Protoplanetary disk
Videos
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
Atacama Large Millimeter Array image of HL Tauri
A 2009 image showing fractions of stars that suggest some evidence of having a protoplanetary disk as a function of their stellar age in millions of years; The samples are nearby young clusters and associations.
Protoplanetary disk. Simulated spiral arm vs observational data.
An artist's illustration giving a simple overview of the main regions of a protoplanetary disk, delineated by the soot and frost line, which for example has been observed around the star V883 Orionis.
Planetesimal
Videos
Planetesimals are solid objects thought to exist in protoplanetary disks and debris disks. Believed to have formed in the Solar System about 4.6 billion years ago, they aid study of its formation.
Protoplanetary disk
…thought to evolve into planetary systems. Electrostatic and gravitational interactions may cause the dust and ice grains in the disk to accrete into planetesimals. This process competes against the stellar wind, which drives the gas out of the system, and gravity (accretion) and internal stresses (viscosity…
Debris disks detected in HST archival images of young stars, HD 141943 and HD 191089, using improved imaging processes (24 April 2014)
PDS 70