CDROM/AJ/V109/P1131
Metal Rich Globulars. I. (Kuchinski+ 1995)
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Infrared Array Photometry of Metal-Rich Globular Clusters. I. Techniques
and
First Results
Leslie E. Kuchinski, Jay A. Frogel, D. M. Terndrup & S. E. Persson
<1995, AJ, 109, 1131>
=1995AJ....109.1131K
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Abstract:
As a first step in investigating the properties of heavily reddened,
metal-rich globular clusters, we present JHK colors and magnitudes for
four objects: NGC 5927, NGC 6712, NGC 6838 (M71), and Terzan 2. These
data begin near the top of the giant branch (GB) and extend to stars
six magnitudes fainter, reaching below the horizontal branch (HB). We
use our sample and previously published data for two other clusters, 47
Tucanae and M69, to develop techniques for deriving basic properties
such as metallicity and distance modulus from observable parameters of
cluster color-magnitude diagrams (CMDs) in the near-IR. We also
analyze the horizontal branches of the clusters in an attempt to set
constraints on mass loss for first-ascent giants. We find that the
slope of the linear fit to the GB stars brighter than the HB can be
used to predict metallicity to an accuracy of +/- 0.25 dex for clusters
with [Fe/H] between -1.0 and -0.3. There appears to be no significant
dependence on [Fe/H] for other reddening-free indices measured from the
CMD, including the width of the HB and the separation between the GB
and HB at the level of the HB. Using the clusters in our sample that
have known distances, we derive a value of <M_K0(HB)> = -1.15 +/- 0.10
for the extinction-corrected absolute K magnitude of the HB. This
provides a means of determining the distance to clusters for which only
infrared CMDs are available. We derive a distance modulus to Terzan 2
of 14.37 +/- 0.2 which places it within a few hundred parsecs of the
galactic center. In the J-H,H-K diagram, Terzan 2 giants are located
near the Baade's Window giants rather than in the region populated by
nearly all other globular cluster stars. The GB of stars in the field
around Terzan 2 has a slope that implies [Fe/H] = +0.1, comparable to
that in Baade's Window.
File Summary:
------------------------------------------------------------------------------File Name
Lrecl
Records
Explanations
------------------------------------------------------------------------------table3.dat
68
174
NGC 5927 data
table4.dat
74
848
Terzan 2 data
table5.dat
68
161
NGC 6712 data (LCO)
table6.dat
68
312
NGC 6712 data (OSIRIS)
table7.dat
68
326
NGC 6838 (M 71) data
------------------------------------------------------------------------------Byte-by-byte Description of file: table3.dat
------------------------------------------------------------------------------Bytes Format Units
Label
Explanations
------------------------------------------------------------------------------1- 4
I4
--ID
ID number
5-16
F12.1 pix
X
X coordinate on frame
17-28
F12.1 pix
Y
Y coordinate on frame
29-38
F10.3 mag
K
Observed K magnitude
39-47
F9.3
mag
J-K
Observed J-K color
48-56
F9.3
mag
H-K
Observed H-K color
57-62
A6
--Code
*Code for data set
63-68
A6
--Note
*Notes
------------------------------------------------------------------------------Notes for file: table3.dat
------------------------------------------------------------------------------Code:
3 = 3sec exposure, 10 = 10sec exposure, 20 = 20sec exposure
Note:
NO = DOPHOT error > 0.06 mag, F? = possible field star
------------------------------------------------------------------------------Byte-by-byte Description of file: table4.dat
------------------------------------------------------------------------------Bytes Format Units
Label
Explanations
------------------------------------------------------------------------------1- 4
I4
--ID
ID number
5-16
F12.1 pix
X
X coordinate on frame
17-28
F12.1 pix
Y
Y coordinate on frame
29-38
F10.3 mag
K
Observed K magnitude
39-47
F9.3
mag
J-K
Observed J-K color
48-56
F9.3
mag
H-K
Observed H-K color
57-62
A6
--Ring
*Ring designation
63-68
A6
--Code
*Code for data set
69-74
A6
--Note
Notes, NO = DoPHOT error > 0.06 mag
------------------------------------------------------------------------------Notes for file: table4.dat
-------------------------------------------------------------------------------
Ring:
Cluster
I =
II =
III =
IV =
Center at x=75, y=40 (pixels), scale = 0.52 arcsec/pixel
R < 75 pixels (39 arcsec) from cluster center
75 pixels (39 arcsec) < R < 110 pixels (57.2 arcsec)
110 pixels (57.2 arcsec) < R < 150 pixels (78 arcsec)
R > 150 pixels (78 arcsec)
Code:
3 = 3sec exposure, 10 = 10sec exposure, 20 = 20sec exposure
A3 = 3sec good seeing exposure, AL = good seeing, long exposure
------------------------------------------------------------------------------Byte-by-byte Description of file: table5.dat
------------------------------------------------------------------------------Bytes Format Units
Label
Explanations
------------------------------------------------------------------------------1- 4
I4
--ID
ID number
5-16
F12.1 pix
X
X coordinate on frame
17-28
F12.1 pix
Y
Y coordinate on frame
29-38
F10.3 mag
K
Observed K magnitude
39-47
F9.3
mag
J-K
Observed J-K color
48-56
F9.3
mag
H-K
Observed H-K color
57-62
A6
--Code
*Code for data set
63-68
A6
--Note
Notes, NO = DoPHOT error > 0.06 mag
------------------------------------------------------------------------------Notes for file: table5.dat
------------------------------------------------------------------------------Code:
A3 = 3sec "A" frame data, AL = long exposure "A" data
------------------------------------------------------------------------------Byte-by-byte Description of file: table6.dat
------------------------------------------------------------------------------Bytes Format Units
Label
Explanations
------------------------------------------------------------------------------1- 4
I4
--ID
ID number
5-16
F12.1 pix
X
X coordinate on frame
17-28
F12.1 pix
Y
Y coordinate on frame
29-38
F10.3 mag
K
Observed K magnitude
39-47
F9.3
mag
J-K
Observed J-K color
48-56
F9.3
mag
H-K
Observed H-K color
57-62
A6
--Ring
*Ring designation
63-68
A6
--Note
Notes, NO = DoPHOT error > 0.06 mag
------------------------------------------------------------------------------Notes for file: table6.dat
------------------------------------------------------------------------------Ring:
Cluster Center at x=135, y=130 (pixels), scale = 1.55 arcsec/pixel
I = R < 60 pixels (93 arcsec) from cluster center
II = R > 60 pixels (93 arcsec)
------------------------------------------------------------------------------Byte-by-byte Description of file: table7.dat
------------------------------------------------------------------------------Bytes Format Units
Label
Explanations
------------------------------------------------------------------------------1- 4
I4
--ID
ID number
5-16
F12.1 pix
X
X coordinate on frame
17-28
F12.1 pix
Y
Y coordinate on frame
29-38
F10.3 mag
K
Observed K magnitude
39-47
F9.3
mag
J-K
Observed J-K color
48-56
F9.3
mag
H-K
Observed H-K color
57-62
A6
--Ring
*Ring designation
63-68
A6
--Note
Notes, NO = DoPHOT error > 0.06 mag
------------------------------------------------------------------------------Notes for file: table7.dat
------------------------------------------------------------------------------Ring:
Cluster Center at x=125, y=130 (pixels), scale = 1.55 arcsec/pixel
I = R < 90 pixels (140 arcsec) from cluster center
II = R > 90 pixels (140 arcsec)
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(End)
Lee Brotzman [ADS] 03May-1995