J/AJ/110/2844 JHK photometry of globular clusters. III. (Kuchinski+ 1995)
Infrared array photometry of metal-rich globular clusters.
III. Two more clusters and an analysis of V-K colors.
Kuchinski L.E., Frogel J.A.
<Astron. J. 110, 2844 (1995)>
=1995AJ....110.2844K 1995AJ....110.2844K (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, globular ; Photometry, infrared
Abstract:
We present new JHK photometry for the disk globular clusters NGC 6440
and NGC 6624. These data are initially used to confirm and refine
several important results from Kuchinski et al. (1995AJ....109.1131K 1995AJ....109.1131K)
for other disk globular. First, we again demonstrate the ability to
derive a reddening-independent estimate for the [Fe/H] of a cluster
from the slope if its giant branch (GB) in a K, J-K color magnitude
diagram (CMD). Second, the reddening corrected J-K color and K
magnitude of the center of the horizontal branch (HB) and the J-K
color of its red edge are confirmed to be independent of [Fe/H] for
these clusters. Thus these parameters can be used to estimate E(J-K)
of metal-rich clusters with no knowledge of distance or [Fe/H] and to
estimate (m-M) if one can first estimate the reddening. We also
confirm that the reddening-independent quantities, the half width of a
cluster's horizontal branch (HB), and the color difference between the
center of the HB and the GB at the level of the HB, both appear to be
insensitive to metallicity. The JHK colors of NGC 6440 are similar to
those of Liller 1; in both cases these colors are unlike those seen
for other globular clusters, field giants, or bulge giants. We have
not been able to identify any other cluster parameter that would help
to explain these anomalous colors. We have assembled V photometry from
the literature for the clusters in our sample and VK photometry for two
additional disk globular clusters from Davidge et al.
(1992ApJS...81..251D 1992ApJS...81..251D). We conclude that K, J-K CMDs are preferable to
K, V-K CMDs as tools to study basic cluster properties. Finally, we
compare our data with theoretical isochrones for metal-rich clusters
and present observational evidence that the dependence of the V-K
color of the GB on [Fe/H] may be different for halo and disk globular
clusters. This difference may be related to differences in the [O/Fe]
values for the two cluster systems.
Objects:
-----------------------------------------
RA (2000) DE Designation(s)
-----------------------------------------
15 27.6 -50 39 NGC 5927
18 23.6 -30 21 NGC 6624
17 48.9 -20 22 NGC 6440
18 53.0 -08 43 NGC 6712
19 53.7 +18 47 M 71 = NGC 6838
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 51 153 NGC 6624 data
table3.dat 52 97 NGC 6440 data
table6.dat 16 77 NGC 5927 data
table7.dat 16 72 NGC 6712 data
table8.dat 16 221 M 71 data
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See also:
J/AJ/109/1131 : NGC 5927, Terzan 2, NGC 6712, NGC 6838 (Kuchinski+ 1995)
(Paper I)
J/AJ/109/1154 : Liller 1 (Frogel+ 1995) (Paper II)
J/AJ/121/3114 : UBVR photometry of NGC 6712 with VLT (Paltrinieri+, 2001)
Byte-by-byte Description of file: table2.dat table3.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- ID Identification number
5- 9 F5.1 pix Xpos X coordinate (from East to West) (1)
11- 15 F5.1 pix Ypos Y coordinate (from South to North) (1)
17- 22 F6.3 mag Kmag K magnitude
24- 28 F5.3 mag J-K J-K color index
30- 35 F6.3 mag H-K H-K color index
37- 41 F5.3 mag V-K ? V-K color index
43- 45 I3 --- Code Exposure code (2)
47- 48 A2 --- Note Notes (3)
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Note (1): the plate scale is 0.35"/pix.
Note (2): 3 = 3s exposure, 10 = 10s exposure, 20 = 20s exposure
203 = color data from both sets (3s and 20s) (table3 only)
Note (3): NO = star with DoPhot error ≥0.06mag (DoPhot, Schechter et al. 1993)
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Byte-by-byte Description of file: table6.dat table7.dat table8.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- ID Identification number
5- 10 F6.3 mag Kmag K Magnitude
12- 16 F5.3 mag V-K V-K color index
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Courtesy: Leslie E. Kuchinski
References:
Schechter et al. 1993 PASP 105, 134
(End) Patricia Bauer [CDS] 09-Aug-1996