Table of Contents

The disk is rotating counter clock
wise. Use *snapscale(1NEMO)*
to flip the sign of velocities.

Another historic
program is the Holmberg 1941 light bulb experiment, see *mkh41(1NEMO)*
.

**out=**- output file name, each ring in a separate
*snapshot(5NEMO)*. Use*snapmerge(1NEMO)* **nbody=**- number of particles per (first) ring. When
**grow=t**the number of particles increases to keep the line density constant. [100] **radius=**- radii of rings. They should be entered in increasing order to prevent interesting effects when grow=t. [1:6:1]
**mass=**- Mass of the central particle. This is used to compute the forces. Default: 1.0
**eps=**- Standard softening length applied between central mass and test particles to compute the forces that set the particles. Default: 0.0
**central=t|f**- Add the central mass point also, as first snapshot? Default: f
**grow=t|f**- Grow the number of particles per ring to keep the line density constant? Default: t
**headline=**- verbiage for output []

% mktt72 - 16 0.1:1:0.1 | snapmerge - snap.outHere is a test to see if the force computations are ok, and rings stay at the same radius. A large value of eps= is used to make sure the first few rings are not pure 1/r^2:

% mktt72 - 10 radius=0.1:1:0.1 central=t eps=0.2 |\snapmerge - - | hackcode1 - snap.out tstop=5 freq=100 freqout=10 eps=0.2 % snapxyz snap.out - | xyzview -

In each example, one of the two point masses arrives at the scene of the encounter surrounded by a flat, annular disk of 120 test particles; the other arrives bare. More exactly, the unperturbed disk consists of five discrete rings, of 12,18, 24, 30, and 36 particles apiece.

Test-particle results in this paper stem

from fourth-order Runge-Kutta numerical integrations of the restricted three-body

equations of motion

2010ApJ...725..353D - D’Onghia et al. (2010)
- *Quasi-resonant Theory of Tidal Interactions*

Teuben

19-Nov-02V0.1 CreatedPJT 5-dec-02V0.3 added grow=,central=PJT