Observation of a Burst of High-Velocity Dust from α Herculis

Interferometric observations of α Herculis at a wavelength of 11.15 μm over the period 1989-2004 show large visibility variations. These variations are interpreted as an ejection of approximately 10-6 M☉ of material in 1990 that has subsequently expanded and dissipated. The expansion rate is approximately 75 km s-1, much larger than previous observations. No substantial material has been emitted during the subsequent 14 years.