 0.034 EW 31 +0.405 0.043
the Sgr stream. We measured elemental abundances for many [Ca/Fe]i 7 +0.299 0.026 EW 35 +0.365 0.067
elementsintheUVESspectraofsevenRGBstarsandofseveral [Sc/Fe]ii 7 −0.088 0.034 EW 34 −0.011 0.053
elementsintheGIRAFFEspectraof35(mainly)RGBandAGB [Ti/Fe]i 7 +0.146 0.016 EW
[Ti/Fe]ii 7 +0.168 0.023 EW
stars(seeFig.1).
[V/Fe]i 7 −0.129 0.026 EW 9 −0.113 0.051
We found clear evidence of multiple stellar populations in
[Cr/Fe]i 7 −0.211 0.029 EW
thiscluster,indicatedbytheclassical(anti)correlationsbetween [Cr/Fe]ii 7 +0.002 0.051 EW
lightelements(O,Na;Mg,Al).Althoughwecouldnotcharac- [Mn/Fe]i 7 −0.499 0.017 EW
terizecompletelytheseanticorrelationsbecausewelackoxygen [Fe/H]i 7 −1.867 0.050 EW 35 −1.869 0.093
abundanceforallGIRAFFEtargets,wecandividetheobserved [Fe/H]ii 7 −1.903 0.025 EW
stars into primordialP and IntermediateI fractions(Carretta et [Co/Fe]i 7 −0.007 0.023 EW
al. 2009a,b) simply using their Na abundance. Apparently, for [Ni/Fe]i 7 −0.106 0.023 EW 31 −0.116 0.062
thisSgrclusterthefractionoffirstandsecondgenerationstarsis [Cu/Fe]i 7 −0.586 0.107 synt
notdramaticallydifferentfromtypicalvaluesfoundinMWGCs [Zn/Fe]i 7 +0.013 0.048 EW
[Y/Fe]ii 7 −0.083 0.119 synt
fromspectroscopy(e.g.Carrettaetal.2009a,2010a,Johnson&
[Zr/Fe]ii 7 +0.169 0.147 synt
Pilachowski2012).
[Ba/Fe]ii 7 −0.063 0.075 EW
We support the connection between NGC 5634 and the [La/Fe]ii 7 +0.107 0.064 synt
Sgr dSph (B02, Law & Majewski 2010a) both on the basis of [Nd/Fe]ii 7 +0.450 0.059 EW
the cluster RV and position and on the chemical abundances. [Eu/Fe]ii 7 +0.585 0.126 synt
The secondevidenceis nothoweverclearcut, since NGC 5634
resembles both MW and low-metallicity Sgr GCs in α and
neutron-capture elements. We do not confirm the very low Y
iiabundancefoundbyS15. Bragaglia,A.,Carretta,E.,Gratton,R.G.etal.2001,AJ,121,327
Bragaglia,A.,Gratton,R.G.,Carretta,E.,etal.2012,A&A,548,A122
This study adds yet another confirmation of the ubiquitous
Bragaglia,A.,Sneden,C.,Carretta,E.,etal.2014,ApJ,796,68
presence of light-element anticorrelations, i.e., multiple popu- Bragaglia,A.,Carretta,E.,Sollima,A.,etal.2015,A&A,583,A69
lations, among old and massive GCs, independentof their for- Carretta,E.2015,ApJ,810,148
mationplace.Metal-poorGCsapparentlyformedfollowingthe Carretta,E.,Bragaglia,A.,Gratton,R.G.etal.2009a,A&A,505,117
Carretta,E.,Bragaglia,A.,Gratton,R.G.,Lucatello,S.2009b,A&A,505,139
samechainofeventsregardlesstheirbirthenvironmentwasthe
Carretta, E., Bragaglia, A., Gratton, R.G., D’Orazi, V., Lucatello, S. 2009c,
central Galaxy (Milky Way) or its most prominent disrupting
A&A,508,695
dwarfsatellite(Sgr). Carretta, E., Bragaglia, A., Gratton, R.G., Recio-Blanco, A., Lucatello, S.,
D’Orazi,V.,Cassisi,S.2010a,A&A,516,55
Acknowledgements. We thank P. Montegriffo for his software CataPack, Carretta,E.,Bragaglia,A.,Gratton,R.G.etal.2010b,A&A,520,95
Michele Bellazzini for useful comments, and the referee Luca Sbordone for Carretta,E.,Gratton,R.G.,Lucatello,S.etal.2010c,ApJ,722,L1
histhoughfulreview.SupportforthisworkhascomeinpartfromtheUSNSF Carretta,E.,Lucatello,S.,Gratton,R.G.,Bragaglia,A.,D’Orazi,V.2011,A&A,
grantAST-1211585.ThisresearchhasmadeuseofVizierandSIMBAD,oper- 533,69
atedatCDS,Strasbourg,France,andNASA’sAstrophysicalDataSystem.The Carretta,E.,Bragaglia,A.,Gratton,R.G.etal.2013,A&A,557,A138
GuideStarCatalogue-IIisajointprojectoftheSpaceTelescopeScienceInstitute Carretta,E.,Bragaglia,A.,Gratton,R.G.,D’Orazi,V.,Lucatello,S.,Sollima,A.
andtheOsservatorioAstronomicodiTorino.SpaceTelescopeScienceInstitute 2014a,A&A,561,A87
is operated by the Association of Universities for Research in Astronomy, Carretta,E.,Bragaglia,A.,Gratton,R.G.etal.2014b,A&A,564,A60
fortheNationalAeronautics andSpaceAdministration undercontract NAS5- Carretta,E.,Bragaglia,A.,Gratton,R.G.,D’Orazi,V.,Lucatello,S.,Sollima,A.,
26555. The participation of the Osservatorio Astronomico di Torino is sup- Momany,Y.,Catanzaro,G.,Leone,F.2015,A&A,578,A116
ported by the Italian Council for Research in Astronomy. Additional support Cohen,J.G.2004,AJ,127,1545
is provided by European Southern Observatory, Space Telescope European Decressin,T.,Meynet,G.,CharbonnelC.Prantzos,N.,Ekstrom,S.2007,A&A,
Coordinating Facility, the International GEMINI project and the European 464,1029
SpaceAgencyAstrophysicsDivision.Thispublicationmakesuseofdataprod- Dekker, H., D’Odorico, S., Kaufer, A., Delabre, B., Kotzlowski, H. 2000,
ucts from the Two Micron All Sky Survey, which is a joint project of Proc.SPIE,4008,534
the University of Massachusetts and the Infrared Processing and Analysis deMink,S.E.,Pols,O.R.,Langer,N.,Izzard,R.G.2009,A&A,507,L1
Center/California InstituteofTechnology,fundedbytheNationalAeronautics Denisenkov,P.A.,Denisenkova,S.N.1989,A.Tsir.,1538,11
andSpaceAdministrationandtheNationalScienceFoundation. Denissenkov,P.A.,&Hartwick,F.D.A.2014,MNRAS,437,L21
Dias, B., Barbuy, B., Saviane, I., Held, E.V., Da Costa, G.S., Ortolani, S.,
Gullieuszik,M.,Va´squez,S.2016,A&A,590,A9
Gratton,R.G.1988,RomeObs.PreprintSer.,29
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