ALMA SURVEY OF LUPUS PROTOPLANETARY DISKS. I. DUST AND GAS MASSES

We present the first high-resolution sub-millimeter survey of both dust and gas for a large population of protoplanetary disks. Characterizing fundamental properties of protoplanetary disks on a statistical level is critical to understanding how disks evolve into the diverse exoplanet population. We use the Atacama Large Millimeter/Submillimeter Array (ALMA) to survey 89 protoplanetary disks around stars with M-* > 0.1 M-circle dot in the young (1-3 Myr), nearby (150-200 pc) Lupus complex. Our observations cover the 890 mu m continuum and the 13CO and (CO)-O-18 3-2 lines. We use the sub-millimeter continuum to constrain M-dust to a few Martian masses (0.2-0.4 M-circle plus) and the CO isotopologue lines to constrain M-gas to roughly a Jupiter mass (assuming an interstellar medium (ISM)-like [CO] [H-2] abundance). Of 89 sources, we detect 62 in continuum, 36 in 13CO, and 11 in (CO)-O-18 at > 3 sigma significance. Stacking individually undetected sources limits their average dust mass to less than or similar to 6 Lunar masses (0.03 M-circle plus), indicating rapid evolution once disk clearing begins. We find a positive correlation between M-dust and M*, and present the first evidence for a positive correlation between M-gas and M*, which may explain the dependence of giant planet frequency on host star mass. The mean dust mass in Lupus is 3x higher than in Upper Sco, while the dust mass distributions in Lupus and Taurus are statistically indistinguishable. Most detected disks have M-gas. 1 M-Jup and gas-to-dust ratios < 100, assuming an ISM-like [CO] [H-2] abundance; unless CO is very depleted, the inferred gas depletion indicates that planet formation is well underway by a few Myr and may explain the unexpected prevalence of super-Earths in the exoplanet population.