Evidence for remnant circumstellar disks around post T tauri stars

We report infrared imaging photometry at 6.5 and 15 mu m of seven Lindroos binaries selected by Pallavicini et al. as "almost certain physical pairs". The photometry was obtained in order to asses whether these adolescent (10-100 Myr) low-mass stars still have infrared excess emission which could be caused by a circumstellar disk. Given the current status of the calibration, we could not perform precise photometry or reliable modeling. We could, however, for the subset of the sample that was well observed, compare the ratio of F-6.5/F-15 for the primaries versus the secondaries. This ratio is significantly higher for the primaries than for the companions, and for the primaries it is close to the expected value for a Rayleigh-Jeans spectrum. While some of the difference is due to the cooler energy distribution of the late-type photospheres, we conclude that a significant part of the difference must come from excess emission at 15 mu m, and thus we have found clear evidence for remnant disks.