Applet for plotting radial velocity of a star in a spectroscopic binary as a function of orbital phase for chosen values of eccentrity (e) and argument of periastron (omega).

Enter values of e (< 0.99) and omega (in degrees) and press the [plot curve] button to see how the radial velocity curve depends on these parameters. Their starting values (and defaults in response to invalid entries) are close to those of WR140, the archetypal colliding-wind binary. Also plotted in blue is the shape of the orbit where the star travels clockwise and the system is viewed from the bottom of the frame.