  AX J1745.6-2901 is a Low Mass X-ray Binary with an accreting neutron star,
showing clear evidence for highly ionized absorption. Strong ionized Fe
K$\alpha$ and K$\beta$ absorption lines are always observed during the soft
state, whereas they disappear during the hard states. We computed
photoionization stability curves for the hard and the soft state, under
different assumptions on the adopted spectral energy distributions and the
physical parameters of the plasma. We observe that the ionized absorber lies
always on a stable branch of the photoionization stability curve during the
soft state, while it becomes unstable during the hard state. This suggests that
photoionization instability plays a key role in defining the observable
properties of the ionized absorber. The same process might explain the
disappearance of the high ionization absorber/wind, during the hard state in
other accreting neutron stars and black holes.
