J/A+A/372/71 King 5 and Berkeley 20 UBVRI photometry (Durgapal+, 2001)
Multicolor CCD photometry of old open clusters: King 5 and Be 20
Durgapal A.K., Pandey A.K., Mohan V.
<Astron. Astrophys. 372, 71 (2001)>
=2001A&A...372...71D 2001A&A...372...71D
ADC_Keywords: Clusters, open ; Photometry, CCD ; Photometry, UBVRI
Keywords: Hertzsprung-Russel (HR) diagram - open clusters -
individual: King 5; Be 20
Abstract:
We present multicolour CCD photometry for two poorly studied open
clusters (King 5 and Be 20). Photometry for a field near King 5 was
also carried out to estimate the contamination by field stars. The
colour magnitude diagrams (CMD) of the clusters show a well defined
main sequence extending to the limit of the photometry, V~=20mag. The
reddening for King 5, estimated from the colour-colour diagram, is
∼0.82, whereas that for Be 20 as estimated by comparing theoretical
main-sequence (MS) with the observed MS is 0.10. The morphology of the
CMDs indicates that these clusters are old. The CMD of Be 20 shows a
globular cluster-like horizontal branch. In case of King 5 the
comparison of observational CMDs with the standard isochrones of
VandenBerg (1985ApJS...58..711V 1985ApJS...58..711V) indicates an apparent discrepancy
between the shape of the turnoff and isochrones. The CMDs of King 5
seem to be better understood in terms of stellar models with
convective overshoot. The comparison of the CMDs with the stellar
models by Bertelli et al. (1985A&A...150...33B 1985A&A...150...33B) with convective
overshoot produces a good fit for a metallicity Z=0.008 and an age of
1Gyr for King 5 and 5Gyr for Be 20. An apparent distance modulus
(m-M)=14.0 and 15.1 has been estimated for King 5 and Be 20
respectively. They correspond to a distance of 1900±100pc and
9026±480pc, respectively. The radial density distribution in King 5
indicates that there is an excess of low mass stars in the outer
region of the cluster, whereas the density distribution in Be 20 shows
a good fit with the empirical King (1962AJ.....67..471K 1962AJ.....67..471K) model. For
both clusters, observations have also been carried out to search for
variable stars.
Objects:
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RA (2000) DE Designation(s)
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03 14 36 +52 43.0 King 5
05 33 00 +00 13.0 Berkeley 20
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 80 470 Magnitude and colours of the stars in the
field of King 5
table3.dat 69 189 Magnitude and colors of the stars in the
nearby east region of King 5
table4.dat 80 362 Magnitude and colours of the stars in the
field of Be 20
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See also:
J/A+AS/122/111 : Berkeley 64 and 69 stars UBVRI photometry (Pandey+, 1997)
Byte-by-byte Description of file: table2.dat table3.dat table4.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Seq Sequential number in the field
5- 10 F6.2 pix Xpos X position (1)
12- 17 F6.2 pix Ypos Y position (1)
19- 24 F6.3 mag Vmag V magnitude
26- 31 F6.3 mag U-B ? (U-B) colour index
33- 38 F6.3 mag B-V ? (B-V) colour index
40- 44 F5.3 mag V-R ? (V-R) colour index
46- 50 F5.3 mag V-I ? (V-I) colour index
52- 56 F5.3 mag e_Umag ? Photometric error in U filter
58- 62 F5.3 mag e_Bmag ? Photometric error in B filter
64- 68 F5.3 mag e_Vmag ? Photometric error in V filter
70- 74 F5.3 mag e_Rmag ? Photometric error in R filter
76- 80 F5.3 mag e_Imag ? Photometric error in I filter
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Note (1): 1 pix = 0.37".
For King 5, the center coordinates are (227, 205)
For Be 20, the center coordinates are (224, 220)
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Acknowledgements: Alok Durgapal
(End) Patricia Bauer [CDS] 18-May-2001