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J/AJ/100/1811   UBV photometry in Ruprecht 106    (Buonanno+ 1990)

Ruprecht 106: a young metal-poor galactic globular cluster. BUONANNO R., BUSCEMA G., FUSI PESCI F., RICHER H.B., FAHLMAN G.G. <Astron. J. 100, 1811 (1990)> =1990AJ....100.1811B
ADC_Keywords: Clusters, globular; Photometry, CCD; Photometry, UBV; Positional data Abstract: UBV CCD photometry for about 2500 stars in the Galactic globular cluster Ruprecht 106 has been performed yielding the first color-magnitude diagram (CMD) for this object. The CMD extends down to about 2 mag fainter than the main-sequence turnoff (TO). The cluster possesses a remarkably flat horizontal branch which lies completely to the red of the instability strip. From the analysis of the CMD the following basic parameters have been determined: [Fe/H] = -1.09 and primordial helium abundance Yp = 0.20 0.05. A sizable, highly centrally concentrated population of blue stragglers has also been detected. The location and morphology of the mean ridge lines in the CMD of Ruprecht 106 have then been differentially compared with that of the metal-rich cluster 47 Tuc, NGC 362, a cluster of intermediate metallicity, and with two well-studied metal-poor clusters, M68 and NGC 6397. Significant differences in the positions of the TOs are apparent in the comparison with the metal-poor clusters. These differences can be explained if Ruprecht 106 is 4-5 Gyr younger than NGC 6397 and M68, although alternative, less straightforward explanations cannot be ruled out. The horizontal branch morphology fits perfectly into this picture using models with non-solar-scaled abundances ([O/Fe]>0.5), showing that two second parameters are at work in this cluster, i.e., age (the dominant) and O enhancement. If these findings are confirmed, Ruprecht 106 will turn out to be the first young metal-poor Galactic globular cluster discovered, with quite strong implications for the study of the collapse and enrichment of the Galactic halo. Notes: Field1 is centered on the cluster center (12 35 53 -50 52.6 1950). Field2 is located 2.7arcmin east of Field1, File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table2 31 2262 Field1 (cluster center) table3 31 296 Field2 (2.7arcmin east)
Byte-by-byte Description of file: table2
Bytes Format Units Label Explanations
1- 4 I4 --- N1 [1/2262]+ Number in Field1 (in Simbad: Cl* Ruprecht 106 BBF 1-N1) 7- 11 F5.2 mag V magnitude 13- 17 F5.2 mag B-V color index 19- 24 F6.1 arcsec X position toward N 26- 31 F6.1 arcsec Y position toward W
Byte-by-byte Description of file: table3
Bytes Format Units Label Explanations
1- 4 I4 --- N2 [1/296]+ Number in Field2 (in Simbad: Cl* Ruprecht 106 BBF 2-N2) 7- 11 F5.2 mag Vmag magnitude 13- 17 F5.2 mag B-V color index 19- 24 F6.1 arcsec X position toward N 26- 31 F6.1 arcsec Y position toward W
History: Keypunched at CDS
(End) M.J. Wagner, Francois Ochsenbein [CDS] 15-Apr-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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