2007ApJ...662.1231K

AG Pegasi has been observed at high angular resolution and sensitivity at the Very Large Array (VLA) at 5 GHz in four epochs between 1984 and 1991. Analysis of the radio visibilities indicate that a mass of 4.0±0.5x10^–5 M_☉ is concentrated in the inner nebula and is moving outward at a velocity of 53±4 km/s (D=600 pc assumed). In order to explain the observed morphology of the inner nebula, a new colliding winds model is derived, which includes the effects of orbital motion (CWo model). Orbital effects cannot be ignored in AG Pegasi since the orbital timescale (2.25 yr; Meinunger (ref???)1981) is short compared to the likely timescale of wind collision (symbiotic nova eruption beginning ∼1850; Merrill (ref???)1959). When these effects are considered, the interaction front between binary stellar winds is wrapped into spiral walls whose density decreases outward with 1/r². Distinctive geometries are found to arise depending on which wind dominates the interaction, the late-type wind from the symbiotic ``cool component'', or the high-velocity wind from the ``hot component.'' Application of the CWo model to AG Peg suggests that the observed transient lobe enhancements of the inner nebula arise due to changes in the mass-loss rate from the hot component. Hot component mass-loss rates ranging between 2.1 and 6.0x10^–8 M_☉/yr are derived. The model is also successful in reproducing the radio spectrum of the central unresolved object of the system. A position angle of -15°±10° is inferred for the orbital pole as projected on the plane of the sky.