2000ApJ...532..467L

The 11 µm fringe visibilities of IRC +10011 (= CIT3) and IRC +10420 have been measured at baselines ranging from 2 to 14 m with a two-telescope interferometer. The visibility data provide one-dimensional profiles of these two stars and their immediate surroundings with higher resolution in this spectral range than is presently possible with a single-aperture telescope. Spherically symmetric radiative transfer models suggest that IRC +10011 is surrounded by a dust shell with an inner radius subtending 0".033, which falls off in density as r^–1.5, slightly slower than the r^–2 expected for constant dust outflow. IRC +10420 appears to have a dust shell of inner radius 0".12, the density of which drops very slowly compared with that in a constant outflow. This implies decreasing outflow or a significant emission in the past.