ALMA observations of GKM stars in Upper Sco

With these data, we measure the 0.88mm continuum and ^12^CO J=3-2 line fluxes of disks around low-mass (0.14-1.66M_{sun}_) stars at an age of 5-11Myr. Of the 75 primordial disks in the sample, 53 are detected in the dust continuum and 26 in CO.

Of the 31 disks classified as debris/evolved transitional disks, five are detected in the continuum and none in CO. The lack of CO emission in approximately half of the disks with detected continuum emission can be explained if CO is optically thick but has a compact emitting area (<~40au), or if the CO is heavily depleted by a factor of at least ~1000 relative to interstellar medium abundances and is optically thin. The continuum measurements are used to estimate the dust mass of the disks.