The low-mass diskless population of Corona Australis

Abstract

We combine published optical and near-infrared photometry to identify new low-mass candidate members in an area of about 0.64 deg^2 in Corona Australis, using the S-parameter method. Five new candidate members of the region are selected, with estimated ages between 3 and 15 Myr, and masses between 0.05 and 0.15 M_Sun. Using Spitzer photometry, we confirm that these objects are not surrounded by optically thick disks. However, one of them is found to display excess at 24 micron, thus suggesting it harbours a disk with an inner hole. With an estimated mass of 0.07 M_Sun 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 other 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 in the case of very low-mass objects. However, this impression needs to be confirmed with better statistics.

Accepted for publication in Astronomy & Astrophysics. Replaced by version after language editing.

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Cited by in corpus (7)

• The Transitional Protoplanetary Disk Frequency as a Function of Age: Disk Evolution in the Coronet Cluster, Taurus, and Other 1--8 Myr-old Regions
• The Spitzer Survey of Interstellar Clouds in the Gould Belt. III. A Multi-Wavelength View of Corona Australis
• ALMA survey of Class II protoplanetary disks in Corona Australis: a young region with low disk masses
• Protostars, multiplicity, and disk evolution in the Corona Australis region: A Herschel Gould Belt Study
• Protostars and stars in the Coronet cluster: Age, evolution, and cluster structure
• The low-mass stellar population in the young cluster Tr37: Disk evolution, accretion, and environment
• The substellar population in Corona Australis