In some circumstances , the mass accretion rate \dot { M } _ { \star } onto a compact star may depend not only on external boundary conditions , but also on the radius R _ { \star } of the star .
Writing the dependence as \dot { M } _ { \star } \propto R _ { \star } ^ { p } , we estimate p for transient binary systems in a quiescent state .
We use the observed luminosities L of accreting neutron stars ( R _ { \star } \sim 10 ^ { 6 } ~ { } { cm } ) in soft X-ray transients and white dwarfs ( R _ { \star } \sim 10 ^ { 9 } ~ { } { cm } ) in similar cataclysmic variables , and estimate \dot { M } _ { \star } in each system through the relation L \approx GM _ { \star } \dot { M } _ { \star } / R _ { \star } , where M _ { \star } is the mass of the star .
From the available data we infer that p \sim 0.9 \pm 0.5 .
This radial dependence is consistent with radiatively inefficient accretion flows that either are convective or lose mass via a wind .