LONG-BASE-LINE INTERFEROMETRIC OBSERVATIONS OF LONG-PERIOD VARIABLE-STARS

Recent observations of long-period variable stars at spatial resolutio ns from approximately 1 arcsec to several milli-arcsecs have provided new insights into pulsation, dust formation, and mass-loss of AGE star s. These insights have come from long baseline interferometric observa tions obtained across a wide range of wavelengths, from the optical, t hrough the infrared, to wavelengths as long as several millimeters. Th e present status and recent results from long baseline interferometry, particularly at optical and infrared wavelengths, are discussed. Such results include diameters and limb-darkening, surface features, mode of pulsation, location of SiO masers, inner radii of dust shells, phys ical conditions in the dust formation zone and of the inner regions of the dust shells. The results are interpreted in terms of present mode ls of dust formation and mass-loss.