AAS 197, January 2001
Session 8. Circumstellar Matter and Winds
Display, Monday, January 8, 2001, 9:30am-7:00pm, Exhibit Hall

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[8.25] 2MASS-IRAS Discovery of New Candidate Vega-type Systems

S.B. Fajardo-Acosta (SSC/Caltech), C.A. Beichman (JPL/Caltech), R.M. Cutri (IPAC/Caltech)

We obtained J (1.25 \mum), H (1.65 \mum), and Ks (2.17 \mum) photometry from the 2-Micron All-Sky Survey (2MASS), and 12, 25, 60, and 100 \mum photometry from the IRAS Faint Source Catalog (FSC), of field stars with galactic latitude > 20\circ. We identified main-sequence (luminosity class IV, IV--V, or V) stars using 3 methods: from previously known classifications; from Hipparcos distances and spectral types or J-Ks colors; or estimated from J-Ks, H-Ks colors. We searched this sample of main-sequence stars for excess 12 \mum emission with respect to the J, H, and Ks photospheric emission. This work is an extension of our previous survey of 2834 field stars, wherein we discovered, out of 296 main-sequence stars, 8 new candidate Vega-type systems with 12 \mum excesses (Fajardo-Acosta et al.\ 2000, ApJ, 538, L155). That survey was based on \approx 35 % of the sky, and our new survey covers \approx 75 % of the sky. We modeled the 12 \mum excess emission of our new cadidate systems, likely to arise from dust at ``terrestrial material'' temperatures, ~ 200--500 K, located at ~ 1-10 AU from the stars. Colder dust, more distant from the stars, might also exist in Kuiper Belt-like regions. We comment on the likelihood of spatially resolving these systems with current ground-based imaging technology. A fuller understanding of this dust may require more sensitive observations at long wavelengths by SIRTF.

We acknowledge the support of the SIRTF Science Center, California Institute of Technology, which is operated under contract with the National Aeronautics and Space Administration.

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