The Ophiuchus DIsk Survey Employing ALMA (ODISEA): Disk Dust Mass
  Distributions across Protostellar Evolutionary Classes
  As protostars evolve from optically faint / infrared bright (Class I) sources
to optically bright / infrared faint (Class II) the solid material in their
surrounding disks accumulates into planetesimals and protoplanets. The nearby,
young Ophiuchus star-forming region contains hundreds of protostars in a range
of evolutionary states. Using the Atacama Large Millimeter Array to observe
their millimeter continuum emission, we have measured masses of, or placed
strong upper limits on, the dust content of 279 disks. The masses follow a
log-normal distribution with a clear trend of decreasing mass from less to more
evolved protostellar infrared class. The (logarithmic) mean Class I disk mass,
M = 3.8 M_Earth, is about 5 times greater than the mean Class II disk mass, but
the dispersion in each class is so high, sigma(logM) ~ 0.8-1, that there is a
large overlap between the two distributions. The disk mass distribution of
flat-spectrum protostars lies in between Classes I and II. In addition, three
Class III sources with little to no infrared excess are detected with low disk
masses, M ~ 0.3 M_Earth. Despite the clear trend of decreasing disk mass with
protostellar evolutionary state in this region, a comparison with surveys of
Class II disks in other regions shows that masses do not decrease monotonically
with age. This suggests that the cloud-scale environment may determine the
initial disk mass scale or that there is substantial dust regeneration after 1
Myr.
