Analysis of Toroidal Magnetic Fields in Accretion Disks Using the Cross-Helicity Effect and Estimate of the Jet Velocity

Publications of the Astronomical Society of Japan

Nishino, Satoru¹  Yokoi, Nobumitsu¹ 

[1] Institute of Industrial Science, The University of Tokyo, Tokyo 106-8558 E-mail (NY):

关键词: "Accretion;    accretion disks";    "Astrophysical jets";    "Cross-helicity dynamo";    Magneto-hydrodynamics;    Turbulence;   

DOI  :  10.1093/pasj/50.6.653

学科分类：天文学(综合)

来源: Oxford University Press

【 摘 要 】

Themagneticfieldsinanaccretiondiskareexaminedusingamagnetohydrodynamic(MHD)turbulentdynamomodelconsistingoftransportequationsforthemeanfields,turbulentenergy,dissipationrate,andcrosshelicity.ThevelocityofaccretinggasesisassumedtoobeytheKeplerianandrigidrotationsintheouterandinnerregionsofadisk,respectively,exceptforthecentralpart.Undertheconditionofaxisymmetryaroundtherotationaxisanduniformityinthedirectionperpendiculartothedisk,theturbulentmodelisexaminedbothnumericallyandanalytically.Asaresult,itispointedoutthatthecross-helicityeffectgeneratesatoroidalmagneticfield,resultingintheoccurrenceofacurrentinadirectionperpendiculartothediskinthecentralpart.Thistoroidalmagneticfieldenablesgastoescapefromacentralhigh-massbodyasbipolarjets,becausethemagneticenergymaybecomecomparabletothegravitationalone.Thevelocityofthejetsinaprotoplanetarysystemwasestimatedbyanumericalsimulationofthepresetmodel.

【 授权许可】

Unknown