Delta Andromedae (K3III) : an IRAS source with an unusual ultraviolet spectrum.

The IRAS survey has revealed anomalous cool infrared emission from a number of otherwise apparently normal K stars. IUE spectra of the brightest of these stars, Delta And, which is a spectroscopic binary and optical standard K3 III star, is obtained. The IUE spectra show the unexpected presence of C IV in emission, implying hot material (about 100,000 K), and evidence for a strong, high-velocity wind. It is argued that the unusual ultraviolet spectrum arises solely from the primary star and that it is another example of a 'hybrid' K star. The infrared excess appears to be caused by a primordial dust shell extending from about 1 to 30 arcsec from the primary. One of the companions of Delta And lies close to the inner edge of the shell and another one (possibly two) lies close to the outer edge, so that interesting dynamical interactions between the companions and the dust shell may be expected. The dust shell may be analogous to the Oort cometary cloud in the Solar System or to a scaled-up version of Saturn's rings.