  We report the discovery of a new transiting extrasolar planet, HAT-P-55b. The
planet orbits a V = 13.207 +/- 0.039 sun-like star with a mass of 1.013 +/-
0.037 solar masses, a radius of 1.011 +/- 0.036 solar radii and a metallicity
of -0.03 +/- 0.08. The planet itself is a typical hot Jupiter with a period of
3.5852467 +/- 0.0000064 days, a mass of 0.582 +/- 0.056 Jupiter masses and a
radius of 1.182 +/- 0.055 Jupiter radii. This discovery adds to the increasing
sample of transiting planets with measured bulk densities, which is needed to
put constraints on models of planetary structure and formation theories.
