A Magnetically Torqued Disk Model for Be Stars

摘要: Despite extensive study, the mechanisms by which Be star disks acquire high densities and angular momentum while displaying variability on many timescales are still far from clear. In this paper, we discuss how magnetic torquing may help explain disk formation with observed quasi-Keplerian ( as opposed to expanding) velocity structure their variability. We focus effects of rapid rotation stars, considering regime where centrifugal forces provide dominant radial support material. Using a kinematic description velocity, v(phi)(r), in parametric model an aligned field strength B(r), develop analytic expressions for properties that allow us estimate stellar surface necessary create such range stars main sequence. The fields required form compared bounds previously derived photospheric limiting conditions. explains why most common main-sequence at about spectral class B2 V. earlier type very fast high-density winds would require unacceptably strong gt 10(3) G) torqued disks, late B low mass-loss rates) tend produce only small fluxes diagnostics. For V average is 300 G. predicted intrinsic polarization flux Halpha comparable observations. extent our dense compatible typical estimates. also whether effect containment time-dependent accumulation matter tubes/disk can some disks.