arXiv subjects

A. Bartolomei

Publications and source records attributed to A. Bartolomei.

3 recordsLinked to original sources

arXiv2026

CRIRES+ reveals the chemistry of the stellar sub-populations in the bulge fossil fragment Liller 1

In this paper we present the chemical screening of the complex stellar population discovered in the Bulge Fossil Fragment Liller 1. This study is part of the Bulge Cluster Origin (BulCO) survey based on a Large Program at the ESO-VLT with the high resolution spectrograph CRIRES+. The survey is aimed at performing an unprecedented chemical screening of 17 stellar systems orbiting the Milky Way bulge, with the ultimate goal of unveiling their origin and true nature. We measured precise chemical abundances of iron, CNO, iron-peak, $α$- other light-elements, and neutron-capture elements for a sample of 30 red giant branch stars, kinematic members of Liller 1. The presented analysis provides the high-resolution spectroscopic proof of the complex chemistry of this massive stellar system, with multi-metallicity sub-populations of different ages that nicely fits into a self-enrichment scenario. We find no evidence for the Na-O anticorrelation associated with genuine globular clusters; rather the overall abundance trends are similar to those seen in the bulge field and in Terzan 5, providing definitive evidence of an in-situ formation of Liller 1 within the Galactic bulge.

astro-ph.GA↗

arXiv2026

The Bulge Cluster Origin (BulCO) survey with CRIRES at the ESO-VLT: a chemical screening of the Globular Cluster NGC 6553

In this paper we present the chemical screening of the stellar population belonging to the globular cluster NGC 6553 in the Galactic bulge. This study has been conducted in the contest of the Bulge Cluster Origin (BulCO) survey, an ESO-VLT Large Program currently ongoing with CRIRES in the NIR domain. This survey is performing an unprecedented chemical screening of 17 stellar systems orbiting the Milky Way bulge, with the aim of unveiling their origin and true nature. Here we present and discuss the abundances of 18 elements produced via distinct nucleosynthetic channels for 14 red giant branch stars belonging to NGC 6553. We found a mean [Fe/H] = -0.20 $\pm$ 0.01 dex, and about solar-scaled iron-peak elements, confirming that this is one of the most metal-rich globular clusters in the Milky Way. We also found [X/Fe] enhancement of $α$ and several other light elements. Furthermore, we assess the presence of multiple populations typical of genuine globular clusters from the significant spreads in Na, N, and C, and an almost vertical Na-O anti-correlation. Finally, by using classical ([$α$/Fe] vs [Fe/H]) and newly-defined ([V/Fe] and [Zn/Fe] vs [Fe/H]) "chemical DNA tests", we prove its in-situ formation within the Galactic bulge.

astro-ph.GA↗

arXiv2025

The Bulge Cluster Origin (BulCO) survey at the ESO-VLT: probing the early history of the Milky Way assembling. Design and first results in Liller1

We present the scientific goals and the very first results of the Bulge Cluster Origin (BulCO) survey. This survey has been specifically designed to perform an unprecedented chemical screening of stellar systems orbiting the Milky Way bulge, with the aim to unveil their true origin. It takes advantage of the improved performances of the spectrograph CRIRES+ operating at the ESO Very Large telescope, in the near-infrared domain. Due to the complex evolutionary history of the Milky Way, a variety of relics tracing different phenomena is expected to populate the Bulge: globular clusters formed in-situ or accreted from outside the Galaxy, nuclear star clusters of cannibalized structures, and possibly a few remnants of the proto-bulge formation process (the so-called ``bulge fossil fragments"). The signatures of the different origins are imprinted in the chemical properties of these stellar systems because specific abundance patterns provide authentic "chemical DNA" tests univocally tracing the enrichment process and, therefore, the environment where the stellar population formed. Thus, each system can provide a new piece of information on the bulge formation and evolutionary history. As first results of the survey, here we discuss the alpha-element and iron abundances of a sample of stars observed in the stellar system Liller 1, which is proposed to be a bulge fossil fragment. By combining this dataset with a recently published sample of high/mid-resolution spectra, we discuss the overall chemical properties of the stellar populations in Liller1, proving its link with the Galactic bulge and providing new constraints on its star formation history.

astro-ph.GA↗