THE DUST DISK AROUND THE VEGA-EXCESS STAR SAO-26804

We present multiwaveband observations of the K2 Vega-excess star SAO 2 6804 (=HD 233517). These include James Clerk Maxwell Telescope millime ter-wave photometry, plus spectra in the 8-13 mu m and 18-24 mu m atmo spheric windows, an image at a wavelength of 10 mu m through a broadba nd N filter and near-IR (JHKLL'M) photometry all taken at the United K ingdom Infrared Telescope. The source is resolved at 10 mu m, and we c an confirm with these observations that the IR excess seen in IRAS obs ervations of this source is associated with the optical star. The imag e is consistent with the dust being confined to a disk with FWHM 1.''5 on the major axis, with an inclination angle of less than 30 degrees away from edge-on. This represents the first confirmation that the dus t in a Vega-excess star other than beta Pic is confined to a disk geom etry. We present models of the source which show that many of the prop erties of the disk and the dust in it are similar to those which we ha ve previously derived for the disk around SAO 179815, but that there a re some very small grains in the disk around the star which give rise to a very prominent and narrow silicate dust feature at 9.7 mu m and t o so-called unidentified infrared bands in the 10 mu m region. The lar ger grains are composed of a mixture of amorphous carbon and silicate with an abundance ratio consistent with an interstellar origin. The to tal mass of dust in the disk is 3.0 x 10(-7) M.. Finally, our model su ggests that there may be a substantial UV and/or soft X-ray flux from SAO 26804, consistent with it being a very young and rather active sta r.