Circumstellar envelope

{{Short description|Part of a star}}

A circumstellar envelope (CSE) is a part of a star that has 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 present before the formation of the star.{{cite journal|arxiv=astro-ph/0703390|title=The circumstellar envelope of IRC+10216 from milli-arcsecond to arcmin scales|author1=Leao|author2=Patrick De Laverny|author3=Mekarnia|author4=De Medeiros|author5=Benoit Vandame|year=2007|doi=10.1051/0004-6361:20054577|volume=455|issue=1|journal=Astronomy & Astrophysics|pages=187–194|bibcode=2006A&A...455..187L|s2cid=18535333 }} Circumstellar envelopes of old stars (Mira variables and OH/IR stars) eventually evolve into protoplanetary nebulae, and circumstellar envelopes of young stellar objects evolve into circumstellar discs.{{cite journal|author1=Leslie Looney|author2=Lee Mundy|author3=Jack Welch|year=2003|title=Envelope Emission in Young Stellar Systems, A Sub-Arcsecond Survey of Circumstellar Structure|journal=The Astrophysical Journal|volume=592|issue=1|pages=255–265|arxiv=astro-ph/0303640|bibcode=2003ApJ...592..255L|doi=10.1086/375582|s2cid=15365363 }}