J/A+A/705/A2 omega Cen stars abundances (Dondoglio+, 2026)
Tracing omega Centauri's origins:
Spatial and chemical signatures of its formation history.
Dondoglio E., Milone A.P., Marino A.F., Mastrobuono-Battisti A.,
Bortolan E., Legnardi M.V., Ziliotto T., Muratore F., Cordoni G.,
Lagioia E.P., Tailo M.
<Astron. Astrophys. 705, A2 (2026)>
=2026A&A...705A...2D 2026A&A...705A...2D (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, globular ; Populations, stellar ; Abundances ;
Spectroscopy ; Optical ; Ultraviolet ; Infrared
Keywords: stars: abundances - stars: chemically peculiar - stars: Population II
Abstract:
omega Centauri (omega Cen) is the most enigmatic Galactic globular
cluster (GC), with unmatched chemical complexity. We combine
photometric and spectroscopic catalogs to identify distinct stellar
populations within omega Cen, to investigate their spatial distribution
and chemical properties, uncovering new insights into the cluster's
formation history. Our population tagging identify the iron-poor stars
commonly found in most GCs: the first population (1P), with halo-like
chemical composition, and the second population (2P), enriched in
elements produced by proton-capture processes. Similarly, we divided
the iron-rich stars (the anomalous stars) into two groups: the AI and
the AII, which exhibit light-element abundance distributions similar
to 1P and 2P stars, respectively. The wide radial extension of our
dataset (five times the half-light radius), allowed to directly and
unambiguously compare, for the first time, the fraction of these
populations at different radii. We find that 2P and AII stars are more
centrally concentrated than the 1P and AI. The remarkable similarities
between the 1P-2P and AI-AII radial distributions strongly suggests
that these two groups of stars originated from similar mechanisms. Our
chemical analysis indicates that the 1P and AI stars (the lower
stream) developed their inhomogeneities through core-collapse
supernova (and possibly other massive stars' ejecta)
self-enrichment, as supported by their increasing alpha-element
abundances with [Fe/H]. These populations contributed
p-capture-processed material to the intracluster medium, from which
the chemically extreme 2P and AII stars (the upper stream) formed.
Additional polluters-such as intermediate-mass asymptotic giant
branch stars and Type Ia supernovae-likely played a role in shaping
the AII population. Finally, we propose that 2P and AII stars with
intermediate light-element abundances (the middle stream) formed via
dilution between the pure ejecta that created the upper stream and
lower-stream material.
Description:
This work explored the different stellar populations in omega Centauri
by exploring several photometric and spectroscopic datasets. We make
use of HST photometry in the UVIS/WFC3 and WFC/ACS (GO) published by
Milone et al. (2017MNRAS.469..800M 2017MNRAS.469..800M) and Haberle et al.
(2024ApJ...970..192H 2024ApJ...970..192H), along with Gaia DR3 photometry (Gaia
Collaboration et al. 2023). Spectroscopy is taken from the APOGEE DR17
(Abdurro'uf et al., 2022ApJS..259...35A 2022ApJS..259...35A, Cat. III/286) and the works
by Marino et al. (2011ApJ...731...64M 2011ApJ...731...64M, Cat. J/ApJ/731/64) and
Mucciarelli et al. (2018A&A...618A.134M 2018A&A...618A.134M, Cat. J/A+A/618/A134). We
combined information from these datasets to identify and chemically
characterize the diverse stellar populations in this cluster.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
catalog.dat 160 1313 Gaia ID, position, and abundances of our
spectroscopic dataset of omega Centauri
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See also:
I/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)
III/286 : APOGEE-2 DR17 final allStar catalog (Abdurro'uf+, 2022)
J/ApJ/731/64 : Spectroscopy of 300 RGBs in ω Cen (Marino+, 2011)
J/A+A/618/A134 : Omega Cen lower red giant stars abundances
(Mucciarelli+, 2018)
Byte-by-byte Description of file: catalog.dat
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Bytes Format Units Label Explanations
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1- 19 I19 --- GaiaDR3 ID of star in the Gaia DR3 catalog
21- 30 F10.6 deg RAdeg Right ascension (ICRS) at Ep=2016.0
32- 41 F10.6 deg DEdeg Declination (ICRS) at Ep=2016.0
43- 48 F6.3 --- A(Li) ?=99.999 Lithium abundance
51- 56 F6.3 --- [C/Fe] ?=99.999 Carbon-to-iron ratio
59- 64 F6.3 --- [N/Fe] ?=99.999 Nitrogen-to-iron ratio
67- 72 F6.3 --- [O/Fe] ?=99.999 Oxygen-to-iron ratio
77- 81 F5.2 --- [Na/Fe] ?=99.99 Sodium-to-iron ratio
85- 90 F6.3 --- [Mg/Fe] ?=99.999 Magnesium-to-iron ratio
94- 99 F6.3 --- [Al/Fe] ?=99.999 Aluminum-to-iron ratio
103-108 F6.3 --- [Si/Fe] ?=99.999 Silicon-to-iron ratio
111-116 F6.3 --- [K/Fe] ?=99.999 Potassium-to-iron ratio
120-125 F6.3 --- [Ca/Fe] ?=99.999 Calcium-to-iron ratio
128-133 F6.3 --- [Fe/H] ?=99.999 Iron-to-hydrogen ratio
137-142 F6.3 --- [Ba/Fe] ?=99.999 Barium-to-iron ratio
146-151 F6.3 --- [La/Fe] ?=99.999 Lanthanium-to-iron ratio
155-160 F6.3 --- [Ce/Fe] ?=99.990 Cerium-to-iron ratio
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Acknowledgements:
Emanuele Dondoglio, emanuele.dondoglio(at)inaf.it
(End) Patricia Vannier [CDS] 26-Sep-2025