Unveiling a cluster of protostellar disks around the massive protostar
  GGD27 MM1
  We used ALMA to observe the star-forming region GGD27 at 1.14 mm with an
unprecedented angular resolution, 40 mas (56 au) and sensitivity (0.002 Msun).
We detected a cluster of 25 continuum sources, most of which are likely tracing
disks around Class 0/I protostars. Excluding the two most massive objects,
disks masses are in the range 0.003-0.05 Msun. The analysis of the cluster
properties indicates that GGD27 displays moderate subclustering. This result
combined with the dynamical timescale of the radio jet (10000 years) suggests
the youthfulness of the cluster. The lack of disk mass segregation signatures
may support this too. We found a clear paucity of disks with Rdisk >100 au. The
median value of the radius is 34 au, smaller than the median of 92 au for
Taurus but comparable to the value found in Ophiuchus and in the Orion Nebula
Cluster. In GGD27 there is no evidence of a distance-dependent disk mass
distribution (i. e., disk mass depletion due to external photoevaporation),
most likely due to the cluster youth. There is a clear deficit of disks for
distances <0.02 pc. Only for distances >0.04 pc stars can form larger and more
massive disks, suggesting that dynamical interactions far from the cluster
center are weaker, although the small disks found could be the result of disk
truncation. This work demonstrates the potential to characterize disks from
low-mass YSOs in distant and massive (still deeply embedded) clustered
environments.
