Outer Jet X-Ray and Radio Emission in R Aquarii: 1999.8 to 2004.0

Chandra and VLA observations of the symbiotic star R Aqr in 2004 reveal significant changes over the 3-4 year interval between these observations and previous observations taken in with the VLA in 1999 and with Chandra in 2000. This paper reports on the evolution of the outer thermal X-ray lobe jets and radio jets. The emission from the outer X-ray lobe jets lies farther away from the central binary than the outer radio jets and comes from material interpreted as being shock-heated to ~=10⁶ K, a likely result of collision between high-speed material ejected from the central binary and regions of enhanced gas density. Between 2000 and 2004, the northeast (NE) outer X-ray lobe jet moved out, away from the central binary, with an apparent projected motion of ~=580 km s^-1. The southwest (SW) outer X-ray lobe jet almost disappeared between 2000 and 2004, presumably due to adiabatic expansion and cooling. The NE radio-bright spot also moved away from the central binary between 2000 and 2004, but with a smaller apparent velocity than the NE X-ray-bright spot. The SW outer lobe jet was not detected in the radio in either 1999 or 2004. The density and mass of the X-ray-emitting material is estimated. Cooling times, shock speeds, pressure, and confinement are discussed.