  We find some exact solutions for constant-density and quark matter equations
of state in stellar structure models framed within the $f(R,T)=R+\lambda
\kappa^2 T$ theory of gravity, where $R$ is the curvature scalar, $T$ the trace
of the stress-energy tensor, and $\lambda$ some constant. These solutions
correspond to specific values of the constant $\lambda$, and represent
different compactness states of the corresponding stars, though only those made
of quark matter can be regarded as physical. The latter modify the compactness
(Buchdahl) limit of neutron stars upwards for $\lambda>0$ until saturating the
one of black holes. Our results show that it is possible to find useful
insights on stellar structure in this class of theories, a fact that could be
used for obtaining constraints on limiting masses such as the minimum hydrogen
burning mass.
