Discovery of ∼9000 new RR Lyrae in the southern Catalina surveys
We present the results of a deep, wide-area variability survey in the Southern hemisphere, the first of its kind. As part of the Catalina Sky Surveys, the Siding Spring Survey (SSS) has covered 14 800 deg^2 in the declination range of −75° ≤ δ ≤ −15°. To mine the enormous SSS data set efficiently, we have developed two algorithms: automatic period selection (APS) and automatic Fourier decomposition (AFD), which aim to sharpen the period estimation and produce robust light-curve models. Armed with the APS and AFD outputs, we classify 10 540 ab-type RR Lyrae (RRab) stars (∼90 per cent of which are new) across the southern sky. As well as the positional information we supply photometric metallicities, and unreddened distances. For the RRab stars in the halo, a study of the photometric metallicity distribution reveals a nearly Gaussian shape with a mean metallicity of [Fe/H] = −1.4 dex and a dispersion of 0.3 dex. A spatial study of the RRab metallicities shows no significant radial gradient in the first ∼7 kpc from the Galaxy centre. However, further out, a small negative gradient is clearly present. This is complemented by a very obvious correlation of the mean RR Lyrae metallicity with distance above the Galactic plane, z. We have also carried out an initial sub-structure search using the discovered RRab, and present the properties of the candidates with significance greater than 2σ. Most prominent among these is a southern extension of the Sagittarius dwarf galaxy's stream system, reaching down to declinations ∼-40 °.
© 2014 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. Accepted 2014 October 28. Received 2014 October 8; in original form 2014 March 27. We thank A. K. Vivas, S. Duffau, and the anonymous referee, for useful comments and discussions. Support for MC and GT is provided by the Ministry for the Economy, Development, and Tourism's Programa Inicativa Científica Milenio through grant IC120009, awarded to the Millennium Institute of Astrophysics (MAS); by Proyecto Basal PFB-06/2007; and by Proyecto FONDECYT Regular #1141141. Additional support for GT is provided by CONICYT Chile. CRTS and CSDR1 are supported by the US National Science Foundation under grants AST-0909182 and CNS-0540369. The SSS survey is funded by the National Aeronautics and Space Administration under grant no. NNG05GF22G issued through the Science Mission Directorate Near-Earth Objects Observations Program. This research has made use of the International Variable Star Index (VSX) database, operated at AAVSO, Cambridge, Massachusetts, USA.
Submitted - 1410.7653v1.pdf
Published - MNRAS-2015-Torrealba-2251-66.pdf
Supplemental Material - Table2Complete.txt