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

¹ ISO Data Centre, ESA Astrophysics Division, Villafranca del Castillo, PO Box 50727, 28080 Madrid, Spain
² LAEFF-INTA, ESA VILSPA, PO Box 50727, 28080 Madrid, Spain
³ DESPA, Observatoire de Paris, 92190 Meudon, France
⁴ ESO, K. Schwarzschildstr. 2, 85748 Garching bei München, Germany
⁵ Astr. Inst. Anton Pannekoek, Univ. Amsterdam, Kruislaan 403, 1098 SJ, Amsterdam, The Netherlands
⁶ Leiden Observatory, PO Box 9513, 2300 RA Leiden, The Netherlands
⁷ Integral Science Operations, ESA ESTEC, Keplerlaan 1, 2201 AZ Noordwijk, The Netherlands

Corresponding author: R. J. Laureijs, Rene.Laureijs@esa.int

Received: 10 August 2001
Accepted: 8 March 2002

Abstract

We present an ISO 25 μm 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 μm. 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 for the mass of the disks which we did not detect.