Discovery of new candidate vega-type systems from IRAS and the 2 micron all-sky survey

We obtained J (1.25 mu m), H (1.65 mu m), and K, (2.17 mu m) photometry from the 2 Micron All-Sky Survey and 12, 25, 60, and 100 mu m photometry from the IRAS Faint Source Catalog of 2834 field stars. We identified in this sample 296 main-sequence (luminosity class IV TV-V, or V) stars. We searched the sample of main-sequence stars for excess 12 mu m emission with respect to J, H, and K, photospheric emission. We discovered eight systems with 12 mu m excess emission newly reported here. These excesses are likely to be from Vega-type circumstellar dust, but small-aperture photometry is needed to confirm their nature. Preliminary models that assume the excesses are circumstellar show the dust to be located similar to 1-10 AU from the stars, where it is heated to "terrestrial" temperatures, similar to 200-500 K. Colder dust might also exist in the systems but below the IRAS sensitivity limit. The exception is HD 93331 (B9.5 V), previously known for its IRAS far-infrared excess.