What is a globular cluster? An observational perspective
Autor: | Angela Bragaglia, Valentina D'Orazi, Sara Lucatello, Raffaele Gratton, Antonio Sollima, Eugenio Carretta |
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Rok vydání: | 2019 |
Předmět: |
Physics
010504 meteorology & atmospheric sciences Milky Way Metallicity FOS: Physical sciences Astronomy and Astrophysics Astrophysics Astrophysics - Astrophysics of Galaxies 01 natural sciences Galaxy Stars Astrophysics - Solar and Stellar Astrophysics Space and Planetary Science Nucleosynthesis Astrophysics of Galaxies (astro-ph.GA) Globular cluster 0103 physical sciences Cluster (physics) Astrophysics::Solar and Stellar Astrophysics 010303 astronomy & astrophysics Solar and Stellar Astrophysics (astro-ph.SR) Astrophysics::Galaxy Astrophysics 0105 earth and related environmental sciences Open cluster |
Zdroj: | The Astronomy and Astrophysics Review. 27 |
ISSN: | 1432-0754 0935-4956 |
DOI: | 10.1007/s00159-019-0119-3 |
Popis: | Globular clusters are large and dense agglomerate of stars. At variance with smaller clusters of stars, they exhibit signs of some chemical evolution. At least for this reason, they are intermediate between open clusters and massive objects such as nuclear clusters or compact galaxies. While some facts are well established, the increasing amount of observational data are revealing a complexity that has so far defied the attempts to interpret the whole data set in a simple scenario. We review this topic focusing on the main observational features of clusters in the Milky Way and its satellites. We find that most of the observational facts related to the chemical evolution in globular clusters are described as being primarily a function of the initial mass of the clusters, tuned by further dependence on the metallicity - that mainly affects specific aspects of the nucleosynthesis processes involved - and on the environment, that likely determines the possibility of indepenedent chemical evolution of the fragments or satellites, where the clusters form. We review the impact of multiple populations on different regions of the colour-magnitude diagram and underline the constraints related to the observed abundances of lithium, to the cluster dynamics, and to the frequency of binaries in stars of different chemical composition. We then re-consider the issues related to the mass budget and the relation between globular cluster and field stars. Any successful model of globular cluster formation should explain these facts. Comment: 136 pages, 28 figures |
Databáze: | OpenAIRE |
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