Circumstellar disc
A circumstellar disc (or circumstellar disk) is a torus, pancake or ring-shaped accumulation of matter composed of gas, dust, planetesimals, asteroids or collision fragments in orbit around a star. Around the youngest stars, they are the reservoirs of material out of which planets may form. Around mature stars, they indicate that planetesimal formation has taken place and around white dwarfs, they indicate that planetary material survived the whole of stellar evolution. Such a disc can manifest itself in various ways.
Young star
According to the currently accepted model of star formation, sometimes referred to as the nebular hypothesis, a star is formed by the gravitational collapse of a pocket of matter within a giant molecular cloud. The infalling material possesses some amount of angular momentum, which results in the formation of a gaseous protoplanetary disc around the young, rotating star. The former is a rotating circumstellar disc of dense gas and dust that continues to feed the central star. It may contain a few percent of the mass of the central star, mainly in the form of gas which is itself mainly hydrogen. The accretion disc phase lasts a few to 10 million years. Accretion rates are typically 10−7 to 10−9 solar masses per year but can vary.
This page contains text from Wikipedia, the Free Encyclopedia -	https://wn.com/Circumstellar_disc
Latest News for: circumstellar disk
5 things to know for January 14: Impeachment, Capitol riot, Covid, Flint water, ISIS
CNN 14 Jan 2021
The system's circumstellar disk is broken, resulting in misaligned rings around its three stars ... The Atacama Large Millimeter/submillimeter Array captured this unprecedented image of two circumstellar disks, in which baby stars are growing, feeding off material from their surrounding birth disk....
A planet-forming disk still fed by the mother cloud
Phys Dot Org 23 Nov 2020
ALMA has now revealed an evolved protoplanetary disk with a large gap still being fed by the surrounding cloud via large accretion filaments ... The structure observed is very unusual for stellar objects at this stage of evolution—with an estimated age of 1,000,000 years—when circumstellar disks are already formed and matured for planet formation....