J/A+A/681/A54 Abundances of 439 stars in Omega Centauri (Alvarez Garay+, 2024)
MgAl burning chain in Omega Centauri.
Alvarez Garay D.A., Mucciarelli A., Bellazzini M., Lardo C., Ventura P.
<Astron. Astrophys. 681, A54 (2024)>
=2024A&A...681A..54A 2024A&A...681A..54A (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, globular ; Stars, giant ; Abundances ;
Spectroscopy ; Optical
Keywords: stars: abundances - globular clusters: general - stars: general -
globular clusters: individual: omega Centauri
Abstract:
In this study, we report the results of the analysis of Fe, Mg, Al,
and Si abundances analysis for a sample of 439 stars in Omega
Centauri, using high-resolution spectra obtained with the VLT/FLAMES
multi-object spectrograph. Our analysis reveals the presence of four
distinct Fe populations, with the main peak occurring at a low
metallicity, consistent with previous literature findings. We observe
a discrete and pronounced Mg-Al anticorrelation, which exhibits
variations in shape and extension as a function of metallicity.
Specifically, this anticorrelation is present in stars with
metallicities lower than approximately -1.3dex, while it becomes less
evident or absent for higher [Fe/H] values. Additionally, we detect
(anti)correlations between Mg and Si, and between Al and Si, whose
extensions also vary with metallicity, similar to the Mg-Al
anticorrelation. These results suggest that the MgAl cycle plays a
crucial role in the formation of multiple populations in Omega
Centauri, with the presence of all (anti)correlations at metallicities
lower than -1.3dex, providing evidence for the burning of Mg at very
high temperatures (>108K), at least in the metal-poor regime.
Furthermore, we observe a clear trend of stars with [Al/Fe]>+0.5dex as
a function of metallicity, confirming for the first time the existence
of the two channels of Al production and destruction. This evidence
can help to provide further constraints on the potential nature of the
polluters responsible for the observed chemical anomalies in this
stellar system. Finally, we find that the two most metal-poor
populations identified in our sample are compatible with null or very
small metallicity dispersion and we discuss how this result fits into
a scenario where Omega Centauri is the remnant of a disrupted
nucleated dwarf galaxy.
Description:
This study is a cOntinuation of our recent work (Alvarez Garay et al.,
2022ApJ...928L..11A 2022ApJ...928L..11A) in which we analyzed the extension of the Mg-K
anticorrelation among the RGB stars of omega Centauri.
Table 1 includes the star name, the abundance of Fe and its
uncertainty, the abundance of Mg and its uncertainty, the abundance of
Al and its uncertainty, and the abundance of Si and its uncertainty.
99.99 stands for no measured abundance.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 57 439 Star names and chemical abundances of the
observed targets
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See also:
J/ApJ/722/1373 : ω Centauri giants abundances (Johnson+, 2010)
J/ApJ/731/64 : Spectroscopy of 300 RGBs in ω Cen (Marino+, 2011)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- ID Star name (NNNNNN_AAA) (1)
12- 16 F5.2 [-] [Fe/H] Abundance relative to the Sun for FeI
18- 21 F4.2 [-] e_[Fe/H] Uncertainty on the abundance for FeI
23- 27 F5.2 [-] [Mg/Fe] ?=99.99 Abundance relative to the Sun for MgI
29- 33 F5.2 [-] e_[Mg/Fe] ?=99.99 Uncertainty on the abundance for MgI
35- 39 F5.2 [-] [Al/Fe] ?=99.99 Abundance relative to the Sun for AlI
41- 45 F5.2 [-] e_[Al/Fe] ?=99.99 Uncertainty on the abundance for AlI
47- 51 F5.2 [-] [Si/Fe] ?=99.99 Abundance relative to the Sun for SiI
53- 57 F5.2 [-] e_[Si/Fe] ?=99.99 Uncertainty on the abundance for SiI
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Note (1): NNNNNN_M11 ang RGBNN_M11 are from Marino et al.,
2011ApJ...731...64M 2011ApJ...731...64M, Cat. J/ApJ/731/64,
NNNNNN_M11 are Cl* NGC 5139 WFI NNNNNN in Simbad
RGBNNN_M11 are [MMP2011] RGB NNN in Simbad,
NNNNN_J10 are from Johnson & Pilachowski, 2010ApJ...722.1373J 2010ApJ...722.1373J,
Cat. J/ApJ/722/1373, Cl* NGC 5139 LEID NNNNN in Simbad,
NNN_NDC, Norris & Da Costa (1995ApJ...447..680N 1995ApJ...447..680N),
NGC 5139 NNN in Simbad
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Acknowledgements:
Deimer Antonio Alvarez Garay, deimer.alvarezgaray2(at)unibo.it
(End) Patricia Vannier [CDS] 29-Nov-2023