J/ApJ/698/2048 Abundances of red giants in ω Cen (Johnson+, 2009)
A large sample study of red giants in the globular cluster omega Centauri
(NGC 5139).
Johnson C.I., Pilachowski C.A., Rich R.M., Fulbright J.P.
<Astrophys. J., 698, 2048-2065 (2009)>
=2009ApJ...698.2048J 2009ApJ...698.2048J
ADC_Keywords: Stars, giant ; Equivalent widths ; Abundances, [Fe/H] ;
Clusters, globular ; Photometry, infrared
Keywords: globular clusters: general - globular clusters: individual
(omega Centauri, NGC 5139) - stars: abundances - stars: Population II
Abstract:
We present abundances of several light, α, Fe-peak, and
neutron-capture elements for 66 red giant branch (RGB) stars in the
Galactic globular cluster Omega Centauri (ω Cen). Our
observations lie in the range 12.0<V<13.5 and focus on the
intermediate and metal-rich RGBs. Abundances were determined using
equivalent width measurements and spectrum synthesis analyses of
moderate resolution (R∼18000) spectra obtained with the Blanco 4m
telescope and Hydra multifiber spectrograph. Combining these data with
previous work, we find that there are at least four peaks in the
metallicity distribution function at [Fe/H]=-1.75, -1.45, -1.05, and
-0.75, which correspond to about 55%, 30%, 10%, and 5% of our sample,
respectively. We conclude that the metal-rich population must be at
least 1-2Gyr younger than the metal-poor stars, owing to the long
timescales needed for strong s-process enrichment and the development
of a large contingent of mass transfer binaries.
Description:
All observations were taken at the Cerro Tololo Inter-American
Observatory on 2006 May 26 and 2006 May 27 using the Blanco 4m
telescope and Hydra multifiber spectrograph.
Target stars, coordinates, photometry, and membership probabilities
were taken from the proper motion study by van Leeuwen et al. (2000,
Cat. J/A+A/360/472).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 84 66 Photometry, membership, and atmospheric parameters
ew.dat 36 5676 Equivalent Widths
table3.dat 95 65 Derived abundances
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See also:
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
J/ApJS/99/637 : Equivalent widths for 54 red giants (Norris+ 1995)
J/ApJ/462/241 : Ca abundance for Omega Cen red giants (Norris+ 1996)
J/A+A/360/472 : Proper motions in omega Centauri (van Leeuwen+, 2000)
J/MNRAS/357/265 : BVI photometry of omega Cen red giants (Sollima+, 2005)
J/ApJ/681/1505 : Abundances of red giants in ω Cen (Johnson+, 2008)
J/MNRAS/396/2183 : Radial velocities of red giants in ω Cen (Sollima+
2009)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 5 I5 --- LEID van Leeuwen et al. identification number (G1)
7- 10 I4 --- ROA ? Woolley (1966ROAn....2....1W 1966ROAn....2....1W) identification
number
12- 17 F6.3 mag Vmag The V band magnitude
19- 23 F5.3 mag B-V The (B-V) color index
25- 30 F6.3 mag Jmag 2MASS Johnson J band magnitude
32- 37 F6.3 mag Hmag 2MASS Johnson H band magnitude
39- 44 F6.3 mag Ksmag 2MASS Johnson Ks band magnitude
46- 51 F6.3 mag VMAG Absolute V band magnitude
53- 55 I3 % Prob van Leeuwen et al. 2000, Cat. J/A+A/360/472
membership probability
57- 60 I4 K Teff Effective temperature
62- 65 F4.2 [cm/s2] log(g) Log surface gravity
67- 71 F5.2 [Sun] [Fe/H] Average metallicity
73- 76 F4.2 km/s Vt Turbulent velocity ξ
78- 80 I3 --- SN6125 ? Signal-to-Noise at 612.5nm
82- 84 I3 --- SN6670 ? Signal-to-Noise at 667.0nm
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Byte-by-byte Description of file: ew.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 I5 --- LEID van Leeuwen et al. identification number (G1)
7- 13 F7.2 0.1nm lambda Wavelength in Angstroms
15- 19 A5 --- Ion Ion identification
21- 24 F4.2 eV ExPot Excitation potential
26- 30 F5.2 [---] log(gf) Log of the oscillator strength
32- 34 I3 0.1pm EW ? Equivalent width, in mÅ = 10-13m (1)
36 A1 --- f_EW [s] Flag indicating synthetic value
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Note (1): Equivalent widths were measured by interactively fitting multiple
Gaussians to isolated and blended line profiles. Suitable lines were
identified using the solar and Arcturus atlases (at
http://www.noao.edu/dpp/library.html). Our adopted log(gf) values were
determined by measuring equivalent widths in the solar atlas and then
modified until all lines yielded abundances consistent with the
photospheric values given in Anders & Grevesse (1989GeCoA..53..197A 1989GeCoA..53..197A).
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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 --- LEID van Leeuwen et al. identification number (G1)
7- 11 F5.2 [Sun] [Fe1/H] Derived [FeI/H] abundance
13- 17 F5.2 [Sun] [Fe2/H] ? Derived [FeII/H] abundance
19- 23 F5.2 [Sun] [Fe/H] Average derived [Fe/H] abundance
25- 29 F5.2 [Sun] [Na1/Fe] ? Derived [NaI/Fe] abundance
31- 35 F5.2 [Sun] [Al1/Fe] ? Derived [AlI/Fe] abundance
37- 41 F5.2 [Sun] [Ca1/Fe] ? Derived [CaI/Fe] abundance
43- 47 F5.2 [Sun] [Sc1/Fe] ? Derived [ScI/Fe] abundance
49- 53 F5.2 [Sun] [Sc2/Fe] ? Derived [ScII/Fe] abundance
55- 59 F5.2 [Sun] [Sc/Fe] ? Average derived [Sc/Fe] abundance
61- 65 F5.2 [Sun] [Ti1/Fe] ? Derived [TiI/Fe] abundance
67- 71 F5.2 [Sun] [Ti2/Fe] ? Derived [TiII/Fe] abundance
73- 77 F5.2 [Sun] [Ti/Fe] ? Average derived [Ti/Fe] abundance
79- 83 F5.2 [Sun] [Ni1/Fe] ? Derived [NiI/Fe] abundance
85- 89 F5.2 [Sun] [La2/Fe] ? Derived [LaII/Fe] abundance
91- 95 F5.2 [Sun] [Eu2/Fe] ? Derived [EuII/Fe] abundance
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Global notes:
Note (G1): van Leeuwen et al. 2000, Cat. J/A+A/360/472 identification number;
<Cl* NGC 5139 Leid NNNNN> in Simbad.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 22-Jun-2011