  We consider the effects of an attractive, long-range Yukawa interaction
between baryons and dark matter (DM), focusing in particular on temperature and
pulsar timing observations of neutron stars (NSs). We show that such a fifth
force, with strength modestly stronger than gravity at ranges greater than tens
of kilometers (corresponding to mediator masses less than $10^{-11}
\text{eV}$), can dramatically enhance dark matter kinetic heating, capture, and
pulsar timing Doppler shifts relative to gravity plus short range interactions
alone. Using the coldest observed NS and pulsar timing array (PTA) data, we
derive limits on fifth force strength over a DM mass range spanning light dark
matter up to order solar mass composite DM objects. We also consider an
indirect limit by combining bullet cluster limits on the DM self-interaction
with weak equivalence principle test limits on baryonic self-interactions. We
find the combined indirect limits are moderately stronger than kinetic heating
and PTA limits, except when considering a DM subcomponent.
