[Previous] | [Session 6] | [Next]
J. D. Monnier (Harvard-Smithsonian Center for Astrophysics), P. G. Tuthill (University of Sydney), W. C. Danchi (NASA-GSFC)
WR 140 is a 7.9-year binary system consisting of a WC-type Wolf-Rayet star and an O-star companion. Both stars drive high-speed winds that collide, producing X-rays and non-thermal radio emission. Most interestingly perhaps, carbon dust is produced for a few-month period before and after the periastron passage of this highly eccentric orbit, when the wind collisions are intense enough to compress the gas to sufficient densities to catalyze dust condensation. Using the high-resolution imaging technique of aperture masking on the Keck-I telescope, we have captured two snapshots of this rarely-seen dust shell as it formed early in 2001, and tracked its outward motions of greater than 1.5 AU per day. These near-infrared images have been analyzed to provide new constraints on the orbital elements of and distance to the binary, as well as new insights into the dust formation process. We also discuss how this system relates to the "pinwheel nebulae" previously imaged, and discuss implications for massive star evolution.