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 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:
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RA (2000) DE Name(s)
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18 36.4 -23 54 M 22 = NGC 6656
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3 124 396 uvbyCa photometry of stars in M22.
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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
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Bytes Format Units Label Explanations
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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 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 1959AJ.....64...28A)
68- 72 A5 --- AL Cross-identifications to Alcaino
and Liller (1983AJ.....88.1330A 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
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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
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Courtesy: Barbara J. Anthony-Twarog
(End) Francois Ochsenbein [CDS] 18-Aug-1995