  We present metallicities of 2690 RR0 Lyrae stars observed toward the MACHO
Survey fields in the Galactic Bulge. These [Fe/H] values are based upon an
empirically calibrated relationship that uses the Fourier coefficients of the
light curve and are accurate to ~0.2 dex. The majority of the RR0 Lyrae stars
in our sample are located in the Galactic Bulge, but 255 RR0 stars are
associated with Sagittarius dwarf galaxy. We find that the RR0 Lyrae stars that
belong to the Galactic Bulge have average metallicities [Fe/H] = -1.25, with a
broad metallicity range from [Fe/H] = -2.26 to -0.15. The RR0 stars from
Sagittarius dwarf galaxy have lower average metallicity of [Fe/H] = -1.55 \pm
0.02, with an intrinsic dispersion of 0.25 dex, similar to that in the bulge. A
correlation between metallicity and galactocentric distance is found, in a
sense that for the metal-poor RR0 Lyrae stars ([Fe/H]< -1.5 dex), the closer a
star is to the Galactic center, on average, the more metal rich it is. However,
for the metal-rich RR0 Lyrae stars ([Fe/H] > -1.2 dex), this trend is reversed.
Using mean magnitudes of MACHO RR Lyrae stars, we searched for the evidence of
the Galactic bar, and found marginal evidence of a bar. The absence of a strong
bar indicates that the RR Lyrae in the bulge represent a different population
than the majority of the bulge stars, which are metal rich and are part of a
bar.

Astrophysics