Virginia TechBoboltz, David Allen Jr.Diamond, Philip J.Kemball, A. J.2014-03-102014-03-101997-10D. A. Boboltz et al. 1997 ApJ 487 L147 doi:10.1086/3108960004-637Xhttp://hdl.handle.net/10919/25857We have made the first detection of circumstellar SiO maser proper motions in the envelope of a late-type star. Using the Very Long Baseline Array (VLBA), we have obtained observations at four epochs of the 43 GHz, upsilon = 1, J = 1-0 SiO maser emission toward the Mira variable in the symbiotic binary R Aqr. The maser emission has a ringlike structure approximately 31 mas across with a slight elongation in the north-south direction. We find that the emission changes significantly over a timescale of about 1-2 months with almost no similarity in structure for timescales greater than or similar to 6 months. Our observations show that over a 98 day period the masers have an average inward proper motion of about 1 mas. This contraction of the ring implies an infall velocity of about 4 km s(-1) for the SiO masers in the circumstellar envelope.en-USIn Copyrightbinaries, symbioticcircumstellar mattermasersstars, individual (r aquarii)starsemissionw3(oh)radiojetArticle - Refereedhttp://iopscience.iop.org/1538-4357/487/2/L147https://doi.org/10.1086/310896