CHEMICAL TAGGING OF THREE DISTINCT POPULATIONS OF RED GIANTS IN THE GLOBULAR CLUSTER NGC 6752
- INAF, Osservatorio Astronomico di Bologna, Via Ranzani 1, 40127 Bologna (Italy)
- INAF, Osservatorio Astronomico di Padova, vicolo dell'Osservatorio 5, 35122 Padova (Italy)
- Department of Physics and Astronomy, Macquarie University, Sydney, NSW 2109 (Australia)
We present aluminum, magnesium, and silicon abundances in the metal-poor globular cluster NGC 6752 for a sample of more than 130 red giants with homogeneous oxygen and sodium abundances. We find that [Al/Fe] shows a spread of about 1.4 dex among giants in NGC 6752 and is anticorrelated with [Mg/Fe] and [O/Fe] and correlated with [Na/Fe] and [Si/Fe]. These relations are not continuous in nature, but the distribution of stars is clearly clustered around three distinct Al values, low, intermediate, and high. These three groups nicely correspond to the three distinct sequences previously detected using Stroemgren photometry along the red giant branch. These two independent findings strongly indicate the existence of three distinct stellar populations in NGC 6752. Comparing the abundances of O and Mg, we find that the population with intermediate chemical abundances cannot originate from material with the same composition of the most O- and Mg-poor population, diluted by material with that of the most O- and Mg-rich one. This calls for different polluters.
- OSTI ID:
- 22047860
- Journal Information:
- Astrophysical Journal Letters, Journal Name: Astrophysical Journal Letters Journal Issue: 1 Vol. 750; ISSN 2041-8205
- Country of Publication:
- United States
- Language:
- English
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