  We consider a $D4-D8-\bar D8$ brane construction which gives rise to a large
N QCD at sufficiently small energies. Using the gravity dual of this system, we
study chiral phase transition at finite chemical potential and temperature and
find a line of first order phase transitions in the phase plane. We compute the
spectral function and the photon emission rate. The trace of the spectral
function is monotonic at vanishing chemical potential, but develops some
interesting features as the value of the chemical potential is increased.
