Publication Date:
2014-11-27
Description:
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° ≤ ≤ –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 2. Most prominent among these is a southern extension of the Sagittarius dwarf galaxy's stream system, reaching down to declinations ~ -40 °.
Print ISSN:
0035-8711
Electronic ISSN:
1365-2966
Topics:
Physics
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