Press [i] for instructions
Press [j] for more information
Press [r] to return ship to L5
Navigate the RSS Lynden-Bell through the rotating barred potential
You begin at the L5 Lagrange point, in a stable orbit at the corotation resonance. Which other orbits can you reach?
Use the Left and Right Arrow Keys to rotate your ship
Use the Up Arrow Key to fire the main engine
Hold Shift while firing to use reduced thrust
Adjust the bar's pattern speed, length, and deceleration rate with the sliders
You can also speed up the simulation and change the length of the projected orbit
Toggle rotating reference frame, projected orbit, effective potential contours, and animated stars with the checkboxes
Press [i] at any time to return to this screen
Press [j] for more information
Press [r] to return the ship to L5
Beware of those coriolis forces!
The barred potential implemented is taken from equation (5) in Williams & Evans (2017). This is produced by convolving a cored axisymmetric logarithmic potential with a needle density along the x-axis spanning [-a, a]. The bar length a is expressed in units of the core radius Rc (equal to 50 pixels). The asymptotic circular speed of the logarithmic potential is v0 = 1.
By default the simulator is run in a frame corotating clockwise with the bar. This adds coriolis and centrifugal forces to the equations of motion. The pattern speed is encoded in the ratio of the corotation radius to the bar length, R = RCR/a. Optionally the pattern speed can be accelerated or decelerated with time. In this case the spaceship also experiences an Euler force. The deceleration rate of the bar is quantified by the dimensionless deceleration parameter η = ṘCR/v0.
The cyan line indicates the future orbit of the spaceship, if no thrust is applied.
The yellow points indicate contours of the effective potential, including a centrifugal term.
The animated stars (off by default) follow circular paths at approximately the circular speed of the background logarithmic potential.
The radius at which the stars are stationary in the rotating frame indicates the corotation radius.