![]() ![]() The discrepancy with literature claims can be explained with the different methods that were adopted to characterise MPs. The silhouette analysis suggests that the population substructure is reliable for high-resolution spectroscopy data, while the actual existence of MP is questionable for the low-resolution spectroscopy data. Two MPs are detected for both data sets, while the literature reports five and four MPs from high- and low-resolution spectroscopy, respectively. For both data sets the results of the statistical pipeline are at odds with those reported in the literature. The results of the clustering algorithms were subjected to a silhouette width analysis to compare the performance of the split into different numbers of MPs. We explicitly addressed the usually neglected problem of measurement errors, for which we relied on techniques that were recently introduced in the statistical literature. ![]() We adopted hierarchical clustering and partition methods. We focus our analysis on the red giant branch phase, where two data sets are available in the recent literature for low- and high-resolution spectroscopy. Using NGC 2808 as test case, we show the use of well-established statistical clustering methods. However, while data availability and quality have improved in the past decades, this is not always true for the techniques that are adopted to analyse them, which creates problems of objectivity for the claims and reproducibility.Īims. The finding of multiple stellar populations (MPs), which are defined by patterns in the stellar element abundances, is considered today a distinctive feature of globular clusters. Tognelli 2ĭipartimento di Fisica “Enrico Fermi”, Università di Pisa, Largo Pontecorvo 3, 56127 Pisa, ItalyĮ-mail: Institute of Physics of the Czech Academy of Sciences, Na Slovance 2, 182 21 Praha 8, Czech RepublicĬontext. Astronomical objects: linking to databases.Including author names using non-Roman alphabets.Suggested resources for more tips on language editing in the sciences ![]() Punctuation and style concerns regarding equations, figures, tables, and footnotes ![]()
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