The small-scale structure and variability of 3C 273 B

Observations of 3C 273 B with the Algonquin--Chilbolton interferometer at 2.8 cm for five epochs in 1972--1973 have been combined with previously published 2.8 cm and 3.8 cm VLBI observations of this source. The brightness distributions derived from these observations are consistent with the closure-phase data of Rogers et al. and consist of a bright central source, a relatively slowly varying component 2 milli-arcsec to the SW, and a third almost collinear component to the NE. The observed changes in visibility are accounted for by brightness changes with little or no significant motion of the components. Most of the change was in the NE component which brightened between 1970 October and 1971 February, faded almost completely by 1972 April, and brightened again between 1972 August and 1973 March. It is suggested that the difference in component lifetimes is related to the large-scale asymmetry in 3C 273 and involves interaction with material in the optical emission-line region in the NE. Inverse Compton scattering from infrared photons could be the dominant loss mechanism in the SW component. (AIP)