Multiple Stellar Populations in Globular Clusters

By N. Bastian, C. Lardo. Annual Review of Astronomy and Astrophysics, 2017

423 citations recorded by the source corpus.

Globular clusters (GCs) exhibit star-to-star variations in specific elements (e.g., He, C, N, O, Na, Al) that bear the hallmark of high-temperature H-burning. These abundance variations can be observed spectroscopically and also photometrically, with the appropriate choice of filters, due to the changing of spectral features within the band pass. This phenomenon is observed in nearly all of the ancient GCs, although, to date, it has not been found in any massive cluster younger than 2 Gyr. Many scenarios have been suggested to explain this phenomenon, with most invoking multiple epochs of star formation within the cluster; however, all have failed to reproduce various key observations, in particular when a global view of the GC population is taken. We review the state of current observations and outline the successes and failures of each of the main proposed models. The traditional idea of using the stellar ejecta from a first generation of stars to form a second generation of stars, while conceptually straightforward, has failed to reproduce an increasing number of observational constraints. We conclude that the puzzle of multiple populations remains unsolved, hence alternative theories are needed.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/9944b36108c3545d2cb3eda5dc936e530475fdab

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

In Instrumentation

Citations in the corpus

A stellar census in globular clusters with MUSE: multiple populations chemistry in NGC 2808 (2019, background): “However such He variations in stars that would otherwise have a rather homogeneous composition is challenging to explain via the current enrichment mechanisms proposed in the literature (Bastian & Lardo 2018).”
Modeling Dense Star Clusters in the Milky Way and Beyond with the CMC Cluster Catalog (2019, background): “These star-to-star abundance variations within clusters are known as multiple populations (MPs), and the study of MPs has emerged as a pillar of research in the field of star clusters (for a recent review, see Bastian & Lardo 2018).”
Angular Momentum Transport in Stellar Interiors (2018, background): “…2018); e isochrone fitting of (Extended) Main-Sequence Turnoffs, (E)MST, of clusters from combined multi-color photometry, spectroscopy, and astrometry (Bastian & Lardo 2017); f from µmag precision time-series space photometry covering many cycles of the rotationally modulated light curve due to…”
Evidence from the H3 Survey That the Stellar Halo Is Entirely Comprised of Substructure (2020, background): “Further, several popular scenarios for GC formation assume they underwent drastic mass loss at some point in their early history (see Bastian & Lardo 2018 for a recent review).”