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rotcurves - rotation curve of a composite potential
name1=potential [parameter=value] ...
rotcurves computes the rotation
curve of a composite mass model. Each component must be supplied in the
form of a potential (see potential(5NEMO)
) from which the forces determine
a rotation curves assuming centrifugal balance. Optionally a Lindblad diagram
can be selected for viewing using mode=omega, and the location of Lindblad
resonances is determined. A choice is also given between a plot and a table
for further processing. An experimental LV option can be used for radial
velocity table along the line of sight distance.
In case a true rotation
curve is requested (mode=velocity) the table contains r, v, v1, v2, ..., whereas
the Lindblad option with mode=omega tabulates r, v, omega, kappa, omega+kappa/2,
The following parameters are recognized:
- Name of first potential, in standard potential(5EMO)
format. No default
- Parameters for first potential. Defaults as defined
by the potential itself.
- Optional file for first potential.
Defaults as defined by the potential itself.
- <etc> for name2, name3, name4.
- Radii where to compute the rotation curve. [default: 0:2:0.1].
- Choice of axis to compute rotation curve along. The rotation curve
is defined from circular orbits balancing the local gravitational force.
- Mode can be velocity or omega, the former selecting
the true rotation curve, the latter a Lindblad diagram. In a Lindblad diagram
only the total curve is given, not the individual components. If a finite
pattern speed is given, it also computes the lindblad resonances, but make
sure the OLR is included, else the program will abort. [default: velocity].
- For angular velocity diagrams (mode=omega) this gives the Lindblad resonance
to be computed. By default the classical n=2 is used, from which the ILR
and OLR can be derived. For n=4 the two UHR can be determined etc. [Default:
- Solar radius, galactic longitude and a list of radii
(distances along the line of sight) to calculate radial velocity for.
Experimental, only in lv mode
- Select viewing in form of a plot.
- Select viewing in form of a table. [Default: f]
style format specification for each of the columns in tabular
output. [Default: %g]
- Range in plot for X-axis, always
radius. Two (min and max), one (min) or zero (autoscaling) values can be
given. [default: autoscaling]
- Range in plot for Y-axis,
either velocity or omega. See also xrange=. [default: autoscaling]
- Any optional text, plotted at the top of the plot for identification purposes.
The default is a list of nameX(parsX)
- If supplied, it should
be a table (a file) consisting of velocities (colum 2) vs. radius (column
1) to be checking with the composite model supplied earlier. Some kind of
statistics will be calculated from which the goodness of fit can be derived.
[default: not used].
- The columns must be provided
here in which columns the radius, velocity, error in radius and error in
velocity can be found. The error columns are optional, and if provided error
bars will be plotted on top of the data. A 0 can be used if an column is
not present in the data, although radius and velocity must always be present.
Sometimes Lindblad diagrams require more resolution in radius near
the center, so radii=0.0001,0.001,0.01,0.02:1:0.02 may do a better job than
Although not really a bug, but a limitation, this program
assumes symmetric potentials, and that circular orbits exist in the selected
plane. For non-axisymmetric potentials the obtained rotation curve is bogus,
and one has to resort to a periodic orbit searching program such as perorb(1NEMO)
You can also try and average the results along the X and Y axes, and average.
Rotating potentials are not implemented, except for the search for Lindblad
resonances in mode=omega.
xx-oct-90 V1.0 derived from potlist PJT
28-oct-90 V1.1 spline fit -> lindblad option PJT
8-nov-90 V1.2 in= table implemented PJT
16-nov-90 V1.3 cols= to select optional error colums PJT
12-nov-93 V1.4 added n= PJT
8-apr-97 V1.6 search for lindblad resonances if omega>0 PJT
7-jul-02 V1.7 added format= PJT
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