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J/AJ/103/460                CCD photometry of M 71               (Hodder+, 1992)

Deep CCD photometry and variable stars in the metal-rich globular cluster M 71 HODDER P.J.C., NEMEC J.M., RICHER H.B., FAHLMAN G.G. <Astron. J. 103, 460 (1992)> =1992AJ....103..460H (SIMBAD/NED Reference)
ADC_Keywords: Clusters, globular; Photometry, CCD; Stars, variable Abstract: Two sets of observations of the metal-rich globular cluster M 71 are presented. The first uses deep CCD exposures to derive a fiducial in V, B-V and compares this with a cluster of similar metallicity, 47 Tuc. Comparison with oxygen enhanced theoretical isochrones leads to age estimates for M 71 of from ∼14±2Gyr to ∼16±2Gyr. Within the limits imposed by the quality of the data, no significant age difference between the two clusters is found. The second set of 73 frames is used to search an overlapping 67"x104" area of the cluster for variable stars. Light curves and phase diagrams (where appropriate) are presented for all four of the variables discovered. One variable blue straggler (or SX Phe star) has been identified with a period of 0.050d. Values for its mass depend, of course, on the assumed pulsation mode-(0.90±0.47)M for the first overtone mode, and (1.57±0.83)M for the fundamental mode. One of the variables, with a 0.0582d period, but with a magnitude 1.75mag below the main sequence turnoff may be a field star. Two candidate eclipsing binary systems were also found. The most likely orbital period of one is 0.372d. This value, and the shape of the light curve, suggest that it could be a W UMa type variable. No period was obtainable for the other candidate binary due to a lack of phase coverage. Further data is needed to confirm and strengthen these claims, and to check for cluster membership. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table2 47 1861 Photometry of M71
Byte-by-byte Description of file: table2
Bytes Format Units Label Explanations
1- 4 I4 --- ID Identification number 5 A1 --- Cud [*] A '*' indicates Cudworth stars that have a cluster membership probability of 50% or more 7- 8 A2 --- n_ID Note on the stars (1) 12- 16 F5.1 pix X X position 18- 23 F6.1 pix Y Y position 27- 31 F5.2 mag Vmag V magnitude 36- 40 F5.2 mag B-V B-V colour 43- 47 F5.2 mag U-B U-B colour
Note (1): Name of the variables discussed in section 4.
References: Cudworth K.M., 1985, AJ, 90, 65 Historical note: Keypunched at CDS
(End) Marie-Jose Wagner, Patricia Bauer [CDS] 05-Dec-1994
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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