Astrophysics (index)about

circumstellar disk

(disk or ring shaped accumulation of matter around a star)

A circumstellar disk (in context, just disk) is matter, typically in a ring, collected around a star. It can be composed of gas, dust, planetesimals, or a combination, in orbit around the star. For young stars, for which the term protoplanetary disk is used, it may be the raw material of later planets. The asteroids around the Sun represent a thin circumstellar disk.

Excess infrared from a star is evidence of a disk, indicating thermal emission for something large and cooler than the star. When the disk can be resolved, the material making up the disk and how it varies by radius can be determined from this electromagnetic radiation, which is effected by the dust grain size: the emission of grains is inefficient for wavelengths long in proportion to their diameter.

Older stars can also have disks such as debris disks.

(disks,object type)

Referenced by:
Be star
Bondi radius
circumplanetary disk
Coriolis force
corotation torque
corotation resonance (CR)
dead zone
debris disk
extra-solar planet
GG Tau
Hall effect
Keplerian disk
Kepler radius
mass transport
Maxwell-Boltzmann distribution
planetary system
planetary nebula (PN)
Poynting-Robertson effect
protoplanetary disk (PPD)
radiation pressure
Roche limit
surface density (Σ)
young stellar object (YSO)