IUE observations of RCB stars during extinction minima.
Evans, A.; Whittet, D. C. B.; Bode, M. F.; Kilkenny, D.; Davies, J. K.
United Kingdom, South Africa
Abstract
The R Coronae Borealis stars RY Sgr and MV Sgr have been observed with the long-wavelength (LWR) camera on the IUE satellite during deep extinction minima. The ultraviolet spectrum of RY Sgr showed a rich chromospheric spectrum, similar to that observed in the optical spectrum of this object during previous extinction episodes. Near-simultaneous optical and near-infrared observations of MV Sgr have enabled us to deduce that the grains responsible for the extinction event in this R Coronae Borealis star had dimensions about 0.2 microns.