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pspeed - calculate the pattern speed of a stellar system.
pspeed
int=ccd-intensity vel=ccd-velocity [parameter=value]
pspeed calculates
the pattern speed of a stellar system using Tremaine & Weinberg’s method
(1984ApJ...282L...5T). For this a line parallel but offset to the line of nodes
of a galaxy must have information on intensity and radial velocity. pspeed
assumes the line of nodes is along the X-axis.
In the following (x,y) are
defined along the major and minor axis of the galaxy resp., and pspeed will
then compute the numerical sums
V(y) = SUM ( vel(x,y) * den(x,y)) / SUM ( den(x,y) )
X(y) = SUM ( x * den(x,y)) / SUM ( den(x,y) )
where the summation is along x. This will result in a correlation
V = Omega * SIN(inc) * X
The output will be a table
The following parameters are recognized
in any order if the keyword is also given:
- int=int-file
- input file, must
be the intensity in image(5NEMO)
format [no default].
- vel=vel-file
- input
file, must be the radial velocity in image(5NEMO)
format [no default].
- debugy=y
- Will produce a table how the numerical integration along only one specific
y value resulted in a pattern speed. For debugging only. [default: -1, i.e.
not used].
pspeed is too sensitive to noise to be useful for all practical
purposes.
snapslit(1NEMO)
, snaprotate(1NEMO)
, snapshot(5NEMO)
, image(5NEMO)
Peter Teuben
~/src/pjt/image authors original sources
17-Aug-87 V1.0: Original created PJT
1-Nov-87 V1.2: more debug output PJT
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