J/A+A/474/121 Galactic globular cluster 2MASS GC02 JKs phot. (Borissova+, 2007)
A deep near-infrared view of the Galactic globular cluster 2MASS GC02.
Borissova J., Ivanov V.D., Stephens A.W., Catelan M., Minniti M., Prieto G.
<Astron. Astrophys. 474, 121 (2007)>
=2007A&A...474..121B 2007A&A...474..121B
ADC_Keywords: Clusters, globular ; Photometry, infrared
Keywords: Galaxy: globular clusters: general - Galaxy: abundances -
Galaxy: globular clusters: individual: 2MASS GC01, 2MASS GC02
Galaxy: globular clusters: individual: NGC 6388, NGC 6441
Abstract:
We have obtained deep infrared images and K-band spectra of the
Galactic globular cluster 2MASS GC02. A variable star search has
also been carried out. Some basic physical properties of the cluster,
such as metallicity, reddening, distance modulus and radial velocity,
are derived. These measurements are based on an analysis of the J-Ks
versus Ks color-magnitude diagram of the cluster. Spectroscopically
derived metallicities and radial velocities of 15 stars are presented.
In addition, periods and amplitudes are provided for five RR Lyrae
stars discovered in the field. The cluster is moderately metal-rich
and has a relatively high radial velocity. Its horizontal branch
appears to be predominantly red, though our photometry cannot rule out
the presence of a blue component as seen in NGC 6388 and NGC 6441.
Similar to these two clusters, the detected RR Lyrae stars in GC02
have anomalously long periods for the cluster's moderately high
metallicity, which suggests that it too is an Oosterhoff type III
cluster. Comparison with the existing kinematic and abundance
information for the Galactic globular clusters shows that GC02 most
probably belongs to the bulge sub population, although an inner halo
association cannot be ruled out.
Objects:
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RA (2000) DE Designation(s)
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18 09 36 -20 46.7 [HJK2000] GC02 = 2MASS GC02
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 102 15 Metallicity and radial velocities of the
program stars
phot.dat 32 2142 Individual J-Ks colors and Ks magnitudes of the
Galactic globular cluster 2MASS GC02
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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- 5 A5 --- --- [2MASS]
6- 22 A17 --- 2MASS 2MASS name (JHHMMSSss+DDMMSSs)
24- 25 I2 h RAh Right ascension (J2000)
27- 28 I2 min RAm Right ascension (J2000)
30- 34 F5.2 s RAs Right ascension (J2000)
36 A1 --- DE- Declination sign (J2000)
37- 38 I2 deg DEd Declination (J2000)
40- 41 I2 arcmin DEm Declination (J2000)
43- 47 F5.2 arcsec DEs Declination (J2000)
49- 53 F5.2 mag Ksmag ? Ks magnitude
55- 58 F4.2 mag J-Ks ? J-Ks colour index
60- 63 F4.2 --- EWNa Equivalent width of NaI (2.21um)
65- 68 F4.2 --- EWCa Equivalent width of CaI (2.26um)
70- 74 F5.2 --- EWCO Equivalent width of CO (2.29um)
77- 80 F4.2 [Sun] [Fe/H] Metallicity
83- 85 I3 km/s RV1 Radial velocity of first template star (1)
88- 90 I3 km/s RV2 Radial velocity of second template star (1)
93- 95 I3 km/s RV Radial velocity (mean of RV1 and RV2) (1)
97- 98 I2 km/s e_RV rms uncertainty on RV
100-102 A3 --- Memb [yes no] Member ?
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Note (1): The radial velocities of these stars were derived using the IRAF
task fxcor, which uses a cross-correlation Fourier method. Since we
did not observe any radial velocity standard, we used two stars from
the literature as templates. The first one, BMB 181 (NGC 6522 NB 69),
an M7 III star with [Fe/H]=-0.21 and RV=12±0.5km/s, is taken from
the stellar library of Ivanov et al. (2004, Cat. J/ApJS/151/387),
whereas the second template, UK2III, is selected from the ISAAC
"Library of Stellar Spectra for Spectrophotometric Calibration"
(Pickles, 1998, Cat. J/PASP/110/863).
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Byte-by-byte Description of file: phot.dat
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Bytes Format Units Label Explanations
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1- 7 F7.2 pix Xpos X coordinate (1)
9- 15 F7.2 pix Ypos Y coordinate (1)
17- 21 F5.2 pix J-Ks J-Ks color index
25- 29 F5.2 pix Ksmag Ks magnitude
32 A1 --- Note [p] p for program star, in table1
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Note (1): 1pix=0.125".
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History:
* 08-Oct-2007: Original version
* 30-Oct-2007: Sign of declination in table1 corrected
* 14-Jan-2008: Positions in table1 corrected
Acknowledgements:
Jura Borissova, jura.borissova(at)uv.cl
(End) Patricia Vannier [CDS] 08-Oct-2007