A 25 micron search for Vega-like disks around main-sequence stars with ISO

Abstract

We present an ISO 25 mu m photometric survey of a sample of 81 nearby main-sequence stars in order to determine the incidence of ``warm'' dust disks. All stars were detected by ISO. We used an empirical relation to estimate the photospheric flux of the stars at 25 mu m. We find 5 stars (6%) with excess above the photospheric flux which we attribute to a Vega-like disk. These stars show disk temperatures not warmer than 120 K. Our study indicates that warm disks are relatively rare. Not a single star in our sample older than 400 Myr has a warm disk. We find an upper limit of M_disk = 2x 10^-5 M_oplus for the mass of the disks which we did not detect. ISO is an ESA project with instruments funded by ESA Member States (especially the PI countries: France, Germany, The Netherlands and the United Kingdom) and with the participation of ISAS and NASA.