  We calculate the equation of state of strange quark matter and the interior
structure of strange quark stars in a Dyson-Schwinger quark model within
rainbow or Ball-Chiu vertex approximation. We emphasize constraints on the
parameter space of the model due to stability conditions of ordinary nuclear
matter. Respecting these constraints, we find that the maximum mass of strange
quark stars is about 1.9 solar masses, and typical radii are 9 --11 km. We
obtain an energy release as large as $3.6 \times 10^{53}\,\text{erg}$ from
conversion of neutron stars into strange quark stars.
