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Ultraviolet, optical and radio observations of the symbiotic star R Aquarii are discussed in the light of the discovery of a bright radio and optical jet from this star. The star is probably a binary with a period of 44 years. The VLA maps of the jet reveal a protruding structure extending-10 arc sec from the central radio source with a position angle virtually identical to that of the optical jet observed at Lick. We interpret the observations of R Aqr as indicating the existence of an accretion disk around an unseen companion. The hot subdwarf has effective temperature ,(65,000 K. We believe that the Mira primary and the hot secondary are in orbit around each other with a high eccentricity. At periastron the hot subdwarf accretes at super critical rates and a jet forms. It is difficult to understand how an accretion disk would have eclipsed the Mira in 1928-1935 and 1974-1980. We prefer to interpret the suppression of maximum light in these two periods as due to a distortion of the Mira envelope at periastron by the tidal interaction with the secondary. The jet may help to explain the excitation of the R Aqr nebula. It is possible that R Aqr flared up as a nova N1OOO years ago forming the nebula.

Publication Date





UV, ultraviolet, astronomy, Aquarii, jet


Instrumentation | Stars, Interstellar Medium and the Galaxy


In Y. Kondo, J.M. Mead, & R.D. Chapman (Eds.), Advances in Ultraviolet Astronomy: Four Years of IUE Research. Proceedings of a Symposium held at NASA Goddard Space Flight Center, Greenbelt, Maryland, March 30-April 1, 1982.

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Observations and Analysis of the Aquarii Jet



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