K I 7699 A emission from the Betelgeuse shell

A map of the circumstellar gas shell around Betelgeuse is presented from observations of the fluorescent emission in the K I 7699 A resonance line. The observations obtained at 3 sec and 5 sec from the star indicate approximate spherical symmetry in the 10 km/s expanding shell responsible for the blueshifted sharp cores seen in strong resonance and low excitation lines. Calculations show that the density of neutral K atoms is approximately constant between 3 sec and 5 sec from the star. The emission profiles in the west show a second, higher velocity, component at 5 sec from the star.