KMHK 1762: Another star cluster in the Large Magellanic Cloud age gap

Gatto, M.; Ripepi, V.; Bellazzini, M.; Tosi, M.; Tortora, C.; Cignoni, M.; Dall’Ora, M.; Cioni, M. R. L.; Cusano, F.; Longo, Giuseppe; Marconi, M.; Musella, I.; Schipani, P.; Spavone, M.

doi:10.1051/0004-6361/202243993

Cited by 5 publications

(1 citation statement)

References 43 publications

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“…However, recent investigations based on relatively deep photometry have shown that several faint candidate star clusters in regions of the LMC not investigated before can have ages falling in the age-gap (Gatto et al 2020). In addition, a reanalysis of the CMDs of the star clusters KMHK 1592 and KMHK 1762 based on deep photometry showed that both star clusters fall inside the age-gap, at odds with previous age estimates based on too-shallow photometry (Gatto et al 2022;Piatti 2022). These findings seem to suggest that the age-gap is not a real physical feature, but the result of an observational bias, originated by the combination of too-shallow photometry carried out in the literature, the lack of a proper decontamination of field stars and an incomplete investigation of the LMC outskirts, where the lower stellar density of the field permits the detection of even faint and sparse star clusters.…”

Section: Census and Properties Of Star Clusters In The Magellanic Cloudsmentioning

confidence: 82%

Rubin Observatory LSST Stars Milky Way and Local Volume Star Clusters Roadmap

Usher,

Dage,

Girardi

et al. 2023

PASP

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The Vera C. Rubin Observatory will undertake the Legacy Survey of Space and Time, providing an unprecedented, volume-limited catalog of star clusters in the Southern Sky, including Galactic and extragalactic star clusters. The Star Clusters subgroup of the Stars, Milky Way and Local Volume Working Group has identified key areas where Rubin Observatory will enable significant progress in star cluster research. This roadmap represents our science cases and preparation for studies of all kinds of star clusters from the Milky Way out to distances of tens of megaparsecs.

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Section: Census and Properties Of Star Clusters In The Magellanic Cloudsmentioning

confidence: 82%

Rubin Observatory LSST Stars Milky Way and Local Volume Star Clusters Roadmap

Usher,

Dage,

Girardi

et al. 2023

PASP

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The chemical DNA of the Magellanic Clouds

Mucciarelli¹,

A.²,

Lardo³

et al. 2023

A&A

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The Small Magellanic Cloud (SMC) is the host of a rich system of globular clusters (GCs) that span a wide age range. The chemical composition of the SMC clusters is still poorly understood, despite their significance to chemical-evolution studies. Here, we provide the first detailed chemical study of evolved giants in three distinct clusters, NGC 121 (10.5 Gyr), NGC 339 (6 Gyr), and NGC 419 (1.4 Gyr). The results are based on high-resolution spectra obtained with FLAMES at the Very Large Telescope. The chemical fingerprints of these clusters closely resemble those of SMC field stars, supporting the SMC’s specific history of chemical enrichment relative to the Milky Way. The approximately solar-scaled [α/Fe] observed in all three clusters, independent of their [Fe/H], demonstrate the SMC’s low star formation efficiency. Compared to their Milky Way counterparts, elements primarily produced by massive stars are severely under-represented. In particular, the young cluster NGC 419’s extremely low [Zn/Fe] shows that hypernovae have contributed relatively little during the past 2 Gyr. The three GCs have high [Eu/Fe] values regardless of their age. This suggests that the production of the r-process elements in the SMC was extremely efficient up to 1.5 Gyr ago, with an enrichment timescale comparable to that from Type Ia supernovae. When the properties of the oldest SMC object, NGC 121, are compared to those of in situ Milky Way clusters and accreted clusters linked to the Gaia-Enceladus merger event, it is shown that the SMC had already attained the same metallicity as Gaia-Enceladus but with lower [Fe/H] ratios at the age of NGC 121. This suggests that the chemical enrichment histories of the early SMC and Gaia-Enceladus differed, and that the SMC probably had a lower mass in its early ages than Gaia-Enceladus.

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First spectroscopic investigation of anomalous Cepheid variables

Ripepi,

Catanzaro,

Trentin

et al. 2024

A&A

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Anomalous Cepheids (ACEPs) are intermediate-mass metal-poor pulsators that are mostly discovered in dwarf galaxies of the Local Group. However, recent Galactic surveys, including the Gaia Data Release 3, found a few hundred ACEPs in the Milky Way. Their origin is only poorly understood. We aim to investigate the origin and evolution of Galactic ACEPs by studying the chemical composition of their atmospheres for the first time. We used UVES at the Very Large Telescope to obtain high-resolution spectra for a sample of nine ACEPs belonging to the Galactic halo. We derived the abundances of 12 elements, C, Na, Mg, Si, Ca, Sc, Ti, Cr, Fe, Ni, Y, and Ba. We complemented these data with literature abundances from high-resolution spectroscopy for an additional three ACEPs that were previously incorrectly classified as type II Cepheids. This increased the sample to a total of 12 stars. All the investigated ACEPs have an iron abundance Fe/H $<-1.5$ dex, as expected from theoretical predictions for these pulsators. The abundance ratios of the different elements to iron show that the chemical composition of ACEPs is generally consistent with that of the Galactic halo field stars, with the exception of sodium, which is found to be overabundant in 9 out of the 11 ACEPs where it was measured. This is very similar to the situation for second-generation stars in Galactic globular clusters. The same comparison with dwarf and ultra-faint satellites of the Milky Way reveals more differences than similarities. It is therefore unlikely that the bulk of Galactic ACEPs originated in a galaxy like this that subsequently dissolved into the Galactic halo. The principal finding of this work is the unexpected overabundance of sodium in ACEPs. We explored several hypotheses to explain this feature, finding that the most promising scenario is the evolution of low-mass stars in a binary system with either mass transfer or merging. Detailed modelling is needed to confirm this hypothesis.

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KMHK 1762: Another star cluster in the Large Magellanic Cloud age gap

Cited by 5 publications

References 43 publications

Rubin Observatory LSST Stars Milky Way and Local Volume Star Clusters Roadmap

Rubin Observatory LSST Stars Milky Way and Local Volume Star Clusters Roadmap

The chemical DNA of the Magellanic Clouds

First spectroscopic investigation of anomalous Cepheid variables

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