J/ApJ/462/241 Ca abundance for Omega Cen red giants (Norris+ 1996)
The giant branch of ω Centauri. V. The calcium abundance distribution.
Norris J.E., Freeman K.C., Mighell K.J.
<Astrophys. J. 462, 241N (1996)>
=1996ApJ...462..241N 1996ApJ...462..241N (SIMBAD/NED BibCode)
ADC_Keywords: Stars, giant ; Abundances ; Clusters, globular
Keywords: globular clusters: individual (omega Centauri) - stars: abundances -
stars: late-type - stars: Population II
Description:
We present an unbiased catalog of calcium abundances for 517 red
giants brighter than MV~-1 in the chemically inhomogeneous globular
cluster omega Centauri. The basic features of the abundance
distribution are as follows: (1) few, if any, stars exist on the giant
branch of omega Cen with [Ca/H] less than -1.6; (2) there is a
well-defined peak in the distribution at [Ca/H]=-1.4, with a long tail
stretching up to ~[Ca/H]~-0.3; and (3) the distribution is bimodal
with a second smaller peak in the distribution at [Ca/H]=-0.9.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 53 521 Ca II line strength measurements and abundances
for omega Centauri giants
table2.dat 39 19 Globular cluster calibration data
table3.dat 32 101 Coordinates (J2000) for omega Centauri giants
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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2- 5 I4 --- Star Star name
8- 12 F5.2 mag Vmag V magnitude
16 I1 --- r_Vmag Source of V magnitude (1)
19- 22 F4.1 arcmin Dist Radial distance from cluster center
26- 30 F5.3 --- A(Ca) ? Ca II H & K line strength index (2)
34- 37 F4.2 --- W ? Calcium triplet (8498-8662A) index (3)
41- 43 A3 --- n Code of number of observations (4)
46- 50 F5.2 Sun [Ca/H] ? Calcium abundance
51- 52 A2 --- n_[Ca/H] [CH ] CH when CH stars
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Note (1): The source of magnitude is:
1: Cannon & Stobie 1973a (1973MNRAS.162..207C 1973MNRAS.162..207C),
Eggen 1972 (1972ApJ...172..639E 1972ApJ...172..639E), and Seitzer 1983
2: Lynga 1996 (J/A+AS/115/297)
3: Woolley et al. 1966 (1966ROAn....2....1W 1966ROAn....2....1W) and present work
Note (2): Strength index W8542+W8662 is formed with the equivalent
widths of the two strongest lines of the triplet as defined in
Armandroff et al. (1991AJ....101.1329A 1991AJ....101.1329A).
Note (3): The triplet index is defined by
A(Ca)=1-2.I{bar}(3916, 3985)/[I{bar}(3883, 3915)+I{bar}(3985, 40118)]
where I{bar}(L1, L2)={integral}{L1 to L2}ILdL/(L2-L1) and
IL is the measured flux at L as defined in
Norris et al. (1981ApJ...244..205N 1981ApJ...244..205N)
Note (4): Three-digit positional code giving number of observations
obtained with AAT (1), 1.9m telescope in 1992 (2) and 1993 (3).
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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- 8 A8 --- Cluster Cluster name
10- 16 A7 --- Star Star name (1)
18- 22 F5.2 mag Vmag V magnitude (2)
24- 27 F4.2 --- WNFM Calcium triplet index, from this work
29 I1 --- o_WNFM Number of observations
31- 34 F4.2 --- Wother ? Calcium line index from other works (3)
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Note (1): Nomenclature from:
Lee (1977b) for 47 Tuc (1977A&AS...27..381)
Lee (1977a) for M4 (1977A&AS...27..367)
Woolley et al. (1961) for NGC 6397 (1961RGOB...43..303W 1961RGOB...43..303W)
Alcaino (1972) for NGC 6752 (1972A&A....16..220A 1972A&A....16..220A)
Note (2): Nomenclature from:
Lee (1977b) for 47 Tuc (1977A&AS...27..381)
Lee (1977a) for M4 (1977A&AS...27..367)
Cannon (1974) for NGC 6397 (1974MNRAS.167..551C 1974MNRAS.167..551C)
Cannon & Stobie (1973b) for NGC 6752 (1973MNRAS.162..227C 1973MNRAS.162..227C)
Note (3): From Armandroff & Da Costa (1991AJ....101.1329A 1991AJ....101.1329A) and
Da Costa et al. (1992AJ....104..154D 1992AJ....104..154D)
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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- 4 I4 --- Star Star name (Section 2)
7- 10 I4 --- Lynga ? Star name, from Lynga 1996 catalog
(see Appendix B)
12- 13 I2 h RAh Right ascension (J2000)
15- 16 I2 min RAm Right ascension (J2000)
18- 21 F4.1 s RAs Right ascension (J2000)
23 A1 --- DE- Declination sign
24- 25 I2 deg DEd Declination (J2000)
27- 28 I2 arcmin DEm Declination (J2000)
30- 31 I2 arcsec DEs Declination (J2000)
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Table2: Globular cluster calibration data
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Cluster VHB <W'> [Fe/H] [Ca/Fe]
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47 Tuc 14.06 5.08 -0.75 0.15
M4 13.35 4.23 -1.15 0.20
NGC 6397 12.90 2.52 -2.00 0.35
NGC 6752 13.95 4.59 -1.55 0.30
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Notes: VHB : V - V(Horizontal Branch), from
Armandroff & Da Costa (1991AJ....101.1329A 1991AJ....101.1329A)
and Da Costa et al. (1992AJ....104..154D 1992AJ....104..154D)
<W'> : Mean reduced calcium triplet index
Abundances: Based on data from Zinn (1985ApJ...293..424Z 1985ApJ...293..424Z) and
Norris & Da Costa (1995ApJ...447..680N 1995ApJ...447..680N)
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Courtesy: John Norris
References:
Alcaino, 1972, A&A 16, 220 =1972A&A....16..220A 1972A&A....16..220A
Armandroff & Da Costa, 1991, AJ, 101, 1329 =1991AJ....101.1329A 1991AJ....101.1329A
Cannon & Stobie, 1973a, MNRAS 162, 207 =1973MNRAS.162..207C 1973MNRAS.162..207C
Cannon & Stobie, 1973b, MNRAS 162, 227 =1973MNRAS.162..227C 1973MNRAS.162..227C
Cannon, 1974, MNRAS 167, 551 =1974MNRAS.167..551C 1974MNRAS.167..551C
Da Costa et al., 1992, AJ 104, 154 =1992AJ....104..154D 1992AJ....104..154D
Eggen, 1972, ApJ 172, 639 =1972ApJ...172..639E 1972ApJ...172..639E
Lee, 1977a, A&AS 27, 367 =1977A&AS...27..367L 1977A&AS...27..367L
Lee, 1977b, A&AS 27, 381 =1977A&AS...27..381L 1977A&AS...27..381L
Lynga, 1996, A&AS 115, 297 =CDS Catalogue J/A+AS/115/297
Norris et al., 1981, ApJ 244, 205 =1981ApJ...244..205N 1981ApJ...244..205N
Norris & Da Costa, 1995, ApJ 447, 680 =1995ApJ...447..680N 1995ApJ...447..680N
Seitzer, 1983, Ph.D.. thesis, Univ. of Virginia
Woolley et al., 1961, R. Obs. Bull., No. 43 =1961RGOB...43..303W 1961RGOB...43..303W
Woolley et al., 1966, R. Obs. Ann., No. 2 =1966ROAn....2....1W 1966ROAn....2....1W
Zinn, 1985, ApJ 293, 424 =1985ApJ...293..424Z 1985ApJ...293..424Z
(End) Patricia Bauer [CDS] 06-Sep-1996