A New Set of Chisels for Galactic Archeology: Sc, V, and Zn as Taggers of Accreted Globular Clusters*

Minelli, A.; Mucciarelli, A.; Massari, D.; Bellazzini, M.; Romano, D.; Ferraro, F. R.

doi:10.3847/2041-8213/ac2156

Cited by 17 publications

(10 citation statements)

References 45 publications

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“…It is an old GC (Ortolani et al 1995) and its high metallicity places the cluster among a near uniform old age group in the age-metallicity relation (AMR). Based on the location on the AMR and in the integral of motion space, Forbes (2020) assigns NGC 6388 to the in situ group of Milky Way GCs, confirming the classification by Massari et al (2019;however, see Myeong et al 2019 andMinelli et al 2021 for a different view). All this confirms the nature of the cluster as an object of interest that merits an in-depth study with regard to both its chemical and astrometric properties.…”

Section: Introductionsupporting

confidence: 60%

Metallicity of the globular cluster NGC 6388 based on high-resolution spectra of more than 160 giant stars

Carretta¹,

Bragaglia²

2022

A&A

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NGC 6388 is one of the most massive Galactic globular clusters (GC) and it is an old, metal-rich Galactic bulge cluster. By exploiting previous spectroscopic observations, we were able to bypass the uncertainties in membership related to the contamination from strong field stars. We present the abundance analysis of 12 new giant stars with UVES spectra and 150 giants with GIRAFFE spectra acquired at the ESO-VLT. We derived radial velocities, atmospheric parameters, and iron abundances for all the stars. When combined with the previous data, we obtained a grand total of 185 stars homogeneously analysed in NGC 6388 from high-resolution spectroscopy. The average radial velocity of the 185 stars is 81.2 ± 0.7, rms 9.4 km s−1. We obtained an average metallicity [Fe/H] = −0.480 dex, rms = 0.045 dex (35 stars), and [Fe/H] = −0.488 dex, rms = 0.040 dex (150 stars) from the UVES and GIRAFFE samples, respectively. Comparing these values to the internal errors in abundance, we excluded the presence of a significant intrinsic metallicity spread within the cluster. Since about a third of giants in NGC 6388 is claimed to belong to the ‘anomalous red giants’ in the HST pseudo-colour map defining the so-called type-II GCs, we conclude that either enhanced metallicity is not a necessary requisite to explain this classification (as also suggested by the null iron spread for NGC 362) or NGC 6388 is not a type-II globular cluster.

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Section: Introductionsupporting

confidence: 60%

Metallicity of the globular cluster NGC 6388 based on high-resolution spectra of more than 160 giant stars

Carretta¹,

Bragaglia²

2022

A&A

View full text Add to dashboard Cite

show abstract

“…It is an old GC (Ortolani et al 1995) and its high metallicity places the cluster among a near uniform old age group in the age-metallicity relation (AMR). Based on the location on the AMR and in the integral of motion space, Forbes (2020) assigns NGC 6388 to the in situ group of Milky Way GCs, confirming the classification by Massari et al (2019; but see Myeong et al 2019 andMinelli et al 2021 for a different view). All this confirms the interest of the cluster, which merits indepth study, both of its chemical and astrometric properties.…”

Section: Introductionsupporting

confidence: 55%

Metallicity of the globular cluster NGC 6388 from high resolution spectra of more than 160 giant stars

Carretta,

Bragaglia

2021

Preprint

View full text Add to dashboard Cite

NGC 6388 is one of the most massive Galactic globular clusters (GC) and it is an old, metal-rich, Galactic bulge cluster. By exploiting previous spectroscopic observations we were able to bypass the uncertainties in membership related to the strong field stars contamination. We present the abundance analysis of 12 new giant stars with UVES spectra and 150 giants with GIRAFFE spectra acquired at the ESO-VLT. We derived radial velocities, atmospheric parameters and iron abundances for all stars. When combined to previous data, we obtain a grand total of 185 stars homogeneously analysed in NGC 6388 from high-resolution spectroscopy. The average radial velocity of the 185 stars is 81.2±0.7, rms 9.4 km s −1 . We obtain an average metallicity [Fe/H]= −0.480 dex, rms = 0.045 dex (35 stars) and [Fe/H]= −0.488 dex, rms = 0.040 dex (150 stars) from the UVES and GIRAFFE samples, respectively. Comparing these values to internal errors in abundance, we exclude the presence of a significant intrinsic metallicity spread within the cluster. Since about a third of giants in NGC 6388 is claimed to belong to the "anomalous red giants" in the HST pseudo-colour map defining the so-called type-II GCs, we conclude that either enhanced metallicity is not a necessary requisite to explain this classification (as also suggested by the null iron spread for NGC 362) or NGC 6388 is not a type-II globular cluster.

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“…Line lists, solar reference abundances, and corrections for a hyperfine structure for Sc and V are from Gratton et al (2003). Minelli et al (2021b). Empty grey circles are field disc and bulge stars from Adibekyan et al (2012), Battistini and Bensby (2015), Bensby et al (2005Bensby et al ( , 2014Bensby et al ( , 2017, Bihain et al (2004), Brewer et al (2016), da Silveira et al (2018), Delgado-Mena et al (2017, Gratton et al (2003), Ishigaki et al (2012Ishigaki et al ( , 2013, Lomaeva et al (2019), Lucey et al (2019), and Reddy et al (2003.…”

Section: The Data Setmentioning

confidence: 99%

“…Minelli et al (2021a: M21a) recently proposed using the iron-peak elements Sc, V, and Zn to explore the metal-rich ([Fe/H] ∼ > − 1 dex) regime since they observed large differences in the abundances between stars in the MW and those in the Large Magellanic Cloud (LMC), as well as in the Sagittarius dwarf spheroidal galaxy (Sag) in this metallicity range. In Minelli et al (2021b: M21b) they compared a handful of stars homogeneously analysed in four metalrich globular clusters (GCs), concluding that NGC 5927 and NGC 6496 are formed in situ, whereas NGC 6388 and NGC 6441 are probably accreted, which is at variance with the classification of NGC 6388 in Massari et al (2019) and Forbes (2020) but in agreement with Horta et al (2020).…”

Section: Introductionmentioning

confidence: 99%

The in situ origin of the globular cluster NGC 6388 from abundances of Sc, V, and Zn of a large sample of stars

Carretta,

Bragaglia

2022

Preprint

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Chemical tagging of globular clusters (GCs) is often done using abundances of α−elements. The iron-peak elements Sc, V, and in particular Zn were proposed as an alternative to α−elements to tag accreted GCs in the metal-rich regime, where the dwarf galaxy Sagittarius and its GCs show peculiarly marked under-abundances of these heavier species with respect to Milky Way stars. A handful of stars in NGC 6388 was used to suggest an accreted origin for this GC, contradicting the results from dynamics. We tested the efficiency of the iron-peak method by using large samples of stars in NGC 6388, compared to thousands of field stars in the disc and the bulge of the Milky Way. Our abundance ratios of Sc (185 stars) and V (35 stars) for NGC 6388 are within about 1.5σ from the average for the field stars with a similar metallicity, and they are in perfect agreement for Zn (31 stars), claimed to be the most sensitive element concerning the accretion pattern. Moreover, the chemo-dynamical plots, coupled to the bifurcated age-metallicity relation of GCs in the Galaxy, clearly rule out any association of NGC 6388 to the groups of accreted GCs. Using a large set of GC abundances from the literature, we also show that the new method with Sc, V, and Zn seems to be efficient in picking up GCs related to the Sagittarius dwarf galaxy. Whether this is also generally true for accreted GCs seems to be less evident, and it should be verified with larger and homogeneous samples of stars both in the field and in GCs.

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A New Set of Chisels for Galactic Archeology: Sc, V, and Zn as Taggers of Accreted Globular Clusters*

Cited by 17 publications

References 45 publications

Metallicity of the globular cluster NGC 6388 based on high-resolution spectra of more than 160 giant stars

Metallicity of the globular cluster NGC 6388 based on high-resolution spectra of more than 160 giant stars

Metallicity of the globular cluster NGC 6388 from high resolution spectra of more than 160 giant stars

The in situ origin of the globular cluster NGC 6388 from abundances of Sc, V, and Zn of a large sample of stars

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