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 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:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2 31 2262 Field1 (cluster center)
table3 31 296 Field2 (2.7arcmin east)
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Byte-by-byte Description of file: table2
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Bytes Format Units Label Explanations
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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
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Byte-by-byte Description of file: table3
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Bytes Format Units Label Explanations
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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
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History: Keypunched at CDS
(End) M.J. Wagner, Francois Ochsenbein [CDS] 15-Apr-1994