Searching for infrared excesses in Sun-like stars observed by WISE

We present the results of a search for infrared-excess (IR-excess) candidates in a comprehensive (29 000 stars) magnitude-limited sample of dwarf stars, spanning the spectral range F2-K0, and brighter than V = 15 mag. We searched the sample within the WISE all sky survey data base for objects within 1 arcsec of the coordinates provided by the SIMBAD data base, and found over 9000 sources detected in all WISE bands. The sample excludes objects that are flagged as extended sources and those images that are affected by various optical artefacts. For each detected object, we compared the observed W4/W2 (22 mu m/4.6 mu m) flux ratio with the expected photospheric value and identified 197 excess candidates at 3 sigma. For the vast majority of candidates, the results of this analysis represent the first reported evidence of an IR excess. Through the comparison with a simple blackbody emission model, we derive estimates of the dust temperature, as well as of the dust fractional luminosities. For more than 80 per cent of the sample, this temperature is higher than 120 K, suggesting the presence of warm circumstellar dust. Complementary observations at longer wavelengths (far-IR and submillimetre) are required for better characterizing and explaining the origin of this emission.