相关论文: A model for the Globular Cluster extreme anomalies

The Na-O anticorrelation seen in almost all globular clusters ever studied using high-resolution spectroscopy is now generally explained by the primordial pollution from the first generation of the intermediate-mass asymptotic giant branch…

We present $\gtrsim 15,000$ metal-rich (${\rm [Fe/H]}>-0.2$dex) A and F stars whose surface abundances deviate strongly from Solar abundance ratios and cannot plausibly reflect their birth material composition. These stars are identified by…

The new generation of 3D hydrodynamical model atmospheres have been employed to study the impact of a realistic treatment of stellar convection on element abundance determinations of globular cluster stars for a range of atomic and…

Context. Carbon, nitrogen, and oxygen are the most abundant elements throughout the universe, after hydrogen and helium. Studying these elements in low-metallicity stars can provide crucial information on the chemical composition in the…

Their ubiquity and extreme densities make star clusters probes of prime importance of galaxy evolution. Old globular clusters keep imprints of the physical conditions of their assembly in the early Universe, and younger stellar objects,…

Globular clusters are dense aggregates of stars that evolve in relative isolation. For the better part of $40$ years these clusters have been known to possess unique chemical signatures called abundance anomalies. Recent observations have…

Globular clusters were thought to be simple stellar populations, but recent photometric and spectroscopic evidence suggests that the clusters' early formation history was more complicated. In particular, clusters show star-to-star abundance…

We present [K/Fe] abundance ratios for a sample of 450 stars in Omega Centauri, using high resolution spectra acquired with the multi-object spectrograph FLAMES@VLT. Abundances for Fe, Na and Mg were also derived. We detected intrinsic K…

The majority of observed mass-to-light ratios of globular clusters are too low to be explained by `canonical' cluster models, in which dynamical effects are not accounted for. Moreover, these models do not reproduce a recently reported…

Recent JWST observations have revealed a growing population of galaxies at $z>4$ with elevated nitrogen-to-oxygen ratios. These "N/O-enhanced" galaxies (NOEGs) exhibit near- to super-solar N/O at sub-solar O/H, clearly deviating from the…

We explore a scenario where metal-poor globular clusters (GCs) are enriched by the first supernovae in the Universe. If the first stars in a 10^7 Msun dark halo were very massive (>180 Msun), then a pair instability supernova from a single…

Star-to-star variations in abundances of the light elements carbon, nitrogen, oxygen, and sodium have been observed in stars of all evolutionary phases in all Galactic globular clusters that have been thoroughly studied. The data available…

Recent observations for the color-magnitude diagrams (CMDs) of the massive globular cluster Omega Centauri have shown that it has a striking double main sequence (MS), with a minority population of bluer and fainter MS well separated from a…

The chemical abundance patterns of the oldest stars in the Galaxy are expected to contain residual signatures of the first stars in the early universe. Numerous studies attempt to explain the intrinsic abundance scatter observed in some…

Recent simulation work has successfully captured the formation of the star clusters that have been observed in merging galaxies. These studies, however, tend to focus on studying extreme starbursts, such as the Antennae galaxies. We aim to…

Observations of globular clusters show that they have universal lognormal mass functions with a characteristic peak at $\sim 2\times 10^{5}\, {\rm{M_{\odot}}}$, but the origin of this peaked distribution is highly debated. Here we…

Almost several decades after the discovery of the first multiple populations in galactic globular clusters (GC) the debate on their formation is still extremely current and NGC2808 remains one of the best benchmark to test any scenario for…

Globular clusters (GCs) are known to host multiple stellar populations showing chemical anomalies in the content of light elements. The origin of such anomalies observed in Galactic GCs is still debated. Here we analyse data compiled from…

Stellar rotation produces an internal mixing of the elements due to shear instability and meridional circulation. This leads to observable $N/C$ enhancements in massive stars above about 7--9 $M_{\odot}$. Rotation also favours mass loss by…

Stellar models with masses ranging from 0.5 to $1.3~M_\odot$ were constructed in order to compare to young cluster observations of Li and of rotation velocities. The amount of Li depletion in cool stars is sensitive to the amount of…