SYLVESTER, RJ; BARLOW, MJ; SKINNER, CJ; (1994) MILLIMETER PHOTOMETRY AND INFRARED-SPECTROSCOPY OF VEGA-EXCESS STARS. In: ASTROPHYSICS AND SPACE SCIENCE. (pp. 261 - 270). KLUWER ACADEMIC PUBL
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JCMT millimetre-wave detections have been obtained for 11 Vega-excess stars having spectral types ranging from B9 to K5. UKIRT 10-mum spectra have been obtained for two of the sources, SAO 179815 and SAO 186777. The spectrum of SAO 179815 shows an unusually broad and diffuse silicate emission feature, whilst SAO 186777 shows the unidentified infrared (UIR) features, which are usually attributed to hydrocarbon vibrational modes. The mm photometry, along with optical, IRAS and near-IR photometry (much of the latter recently obtained by the authors), have been used to define the spectral energy distributions of the objects. A number of them show a 1-5 mum excess in addition to the longer wavelength excess. Values of the fractional excess luminosity, L(dust)/L*, have been derived from the spectral energy distributions; they exhibit a substantial range, from approximately 10(-5) up to almost 0.5, the theoretical maximum for a passive optically thick flared disc. Radiative transfer models have been constructed for several sources. One needs a well defined overall energy distribution, 10- and/or 20-mum spectra, and sub-mm and mm photometry in order to significantly constrain the model free parameters (disc density distribution, grain size power-law index, minimum and maximum grain radii).
|Title:||MILLIMETER PHOTOMETRY AND INFRARED-SPECTROSCOPY OF VEGA-EXCESS STARS|
|Event:||1st International Conference on Planetary Systems: Formation, Evolution, and Detection|
|Location:||JET PROPULS LAB, PASADENA, CA|
|Dates:||1992-12-08 - 1992-12-10|
|UCL classification:||UCL > School of BEAMS > Faculty of Maths and Physical Sciences > Physics and Astronomy|
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