Gravitational Collapse of Filamentary Clouds

Publications of the Astronomical Society of Japan

Hanawa, Tomoyuki¹  Kawachi, Takeshi¹ 

[1] Department of Astrophysics, Nagoya University, Chikusa-ku, Nagoya 464-8602; E-mail (TH):

关键词: Gravitation;    Hydrodynamics;    "Interstellar: clouds";    "Stars: formation";   

DOI  :  10.1093/pasj/50.6.577

学科分类：天文学(综合)

来源: Oxford University Press

【 摘 要 】

Weconsidergravitationalcollapseofafilamentarycloudundertheassumptionthatitisaxisymmetricanduniformalongtheaxis.ThepressureisapproximatedbyapolytropeofP=Kργ.Wefoundasimilaritysolutionforthecollapsewhenthepolytropicindexliesintherange0lt;γlt;1.Accordingtothesimilaritysolution,thecollapseconsitsoftwophases.Inthefirstphasethefilamentbecomesdenserandthiner.Thedensityatthecenter(ρc)increasesinproportionto(t0–t)−2,wheret0denotestheepochattheendofthefirstphase.Meanwhile,thefilamentdiameter(FWHM)decreasesinproportionto(t0–t)(2−γ).Thelinedensityofthecentralfilamentofρgt;0.1ρcvanishesatt=t0,sinceitisproportionaltothecentraldensityandthesquareofthediameter[∝(t0–t)2(1−γ)].Inthesecondphasethecentralfilamentgrowsinmassbyaccretion.Thecollapseinthesecondphaseissimilartotheinside-outcollapseofasphericalgascloud.Whenthepolytropicindexγisclosertounity,thecollapseisslower.Whenγ=0.999,thecollapseis12-timesslowerthanthedynamicalone.Wealsofoundfromnumericalsimulationshavingvariousinitialconditionsthatthecollapseofafilamentarycloudapproachesasymptoticallythesimilaritysolutionirrespectivelyoftheinitialcondition.

【 授权许可】

Unknown