A Census of the Circumstellar Disk Populations in the Sco-Cen Complex*

I have used mid-infrared (IR) photometry from the Wide-field Infrared Survey Explorer (WISE) to perform a census of circumstellar disks among similar to 10,000 candidate members of the Sco-Cen complex that were recently identified with data from the Gaia mission. IR excesses are detected for more than 1200 of the WISE counterparts that are within the commonly adopted boundary for Sco-Cen, similar to 400 of which are newly reported in this work. The richest population in Sco-Cen, UCL/LCC, contains the largest available sample of disks (>500) for any population near its age (similar to 20 Myr). UCL/LCC also provides the tightest statistical constraints to date on the disk fractions of low-mass stars for any single age beyond that of Upper Sco (similar to 11 Myr). For Upper Sco and UCL/LCC, I have measured the disk fractions as a function of spectral type. The disk fraction in Upper Sco is higher at later spectral types, which is consistent with the results for previous samples of candidate members. In UCL/LCC, that trend has become more pronounced; the disk fractions in UCL/LCC are lower than those in Upper Sco by factors of similar to 10, 5.7, and 2.5 at B7-K5.5, K6-M3.5, and M3.75-M6, respectively. The data in UCL/LCC also demonstrate that the disk fraction for low-mass stars remains nonnegligible at an age of 20 Myr (0.09 +/- 0.01). Finally, I find no significant differences in the ages of disk-bearing and diskless low-mass stars in Upper Sco and UCL/LCC based on their positions in color-magnitude diagrams.

Automated summary

I have used mid-infrared (IR) photometry from the Wide-field Infrared Survey Explorer (WISE) to study circumstellar disks in the Sco-Cen complex. The UCL/LCC region in Sco-Cen has the highest number of disks (>500) for its age and provides the most stringent constraints on disk fractions for low-mass stars. The disk fractions in UCL/LCC are lower than those in Upper Sco and decrease with later spectral types. The data show that disk fractions for low-mass stars remain significant at an age of 20 Myr. Age differences between disk-bearing and diskless low-mass stars in Upper Sco and UCL/LCC were not found based on their positions in color-magnitude diagrams.