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Evidence for Distinct Components of the Galactic Stellar Halo from 838 RR Lyrae Stars Discovered in the LONEOS-I Survey
Ist Teil von
The Astrophysical journal, 2008-05, Vol.678 (2), p.865-887
Ort / Verlag
Chicago, IL: IOP Publishing
Erscheinungsjahr
2008
Quelle
EZB Electronic Journals Library
Beschreibungen/Notizen
We present 838 ab-type RR Lyrae stars from the Lowell Observatory Near Earth Objects Survey Phase I (LONEOS-I). These objects cover 1430 deg super(2) and span distances ranging from 3 to 30 kpc from the Galactic center. Object selection is based on phased, photometric data with 28-50 epochs. We use this large sample to explore the bulk properties of the stellar halo, including the spatial distribution. The period-amplitude distribution of this sample shows that the majority of these RR Lyrae stars resemble Oosterhoff type I, but there is a significant fraction (26%) which have longer periods and appear to be Oosterhoff type II. We find that the radial distributions of these two populations have significantly different profiles ([image] and [image]). This suggests that the stellar halo was formed by at least two distinct accretion processes and supports dual-halo models.