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J/PASP/107/32       uvby-hk photometry in M22  (Anthony-Twarog+ 1995)

CN and Ca abundance variations among the giants in M 22 Anthony-Twarog B.J., Twarog B.A., Craig J. <Publ. Astron. Soc. Pac. 107, 32 (1995)> =1995PASP..107...32A (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, globular ; Photometry, K-line ; Photometry, uvby Astract: We have obtained uvbyCa data for over 300 giants and horizontal branch stars in three fields of M22. The spread in (b-y) for the giant and horizontal branches is consistent with a spread in foreground reddening Delta-E(B-V) ∼ 0.08. Reanalysis of the data of Norris and Freeman (1983) indicates not only positive correlations between CH, CN and a unimodal distribution for Ca. Our photometric indices, m_1, and hk, demonstrate a range in metallicity that persists to two magnitudes below the horizontal branch, and confirm the correlation between calcium abundance and CN/CH. We infer from comparisons to spectroscopic data that m_1 is dominated by the CN and CH abundance and find no independent evidence of a range in [Fe/H]. The excessive ranges in m_1 and hk also suggest the influence of a continuous opacity source, reminiscent of the Bond-Neff effect, that is correlated with CNO abundance. The relative contributions of internal mixing and primordial variations for M22's giants are discussed. Copyright: Astronomical Society of the Pacific Object: --------------------------------- RA (2000) DE Name(s) --------------------------------- 18 36.4 -23 54 M 22 = NGC 6656 --------------------------------- File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table3 124 396 uvbyCa photometry of stars in M22.
See also: GCPD/81 : General Catalog of Photometric Data, CaII HK photometric system GCPD/04 : General Catalog of Photometric Data, uvby (Stromegren) system Byte-by-byte Description of file: table3
Bytes Format Units Label Explanations
2- 6 I5 --- ID Designation of the star (1) 8- 9 I2 --- Pr [0-99]?=-1 Probability of membership, from Peterson and Cudworth (1994ApJ...420..612P) 11- 16 F6.1 arcsec Xpos X-position, increasing to positive R.A. (2) 18- 23 F6.1 arcsec Ypos Y-position north of field center (2) 26- 31 F6.3 mag Vmag Johnson's V 33- 38 F6.3 mag b-y Stroemgren index (see e.g. GCPD/04) 40- 45 F6.3 mag m1 Stroemgren index ((v - b) - (b - y)) 47- 52 F6.3 mag c1 Stroemgren index ((u - v) - (v - b)) 54- 59 F6.3 mag hk index = (Ca-b)-(b-y) (see e.g. GCPD/81) 62- 66 A5 --- AM Cross-identifications to Arp and Melbourne (1959AJ.....64...28A) 68- 72 A5 --- AL Cross-identifications to Alcaino and Liller (1983AJ.....88.1330A) 76- 80 F5.3 mag e_Vmag []?=0.000 Mean error on Vmag 83- 87 F5.3 mag e_b-y []?=0.000 Mean error on b-y 90- 94 F5.3 mag e_m1 []?=0.000 Mean error on m1 97-101 F5.3 mag e_c1 []?=0.000 Mean error on c1 104-108 F5.3 mag e_hk []?=0.000 Mean error on hk 112 I1 --- Ny Number of y frames 115 I1 --- Nb Number of b frames 118 I1 --- Nv Number of v frames 121 I1 --- Nu Number of u frames 124 I1 --- NCa Number of Ca frames
Note (1): the first digit denotes the CCD field: 5 for NE, 2 for South, 4 for Southwest, 3 for overlap between 2 and 4. Note (2): Field center is at 18 33 21.5 -23 56 44 (1950). in J2000: 18 36 24.6 -23 54 12
Courtesy: Barbara J. Anthony-Twarog
(End) Francois Ochsenbein [CDS] 18-Aug-1995
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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