J/AJ/109/269 Photometry of NGC 5053 (Sarajedini+ 1995)
BVI CCD Photometry of NGC 5053: The Most Metal-Poor Galactic Globular Cluster
Sarajedini A., Milone A.A.E.
<Astron. J. 109, 269 (1995)>
=1995AJ....109..269S 1995AJ....109..269S
ADC_Keywords: Clusters, globular; Photometry, CCD
Abstract:
We present (V,B-V), (V,V-I), and (V,B-I) color-magnitude diagrams for
NGC 5053, which is the most metal-poor globular cluster known in the
galaxy. The horizontal branch (HB) is predominantly blueward of the RR
Lyrae instability strip and the slope of the red giant branch (RGB) is
relatively steep, both characteristic of a metal-poor system. Monte-
Carlo simulations show that both the RGB and HB are underpopulated
relative to those of the metal-poor cluster M15, indicative of the
relatively lower total luminosity of NGC 5053. Based on the mean
magnitude of stars located at the red and blue edges of the instability
strip, we find V(HB) = 16.65 ± 0.03. At this magnitude, polynomial
fits to the cluster RGBs in the two measured colors yield (B-V)_g =
0.71 ± 0.016 and (V-I)_g = 0.93 ± 0.016. Using the BVI two-color
diagram in a differential manner with respect to M68 and M15 gives a
reddening of E(B-V) = 0.06 ± 0.02 for NGC 5053. We have utilized
these quantities to extend the calibration of the simultaneous
reddening and metallicity method [Sarajedini, AJ, 107, 618 (1994a)] to
[Fe/H] = -2.4. Another feature of the color-magnitude diagram that is
evident is the rich population of blue straggler stars (BSSs). We are
able to recover 22 of 24 previously known BSSs, and we have added 3
more BSSs.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 47 846 NGC 5053 photometry
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Star Star number
4-13 F10.2 pix Xpos X pixel position
14-22 F9.2 pix Ypos Y pixel position
23-29 F7.2 mag Vmag V magnitude
30-35 F6.2 mag B-V []? B-V color
36-41 F6.2 mag V-I []? V-I color
42-44 I3 --- o_B-V Number of frame pairs on which each B-V
measurement was made
45-47 I3 --- o_V-I Number of frame pairs on which each V-I
measurement was made
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Origin: AAS CD-ROM series, Volume 4, 1995 Lee Brotzman [ADS] 29-Apr-1995
(End) [CDS] 10-Jul-1995