Abstract:
HD 218393 is a well known shell star having several interesting spectral
features. Struve (1944), Merrill (1949), Holliday (1950) and Doazan and
Peton (1970) observed this star spectroscopically and noticed a series of
changes in the spectrum. The radial velocity variations of the circumstellar
lines suggested a period of 35 to 40 days but the amplitude was not exactly
the same. Doazan and Peton (1970) interpreted the radial velocity variations
as caused by an expanding envelope with variable accelerations, while after
analysing all the available radial velocity data of HD 218393, Kriz and
Harmanec (1975) suggested that the object may be an interacting binary with
a possible orbital period of 38.873d.
