VARIATION OF SILICATE DUST FEATURES WITH PHASE - MID-IR MONITORING OFOXYGEN-RICH MIRA VARIABLE-STARS

We present photometric and spectroscopic data, on a subset of over 30 oxygen-rich Long Period Variable (LPV) stars which we have been monito ring between 8/95 & 4/97. With these data, we are attempting to ascert ain the relationship of dust formation to optical period. Our ultimate goal is to determine what conditions lead to dust formation and destr uction in these environments, and whether or not an evolutionary seque nce can be inferred for AGE stars also based on their spectra and dust formation.