2006ApJ...653L.109D

We present V, I light curves for 12 variable stars identified in the newly discovered satellite of the Milky Way in the Bootes constellation. Our sample includes 11 RR Lyrae stars (five first overtone, five fundamental mode, and one double-mode pulsator) and one long-period variable close to the galaxy red giant branch tip. The RR Lyrae stars trace very well the average V luminosity of the galaxy horizontal branch, leading to a true distance modulus for the galaxy of µ₀=19.11±0.08 mag for an assumed metal abundance of [Fe/H]=-2.5 and for E(B-V)=0.02 mag. Average periods are <P_ab≥0.69 days and <P_c≥0.37 days for ab- and c-type RR Lyrae stars, respectively, making Bootes the second pure Oosterhoff type II (OoII) dSph after Ursa Minor. The location of the double-mode RR Lyrae (RRd) in the Petersen diagram is consistent with RRd stars in OoII clusters and corresponds to an intrinsic luminosity of logL/logL_☉=1.72 (for Z=10^–4 and M=0.80 M_☉) according to nonlinear convective pulsation models.