Volume 474, Number 1, October IV 2007
|Page(s)||121 - 127|
|Section||Galactic structure, stellar clusters, and populations|
|Published online||13 August 2007|
Departamento de Física y Astronomía, Facultad de Ciencias, Universidad de Valparaíso, Ave. Gran Bretaña 1111, Playa Ancha, Casilla 5030, Valparaíso, Chile e-mail: firstname.lastname@example.org
2 European Southern Observatory, Av. Alonso de Córdoba 3107, Casilla 19, Santiago 19001, Chile e-mail: email@example.com
3 Gemini Observatory, 670 N. Aóhoku Place, Hilo, HI 96720, USA e-mail: firstname.lastname@example.org
4 Departmento de Astronomía y Astrofísica, Pontificia Universidad Católica de Chile, Av. Vicuña Mackenna 4860, 782-0436 Macul, Santiago, Chile e-mail: [mcatelan;dante]@astro.puc.cl
5 Carnegie Institution of Washington, Las Campanas Observatory, Av. Colina El Pino s/n, Casilla 601, La Serena, Chile e-mail: email@example.com
Accepted: 8 August 2007
Context.We have obtained deep infrared images and K-band spectra of the Galactic globular cluster 2 MASS GC 02. A variable star search has also been carried out.
Aims.Some basic physical properties of the cluster, such as metallicity, reddening, distance modulus and radial velocity, are derived.
Methods.These measurements are based on an analysis of the 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.
Results.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 GC 02 have anomalously long periods for the cluster's moderately high metallicity, which suggests that it too is an Oosterhoff type III cluster.
Conclusions.Comparison with the existing kinematic and abundance information for the Galactic globular clusters shows that GC 02 most probably belongs to the bulge sub population, although an inner halo association cannot be ruled out.
Key words: Galaxy: globular clusters: general / Galaxy: globular clusters: individual: 2 MASS GC 01 / Galaxy: abundances / Galaxy: globular clusters: individual: 2 MASS GC 02 / Galaxy: globular clusters: individual: NGC 6388 / Galaxy: globular clusters: individual: NGC 6441
The spectroscopy is based on observations collected with the Very Large Telescope of the European Southern Observatory within Observing Program 73.D-0158(A). The photometry is based on data gathered with the 6.5-m Magellan telescopes and the Henrietta Swope 1.0 m telescope, located at Las Campanas Observatory, Chile.
© ESO, 2007
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