The be Spectrum Variable HD 20336.

Abstract

The spectrum of HD 20336 has been studied on more than 300 spectrograms taken between 1903 and 1961, of whIch 261 were measured for radial velocities of absorption and emission features Conspicuous variation of the ratio V/R of the hydrogen emissions occurred from 1903 to 1937. A fairly regular period of about 4 5 years was adhered to from 1916 to 1931. Before and after that interval the cycles were appreciably longer. About 1937, variation practically ceased and had not yet resumed in 1961 The bright lines weakened appreciably in 1933, but bright Ha and H were still present in 1961 Displacements of the hydrogen emissions and their central absorptions accompanied the variations V/R, with amplitudes up to 110 km/sec. The correlation of phenomena was of the usual type, with maxima of both V/R and velocity approximately coincident in time. Helium absorption lines often appeared double or triple. Their displacements and structures showed no correlation with hydrogen velocfties and structures In this respect HD 20336 differed from Aquarii. In spite of the apparent regularity from 1916 to 1931, a binary-star interpretation appears very improbable. As in the much less regular Be variable Aquarii, the preferred model is an equatorial "shell" of elliptical outline whose line of apsides rotates slowly.