This is a Java simulation of both a
set of real double stars and fictitious double stars with parameters
controlled by the user. A detailed description
of how the applet functions is given below.
Functions:
The choice menu at bottom right gives a list of some doubles with accurately
known orbits.
'Start' begins the simulation.
'Stop' halts the motion, which is resumed by a second 'Start'.
'Reset' return the simulation to time=0.
'Orbits' highlights the elliptical orbits followed by the components of the
double.
'Grid' shows a calibrated length scale (in [AU]), centered on the stars'
center of mass,
'Data'
shows the distance from Earth to the double (in parsecs, [pc]), the
elapsed time (in [yrs]),
and the separation between the two stars (in [AU]).
'Labels' attaches text labels to the stars.
'Params'
shows the double parameters: mass1 and mass2 (in [solar masses]),
the semimajor axis (in [AU]), the eccentricity of the orbits, and the
orbital period (in [yrs]).
Designing Your Own:
'Sliders'
activates the scrollbars at the bottom, so you can design your own
double star system
and see how the properties (such as the geometry and period) change.
(The choice window then blacks out, to indicate that you are not simulating
a double from its list.)
The Simulation:
The stars are started at greatest separation (apoastron) at time=0 and their
motion
is followed through simple elliptical trajectories using a fixed time step,
with orbit parameters taken either from stored data (for a real double)
or from the scrollbars. The axes automatically rescale if the orbit takes the
star beyond the boundaries of the display area.