Time variation of SiO masers in VX sagittarii over an optically quiescent phase

The time variation of SiO masers in a semi-regular variable, VX Sgr, was investigated in the period between 1994 and 2004 when the optical light curve exhibited an ∼ 6-yr quiescent phase intercepting a regularly pulsating era. The quiescent period occurred with a delay of several years after a decrease in the SiO maser flux. VLBA observations of SiO masers made during this period showed no drastic spatial variation except for emission features being shifted from south-west to north-east. The SiO maser flux decrease, and a succeeding optical quiescent phase, may indicate that the stellar mass-loss rate diminished over a few years around 1994. A SiO maser flare occurring in 1999 may be a reminiscence of a final gas blow, which resulted in the optically quiescent period