Binary Star Simulation

ORBITING BINARY STARS

Astronomy 101/103

Cornell University

Terry Herter

You need a JAVA enabled browser to view this simulation. This simulation is a bit unstable and may bring down the machine you are running.

DESCRIPTION:

Allows you to set the masses, orbital separation, orbital eccentricity, the inclination angle to our line of sight, and the angle of the nodes of an orbiting star pair. You see the privileged (from above the orbit) and the earth view of the system (which depends on the inclination angle). The observed velocities of the two stars, and the Doppler shifted spectral lines (as seen against the combined continuum from the two stars) are also shown in the upper right box. The spectral lines associated with each star are indicated and the unshifted line positions are also marked. The movement of the spectral lines against the continuum has been greatly exaggerated for display purposes, and the difference in brightness of the two stars has been ignored.

We have the following definitions:

Mass 1 or Mass 2	The mass of each of the two stars.
Separation	The distance between the two stars in solar radii.
Eccentricity	Eccentricity of the orbit
Inclination angle	Angle of the orbital plane of the stars to our line-of-sight. 0^o - face on 90^o - edge on Note that this is opposite from the Eclipse simulation - we'll fix this in the future.
Node angle	Angle of the major axis as measured in the orbital plane (see privileged view)

INSTRUCTIONS:

Adjust the star masses, separation, etc.
Click "enter" to update the simulation parameters.
Use "pause" to start and stop the simulation, if desired.
If the picture is messed up at anytime, use "enter" to redraw it.
The number between the "<=" and "=>" buttons, is the rough time (in seconds) it takes the simulation to complete and orbit. Make this number larger or smaller by clicking the "arrow" buttons.

EXAMPLE TO TRY:

Change the eccentricity to 0.7.
Change the inclination angle to 45^o.
Change the node angle to 45^o.
Click "Enter" to restart simulation with these values.

Please note:

Vary the node angle between 0 and 90^o while keeping everything else fixed. You can see how the major axes of the ellipse (the long part) rotates in the orbital plane of the two stars.
Vary the inclination angle between 0 and 90^o, again while keeping every thing else fixed. You can see the change in the observed velocity (curve in upper right box), and that the amount doppler shift of the spectral lines varies.

Play around by changing the values of the parameters. Be sure, however, to only change one at a time to see what effect it has on the motion and velocities we see.