  Compact stars consisting of massless quark matter and fermionic dark matter
are studied by solving the Tolman-Oppenheimer-Volkoff equations for two fluids
separately. Dark matter is further investigated by incorporating
inter-fermionic interactions among the dark matter particles. The properties of
stars made of quark matter particles and self-interacting and free dark matter
particles are explored by obtaining their mass-radius relations. The regions of
stability for such a compact star are determined and it is demonstrated that
the maximum stable total mass of such a star decreases approximately linearly
with increasing dark matter fraction.
