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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 (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:
FileName Lrecl Records Explanations
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
Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
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
Note (1): The source of magnitude is: 1: Cannon & Stobie 1973a (1973MNRAS.162..207C), Eggen 1972 (1972ApJ...172..639E), and Seitzer 1983 2: Lynga 1996 (J/A+AS/115/297) 3: Woolley et al. 1966 (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). 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) Note (4): Three-digit positional code giving number of observations obtained with AAT (1), 1.9m telescope in 1992 (2) and 1993 (3).
Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
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)
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) Alcaino (1972) for NGC 6752 (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) Cannon & Stobie (1973b) for NGC 6752 (1973MNRAS.162..227C) Note (3): From Armandroff & Da Costa (1991AJ....101.1329A) and Da Costa et al. (1992AJ....104..154D)
Byte-by-byte Description of file: table3.dat
Bytes Format Units Label Explanations
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)
Table2: Globular cluster calibration data ---------------------------------------------------------- Cluster VHB <W'> [Fe/H] [Ca/Fe] ---------------------------------------------------------- 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 ---------------------------------------------------------- Notes: VHB : V - V(Horizontal Branch), from Armandroff & Da Costa (1991AJ....101.1329A) and Da Costa et al. (1992AJ....104..154D) <W'> : Mean reduced calcium triplet index Abundances: Based on data from Zinn (1985ApJ...293..424Z) and Norris & Da Costa (1995ApJ...447..680N) ---------------------------------------------------------- Courtesy: John Norris References: Alcaino, 1972, A&A 16, 220 =1972A&A....16..220A Armandroff & Da Costa, 1991, AJ, 101, 1329 =1991AJ....101.1329A Cannon & Stobie, 1973a, MNRAS 162, 207 =1973MNRAS.162..207C Cannon & Stobie, 1973b, MNRAS 162, 227 =1973MNRAS.162..227C Cannon, 1974, MNRAS 167, 551 =1974MNRAS.167..551C Da Costa et al., 1992, AJ 104, 154 =1992AJ....104..154D Eggen, 1972, ApJ 172, 639 =1972ApJ...172..639E Lee, 1977a, A&AS 27, 367 =1977A&AS...27..367L Lee, 1977b, A&AS 27, 381 =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 Norris & Da Costa, 1995, ApJ 447, 680 =1995ApJ...447..680N Seitzer, 1983, Ph.D.. thesis, Univ. of Virginia Woolley et al., 1961, R. Obs. Bull., No. 43 =1961RGOB...43..303W Woolley et al., 1966, R. Obs. Ann., No. 2 =1966ROAn....2....1W Zinn, 1985, ApJ 293, 424 =1985ApJ...293..424Z
(End) Patricia Bauer [CDS] 06-Sep-1996
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