A protoplanetary disk is a rotating circumstellar disk of dense gas surrounding a young newly formed star, a T Tauri star, or Herbig Ae/Be star. The protoplanetary disk may be considered an accretion disc because gaseous material may be falling from the inner edge of the disk onto the surface of the star, but 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.
Other articles related to "protoplanetary disk, disk, protoplanetary disks, disks":
... In January 1999, NASA announced a protoplanetary disk around HD 141569 ... The Hubble Space Telescope showed that the disk appears to come in two parts (inner and outer) ... The vast disk is 75 billion miles across (13 times the diameter of Neptune's orbit) ...
... molecules necessary for life may have formed in the protoplanetary disk of dust grains surrounding the Sun before the formation of the Earth ...
... variant of the nebular hypothesis is Solar Nebular Disk Model (SNDM) or simply Solar Nebular Model ... Star formation is a complex process, which always produces a gaseous protoplanetary disk around the young star ... The protoplanetary disk is an accretion disk which continues to feed the central star ...
... The first one is the disk instability model, where giant planets form in the massive protoplanetary disks as a result of its gravitational fragmentation (see above) ... explain the formation of the giant planets in relatively low mass disks (less than 0.1 solar masses) ... a core of approximately 10 Earth masses and b) accretion of gas from the protoplanetary disk ...
Famous quotes containing the word disk:
“Unloved, that beech will gather brown,
This maple burn itself away;
Unloved, the sun-flower, shining fair,
Ray round with flames her disk of seed,
And many a rose-carnation feed
With summer spice the humming air;”
—Alfred Tennyson (18091892)