J/AJ/109/1131 JHK Photometry in Metal Rich Globulars. (Kuchinski+ 1995)
Infrared Array Photometry of Metal-Rich Globular Clusters.
I. Techniques and First Results
Kuchinski L.E., Frogel J.A., Terndrup D.M., Persson S.E.
<Astron. J. 109, 1131 (1995)>
=1995AJ....109.1131K 1995AJ....109.1131K
ADC_Keywords: Photometry, infrared ; Clusters, globular
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.
Objects:
-----------------------------------------------------------------------
RA (2000) DE Designation(s)
-----------------------------------------------------------------------
15 27 41 -50 39.5 C 1524-505 = NGC 5927
17 27 33 -30 48.1 C 1724-307 = Terzan 2 = Haute-Provence 3 = VDBH 228
18 53.0 -08 43 C 1850-087 = NGC 6712
19 53.7 +18 47 C 1951+186 = NGC 6838 = M 71
-----------------------------------------------------------------------
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
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
--------------------------------------------------------------------------------
See also:
J/AJ/109/1154 : Paper II, JHK Photometry of Liller 1 (Frogel+ 1995)
J/AJ/110/2844 : Paper III: JHK Photometry of M 71, NGC 5927, NGC 6624,
NGC 6440, NGC 6712 (Kuchinski+ 1995)
J/AJ/121/3114 : UBVR photometry of NGC 6712 with VLT (Paltrinieri+, 2001)
Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 I4 --- ID ID number
5-16 F12.1 pix Xpos X coordinate on frame
17-28 F12.1 pix Ypos Y coordinate on frame
29-38 F10.3 mag Kmag 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
--------------------------------------------------------------------------------
Note on Code:
3 = 3s exposure, 10 = 10s exposure, 20 = 20s exposure
Note on 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 Xpos X coordinate on frame
17-28 F12.1 pix Ypos Y coordinate on frame
29-38 F10.3 mag Kmag 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
--------------------------------------------------------------------------------
Note on Ring:
Cluster Center at x=75, y=40 (pixels), scale = 0.52 arcsec/pixel
I = R < 75 pixels (39 arcsec) from cluster center
II = 75 pixels (39 arcsec) < R < 110 pixels (57.2 arcsec)
III = 110 pixels (57.2 arcsec) < R < 150 pixels (78 arcsec)
IV = R > 150 pixels (78 arcsec)
Note on 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 Xpos X coordinate on frame
17-28 F12.1 pix Ypos Y coordinate on frame
29-38 F10.3 mag Kmag 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
--------------------------------------------------------------------------------
Note on 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 Xpos X coordinate on frame
17-28 F12.1 pix Ypos Y coordinate on frame
29-38 F10.3 mag Kmag 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
--------------------------------------------------------------------------------
Note on 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 Xpos X coordinate on frame
17-28 F12.1 pix Ypos Y coordinate on frame
29-38 F10.3 mag Kmag 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
--------------------------------------------------------------------------------
Note on 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)
--------------------------------------------------------------------------------
Author's address:
Leslie Kuchinski
Origin: AAS CD-ROM series, Volume 4, 1995 Lee Brotzman [ADS] 03-May-1995
(End) [CDS] 11-Jul-1995