LA SILLA QUEST RR LYRAE STAR SURVEY: REGION I

• Published in: The Astrophysical journal 2014-01, Vol.781 (1), p.1-25
• Main Authors: Zinn, R, Horowitz, B, Vivas, A K, Baltay, C, Ellman, N, HADJIYSKA, E, Rabinowitz, D, Miller, L
• Format: Article
• Language: English
• Subjects: ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; CEPHEIDS; Declination; DENSITY; DISTANCE; Galactic halos; GALAXIES; MILKY WAY; SATELLITES; Searching; Slopes; Stars; STREAMS; Substructures
• ISSN: 0004-637X; 1538-4357
• DOI: 10.1088/0004-637X/781/1/22

A search for RR Lyrae stars (RRLSs) in ~ 840 deg super(2) of the sky in right ascension 150[degrees]-210[degrees] and declination -10[degrees] to + 10[degrees] yielded 1013 type ab and 359 type c RRLS. This sample is used to study the density profile of the Galactic halo, halo substructures, and the Oosterhoff type of the halo over distances (d sub([odot])) from ~5 to ~80 kpc. The halo is flattened toward the Galactic plane, and its density profile steepens in slope at galactocentric distances greater than ~25kpc. The RRLS in the stellar stream from the Sagittarius dwarf spheroidal (dSph) galaxy match well the model of Law & Majewski for the stars that were stripped 1.3-3.2 Gyr ago, but not for the ones stripped 3.2-5.0 Gyr ago. Over densities are found at the locations of the Virgo Overdensity and the Virgo Stellar Stream. Within 1[degrees] of 1220-1, which Jerjen et al. identify as a halo substructure at d sub([odot]) ~ 24 kpc, there are four RRLS that are possibly members. Away from substructures, the RRLS are a mixture of Oosterhoff types I and II, but mostly OoI (~73%). The accretion of galaxies resembling in RRLS content the most massive Milky Way satellites (LMC, SMC, For, Sgr) may explain this preponderance of OoI. Six new RRLS and three new anomalous Cepheids were found in the Sextans dSph galaxy.