Relativistic stars in degenerate higher-order scalar-tensor theories
  after GW170817
  We study relativistic stars in degenerate higher-order scalar-tensor theories
that evade the constraint on the speed of gravitational waves imposed by
GW170817. It is shown that the exterior metric is given by the usual
Schwarzschild solution if the lower order Horndeski terms are ignored in the
Lagrangian and a shift symmetry is assumed. However, this class of theories
exhibits partial breaking of Vainshtein screening in the stellar interior and
thus modifies the structure of a star. Employing a simple concrete model, we
show that for high-density stars the mass-radius relation is altered
significantly even if the parameters are chosen so that only a tiny correction
is expected in the Newtonian regime. We also find that, depending on the
parameters, there is a maximum central density above which solutions cease to
exist.
