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http://hdl.handle.net/20.500.12386/34670
Title: | The HST Large Programme on NGC 6752 - II. Multiple populations at the bottom of the main sequence probed in NIR | Authors: | Milone, A. P. Marino, A. F. BEDIN, Luigi Anderson, J. Apai, D. Bellini, A. Dieball, A. Salaris, M. Libralato, M. Nardiello, D. Bergeron, P. Burgasser, A. J. Rees, J. M. Rich, R. M. Richer, H. B. |
Issue Date: | 2019 | Journal: | MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY | Number: | 484 | Issue: | 3 | First Page: | 4046 | Abstract: | Historically, multiple populations in globular clusters (GCs) have been mostly studied from ultraviolet and optical filters down to stars that are more massive than ∼0.6 M_{\odot }. Here, we exploit deep near-infrared (NIR) photometry from the Hubble Space Telescope to investigate multiple populations among M-dwarfs in the GC NGC 6752. We discovered that the three main populations (A, B, and C), previously observed in the brightest part of the colour-magnitude diagram (CMD), define three distinct sequences that run from the main-sequence (MS) knee towards the bottom of the MS (∼0.15 {M}_{\odot }). These results, together with similar findings on NGC 2808, M 4, and ω Centauri, demonstrate that multiple sequences of M-dwarfs are common features of the CMDs of GCs. The three sequences of low-mass stars in NGC 6752 are consistent with stellar populations with different oxygen abundances. The range of [O/Fe] needed to reproduce the NIR CMD of NGC 6752 is similar to the oxygen spread inferred from high-resolution spectroscopy of red giant branch (RGB) stars. The relative numbers of stars in the three populations of M-dwarfs are similar to those derived among RGB and MS stars more massive than ∼0.6 M_{\odot }. As a consequence, the evidence that the properties of multiple populations do not depend on stellar mass is a constraint for the formation scenarios. | URI: | http://hdl.handle.net/20.500.12386/34670 | URL: | http://arxiv.org/abs/1901.07230v1 https://academic.oup.com/mnras/article/484/3/4046/5301422 |
ISSN: | 0035-8711 | DOI: | 10.1093/mnras/stz277 | Bibcode ADS: | 2019MNRAS.484.4046M | Fulltext: | open |
Appears in Collections: | 1.01 Articoli in rivista |
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stz277.pdf | PDF editoriale | 1.97 MB | Adobe PDF | View/Open |
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