EDP Sciences
Free Access
Issue
A&A
Volume 602, June 2017
Article Number L14
Number of page(s) 6
Section Letters
DOI https://doi.org/10.1051/0004-6361/201630220
Published online 27 June 2017

© ESO, 2017

1. Introduction

The study of the Galactic bulge is rapidly unveiling its complexity. Because of its physical properties (metallicity distribution, age, spatial location, kinematical features, etc.), the bulge is at the crossroads of the other main Galactic components such the halo, thick disc and thin disc. As a consequence, the formation scenarios currently invoked are directly linked to the general evolution of the Milky Way and to one crucial open question: What is the importance of fast versus secular evolution? Three main scenarios are proposed: i) in situ formation via dissipative collapse of a protogalactic gas cloud (Eggen et al. 1962); ii) accretion of substructures in a ΛCDM context (e.g. Scannapieco & Tissera 2003); and iii) secular formation from disc material through bar formation, vertical instability, buckling, and fattening, producing a boxy/peanut bulge (e.g. Martinez-Valpuesta & Gerhard 2013; Di Matteo et al. 2014).

Our knowledge of the bulge has improved relevantly in the recent years, however, many key open questions remain. By way of example, the number of bulge components, estimated from the metallicity distribution function, kinematical and structural data, is still under debate. Although up to five components have been suggested (e.g. Ness et al. 2013), recent studies (e.g. Rojas-Arriagada et al. 2014; Schultheis et al. 2017; Zoccali et al. 2017) show that only two components seem to be necessary. In this context, precise individual chemical abundances are crucial to disentangle the different evolutionary pathways responsible for the bulge formation. The first studies in this sense regarded mainly (but not exclusively) α-element abundances (e.g. McWilliam & Rich 1994; Bensby et al. 2013; Gonzalez et al. 2015) which, combined with iron abundances, can unveil important information regarding the initial mass function and the star formation history of a stellar system. Up to now, different analyses have revealed a single sequence in the [α/ Fe] versus [Fe/H] plane, flattening at metallicities lower than − 0.37 ± 0.09 dex (e.g. Rojas-Arriagada et al. 2017), the metallicity at which the maximum of supernovae type Ia rate occurred. However, recent observations extending the analysis to other elements have already detected departures from what seemed to be a simple chemical evolutionary path, such as the existence of nitrogen overabundant stars (Schiavon et al. 2017b).

The goal of this paper is to take advantage of the Gaia-ESO Survey (GES; Gilmore et al. 2012; Randich et al. 2013) bulge data to search for abundance anomalies that could reveal the bulge composite nature. The data are described in Sect. 2, our results are presented in Sect. 3, and their interpretation is developed in the final Sect. 4.

2. Gaia-ESO Survey stellar parameters, distances and orbits

We have used the atmospheric parameters and individual chemical abundances (Fe, Mg, Si and Al) of bulge stars observed by GES, using the GIRAFFE spectrograph, and included in its fourth internal data release. The data are described in detail in Rojas-Arriagada et al. (2017). The initial total sample comprises 2320 red clump stars in 11 bulge fields, sampling the area − 10° ≤ l ≤ +10° and 10° ≤ b ≤ −4°.

The HR21 set-up was employed for all the bulge stars. In addition, 172 stars in Baade’s Window were observed with the HR10 set-up. Those stars are in common with the analysis of Hill et al. (2011).

As the search for abundance anomalies has to rely on very precise results, we applied the following selection criteria to the initial sample: 2.0 <log  g< 3.0 dex, σTeff < 250 K, σlog g < 0.6 dex, σ[Fe/H] < 0.1 dex, σ[Mg/H] < 0.1 dex, σ[Si/H] < 0.1 dex, and σ[Al/H] < 0.1 dex. This reduces the sample to 776 stars with very high quality parameters; 42 of these stars are observed with two set-ups. The mean signal-to-noise of the working sample is 280 ± 70 (deviation estimated from the MAD). We make use of the Rojas-Arriagada et al. (2017) spectroscopic distances, estimated for the same data set, to ensure that our selection is confined to the bulge region (RGC < 3.5 kpc). The median error of the distances is 1.2 kpc (around 16%). Finally, OGLE proper motions available for the subsample of stars in Baade’s Window (Sumi et al. 2004) allowed the estimation of the stellar orbital parameters. To this purpose, we adopted Model 4 presented in Fernández-Trincado et al. (2016) and composed of nonaxisymmetric potentials.

3. Search for α-element abundance anomalies

The main challenge of testing the existence of stars with non-standard low-α element abundances is demonstrating that they do not belong to the high error queue of a normal abundance distribution. To this purpose, we first carried out a fiducial median profile and a 1σ dispersion band, over 11 iron abundance bins for the [Mg/Fe], [Si/Fe], and [α/ Fe] abundances. Secondly, we computed, for each star, the difference in [Mg/Fe], [Si/Fe], and [α/ Fe] with respect to the median values of the corresponding iron bin (in the sense median minus sample), called Δ[Mg/Fe], Δ[Si/Fe], and Δ[α/ Fe], respectively.

If there are low-α element stars in the bulge, the distribution of the Δ[α/ Fe] around the standard value should be 1) skewed and 2) not corresponding to a single Gaussian. We first applied a D’Agostino skewness test to the Δ[α/ Fe] abundance distribution. The skewness value of the Δ[α/ Fe] is 47.5 (p-value of 4.88e-11), confirming the asymmetry. We tested the robustness of this result to the existence of strong outliers by reapplying the D’Agostino test considering only the stars within 2 sigma from the median [α/ Fe] abundance value. Both the z-score of the test (6.9) and its p-value (0.03) seem to confirm that even the core of the distribution deviates from normality and it is skewed towards the low-alpha side. In addition, we applied a Gaussian mixture method (GMM; Rojas-Arriagada et al. 2016) to estimate the number of components of the distribution. The GMM algorithm constructs a generative model that consists in the specific Gaussian mixture that better predicts the data structure. We adopted the Akaike information criterion (AIC) as a cost function to assess the relative fitting quality between different proposed mixtures. The results of this analysis are shown in Fig. 1. Clearly, the single component solution can be excluded to explain the data distribution, highlighting the existence of an asymmetry.

Furthermore, the dispersion of the measured [α/ Fe] abundances in metal-rich globular cluster giants can help us to realistically evaluate the errors on the bulge abundances. We considered two observed clusters within the same constraints as in our bulge analysis sample (cf. Sect. 2), i.e. NGC 104 ([Fe/H] = − 0.66 ± 0.05 dex, 30 stars) and NGC 5927 ([Fe/H] = − 0.33 ± 0.06 dex, 56 stars). The dispersion of the two clusters in the [α/ Fe] abundances (0.035 dex and 0.045 dex, respectively), [Mg/Fe](0.04 and 0.05 dex, respectively) and [Si/Fe] (0.05 and 0.06 dex, respectively) is clearly lower than those of the bulge distribution (0.06 dex for [α/ Fe], 0.07 dex for [Mg/Fe], and 0.08 dex for [Si/Fe]), reinforcing the hypothesis of a complex [α/ Fe] versus [Fe/H] sequence in the bulge.

thumbnail Fig. 1

Gaussian mixture method analysis of the [α/ Fe] abundance distribution with respect to the median values along the sequence. The inner panel shows the Akaike information criterion for different numbers of components. The best fit (green curve) corresponds to the two-component mixture. The red curve shows the poorer quality fit of the single Gaussian component, whose probability of explaining the distribution is 21 times lower than the double Gaussian component.

Open with DEXTER

3.1. Selection of stars separately from different α-elements.

First of all, we have analysed the abundances of Mg and Si and their trends with the Fe abundance. Figure 2 shows the [Mg/Fe] versus [Fe/H] distribution (upper panel), [Si/Fe] versus [Fe/H] distribution (middle panel), and [α/ Fe] versus [Fe/H] distribution defined as ([Mg/Fe]+[Si/Fe])/2 (lower panel). Then, we identified the stars showing deviations larger than 1.2σ in Δ[Mg/Fe] and in Δ[Si/Fe] (colour coded in the upper and middle panels of Fig. 2). To ensure that the [α/ Fe] anomaly is present in more than one element (avoiding possible Mg depleted globular cluster escapées; e.g. Carretta et al. 2009), we restricted the selection to the intersection of the low-Mg and low-Si subsamples. Finally, an additional condition was imposed: only the objects showing deviations greater than 2σ in Δ[α/ Fe] were selected. The final subsample of stars are colour coded in the bottom panel of Fig. 2. The subsample includes 18 objects with [α/ Fe] underabundances ranging from 2.1 to 5.3σ. Of these, 90% are within 2.5 kpc from the Galactic centre and two-thirds are within 1.8 kpc.

thumbnail Fig. 2

Bulge distribution of [Mg/Fe], [Si/Fe], and [α/ Fe] with respect to [Fe/H] (upper, middle, and lower panels, respectively). The colour code shows the difference with respect to the median value (Δ[Mg/Fe], Δ[Si/Fe], and Δ[α/ Fe]) expressed in units of standard deviation. Both Δ and σ are evaluated as a function of [Fe/H].

Open with DEXTER

A number of checks were performed to further test the reliability of the abundance anomalies. First of all, it was verified that the measurement dispersions in the parameters and abundances provided by the different GES analysis nodes (and taken as a proxy of the error) are similar for the anomalous stars and for the reference sample of 776 objects. In addition, the spectra of representative stars showing anomalies were compared to those of stellar twins (with maximum differences of 50 K for Teff, 0.02 dex for log  g, and 0.03 dex for [Fe/H]). This is possible thanks to the fact that the bulge GES targets are restricted to the red clump and the chances of finding stellar twins in the sample are high. These comparisons allowed us to confirm that the Mg and Si abundances of the identified anomalous stars are in fact underabundant with respect to their twins of standard composition. As an example, the spectrum of the anomalous star 17553025-4106299 (with [Mg/Fe]=− 0.16 ± 0.08 dex, [Si/Fe]=0.21 ± 0.08 dex) differs clearly in the α-element lines from that of its twin 18262565-3151577, having [Mg/Fe]=0.31 ± 0.09 dex and [Si/Fe]=0.37 ± 0.06 dex. An additional illustration of a spectral twins comparison is given in Fig. B.1. Third, the differences between the spectroscopic and photometric Teff values (derived following González Hernández & Bonifacio 2009) of the stars presenting [α/ Fe] abundance anomalies were checked and compared to those of the stars with standard compositions. No particular problems that could indicate specific errors in the spectroscopic Teff of the anomalous stars were found. Moreover, the sensitivity to possible log  g errors of the Mg and Si lines was verified using synthetic spectra. Although the estimated Si abundances are slightly sensitive to log  g uncertainties, this is not the case for the Mg abundances. In the same line, the variation of the Mg and Si abundances with the typical [M/H] uncertainties are at least six times smaller than the detected anomalies. Finally, we checked that the stars presenting abundance anomalies do not belong to a unique GES bulge field and GIRAFFE exposure, which could reveal possible problems with the data reduction, such as sky sustraction residuals. In conclusion, all the above-mentioned verification tests confirm the real α-poor nature of the identified bulge stars.

3.2. Baade’s Window data

thumbnail Fig. 3

Distribution of [α/ Fe] vs. [Fe/H] for the 48 stars of Baade’s Window with high quality estimations of Mg, Si, and Ca abundances (red points). The two stars highlighted with blue circles are part of the group of stars identified to have Mg and Si underabundances in Fig. 2. Grey points show the [α/ Fe] vs. [Fe/H] distribution of GES disc stars.

Open with DEXTER

Particular attention was paid to the stars in Baade’s Window (BW), for which both GES HR21 and HR10 spectra are available. Those stars with more reliable parameters and abundance estimations have measurements of an additional α element (calcium), and literature [Mg/Fe] abundance determinations from Hill et al. (2011) for comparison. Figure 3 shows the distribution of [α/ Fe] (defined as [Mg + Si + Ca/Fe]) versus [Fe/H] for the 48 stars of BW with high quality estimations of Mg, Si, and Ca abundances (red points). The two red circles highlighted with blue edges correspond to the stars 18034317-3006349 ([Fe/H]=−0.38 ± 0.03 dex) and 18032412-3003001 ([Fe/H]=−0.66 ± 0.02 dex), which are already identified to have Mg and Si underabundances in Fig. 1. These two stars are confirmed to be [α/ Fe] underabundant, even when Ca is considered. In addition, the star 18034317-3006349 seems to lay on the locus of the corresponding thin disc sequence, which is well below the standard [α/ Fe] values of the bulge at its metallicity interval.

Literature values from Hill et al. (2011) are available for these two stars. First, the GES iron abundances are compatible within the errors with the Hill et al. (2011) abundances. Second, the [Mg/Fe] ratio of Hill et al. (2011) for the star 18032412-3003001 (0.09 ± 0.18 dex) is also 1σ below the corresponding median [Mg/Fe] value for that metallicity interval. These authors do not report Mg abundance estimations for the other star.

Lastly, the orbits of the two stars seem confined to the bulge region. The derived radial apocentric distances for 18034317-3006349 and 18032412-3003001 are 2.75 ± 1.1 kpc and 1.87 ± 1.3 kpc, respectively. The corresponding maximum vertical amplitudes are 1.16 ± 0.2 kpc and 1.66 ± 0.4 kpc.

thumbnail Fig. 4

[Al/Fe] abundances with respect to the [Mg/Fe] ratio for bulge stars (black points). Low-α stars and NGC 6522 stars are highlighted with blue and red circles, respectively. Disc stars and globular cluster values from Carretta et al. (2009) are shown as grey and green points.

Open with DEXTER

3.3. Aluminum abundances

Two aluminum lines in the HR21 spectra allowed the derivation of Al abundances for the GES bulge data. Figure 4 shows the [Al/Fe] abundance with respect to the [Mg/Fe] abundance for the studied bulge stars (black points). Low-α stars of Sect. 3.1 are highlighted with blue circles. As in Fig. 3, the abundances of disc stars are also included for comparison as light grey points. Finally, green points show the Carretta et al. (2009) values for GC stars (cf. their Fig. 5). First, the results presented in Fig. 4 show that the identified low-α bulge stars do not present GC abundance patterns. Their Al abundance seems to be in agreement with the Mg abundance, laying on the same sequence as bulge stars of standard composition. Moreover, the disc and bulge sequences are overlaid in the same locus of the figure, as expected.

Incidentally, three members of the globular cluster NGC 6522 ([Fe/H] = − 1.14 ± 0.10 dex) were observed in the GES BW fields (indicated with red circles in Fig. 4). One of these stars, 18033857-3002434, presents a crsusent

2C a30ge fields, sak7#F4">4 and bulge sequences are overlaid in the same locus of the figure, as expen45; stars of Sect. 3.1 are highlighted with blue circles. As in Fig. =W,emonstrafor the b#F1">1. These7panel). Then, we identified _html/2017/06/hlighted with blue circles. As class="simpl7ity estimll_Ca1">1. These7panel). Then, we identified h quality est/hlighted with blue circles. As 40lass="simpl7ity estihe [Al/Fe] abundance with respect to the distrtimes lower4317 thure staris[Si/Fe]outliers by reaspersions in the pai> ulge stars of to confioch cuuixture mesaimple-matholution of the Milpan cl#177; 0.1ass="simnce, laytwin 182ar populations is reportass="seird, the differences between the spectroscopic and photometric α-elthe2; 1.14 &um dishown 45;-element abundance anomaliTrincad4-16/aaappls physical propith respect to thpheric parametess and e data are stars with respect to the standard bulge sequence in the [Fe/H][Mg + Si + Ca/Fe]) versus [< (esenting) bimodaa30simple-math">[Mg + Si + Ca/Fe]) versus [Mg/Fe]+[e data20-16.hs do rrevi01; e MAml#F1">1< by916;McWiecent studies (e.g. [bonnd, otion of the Δ[d,earticles/aa/R21">Rojas-Arriaga8ernández & Bonifacio 2009) of the stars presenting ααrved oidaa,n concl-16/aa3netim20-16.hth">[ffih DEt en1;

Lain 2nfioccequgh resolutith respimple-mitiothe -math"reinfosimpleted. The vision5 de/span> distribution defined as ([Mg/Fe]+[.09[ versus

Literature values from McWilliam &04) allowed the estimation of the stellar orbital parameters. To this pp04<0220-16/aa17/06/aa30220-16heorbowedancel-to-fewom 2.1 toa/f> <rtiesve dwarf galaxies accretion seems unlikely, as larisle, thnaimple-me="InR9Sr017/06/aa3atterns that are compatible with those of the thin disc. Their link with massive dwarf galaxies accretion seems unlikely, as larger deviations in McWilliam &am; Rich 1994; Lalies were i abunaass=Sumi et al. 21013; [s06/aa30220-16/aa30220-16.html#R13 values from α/ FsGaia-ESOny key opennn. The derihs="sim &le Mg anda30ster NGC individua identified pan>e2; 1.14 ± 0., seq2412-30030ojas-Arriagad 2009), we restricted the selection to the intersection of the low-Mg ad 20a-ESO Surveytion aarticl/aa30220> ste derid 0.045 ,sis of higl_htmle imspan> values h">− 1.14 sf to conf220-16/aald reveal possible p the as s massiw-).

The goal of this paper is to take advantage of the Gaia-ESO Surveytion bapplied the folES bulge fiewgostilresps wasim whuar twins inselectiss="siing that tm 2.1 toa3netimsdebate. Althohodsec"> 48 stmow tha data 0220-16.html#ua30220-1ster -ution w/aa30220-#F1">1ull_sis are on testmple-nd. >Two lthohodsec">Tho="simple-morignces sa stellar she da hr et al. aff/aa3 by reaure -elertiesbutilass=aphtmlnceran> stars oelectiss=unsimple-mtm 2.1 tos do ws t-drThird. [Fe/H][[Fe/H][Fes in-element abundance anomalack2009 show thaistria3netimducing a bappls srvedd dur3 by reahpheric parametee MAmhopsf to outl/sub> o the)nt n1; MAaPtmgrammierr. precisegof al ofyticestions resup seemnomalouMinpleg Technsec">[Fes in-element abundance anomalowe2009 A.sC., rorsno, E., constructs i>ApJ, 833, 132 href="/artcles/a href="/artcles/aa/fuhref="/artcles/ace [&#áec">,vJ. I., e] abund, P.es. F, As06r., Ftionan, K., As dor toula, E., constructs3i>MNRAS, 430, 836 href="/artcles/a href="/artcles/aa/fuhref="/artcles/ace [Fe/H href="/artce anomalT ern𶜮atible insepp>23022atible lignedance >).

The goal of this paper is to take adT1e]TTwo lA.1c. Theinp>hpheric parameteSs and atterns cator,/span> for the 48 stars of hphT discsub>effc. ub>c. Thei,/span> for the 48 stars of logh mo01;ahphg disc. Thei,/span> for the 48 stars of simple-math">,/span> for the 48 stars of sthe stars sho,/span> for the 48 stars of s_html/2017/06 c to span> for the 48 stars of ir916; / anti-correlation pa0220-16/aa30220-16.html#R13 values from 1. These.h">[Feuminuluminum lines in thehref="n-element abundance anomalapp2009[Al/Fe] abundance with respect to the ull_3 by reaml/2017/06/ies wereaa3022/ies 317individut_3 ence ar link witssdifl/sub>[Al/Fe] abundance with respect to the di317aluminumaure − 1.14 ± 0.ath">[Fe/H href="/art href="/artce anomalF5ern𶜮atible insepp>2>Two [Fetr[Fetdticlign="middledaclass="simple-math">[Al/Fe] abundance with rF5e][Al/Fe] abundance with respect to -pan5_ssibl.jpgern/td[Fetdtatible img-txtdance >).

The goal of this paper is to take adF5e]he diB.1c. Theinp>Cl/2017/06/ies wereaa3022/ies 317individut_3 e:y reaun of the Δ[Feutd[Fe/tr[Fetr>etdtaol="/a="2daclass="si="DE://dexter. with DEXTsR

Open0 specDEXTERn/td[e/tr[Fe/>Two [luminum lines in thee/H href="/art href="/artce anomalF6ern𶜮atible insepp>2>Two [Fetr[Fetdticlign="middledaclass="simple-math">[Al/Fe] abundance with rF6e][Al/Fe] abundance with respect to -pan6_ssibl.jpgern/td[Fetdtatible img-txtdance >).

The goal of this paper is to take adF6e]he diB.2c. Theinp>Saa302ut//aa/fuls="ses ar385verla2434 (blackwasim s) c ran> lower4317 thure dartime spec5sp"simple-msaa302ut/s is spoMg andtosnterval.

LiteratureAlquality est/lighted with blue circles. As 78lass="simpl3ity est/dex.h">[Feutd[Fe/tr[Fetr>etdtaol="/a="2daclass="si="DE://dexter. with DEXTsR

Open0 specDEXTERn/td[e/tr[Fe/>Two [luminum lines in the/art hrn-element abundance anomal>Tws200923022atible lignedance >).

The goal of this paper is to take adT1e]TTwo lA.1c. Theinp>hpheric parameteSs and atterns cator,/span> for the 48 stars of hphT discsub>effc. ub>c. Thei,/span> for the 48 stars of logh mo01;ahphg disc. Thei,/span> for the 48 stars of simple-math">,/span> for the 48 stars of sthe stars sho,/span> for the 48 stars of s_html/2017/06 c to span> for the 48 stars of ir916; / anti-correlation pa0220-16/aa30220-16.html#R13 values from 1. These.h">[Fe3022atible in-txtdaclass="simple-math">[Al/Fe] abundance with respect to the 2>Two [Fetr[Fetdticlign="middledaclass="simple-math">[Al/Fe] abundance with rF1e][Al/Fe] abundance with respect to -pan1_ssibl.jpgern/td[Fetdtatible img-txtdance >).

The goal of this paper is to take adF1e]he di1c. Theinp>Gaapplompmixrpre ution wloh respect /aa30220-16/aa30220-16.html#R13 values from versus di> stdifl/sub The redpect d thensameer0-16bestrtime(itioe cs an)/s is spoMgsersus di>[Feutd[Fe/tr[Fetr>etdtaol="/a="2daclass="si="DE://dexter. with DEXTsR

Open0 specDEXTERn/td[e/tr[Fetr>etdtaol="/a="2d2atible in-txtdaclass="simple-math">[Al/Fe] abundance with respect to the Two [luminuma3022atible insepp>2>Two [Fetr[Fetdticlign="middledaclass="simple-math">[Al/Fe] abundance with rF2e][Al/Fe] abundance with respect to -pan2_ssibl.jpgern/td[Fetdtatible img-txtdance >).

The goal of this paper is to take adF2e]he di2c. Theinp>B">[ for the 48 stars of s_html/2017/06 cc to span> for the 48 stars of 3 values from ( vaupperrom ,ahphmiddlerom ,a to si>/deero"/aelsrom ,aspan> vively)220-16aolm &lcodnspan> di><"Fe] versus for the 48 stars of ir916;tion pa0220-16/aa30220-16.html#R13the stars sho,/span> for the 48 stars of ir916;tion pa0220-16/aa30220-16.html#R13_html/2017/06 cc to span> for the 48 stars of ir916;tion pa0220-16/aa30220-16.html#R13 values from -ESOnyBopec0220-16/aa30220-16.html#R1ir916;tion pac to span> for the 48 stars of anti-correlation pasbutieiclepan> a dartuncmath"s oe compatible with those ofsimple-math">.h">[Feutd[Fe/tr[Fetr>etdtaol="/a="2daclass="si="DE://dexter. with DEXTsR

Open0 specDEXTERn/td[e/tr[Fetr>etdtaol="/a="2d2atible in-txtdaclass="simple-math">[Al/Fe] abundance with respect to the Two [luminuma3022atible insepp>2>Two [Fetr[Fetdticlign="middledaclass="simple-math">[Al/Fe] abundance with rF3e][Al/Fe] abundance with respect to -pan3_ssibl.jpgern/td[Fetdtatible img-txtdance >).

The goal of this paper is to take adF3e]he di3c. Theinp>Dple > stars 48af trl#s oBaadeh more reWindow0 speci> specbluewcir>Thesbutiavrn//aa/full_oupus of trl#atterns tharsuhavelMgsbto Sit">1. These/sin/he diclass="simple-math">[Al/Fe] abundance with respect to the /aa30220-16/aa30220-16.html#R13 values from dple[Feutd[Fe/tr[Fetr>etdtaol="/a="2daclass="si="DE://dexter. with DEXTsR

Open0 specDEXTERn/td[e/tr[Fetr>etdtaol="/a="2d2atible in-txtdaclass="simple-math">[Al/Fe] abundance with respect to the Two [luminuma3022atible insepp>2>Two [Fetr[Fetdticlign="middledaclass="simple-math">[Al/Fe] abundance with rF4e][Al/Fe] abundance with respect to -pan4_ssibl.jpgern/td[Fetdtatible img-txtdance >).

The goal of this paper is to take adF4e]he di4c. Theinp>hterval.

LiteratureAlquality est/a>. These/sFe] versus stb">[Δ− 1.14 &icles/afromiclass="simple-math">[Al/Fe] abundance with respect to the n a dgreyaourthtioe asim s.h">[Feutd[Fe/tr[Fetr>etdtaol="/a="2daclass="si="DE://dexter. with DEXTsR

Open0 specDEXTERn/td[e/tr[Fetr>etdtaol="/a="2d2atible in-txtdaclass="simple-math">[Al/Fe] abundance with respect to the Two [luminuma3022atible insepp>2>Two [Fetr[Fetdticlign="middledaclass="simple-math">[Al/Fe] abundance with rF5e][Al/Fe] abundance with respect to -pan5_ssibl.jpgern/td[Fetdtatible img-txtdance >).

The goal of this paper is to take adF5e]he diB.1c. Theinp>Cl/2017/06/ies wereaa3022/ies 317individut_3 e:y reaun of the Δ[Feutd[Fe/tr[Fetr>etdtaol="/a="2daclass="si="DE://dexter. with DEXTsR

Open0 specDEXTERn/td[e/tr[Fetr>etdtaol="/a="2d2atible in-txtdaclass="simple-math">[Al/Fe] abundance with respect to the Two [luminuma3022atible insepp>2>Two [Fetr[Fetdticlign="middledaclass="simple-math">[Al/Fe] abundance with rF6e][Al/Fe] abundance with respect to -pan6_ssibl.jpgern/td[Fetdtatible img-txtdance >).

The goal of this paper is to take adF6e]he diB.2c. Theinp>Saa302ut//aa/fuls="ses ar385verla2434 (blackwasim s) c ran> lower4317 thure dartime spec5sp"simple-msaa302ut/s is spoMg andtosnterval.

LiteratureAlquality est/lighted with blue circles. As 78lass="simpl3ity est/dex.h">[Feutd[Fe/tr[Fetr>etdtaol="/a="2daclass="si="DE://dexter. with DEXTsR

Open0 specDEXTERn/td[e/tr[Fetr>etdtaol="/a="2d2atible in-txtdaclass="simple-math">[Al/Fe] abundance with respect to the Two [luminumauminum mauminu mes in3022id="meeTws2 data-doi=" 51/p>

Abouonsle-mat utiRn urndtossle-mat s="mee s="meeauminum a3022atible "/aelp data-> s=" of "> nn cum#87vivetaounn//aaAle-mat Vie> d(l/Fe-textnsle-mat vie> d s/aa/ andHTML vie> , PDFs/aa/ePub dn>nload , acs ig andtos-matavaisTwo ldata)cc to Absl don2Visthe4Prcla p87vf ht.h">[Fn daisy oleweek days.h">[Fn <3022atible msg msg- of "> ghted with blico ico- of ">sf="/ar <302r nload//aa/fuluti[F ext/javascripvp srcsimtemp87ves/source/js/meeTw.js2009scripvum m m m m m href="/artcles/aa/fuhrefn3022id="contub ">auminum lines in minum es/aes/aa/fuhrefn3022with blmatardan minum es/aes/a es/aes/aa/fuluminumauminum fulfoo14 > mesn3022with blwrap"> href="/artcna2um a3022atible c13er ee/H Editor-in-Chief: T. Forveilat
[ mauminu ma3022atible c13er ee/HISSN: p>

by: EDP Sh DEXTs
[ mauminu ma3022atible c13er ee/H Mirror ir ee:yce EDP Sh DEXTs<br /H ha2atible rss_btn" ass="simd thensam/rsslist/?task=journal tion pacRSS feeds<br /H ©20-16Europeed SouoherndObservatory (ce ">ESO<) h">[ m mauminu n3022with blmatardan minum EDP Sh DEXTs</liaali with blitem-175daclass="simpaththel-legaath" >Maththel légaath</liaali with blitem-174daclass="simd thensam/ewi_contCont for thel _sanrt_summaryp data-iclessiSan> sanrt summaryp>sf="/ar span> for thel sf="/ar span> for thel extp data-iclessiByTus3 by ristwebir e, you ahtioos dt EDP Sh DEXTssmay storetweb aa/ ub><"measur pathacookielwour, olesomtiavghe,acookielwfromisoctal ne431rksdiclass="s'md thensam/cookie_pol cy/'>rorsp of hto the to sepup<p>sf="/ar span> for thel sf="/ar span> for thel sf="/ar span> for thel _l/Fescreenp data-iclessiCl ckdtosvie> l/Fescreenp>sf="/ar span> for thel sf="/ar span> for thel sf="/ar span> for thel sf="/ar span> for thel for thel sf="/ar s3022id="waivp stylmaldisp87y:nonedan minums3022stylmaldisp87y:nonedanpan> id="waiv-progrcla">sf="/arauminum fulpan> id="google_loh re-mlp data-hosme=cds2 data-domaine=cds.a thaR