Bare Quark Matter Surfaces of Strange Stars and $e^+e^-$ Emission

We show that the Coulomb barrier at the quark surface of a hot strange star may be a powerful source of $e^+e^-$ pairs which are created in an extremely strong electric field of the barrier and flow away from the star. The luminosity in the outflowing pair plasma depends on the surface temperature $T_{_S}$ and may be very high, up to $\sim 3\times 10^{51} ergs/s$ at $T_{_S}\sim 10^{11}$ K. The effect of pair creation by the Coulomb barrier may be a good observational signature of strange stars which can give an answer to the question of whether a compact object is a neutron or strange star.