R Aquarii - Wolf-Rayet Star

R Aquarii (R Aqr) is a variable star in the constellation Aquarius.

R Aquarii is a symbiotic star containing a red giant primary and a white dwarf secondary in a binary system. The orbital period is approximately 44 years. The main star is a Mira variable, and varies in brightness by a factor of several hundred and with a period of slightly more than a year. The total range of 5.2 - 12.4 is a variation of 750 times in brightness, from a naked eye star to one beyond the range of binoculars. The pulsations occur every 390 days but are not entirely regular.
The nebula around R Aquarii is also known as Cederblad 211. It is possible that the nebula is the remnant of a nova-like outburst, which may have been observed by Japanese astronomers, in the year 930 AD. It is reasonably bright but small and dominated by its central star. Visual observations are difficult and rare. The central region of the jet shows an ejection that took place around 190 years ago, as well as much younger structures. Another jet launched in January 2020 was announced by a 2025 publication. The expansion rate of the jet constrains the distance of the system to 260 ± 27 parsecs (848 ± 88 ly).