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mktt72 - Create a Toomre & Toomre 1972 test disk


mktt72 [parameter=value]


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.


The following parameters are recognized in any order if the keyword is also given:
output file name, each ring in a separate snapshot(5NEMO) . Use snapmerge(1NEMO)
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 of the central particle. This is used to compute the forces, and hence the
Standard softening length applied between central mass and test particles to compute the forces that set the particles
Add the central mass point also, as first snapshot? Default: f
Grow the number of particles per ring to keep the line density constant? Default: t
verbiage for output []


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 -


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

See Also

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
5-dec-02    V0.3 added grow=,central=    PJT

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