J/AJ/112/1054 VI photometry of NGC 6426 (Zinn+ 1996)
The horizontal branches of globular clusters. I.
The color-magnitude diagram of
NGC 6426
Zinn R., Barnes S.
<Astron. J. 112, 1054 (1996)>
=1996AJ....112.1054Z 1996AJ....112.1054Z
ADC_Keywords: Stars, horizontal branch ; Clusters, globular ; Photometry
Abstract:
A color-magnitude diagram of the globular cluster NGC 6426 has been
constructed from photometry in the V and I passbands. The cluster has
the steep giant branch indicative of a very metal-poor composition.
Following the technique of Sarajedini (1994AJ....107..618S 1994AJ....107..618S), we derive
[Fe/H]=-2.31±0.10 and E(V-I)=0.54±0.03 [E(B-V)=0.40±0.02] from a
comparison with the giant branches of other globular clusters. These
values are very close to the ones obtained from photometry of the
cluster's integrated light, and the weighted means of our results and
the previous ones are [Fe/H]=-2.28±0.09 and E(B-V)=0.41±0.02. The
mean V magnitude of the horizontal branch (HB) at the instability
strip is 18.12±0.05, from which we estimate that NGC 6426 lies
17.4kpc from the Sun, 11.5kpc from the galactic center, and 4.9kpc
from the galactic plane. NGC 6426 resembles NGC 5466 and M68 in both
[Fe/H] and HB morphology. The HB of NGC 6426 overlaps the one in M15
from the red HB to M15's gap in the blue HB, but there is no evidence
of significant numbers of faint blue HB stars in NGC 6426 that are
analogous to the ones constituting the "extended HB" in M15.
Objects:
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RA (2000) DE Designation(s)
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17 44.9 +03 11 NGC 6426
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 50 1807 Photometry of NGC 6426
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- Star Star number in cluster
6- 13 F8.3 pix Xpos X coordinate on the master frame (1)
15- 22 F8.3 pix Ypos Y coordinate on the master frame (1)
24- 29 F6.3 mag Vmag V magnitude
32- 36 F5.3 mag e_Vmag Error in V as given by DAOPHOT
39- 43 F5.3 mag V-I V-I color index
46- 50 F5.3 mag e_V-I Error in V-I as given by DAOPHOT
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Note (1): The origin of the pixel numbers is at lower left corner. North is
at the left, and east is at the bottom.
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Origin: AAS CD-ROM series, Volume 7, 1996 Lee Brotzman [ADS] 25-Sep-1996
(End) [CDS] 30-Jan-1997