Discovery of a sub-Keplerian disk with jet around a 20Msun young star.
  ALMA observations of G023.01-00.41
  It is well established that Solar-mass stars gain mass via disk accretion,
until the mass reservoir of the disk is exhausted and dispersed, or condenses
into planetesimals. Accretion disks are intimately coupled with mass ejection
via polar cavities, in the form of jets and less collimated winds, which allow
mass accretion through the disk by removing a substantial fraction of its
angular momentum. Whether disk accretion is the mechanism leading to the
formation of stars with much higher masses is still unclear. Here, we are able
to build a comprehensive picture for the formation of an O-type star, by
directly imaging a molecular disk which rotates and undergoes infall around the
central star, and drives a molecular jet which arises from the inner disk
regions. The accretion disk is truncated between 2000-3000au, it has a mass of
about a tenth of the central star mass, and is infalling towards the central
star at a high rate (6x10^-4 Msun/yr), as to build up a very massive object.
These findings, obtained with the Atacama Large Millimeter/submillimeter Array
at 700au resolution, provide observational proof that young massive stars can
form via disk accretion much like Solar-mass stars.
