J/ApJ/780/94 Abundances of red giants in 47 Tuc (Cordero+, 2014)
Detailed abundances for a large sample of giant stars in the globular cluster
47 Tucanae (NGC 104).
Cordero M.J., Pilachowski C.A., Johnson C.I., McDonald I., Zijlstra A.A.,
Simmerer J.
<Astrophys. J., 780, 94 (2014)>
=2014ApJ...780...94C 2014ApJ...780...94C
ADC_Keywords: Clusters, globular ; Stars, giant ; Effective temperatures ;
Abundances ; Stars, distances
Keywords: globular clusters: individual: 47 Tucanae - stars: abundances -
stars: Population II
Abstract:
47 Tuc is an ideal target to study chemical evolution and globular
cluster (GC) formation in massive more metal-rich GCs, as it is the
closest massive GC. We present chemical abundances for O, Na, Al, Si,
Ca, Ti, Fe, Ni, La, and Eu in 164 red giant branch stars in the
massive GC 47 Tuc using spectra obtained with both the Hydra
multifiber spectrograph at the Blanco 4m telescope and the FLAMES
multiobject spectrograph at the Very Large Telescope. We find an
average [Fe/H]=-0.79±0.09dex, consistent with literature values, as
well as overabundances of alpha-elements ([α/Fe]∼0.3dex). The
n-capture process elements indicate that 47 Tuc is r process-dominated
([Eu/La]=+0.24), and the light elements O, Na, and Al exhibit
star-to-star variations. The Na-O anticorrelation, a signature
typically seen in Galactic GCs, is present in 47 Tuc, and extends to
include a small number of stars with [O/Fe]~-0.5. Additionally, the
[O/Na] ratios of our sample reveal that the cluster stars can be
separated into three distinct populations. A Kolmogorov-Smirnov test
demonstrates that the O-poor/Na-rich stars are more centrally
concentrated than the O-rich/Na-poor stars. The observed number and
radial distribution of 47 Tuc's stellar populations, as distinguished
by their light element composition, agrees closely with the results
obtained from photometric data. We do not find evidence supporting a
strong Na-Al correlation in 47 Tuc, which is consistent with current
models of asymptotic giant branch nucleosynthesis yields.
Description:
Spectroscopic observations were obtained using two multifiber
positioners and spectrographs: Hydra on the Blanco 4m telescope at the
Cerro Tololo Interamerican Observatory during two observing runs in
2003 July (2003 July 18-19, λ=6490-6800Å) and 2010 August 23
(λ=6100-6400Å, R=20000), and FLAMES-GIRAFFE on the Very
Large Telescope (VLT)-UT2 telescope at the European Southern
Observatory on Cerro Paranal during a single observing run in 2011
November 26 (λ∼6115-7000Å, R=20000).
Stars observed with Hydra were selected for observation from the
proper motion survey of Tucholke 1992 (cat. J/A+AS/93/293). Stars
observed with FLAMES were selected from photometry compiled by
McDonald et al. 2011 (cat. J/ApJS/193/23).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 102 181 Atmospheric parameters and abundances
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See also:
VII/202 : Globular Clusters in the Milky Way (Harris, 1997)
J/A+A/550/A34 : Abundances of red giants in M4 and 47 Tuc (Carretta+, 2013)
J/ApJS/193/23 : Fundamental stellar parameters in 47 Tucanae (McDonald+, 2011)
J/ApJ/713/L1 : Lithium and proton-capture elements in 47 Tuc (D'Orazi+, 2010)
J/A+A/505/139 : Abundances of red giants in 17 GCs (Carretta+, 2009)
J/A+A/505/117 : Abundances of red giants in 15 GCs (Carretta+, 2009)
J/AJ/135/1551 : Abundances of stars in 47 Tuc (Koch+, 2008)
J/A+A/435/657 : Equivalent widths of 5 giants in 47 Tuc (Alves-Brito+, 2005)
J/A+AS/93/293 : Astrometry of globular clusters (47 Tuc) (Tucholke 1992)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 6 A6 --- Inst Instrument (Hydra or FLAMES) (1)
8 A1 --- r_Star [DEFMTt] Reference for identification number (2)
9- 13 I5 --- Star Star identification
15- 18 I4 K Teff [3650/5525] Effective temperature
20- 23 F4.2 [cm/s2] logg [0.41/2.87] Log of the surface gravity
25- 29 F5.2 [Sun] [Fe/H] [-1/-0.55] Metallicity
31- 34 F4.2 km/s Vt [1.35/2.6] Microturbulent velocity
36- 41 F6.3 [Sun] [O/Fe] [-0.52/0.6]? Log O/Fe number abundance ratio
43- 49 F7.3 [Sun] [Na/Fe] [-0.05/222]? Log Na/Fe number abundance ratio
51- 56 F6.3 [Sun] [Al/Fe] [-0.09/0.775]? Log Al/Fe number abundance ratio
58- 61 F4.2 [Sun] [Si/Fe] [0.01/0.65]? Log Si/Fe number abundance ratio
63- 67 F5.2 [Sun] [Ca/Fe] [-0.09/0.47]? Log Ca/Fe number abundance ratio
69- 73 F5.2 [Sun] [Ti/Fe] [-0.11/0.59]? Log Ti/Fe number abundance ratio
75- 79 F5.2 [Sun] [Ni/Fe] [-0.25/0.2]? Log Ni/Fe number abundance ratio
81- 88 F8.2 [Sun] [La/Fe] [-0.12/11111]? Log La/Fe number abundance ratio
90- 93 F4.2 [Sun] [Eu/Fe] [0.04/0.83]? Log Eu/Fe number abundance ratio
95- 96 A2 --- Pop Population generation (P=Primordial,
I=Intermediate, IE=Intermediate-Extreme)
98-102 F5.2 arcmin Dist [0.88/21.23]? Distance from 47 Tuc center
(RA=00:24:05.67, Dec=-72:04:52.6; J2000)
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Note (1): The two spectrographs are:
hydra = Hydra multifiber spectrograph at the Blanco 4m telescope at the
Cerro Tololo Interamerican Observatory;
FLAMES = FLAMES multiobject spectrograph at the Very Large Telescope at the
European Southern Observatory on Cerro Paranal.
Note (2): The identification numbers were taken from:
(no prefix) = Lee (1977A&AS...27..381L 1977A&AS...27..381L)
D,E,F = Taken from Chun & Freeman (1978AJ.....83..376C 1978AJ.....83..376C);
M = McDonald & van Loon 2011 (J/ApJS/193/23),
<[MBV2011] NNNNN> in Simbad
T = Tucholke 1992 (J/A+AS/93/293), <Cl* NGC 104 Tuc NNNN> in Simbad
t = Tucholke 1992 (added at CDS, was missing in the original table)
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History:
From electronic version of the journal
(End) Greg Scwharz [AAS], Sylvain Guehenneux [CDS] 29-Jan-2015