  We investigate the general stability of 1D spherically symmetric ionized
Bondi accretion onto a massive object in the specific context of accretion onto
a young stellar object. We first derive a new analytic expression for a steady
state two temperature solution that predicts the existence of compact and
hypercompact HII regions. We then show that this solution is only marginally
stable if ionization is treated self-consistently. This leads to a recurring
collapse of the HII region over time. We derive a semi-analytic model to
explain this instability, and test it using spatially converged 1D radiation
hydrodynamical simulations. We discuss the implications of the 1D instability
on 3D radiation hydrodynamics simulations of supersonic accreting flows.
