  We study the mass-radius relation and the second Love number of compact
objects made of ordinary matter and non-selfannihilating fermionic dark matter
for a wide range of dark matter particle masses, and for the cases of weakly
and strongly interacting dark matter. We obtain stable configurations of
compact objects with radii smaller than 10 km and masses similar to Earth- or
Jupiter-like stellar objects. In certain parameter ranges we find second Love
numbers which are markedly different compared to those expected for neutron
stars without dark matter. Thus, by obtaining the compactness of these compact
objects and measuring their tidal deformability from gravitational wave
detections from binary neutron star mergers, the extracted value of second Love
number would allow to determine the existence of dark matter inside neutron
stars irrespective of the equation of state of ordinary matter.
