Infrared Space Observatory Photometric Search of Main-Sequence Stars for Vega-Type Systems

Abstract

We obtained 3.6-20 μm photometry of 38 bright [IRAS F_ν(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.

Based on observations with ISO, an ESA project with instruments funded by ESA member states, with the participation of ISAS and NASA.