The structure and magnitude of the electromagnetic field produced by a rotating accretion disk around a black hole were determined. The disk matter is assumed to be a magnetized plasma with a frozenin poloidal magnetic field. The vacuum approximation is used outside the disk.

A single merger scenario for making galaxies such as NGC 4550 possessing equal coplanar counter-rotating stellar disks is investigated by collisionless N-body technique. The scenario is successful in producing an axisymmetric disk made of two almost equal counter-rotating populations. The final disk shows a clear bimodal line profile in the outer part, which demonstrates that disk-disk mergers ...

A single merger scenario for making galaxies such as NGC 4550 possessing equal coplanar counter-rotating stellar disks is investigated by collisionless N-body technique. The scenario is successful in producing an axisymmetric disk made of two almost equal counter-rotating populations. The final disk shows a clear bimodal line profile in the outer part, which demonstrates that disk-disk mergers ...

MHD winds can emanate from both stars and surrounding disks. When the two systems are coupled by accretion, it is of interest to know which (if either) of the two dominates the outflow power. Recent observations lead us to consider how such coupled MHD winds may be operating in planetary nebulae (PN). In this context, we calculate the MHD wind power from a coupled disk and star, where the forme...

Existence of an exact solution of the Navier-Stokes equations representing swirling flow consisting of two fluid layers is proven. It is assumed that the fluid in the bottom layer is injected into the swirl from a rotating disk. This describes the case when a disk melts in an ambient fluid and the melted fluid is removed by rotation of the disk.

The Bardeen-Petterson effect around a rapidly-rotating compact object causes a tilted accretion disk to warp into the equatorial plane of the rotating body. Viscous forces cause the accretion flow to divide into two distinct regions an inner aligned accretion disk and an outer tilted accretion disk. The transition between these two occurs at a characteristic radius that depends on the mass and ...

We report the detection of a massive rotating disk around the high-mass Class 0 candidate NGC7538 S. The disk is well-resolved with BIMA (θA =3 ′′ . 7) in 3.4 mm continuum and in HCN J=1→0. It is seen nearly edge on and has a size of ∼30,000 AU. A young, powerful outflow perpendicular to the rotating disk is mapped in SiO J=2→1 and HCO J=1→0. The dynamical age of the outflow is ≤ 10,000 yr. The...

We present similarity solutions which describe the runaway collapse of a rotating isothermal cloud and its subsequent inside-out collapse. The similarity solutions contain the sound speed, c s , and the ratio of the speci c angular momentum to the mass, !, as model parameters. During the runaway collapse, the surface density of the disk is nearly constant in the central part and inversely propo...

MHD winds can emanate from both stars and surrounding disks. When the two systems are coupled by accretion, it is of interest to know how much wind power is available and which (if either) of the two rotators dominates that power. We investigate this in the context of multi-polar planetary nebulae (PNe) and proto-planetary nebulae (PPNe), for which recent observations have revealed the need for...