OH/IR stars in the inner bulge detected by ISOGAL

We present a study of known OH/IR stars in the inner bulge, observed by the ISOGAL survey at $\lambda = 6.8~\mu$m and $\lambda = 14.9~\mu$m. Bolometric corrections and luminosities are computed, based on near and mid-infrared data. The vast majority of the sources exhibit mass-loss rates in the range: $3 \times 10^{-7}$ up to a few times $10^{-5}~M_{\odot }$/year. The bolometric magnitude distribution peaks at $M_{\rm bol} = -5.0$. There is no clear evidence that the luminosity is related to the expansion velocity of the envelope for the sample in the bulge observed by ISOGAL. We find that the bulge OH/IR stars do not follow a period-luminosity (PL) law and that they are systematically less luminous than the OH/IR extension of the PL relationship for Miras