TY - JOUR
T1 - Bulge RR Lyrae stars in the VVV tile b201
AU - Gran, F.
AU - Minniti, D.
AU - Saito, R. K.
AU - Navarrete, C.
AU - Dékány, I.
AU - McDonald, I.
AU - Contreras Ramos, R.
AU - Catelan, M.
N1 - Funding Information:
We thank the anonymous referee for comments that helped improve the presentation of our results. We gratefully acknowledge the use of data from the ESO Public Survey program ID 179.B-2002 taken with the VISTA telescope, data products from the Cambridge Astronomical Survey Unit. Support for the authors is provided by the BASAL CATA Center for Astrophysics and Associated Technologies through grant PFB-06, and the Ministry for the Economy, Development, and Tourism’s Programa Iniciativa Científica Milenio through grant IC 120009, awarded to Millenium Institute of Astrophysics (MAS), FONDECYT Regular grants No. 1130196 (D.M.) and 1141141 (M.C., C.N., F.G.). F.G. and C.N. acknowledge support from CONICYT-PCHA Magíster Nacional 2014-22141509 and 2012-22121934, respectively. R.C.R. acknowledges support by Proyecto Fondecyt Postdoctoral #3130320. R.K.S. acknowledges support from CNPq/Brazil through projects 310636/2013-2 and 481468/2013-7. We gratefully acknowledge the use of IPython (Pérez & Granger 2007), TOPCAT (Taylor 2005), and the ALADIN sky atlas (Bonnarel et al. 2000) in this research and the International Variable Star Index (VSX) database, operated at AAVSO, Cambridge, Massachusetts, USA.
Publisher Copyright:
© ESO 2015.
PY - 2015/3/1
Y1 - 2015/3/1
N2 - Context. The VISTA Variables in the Vía Láctea (VVV) Survey is one of the six ESO public surveys currently ongoing at the VISTA telescope on Cerro Paranal, Chile. VVV uses near-IR (ZYJHKs) filters that at present provide photometry to a depth of Ks ∼ 17:0 mag in up to 36 epochs spanning over four years, and aim at discovering more than 106 variable sources as well as trace the structure of the Galactic bulge and part of the southern disk. Aims. A variability search was performed to find RR Lyrae variable stars. The low stellar density of the VVV tile b201, which is centered at (l, b) ∼ (-9°, -9°), makes it suitable to search for variable stars. Previous studies have identified some RR Lyrae stars using optical bands that served to test our search procedure. The main goal is to measure the reddening, interstellar extinction, and distances of the RR Lyrae stars and to study their distribution on the Milky Way bulge. Methods. For each star in the tile with more than 25 epochs (∼90% of the objects down to Ks ∼ 17:0 mag), the standard deviation and x2 test were calculated to identify variable candidates. Periods were determined using the analysis of variance. Objects with periods in the RR Lyrae range of 0:2 ≤ P ≤ 1:2 days were selected as candidate RR Lyrae. They were individually examined to exclude false positives. Results. A total of 1.5 sq deg were analyzed, and we found 39 RR Lyr stars, 27 of which belong to the ab-type and 12 to the c-type. Our analysis recovers all the previously identified RR Lyrae variables in the field and discovers 29 new RR Lyr stars. The reddening and extinction toward all the RRab stars in this tile were derived, and distance estimations were obtained through the period-luminosity relation. Despite the limited amount of RR Lyrae stars studied, our results are consistent with a spheroidal or central distribution around ∼8.1 and ∼8.5 kpc. for either the Cardelli or Nishiyama extinction law. Our analysis does not reveal a stream-like structure. Nevertheless, a larger area must be analyzed to definitively rule out streams.
AB - Context. The VISTA Variables in the Vía Láctea (VVV) Survey is one of the six ESO public surveys currently ongoing at the VISTA telescope on Cerro Paranal, Chile. VVV uses near-IR (ZYJHKs) filters that at present provide photometry to a depth of Ks ∼ 17:0 mag in up to 36 epochs spanning over four years, and aim at discovering more than 106 variable sources as well as trace the structure of the Galactic bulge and part of the southern disk. Aims. A variability search was performed to find RR Lyrae variable stars. The low stellar density of the VVV tile b201, which is centered at (l, b) ∼ (-9°, -9°), makes it suitable to search for variable stars. Previous studies have identified some RR Lyrae stars using optical bands that served to test our search procedure. The main goal is to measure the reddening, interstellar extinction, and distances of the RR Lyrae stars and to study their distribution on the Milky Way bulge. Methods. For each star in the tile with more than 25 epochs (∼90% of the objects down to Ks ∼ 17:0 mag), the standard deviation and x2 test were calculated to identify variable candidates. Periods were determined using the analysis of variance. Objects with periods in the RR Lyrae range of 0:2 ≤ P ≤ 1:2 days were selected as candidate RR Lyrae. They were individually examined to exclude false positives. Results. A total of 1.5 sq deg were analyzed, and we found 39 RR Lyr stars, 27 of which belong to the ab-type and 12 to the c-type. Our analysis recovers all the previously identified RR Lyrae variables in the field and discovers 29 new RR Lyr stars. The reddening and extinction toward all the RRab stars in this tile were derived, and distance estimations were obtained through the period-luminosity relation. Despite the limited amount of RR Lyrae stars studied, our results are consistent with a spheroidal or central distribution around ∼8.1 and ∼8.5 kpc. for either the Cardelli or Nishiyama extinction law. Our analysis does not reveal a stream-like structure. Nevertheless, a larger area must be analyzed to definitively rule out streams.
KW - Galaxy: bulge
KW - Stars: horizontal-branch
KW - Stars: variables: RR Lyrae
KW - Surveys
UR - http://www.scopus.com/inward/record.url?scp=84924390233&partnerID=8YFLogxK
U2 - 10.1051/0004-6361/201424333
DO - 10.1051/0004-6361/201424333
M3 - Article
AN - SCOPUS:84924390233
SN - 0004-6361
VL - 575
JO - Astronomy and Astrophysics
JF - Astronomy and Astrophysics
M1 - A114
ER -