Tags: Star.
The circumstellar envelope is the part of the star whichhas a roughly spherical shape and is not gravitationally bound to the star core.Usually circumstellar envelopes are formed from the dense stellar wind or they are presentbefore the formation of the star. Circumstellar envelopes of the old stars (Mira variables and OH/IR stars) eventually evolveinto protoplanetary nebulae and circumstellar envelopes of the young stellar objects evolve into circumstellar discs.