J/MNRAS/464/2730 M28 red giant branch stars abundances (Villanova+, 2017)
A spectroscopic study of the globular cluster M28 (NGC 6626).
Villanova S., Moni Bidin C., Mauro F., Munoz C., Monaco L.
<Mon. Not. R. Astron. Soc., 464, 2730-2740 (2017)>
=2017MNRAS.464.2730V 2017MNRAS.464.2730V (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, globular ; Abundances
Keywords: globular clusters: individual: M28 (NGC 6626)
Abstract:
We present the abundance analysis for a sample of 17 red giant branch
stars in the metal-poor globular cluster M28 based on high-resolution
spectra. This is the first extensive spectroscopic study of this
cluster. We derive abundances of O, Na, Mg, Al, Si, Ca, Ti, V, Cr, Mn,
Fe, Co, Ni, Cu, Zn, Y, Zr, Ba, La, Ce, and Eu. We find a metallicity
of [Fe/H]=-1.29±0.01 and an α-enhancement of +0.34±0.01
(errors on the mean), typical of halo globular clusters in this
metallicity regime. A large spread is observed in the abundances of
light elements O, Na, and Al. Mg also shows an anti-correlation with
Al with a significance of 3σ. The cluster shows a Na-O
anti-correlation and a Na-Al correlation. This correlation is not
linear but 'segmented' and that the stars are not distributed
continuously, but form at least three well-separated sub-populations.
In this aspect, M28 resembles NGC 2808 that was found to host at least
five sub-populations. The presence of a Mg-Al anti-correlation favour
massive AGB stars as the main polluters responsible for the
multiple-population phenomenon.
Description:
Our data set consists of high-resolution spectra collected at the
FLAMES@UVES spectrograph mounted at the VLT-UT2 telescope. Targets
were selected from the infrared photometry collected with the Vista
Variables in the Via Lactea survey (VVV; Minniti et al.
2010NewA...15..433M 2010NewA...15..433M; Saito et al. 2012A&A...537A.107S 2012A&A...537A.107S, Cat. II/337).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 91 21 ID numbers, coordinates, VVV (J,H,K) magnitudes,
heliocentric radial velocities and atmospheric
parameters for the observed stars
table2.dat 61 21 Chemical abundances of our stars (Part 1)
table3.dat 63 21 Chemical abundances of our stars (Part 2)
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See also:
II/337 : VISTA Variables in the Via Lactea Survey DR1 (Saito+, 2012)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 5 I5 --- ID Identification number
7- 22 A16 --- 2MASS 2MASS identified (HHMMSSss+DDMMSSs)
24- 33 F10.6 deg RAdeg Right ascension (J2000)
35- 44 F10.6 deg DEdeg Declination (J2000)
46- 51 F6.3 mag Jmag VVV J magnitude
53- 58 F6.3 mag Hmag VVV H magnitude
60- 65 F6.3 mag Kmag VVV K magnitude
67- 70 F4.1 km/s HRV Heliocentric radial velocity
(cluster mean value 13.3±2.0)
72- 75 I4 K Teff Effective temperature
77- 80 F4.2 [cm/s2] logg Surface gravity
82- 85 F4.2 km/s vt Microturbulent velocity
87- 91 F5.2 [-] [Fe/H] Metallicity (cluster mean value -1.29±0.01)
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 5 I5 --- ID Identification number
9- 13 F5.2 [-] [OI/Fe] Abundance [OI/Fe] (cluster -0.12±0.09)
15- 19 F5.2 [-] [NaI/Fe] Abundance [NaI/Fe] (cluster 0.27±0.06)
21- 24 F4.2 [-] [MgI/Fe] Abundance [MgI/Fe] (cluster 0.47±0.01)
26- 29 F4.2 [-] [AlI/Fe] Abundance [AlI/Fe] (cluster 0.58±0.08)
31- 34 F4.2 [-] [SiI/Fe] Abundance [SiI/Fe] (cluster 0.34±0.01)
36- 39 F4.2 [-] [CaI/Fe] Abundance [CaI/Fe] (cluster 0.37±0.01)
41- 44 F4.2 [-] [Ti/Fe] Abundance [Ti/Fe] (cluster 0.32±0.01) (1)
46- 49 F4.2 [-] [VI/Fe] Abundance [VI/Fe] (cluster 0.34±0.02)
51- 55 F5.2 [-] [CrI/Fe] Abundance [CrI/Fe] (cluster -0.02±0.01)
57- 61 F5.2 [-] [MnI/Fe] Abundance [MnI/Fe] (cluster -0.38±0.01)
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Note (1): The abundance for Ti is the mean of those obtained from the neutral
and singly ionized species.
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 5 I5 --- ID Identification number
9- 13 F5.2 [-] [CoI/Fe] Abundance [CoI/Fe] (cluster 0.08±0.01)
15- 19 F5.2 [-] [NiI/Fe] Abundance [NiI/Fe] (cluster -0.03±0.01)
21- 25 F5.2 [-] [CuI/Fe] ?=- Abundance [CuI/Fe] (cluster -0.22±0.02)
27- 31 F5.2 [-] [ZnI/Fe] ?=- Abundance [ZnI/Fe] (cluster 0.18±0.03)
33- 36 F4.2 [-] [YII/Fe] ?=- Abundance [YII/Fe] (cluster 0.14±0.01)
38- 41 F4.2 [-] [ZrII/Fe] Abundance [ZrII/Fe] (cluster 0.26±0.01)
43- 46 F4.2 [-] [BaII/Fe] ?=- Abundance [BaII/Fe] (cluster 0.30±0.02)
48- 52 F5.2 [-] [LaII/Fe] ?=- Abundance [LaII/Fe] (cluster -0.03±0.04)
54- 58 F5.2 [-] [CeII/Fe] ?=- Abundance [CeII/Fe] (cluster -0.17±0.03)
60- 63 F4.2 [-] [EuII/Fe] Abundance [EuII/Fe] (cluster 0.35±0.02)
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 25-May-2018