Ca II triplet spectroscopy of Small Magellanic Cloud red giants

We present the chemical composition of 206 red giant branch stars that are members of the Small Magellanic Cloud (SMC) using optical high-resolution spectra collected with the multi-object spectrograph FLAMES-GIRAFFE at the ESO Very Large Telescope. This sample includes stars in three fields that are located in different positions within the parent galaxy. We analysed the main groups of elements, namely light- (Na), α- (O, Mg, Si, Ca, and Ti), iron-peak (Sc, V, Fe, Ni, and Cu), and s-process elements (Zr, Ba, and La). The metallicity distribution of the sample displays a main peak around [Fe/H]∼–1 dex and a weak metal-poor tail. However, the three fields display different [Fe/H] distributions. In particular, a difference of 0.2 dex is found between the mean metallicities of the two innermost fields. The fraction of metal-poor stars increases significantly (from ∼1 to ∼20%) from the innermost fields to the outermost field, likely reflecting an age gradient in the SMC. We also found an indication of possible chemically and kinematic distinct substructures. The ratios of the SMC stars are clearly distinct from those of Milky Way stars, in particular, for the elements produced by massive stars (e.g. Na, α, and most iron-peak elements), whose abundance ratios are systematically lower than those measured in our Galaxy. This shows that massive stars contributed less to the chemical enrichment of the SMC than the Milky Way, according to the low star formation rate expected for this galaxy. Finally, we identified small systematic differences in the abundances of some elements (Na, Ti, V, and Zr) in the two innermost fields, suggesting that the chemical enrichment history in the SMC has not been uniform.

show abstract

“…This is also confirmed by the metallicities of the stellar clusters with ages around 1 Gyr (see e.g. Parisi et al 2022).…”

Section: [Fe/h] Distribution and The Age-metallicity Relationsupporting

confidence: 66%

The chemical DNA of the Magellanic Clouds

Mucciarelli

Minelli

Bellazzini³

et al. 2023

A&A

View full text Add to dashboard Cite

show abstract

“…This is confirmed also by the metallicities of the stellar clusters with ages around 1 Gyr (see e.g. Parisi et al 2022)…”

Section: [Fe/h] Distribution and The Age-metallicity Relationsupporting

confidence: 60%

The chemical DNA of the Magellanic Clouds -- I. The chemical composition of 206 Small Magellanic Cloud red giant stars

Mucciarelli¹,

A.²,

M.³

et al. 2023

Preprint

View full text Add to dashboard Cite

We present the chemical composition of 206 red giant branch stars members of the Small Magellanic Cloud (SMC) using optical, highresolution spectra collected with the multi-object spectrograph FLAMES-GIRAFFE at the ESO Very Large Telescope. This sample includes stars in three fields located in different positions within the parent galaxy. We analysed the main groups of elements, namely light-(Na), α-(O, Mg, Si, Ca, Ti), iron-peak (Sc, V, Fe, Ni, Cu) and s-process elements (Zr, Ba, La). The metallicity distribution of the sample displays a main peak around [Fe/H]∼-1 dex and a weak metal-poor tail. However, the three fields display [Fe/H] distributions different with each other, in particular a difference of 0.2 dex is found between the mean metallicities of the two most internal fields. The fraction of metal-poor stars increases significantly (from ∼1 to ∼20%) from the innermost fields to the most external one, likely reflecting an age gradient in the SMC. Also, we found a hint of possible chemically/kinematic distinct substructures. The SMC stars have abundance ratios clearly distinct with respect to the Milky Way stars, in particular for the elements produced by massive stars (like Na, α and most iron-peak elements) that have abundance ratios systematically lower than those measured in our Galaxy. This points out that the massive stars contributed less to the chemical enrichment of the SMC with respect to the Milky Way, according to the low star formation rate expected for this galaxy. Finally, we identified small systematic differences in the abundances of some elements (Na, Ti, V and Zr) in the two innermost fields, suggesting that the chemical enrichment history in the SMC has been not uniform.

show abstract

“…Therefore, the stars most likely currently within the cluster BH 261 (1) are within the cluster tidal radius, (2) have an RV that falls within the error plus intrinsic dispersion (generously adopted as ±15 km s −1 ) from the cluster mean, (3) have an [Fe/H] value within ±0.3 dex of the mean metallicity of the cluster, and (4) have a proper motion that lies within two standard deviations from the cluster mean. These criteria have been used by a number of similar studies discriminating between bulge cluster members and surrounding field stars (e.g., Dias et al 2022;Parisi et al 2022;Geisler et al 2023).…”

Section: Velocitiesmentioning

confidence: 99%

The Milky Way Bulge Extra-tidal Star Survey: BH 261 (AL 3)

Kunder,

Prudil,

Covey

et al. 2023

View full text Add to dashboard Cite

The Milky Way Bulge extra-tidal star survey is a spectroscopic survey with the goal of identifying stripped globular cluster stars from inner Galaxy clusters. In this way, an indication of the fraction of metal-poor bulge stars that originated from globular clusters can be determined. We observed and analyzed stars in and around BH 261, an understudied globular cluster in the bulge. From seven giants within the tidal radius of the cluster, we measured an average heliocentric radial velocity of 〈RV〉 = −61 ± 2.6 km s−1 with a radial velocity dispersion of 〈σ〉 = 6.1 ± 1.9 km s−1. The large velocity dispersion may have arisen from tidal heating in the cluster’s orbit about the Galactic center, or because BH 261 has a high dynamical mass as well as a high mass-to-light ratio. From spectra of five giants, we measure an average metallicity of 〈[Fe/H]〉 = −1.1 ± 0.2 dex. We also spectroscopically confirm an RR Lyrae star in BH 261, which yields a distance to the cluster of 7.1 ± 0.4 kpc. Stars with 3D velocities and metallicities consistent with BH 261 reaching to ∼0.°5 from the cluster are identified. A handful of these stars are also consistent with the spatial distribution of potential debris from models focusing on the most recent disruption of the cluster.

show abstract

Ca II triplet spectroscopy of Small Magellanic Cloud red giants

Cited by 15 publications

References 126 publications

The chemical DNA of the Magellanic Clouds

The chemical DNA of the Magellanic Clouds

The chemical DNA of the Magellanic Clouds -- I. The chemical composition of 206 Small Magellanic Cloud red giant stars

The Milky Way Bulge Extra-tidal Star Survey: BH 261 (AL 3)

Contact Info

Product

Resources

About