An Etymological Dictionary of Astronomy and Astrophysics

A peculiar → Mira variable with a → pulsation period of 387 days surrounded by an extended → emission nebula. R Aqr is a → symbiotic  → binary star with a mass-losing, pulsating → red giant and an accreting hot companion with a jet → outflow which ionizes an emission nebula. The orbital period of the R Aqr binary is about 44 years as inferred from periodic phases of reduced brightness observed around 1890, 1933, and 1977. These phases are interpreted as partial obscurations of the mira by the companion with its → accretion disk and the associated gas and dust flows. The inferred orbital period is supported by → radial velocity measurements (Schmid et al., 2018, A&A 602, A53 and references therein).

See also: R, → Beyer designation; → Aquarius.