2010A&A...515A..31L

We combine published optical and near-infrared photometry to identify new low-mass candidate members in an area of about 0.64deg² in Corona Australis with the S-parameter method. Five new candidate members of the region are selected. They have estimated ages between 3 and 15Myr and masses between 0.05 and 0.15M_☉. With Spitzer photometry we confirm that these objects are not surrounded by optically thick disks. However, one of them is found to display excess at 24µm, thus suggesting it harbors a disk with an inner hole. With an estimated mass of 0.07M_☉ according to the SED fitting, this is one of the lowest-mass objects reported to possess a transitional disk. Including these new members, the fraction of disks is about 50% among the total Corona Australis population selected by the same criteria, lower than the 70% fraction reported earlier for this region. Even so, we find a ratio of transitional to primordial disks (45%) very similar to the value derived by previous authors. This ratio is higher than for solar-type stars (5-10%), suggesting that disk evolution is faster in the latter, and/or that the ``transitional disk'' stage is not such a short-lived step for very low-mass objects. However, this impression needs to be confirmed with better statistics.