Discovery of New Candidate Vega-type Systems from [ITAL]IRAS[/ITAL] and the 2 Micron All-Sky Survey

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Abstract
We obtained J (1.25 μm), H (1.65 μm), and Ks (2.17 μm) photometry from the 2 Micron All-Sky Survey and 12, 25, 60, and 100 μm photometry from the IRAS Faint Source Catalog of 2834 field stars. We identified in this sample 296 main-sequence (luminosity class IV, IV-V, or V) stars. We searched the sample of main-sequence stars for excess 12 μm emission with respect to J, H, and Ks photospheric emission. We discovered eight systems with 12 μm 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 ~1-10 AU from the stars, where it is heated to "terrestrial" temperatures, ~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.

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