## Name

mktt72 - Create a Toomre & Toomre 1972 test disk

## Synopsis

mktt72 [parameter=value]

## Description

mktt72 creates a test disk of particles similar to the one used in Toomre & Toomre’s 1972 paper (1972ApJ...178..623T). Currently each ring is placed in a separate snapshot. Use snapmerge(1NEMO) if they must be in a single snapshot.

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

## Parameters

The following parameters are recognized in any order if the keyword is also given:
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]
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, and hence the
eps=
Standard softening length applied between central mass and test particles to compute the forces that set the particles
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
verbiage for output []

## Examples

Create a single snapshot with 10 rings and 16 in the first ring (and about 160 in the outer ring).
```   % mktt72 - 16 0.1:1:0.1 | snapmerge - snap.out
```
Here 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 -
```

## Caveat

It is near impossible to create the exact same initial conditions (at T=-10) of the TT72 paper.

mkconfig(1NEMO) , mkh41(1NEMO) , mkdisk(1NEMO) , snapscale(1NEMO) , snapstack(1NEMO)

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

Peter Teuben

## Update History

```19-Nov-02    V0.1 Created    PJT