Evidence for Distinct Components of the Galactic Stellar Halo from 838 RR Lyrae Stars Discovered in the LONEOS-I Survey Academic Article uri icon


  • 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 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 (OoI R-2.260.07 and OoII R -2.880.11. This suggests that the stellar halo was formed by at least two distinct accretion processes and supports dual-halo models. 2008. The American Astronomical Society. All rights reserved.

published proceedings

  • The Astrophysical Journal

author list (cited authors)

  • Miceli, A., Rest, A., Stubbs, C. W., Hawley, S. L., Cook, K. H., Magnier, E. A., ... Koehn, B.

citation count

  • 87

complete list of authors

  • Miceli, Antonino||Rest, Armin||Stubbs, Christopher W||Hawley, Suzanne L||Cook, Kem H||Magnier, Eugene A||Krisciunas, Kevin||Bowell, Edward||Koehn, Bruce

publication date

  • May 2008