AAS Meeting #193 - Austin, Texas, January 1999
Session 69. Circumstellar Material
Display, Friday, January 8, 1999, 9:20am-6:30pm, Exhibit Hall 1

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[69.16] The Changing Circumstellar Shell Around UW Cen

G.C. Clayton (LSU), K.D. Gordon (LSU), F. Kerber (ESO)

We present new images of the reflection nebula surrounding the R Coronae Borealis Star, UW Cen. This nebula surrounding, first detected in 1990, has changed its appearance significantly. At the estimated distance of UW Cen, this nebula is approximately 0.4 ly in radius so the nebula cannot have visibly moved in only 8 years. Instead the morphology of the nebula appears to change as different parts are illuminated by light from the central star modulated by thick dust clouds near its surface. These dust clouds form and dissipate at irregular intervals causing the well-known declines in the R Coronae Borealis stars. In this way, the central star acts like a lighthouse shining through holes in the dust clouds and lighting up different portions of the nebula.


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