Articulo
FSR 1716: A New Milky Way Globular Cluster Confirmed Using VVV RR Lyrae Stars
Astrophysical Journal Letters
Registro en:
1150060
1150060
Autor
Minniti, Dante
Palma, Tali
Dekany, Istvan
Hempel, Maren
Rejkuba, Marina
Pullen, Joyce
Alonso-García, Javier
Barba, Rodolfo
Barbuy, Beatriz
Bica, Eduardo
Bonatto, Charles
Borissova, Jura
Catelan, Marcio
Carballo-Bello, Julio A
Chene, Andre Nicolas
Contreras-Ramos, Rodrigo
Dias, Bruno
Emerson, Jim
Moni-Bidin, Christian
Institución
Resumen
We use deep multi-epoch near-IR images of the VISTA Variables in the Via Lactea (VVV) Survey to search for RR Lyrae stars toward the Southern Galactic plane. Here, we report the discovery of a group of RR Lyrae stars close together in VVV tile d025. Inspection of the VVV images and PSF photometry reveals that most of these stars are likely to belong to a globular cluster that matches the position of the previously known star cluster FSR 1716. The stellar density map of the field yields a > 100 sigma detection for this candidate globular cluster that is centered at equatorial coordinates R.A.(J2000) = 16:10:30.0, decl.(J2000) = -53:44:56 and galactic coordinates l -329.77812, b - -1.59227. The color-magnitude diagram of this object reveals a well-populated red giant branch, with a prominent red clump at K-s = 13.35 +/- 0.05, and J K-s = 1.30 +/- 0.05. We present the cluster RR Lyrae positions, magnitudes, colors, periods, and amplitudes. The presence of RR Lyrae indicates an old globular cluster, with an age > 10 Gyr. We classify this object as an Oosterhoff type I globular cluster, based on the mean period of its RR Lyrae type ab, < P > = 0.540 days, and argue that this is a relatively metal-poor cluster with [Fe/H] = -1.5 +/- 0.4 dex. The mean extinction and reddening for this cluster are A(Ks) = 0.38 +/- 0.02 and E(J - Ks) = 0.72 +/- 0.02 mag, respectively, as measured from the RR Lyrae colors and the near-IR color-magnitude diagram. We also measure the cluster distance using the RR Lyrae type ab stars. The cluster mean distance modulus is (m - M)(0) = 14.38 +/- 0.03 mag, implying a distance D = 7.5 +/- 0.2 kpc and a Galactocentric distance R-G = 4.3 kpc. Keywords Author Keywords:globular clusters: general galaxies: photometry stars: variables: RR Lyrae
KeyWords Plus:RED-CLUMP BRANCH STARS METALLICITY DISTANCE MAGNITUDE EVOLUTION PROJECT BULGE Regular 2015 FONDECYT FONDECYT