Infrared Space ObservatoryPhotometric Search of Main‐Sequence Stars for Vega‐Type Systems

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Abstract
We obtained 3.6-20 μm photometry of 38 bright [IRAS Fν(12 μm) > 0.7 Jy] main-sequence stars with the Infrared Space Observatory (ISO). Observations were conducted with the ISOPHOT instrument, in the single-pointing photometry mode, through filters at 3.6, 11.5, and 20.0 μm. We searched for excess (Vega-type) emission from dust at temperatures 100 K, located at ~1-60 AU from the stars. We thus sampled dust at warm, terrestrial material temperatures and at cool (~100 K) temperatures of possible Kuiper Belt-type regions in these systems. We detected 20 μm excesses from ~14% of our sources, but we did not detect 11.5 μm excesses from any of them. We present single-temperature blackbody models of the location and density of dust emission around 10 stars, two of them (29 Cyg and Gl 816) with excesses newly reported here. We make a thorough comparison of ISO and IRAS data on our target stars and propose a new calibration procedure for ISOPHOT staring measurements at 3.6, 11.5, and 20 μm.