|
Description
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*>0.1M_{sun}_ in the young (1-3Myr), nearby (150-200pc) Lupus complex. Our observations cover the 890{mu}m continuum and the ^13^CO and C^18^O 3-2 lines. We use the sub-millimeter continuum to constrain M_dust_ to a few Martian masses (0.2-0.4M_{Earth}_) 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 ^13^CO, and 11 in C^18^O at >3{sigma} significance. Stacking individually undetected sources limits their average dust mass to <~6 Lunar masses (0.03M_{Earth}_), 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_<~1M_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.
|
