Creating the Initial Conditions
Under construction
-
Starlab v3.2 was used to create 16384 points distributed as a King model
with W0 = 5: mkking -n 16384 -o -w 5 >&
initial_snapshot (Beware! 1.1Mb)
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From this a list of 16384 phase space coordinates was created
with
awk -f make_phase_list.awk
initial_snapshot > initial_phase_list (Beware! 1Mb)
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The masses of the first 12288 were created according to the
specification, and the remainder were split into binaries, again
according to specification, using the f77 code
make_ic.f.
Testing the Initial Conditions
1. make_ic produces the fundamental list of initial conditions
(ic.dat) and the following data:
- Total mass 10174.2720189169 solar masses
- Galactocentric radius 8490.49 pc
- kT = 0.709278 solar masses*(km/s)**2
- median a: 8.61854E-07 pc
- median e: 0.586226
2. another code analyses ic.dat and
prduces the following data:
- total mass, N: 10174.2720340000 20480
- cm position 1.9714438172285D-02 5.0410882363923D-02 4.3476247750797D-02
- cm velocity 1.6761459116220D-02 -1.1675330167132D-02 -1.7084032622201D-02
- median single mass 0.25310300290585
- median binary mass 0.58639198541641
- median radius 5.1955181628045
- median a, e 8.6185507453150D-07 0.58622576933932
and also the following plots of the
distribution of
- cosine of inclination
- e**2
- log a
- longitude of node of binary orbit
- mass ratio q
(In each case the values are plotted in rank order. Thus these plots
are plots of the cumulative distribution, with the axes exchanged:
steep slope means low frequency.)
Comments
- The median single and binary masses, and the median radius, agree (within O(N**(-1/2))
fluctuations) with those expected from the corresponding distributions
- The median a and e agree with those of make_ic.f
- The distributions of cos i and node are as expected
- The distribution of e^2 is not flat; small values are relatively
more probable, presumably because of the cutoff in small pericentre
distances at 2(R1+R2)
- The distribution of log a is not flat. Very large values require
large masses to satisfy the condition E>10kT, and large masses are
rare; the steepening at very small values may be caused by a
steepening in the radius-mass relationship below about 0.3 solar
masses.
- The distribution of q is not flat. Low values are relatively
improbable, presumably because of the limits on the individual stellar mass.