The Spectrum of R Aquarii, 1936-1949.

Fifty spectrograms of R Aquar , including fifteen with dispersion 10 A/mm, have been obtained from 1936 to 1949. During this interval the red variable has continued to exhibit the striking periodic changes characteristic of Me variables. The "companion" or nuclear star seems to have made little direct contribution to the photographed spectrum. The nebular lines were weak in 1936, increased in intensity toward 1940, and have since remained strong. The radial velocities from various groups of lines were studied in some detail. The displacement of the absorption lines, -22 km/sec, probably represents the actual velocity of the red variable. Emission lines definitely associated with the variable yield a velocity of - 33 km/sec. The nebular lines exhibit variable velocities, those arising in regions of lowest density yielding the largest changes. The curve for X 4363 [0 iii] resembles that of a spectroscopic binary of period 26.7 years, e = 0.5. The orbital interpretation is dubious. R Aquarii might be characterized as a "simmering nova."