The R Aquarii symbiotic star system is surrounded by a large-scale optical nebula. We present observations of the nebular [O III] structure and discuss its morphological significance in context with previously observed small-scale radio-continuum features, which may be related. We suggest that a precessing accretion disk may explain the global features of both the large-scale optical emission and the small-scale radio emission. Moreover, we have determined an accurate position of the system's Mira, which suggests that a recent theoretical model, yielding an egg-shaped central H II region for symbiotic systems with certain physical parameters, may apply to R Aquarii. The optical position of the 387d period Mira variable is consistent with our previous findings in the radio, that SiO maser emission is far removed from the Mira photosphere.
Michalitsianos, A.G., Oliversen, R.J., Hollis, J.M., Kafatos, M., Crull, H.E., Miller, R.J. (1988) R Aquarii: The Large-Scale Optical Nebula and the Mira Variable Position, The Astronomical Journal, Vol. 95, No. 5:1478-1483. doi: 10.1086/114743