We have detected collimated 4.86 GHz (~6 cm) radio continuum emission southwest (SW) of the symbiotic vanable R Aquarii by combining data corresponding to different configurations of the Very Large Array (VLA). In the xontext of a previously reported northeast (NE) 6 cm jet structure, the orientation of the newly found SW radto structure suggests bipolar symmetry, extending to distances of ~2500 AU on either side of the central H II region. The amorphous morphology of the new collimated SW structure is distinct from the discrete radio knots NE of the central object. Further, we have determined the radio spectral index distribution between 2 and 6 cm for nearly all of the radio features found in R Aquarii. Additionally, we have detected 14.94 GHz (~2 cm) continuum emission at the SiO maser position which is located ~250 AU away from the binary system whose orbital semimajor axis is ~17 AU. This provides further evidence that the maser-emitting region is far removed from the system's Mira envelope and may well be due to local shock phenomena in the circumbinary nebulosity. The implications concerning the newly detected bipolar 6 cm structure, the spectral index gradient of the NE jet structure, and the 2 cm emission component at the SiO maser location are described in context of a thick accretion disk model that has been previously proposed to explam the morphology and kinematics of the R Aquarii radio/optical jet.
Kafatos, M., Hollis, J.M., Yusef-Zadeh, F., Michalitsianos, A.G., Elitzur, M. (1989) R Aquarii: Evidence for a Two-Sided radio Jet and a Circumbinary SiO Maser, The Astrophysical Journal, 346:991-996. doi: 10.1086/168081