  In ultra-peripheral relativistic heavy ion collisions the beam ions scatter
at impact parameters larger than the sum of their radii, so that they interact
via long range electromagnetic forces. Due to the Lorentz-boost of the beam
particles, the exchanged virtual photons have high energies and can induce the
photoproduction of vector-mesons. We present recent results of the STAR
experiment at RHIC on $\rho^0(770)$ production in Au-Au ultra-peripheral
collisions at various energies. STAR has also observed the photoproduction of
$\pi^+\pi^-\pi+\pi^-$, which is related to the still poorly known excited
states of the $\rho^0$.
