J/ApJ/681/1505 Abundances of red giants in ω Cen (Johnson+, 2008)
Fe and Al abundances for 180 red giants in the globular cluster omega Centauri
(NGC 5139).
Johnson C.I., Pilachowski C.A., Simmerer J., Schwenk D.
<Astrophys. J., 681, 1505-1523 (2008)>
=2008ApJ...681.1505J 2008ApJ...681.1505J (SIMBAD/NED BibCode)
ADC_Keywords: Stars, giant ; Abundances, [Fe/H] ; Radial velocities ;
Clusters, globular ; Equivalent widths ; Photometry ; Spectroscopy
Keywords: globular clusters: general - stars: abundances - stars: Population II
globular clusters: individual (ω Centauri, NGC 5139)
Abstract:
We present radial velocities and Fe and Al abundances for 180 red
giant branch (RGB) stars in the Galactic globular cluster Omega
Centauri (ω Cen). The majority of our data lie in the range
11.0<V<13.5, which covers the RGB from about 1mag above the horizontal
branch to the RGB tip. The selection procedures are biased toward
preferentially observing the more metal-poor and luminous stars of
ω Cen. Abundances were determined using equivalent width
measurements and spectrum synthesis analyses of moderate resolution
spectra (R∼13000) obtained with the Blanco 4m telescope and Hydra
multifiber spectrograph. Our results are in agreement with previous
studies as we find at least four different metallicity populations
with [Fe/H]=-1.75, -1.45, -1.05, and -0.75, with a full range of
-2.20≲[Fe/H]≲-0.70. Results seem to fit in the adopted scheme that
star formation occurred in ω Cen over >1Gyr.
Description:
The observations of all 180 giants in ω Cen were obtained with
the Blanco 4m telescope using the Hydra multifiber positioner and
bench spectrograph at the Cerro Tololo Inter-American Observatory, in
UT 2003 July 17, 18 and 19. Spectra include the region from
6500-6750Å.
Target stars, coordinates, photometry, and membership probability were
taken from the proper motion study by van Leeuwen et al. (2000, Cat.
J/A+A/360/472).
Objects:
----------------------------------------------------------
RA (2000) DE Designation(s)
----------------------------------------------------------
13 26 45.9 -47 28 37 omega Centauri = NGC 5139
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File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table2.dat 28 180 *Radial velocity and membership information
table3.dat 57 180 Photometry and model atmosphere parameters
table4.dat 24 23 Line list
table5.dat 89 180 Equivalent widths
table6.dat 41 180 Derived abundances
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Note on table2.dat : The cluster mean radial velocity, error and 1σ values
are given here:
---------------------
HRV e_HRV Sigma
---------------------
231.8 1.6 0.8
232.0 1.5 0.6
11.7 0.3 0.6
---------------------
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See also:
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/A+A/445/503 : Radial velocities in Omega Cen (NGC5139) (Reijns+, 2006)
J/ApJ/647/1075 : Age-metallicity relation of ω Cen (Stanford+, 2006)
J/ApJ/661/L155 : Radial velocities Rgb stars in omega Cen (Pancino+, 2007)
J/MNRAS/396/2183 : Radial velocities of red giants in ω Cen (Sollima+,
2009)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 I5 --- Star Van Leeuwen et al. (2000, Cat. J/A+A/360/472)
identification (G1)
7- 10 I4 --- OName ? Woolley (1966ROAn....2....1W 1966ROAn....2....1W) identification
number (G2)
12- 16 F5.1 km/s HRV Heliocentric radial velocity
18- 20 F3.1 km/s e_HRV Error in HRV
22- 24 F3.1 --- sigma The 1σ deviation from mean
26- 28 I3 % Mm ? van Leeuwen et al. (2000, Cat. J/A+A/360/472)
membership probability
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Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 I5 --- Star Van Leeuwen et al. (2000, Cat. J/A+A/360/472)
identification (G1)
7- 10 I4 --- OName ? Woolley (1966ROAn....2....1W 1966ROAn....2....1W) identification
number (G2)
12- 17 F6.3 mag Vmag van Leeuwen et al. (2000, Cat. J/A+A/360/472)
V band magnitude
19- 23 F5.3 mag B-V The (B-V) color index
25- 29 F5.3 mag V-K The (V-Ks) color index (1)
31- 36 F6.3 mag VMAG Extinction corrected absolute V band magnitude
38- 41 I4 K Teff Effective temperature
43- 46 F4.2 [cm/s2] log(g) Log of surface gravity
48- 52 F5.2 [Sun] [Fe/H] Metallicity
54- 57 F4.2 km/s Vturb Microturbulent velocity
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Note (1): Transformed to the Carlos Sanchez Telescope (TCS) photometric system.
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 5 A5 --- Ion Element name
7- 13 F7.2 0.1nm Wave Wavelength in Angstroms
15- 18 F4.2 eV ExPot Excitation Potential
20- 24 F5.2 [-] log(gf) Log of oscillator strength
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 I5 --- Star Van Leeuwen et al. (2000, Cat. J/A+A/360/472)
identification (G1)
7- 8 I2 0.1pm W6516 ? Equivalent width at 6516 Angstroms (1)
10- 11 I2 0.1pm W6533 ? Equivalent width at 6533 Angstroms (1)
13- 15 I3 0.1pm W6546 ? Equivalent width at 6546 Angstroms (1)
17- 19 I3 0.1pm W6551 ? Equivalent width at 6551 Angstroms (1)
21- 23 I3 0.1pm W6574 ? Equivalent width at 6574 Angstroms (1)
25- 27 I3 0.1pm W6592 Equivalent width at 6592 Angstroms (1)
29- 31 I3 0.1pm W6593 ? Equivalent width at 6593 Angstroms (1)
33- 34 I2 0.1pm W6597 ? Equivalent width at 6597 Angstroms (1)
36- 38 I3 0.1pm W6608 ? Equivalent width at 6608 Angstroms (1)
40- 42 I3 0.1pm W6609 ? Equivalent width at 6609 Angstroms (1)
44- 46 I3 0.1pm W6625 ? Equivalent width at 6625 Angstroms (1)
48- 49 I2 0.1pm W6627 ? Equivalent width at 6627 Angstroms (1)
51- 52 I2 0.1pm W6633 ? Equivalent width at 6633 Angstroms (1)
54- 55 I2 0.1pm W6646 ? Equivalent width at 6646 Angstroms (1)
57- 59 I3 0.1pm W6648 ? Equivalent width at 6648 Angstroms (1)
61- 63 I3 0.1pm W6677 ? Equivalent width at 6677 Angstroms (1)
65- 66 I2 0.1pm W6696 ? Equivalent width at 6696 Angstroms (1)
67 A1 --- f_W6696 [S] Flag on W6696 (2)
69- 70 I2 0.1pm W6698 ? Equivalent width at 6698 Angstroms (1)
71 A1 --- f_W6698 [S] Flag on W6698 (2)
73- 75 I3 0.1pm W6703 ? Equivalent width at 6703 Angstroms (1)
77- 79 I3 0.1pm W6710 ? Equivalent width at 6710 Angstroms (1)
81- 82 I2 0.1pm W6726 ? Equivalent width at 6726 Angstroms (1)
84- 85 I2 0.1pm W6733 ? Equivalent width at 6733 Angstroms (1)
87- 89 I3 0.1pm W6739 ? Equivalent width at 6739 Angstroms (1)
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Note (1): In units of milli-Angstroms (mÅ=0.1pm)
Note (2): 'S' indicates a synthetic spectrum comparison method was used.
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Byte-by-byte Description of file: table6.dat
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Bytes Format Units Label Explanations
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1- 5 I5 --- Star Van Leeuwen et al. (2000, Cat. J/A+A/360/472)
identification (G1)
7- 10 F4.2 [-] logFe Log of Fe number ε abundance (1)
12- 16 F5.2 [Sun] [Fe/H] Log of Fe/H number abundance relative to
solar (2)
18- 19 I2 --- o_[Fe/H] Number of lines used to derive [Fe/H]
21- 24 F4.2 [Sun] e_[Fe/H] The σ/N0.5 deviation of [Fe/H]
26- 29 F4.2 [-] logAl ? Log of Al number abundance (1)
31- 34 F4.2 [Sun] [Al/H] ? Log of Al/H number abundance relative to
solar (3)
36 I1 --- o_[Al/H] ? Number of lines used to derive [Al/H]
38- 41 F4.2 [Sun] e_[Al/H] ? The σ/N0.5 deviation of [Al/H]
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Note (1): Where log(H)=12
Note (2): Assumed the solar logε(Fe)=7.52 (Sneden et al.,
1991AJ....102.2001S 1991AJ....102.2001S).
Note (3): Assumed the solar logε(Al)=6.47 (Anders & Grevesse,
1989GeCoA..53..197A 1989GeCoA..53..197A).
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Global notes:
Note (G1): Objects are designated by <Cl* NGC 5139 Leid NNNNN> in Simbad.
Note (G2): Objects are in Simbad.
History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 03-Nov-2010