Protoplanetary disk

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 also be considered an accretion disk for the star itself, because gases or other material may be falling from the inner edge of the disk onto the surface of the star. 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.

Not to be confused with Protoplanetary nebula.

Debris disks[edit]

Gas-poor disks of circumstellar dust have been found around many nearby stars—most of which have ages in the range of ~10 million years (e.g. Beta Pictoris, 51 Ophiuchi) to billions of years (e.g. Tau Ceti). These systems are usually referred to as "debris disks". Given the older ages of these stars, and the short lifetimes of micrometer-sized dust grains around stars due to Poynting Robertson drag, collisions, and radiation pressure (typically hundreds to thousands of years), it is thought that this dust is from the collisions of planetesimals (e.g. asteroids, comets). Hence the debris disks around these examples (e.g. Vega, Alphecca, Fomalhaut, etc.) are not truly "protoplanetary", but represent a later stage of disk evolution where extrasolar analogs of the asteroid belt and Kuiper belt are home to dust-generating collisions between planetesimals.

Illustration of the dynamics of a proplyd

20 protoplanetary discs captured by the High Angular Resolution Project (DSHARP).^[21]

A shadow is created by the protoplanetary disc surrounding the star HBC 672 within the nebula.^[22]

Protoplanetary disc AS 209 nestled in the young Ophiuchus star-forming region.^[23]

Protoplanetary disk HH 212.^[24]

By observing dusty protoplanetary discs, scientists investigate the first steps of planet formation.^[25]

Concentric rings around young star HD 141569A, located some 370 light-years away.^[26]

Debris disks detected in HST images of young stars, HD 141943 and HD 191089 - images at top; geometry at bottom.^[27]

Protoplanetary disk HH-30 in Taurus - disk emits the reddish stellar jet.

Artist's impression of a protoplanetary disk.

A proplyd in the Orion Nebula.

Video shows the evolution of the disc around a young star like HL Tauri (artist concept).

Image of the circumtrinary disc around GW Orionis.^[28]

An artist's concept of a protoplanetary disk

Williams, J. P.; Cieza, L. A. (2011). "Protoplanetary Disks and Their Evolution". . 49 (1): 67–117. arXiv:1103.0556. Bibcode:2011ARA&A..49...67W. doi:10.1146/annurev-astro-081710-102548. S2CID 58904348.

Annual Review of Astronomy and Astrophysics

Armitage, P. J. (2011). "Dynamics of Protoplanetary Disks". . 49 (1): 195–236. arXiv:1011.1496. Bibcode:2011ARA&A..49..195A. doi:10.1146/annurev-astro-081710-102521. S2CID 55900935.