Abstract

We report on the detection of variable stars in the Canes Venatici II (CVn II) dwarf spheroidal galaxy, a new satellite of the Milky Way recently discovered by the Sloan Digital Sky Survey. We also present a V, B - V color-magnitude diagram that reaches V ∼ 25.5 mag, showing the galaxy's main-sequence turnoff at V ∼ 24.5 mag and revealing several candidate blue straggler stars. Two RR Lyrae stars have been identified within the half-light radius of CVn II, a fundamental-mode variable (RRab) with period Pab = 0.743 days, and a firstovertone (RRc) RR Lyrae star with Pc = 0.358 days. The rather long periods of these variables along with their position on the period-amplitude diagram support an Oosterhoff type II classification for CVn II. The average apparent magnitude of the RR Lyrae stars, 〈V〉 = 21.48 ± 0.02 mag, is used to obtain a precision distance modulus of μ0 = 21.02 ± 0.06 mag and a corresponding distance of 160+4 -5 kpc, for an adopted reddening E(B - V) = 0.015 mag. © 2008. The American Astronomical Society. All rights reserved.