Protoplanetary disk

Atacama Large Millimeter Array image of HL Tauri[1][2]

A protoplanetary disk is a rotating circumstellar disc of dense gas and dust surrounding a young newly formed star, a T Tauri star, or Herbig Ae/Be star. The protoplanetary disk may not be considered an accretion disk, while the two are similar. While they are similar, an accretion disk is hotter, and spins much faster. It is also found on black holes, not stars. This process should not be confused with the accretion process thought to build up the planets themselves. Externally illuminated photo-evaporating protoplanetary disks are called proplyds.

  1. ^ Johnathan Webb (2014-11-06). "Planet formation captured in photo". BBC.
  2. ^ "Birth of Planets Revealed in Astonishing Detail in ALMA's 'Best Image Ever'". NRAO. 2014-11-06. Archived from the original on 2014-11-06.