Detailed abundances of 15 stars in the metal-poor globular cluster NGC 4833
We have observed 15 red giant stars in the relatively massive, metal-poor globular cluster NGC 4833 using the Magellan Inamori Kyocera Echelle spectrograph at Magellan. We calculate stellar parameters for each star and perform a standard abundance analysis to derive abundances of 43 species of 39 el...
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Veröffentlicht in: | Monthly notices of the Royal Astronomical Society 2015-06, Vol.449 (4), p.3889-3910 |
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Sprache: | eng |
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Zusammenfassung: | We have observed 15 red giant stars in the relatively massive, metal-poor globular cluster NGC 4833 using the Magellan Inamori Kyocera Echelle spectrograph at Magellan. We calculate stellar parameters for each star and perform a standard abundance analysis to derive abundances of 43 species of 39 elements, including 20 elements heavier than the iron group. We derive 〈[Fe/H]〉 = −2.25 ± 0.02 from Fe i lines and 〈[Fe/H]〉 = −2.19 ± 0.013 from Fe ii lines. We confirm earlier results that found no internal metallicity spread in NGC 4833, and there are no significant star-to-star abundance dispersions among any elements in the iron group (19 ≤Z ≤ 30). We recover the usual abundance variations among the light elements C, N, O, Na, Mg, Al, and possibly Si. The heavy-element distribution reflects enrichment by r-process nucleosynthesis ([Eu/Fe] = +0.36 ± 0.03), as found in many other metal-poor globular clusters. We investigate small star-to-star variations found among the neutron-capture elements, and we conclude that these are probably not real variations. Upper limits on the Th abundance, log ϵ (Th/Eu) |
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ISSN: | 0035-8711 1365-2966 |
DOI: | 10.1093/mnras/stv546 |