A Search for RR Lyrae Stars in Segue 2 and Segue 3
  We present an extensive search for RR Lyrae stars in and around the
ultra-faint Milky Way companions Segue 2 and Segue 3. The former (M_V = -2.5,
Belokurov et al. 2009) appears to be an extremely faint dwarf galaxy companion
of the Milky Way. The latter (M_V = 0.0, Fadely et al. 2011) is among the
faintest star clusters known. We use B and V band time-series imaging obtained
at the WIYN 0.9 meter telescope at Kitt Peak National Observatory to search for
RR Lyrae in these objects. In our Segue 2 observations, we present a previously
unknown fundamental mode (RRab) RR Lyrae star with a period of P_ab = 0.748
days. With this measurement, we revisit the inverse correlation between <P_ab>
and <[Fe/H]> established in the literature for Milky Way dwarf galaxies and
their RR Lyrae. In this context, the long period of Segue 2's RRab star as well
as the known significant spread in metallicity in this dwarf galaxy are
consistent with the observed trend in <P_ab> and <[Fe/H]>. We derive the first
robust distance to Segue 2, using both its RRab star and spectroscopically
confirmed blue horizontal branch stars. Using [Fe/H] = -2.16 and -2.44 dex, we
find d_RRL = 36.6 +2.5/-2.4 and 37.7 +/- 2.7 kpc; assuming [Fe/H] = -2.257 dex,
we find d_BHB = 34.4 +/- 2.6 kpc. Although no RR Lyrae were present in the
Segue 3 field, we found a candidate eclipsing binary star system.
