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2009MNRAS.398.1757W - Mon. Not. R. Astron. Soc., 398, 1757-1770 (2009/October-1)
Substructure revealed by RRLyraes in SDSS stripe 82.
WATKINS L.L., EVANS N.W., BELOKUROV V., SMITH M.C., HEWETT P.C., BRAMICH D.M., GILMORE G.F., IRWIN M.J., VIDRIH S., WYRZYKOWSKI L. and ZUCKER D.B.
Abstract (from CDS):
We fit a smooth density law to the distribution as a simple representation of the data. For Galactocentric radii 5-25kpc the number density of RRLyraes falls as r–2.4, but beyond 25kpc, the number density falls much more steeply, as r–4.5. However, we stress that in practice the density distribution is not smooth, but dominated by clumps and substructure. Samples of 55 and 237 RRLyraes associated with the Sagittarius Stream and the Hercules-Aquila Cloud, respectively, are identified. Hence, ∼70 per cent of the RRLyraes in Stripe 82 belong to known substructure, and the sharp break in the density law reflects the fact that the dominant substructure in Stripe 82 - the Hercules-Aquila Cloud and the Sagittarius Stream - lie within 40kpc. In fact, almost 60 per cent of all the RRLyraes in Stripe 82 are associated with the Hercules-Aquila Cloud alone, which emphasizes the cloud's pre-eminence. Additionally, evidence of a new and distant substructure - the Pisces Overdensity - is found, consisting of 28 faint RRLyraes centred on Galactic coordinates (ℓ ~ 80°, b ~ -55°), with distances of ∼80kpc. The total stellar mass in the Pisces Overdensity is ∼104M☉ and its metallicity is [Fe/H] ∼ -1.5.
Abstract Copyright: © 2009 The Authors. Journal compilation © 2009 RAS
Journal keyword(s): catalogues - astrometry - stars: variables: other - Galaxy: halo - Galaxy: stellar content - Galaxy: structure
VizieR on-line data: <Available at CDS (J/MNRAS/398/1757): vars.dat lyraes.dat>
Simbad objects: 420
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