Systemic Project - Simulations

The Systemic project  is seeking to improve our understanding of extra-solar planetary systems and is described in detail on their website at systemic. This page has been set up to provide animated views of extra-solar planetary systems (real or simulated) that have been defined using the Systemic Console.

Mandatory fields

  Fit file: Select a Systemic fit file.

  Mass: Enter the mass of the central star in solar masses, default is 1.0.

  Start: Press to see the simulation.

Options

 

   Inclination: Enter inclination of plane of orbits vs. the plane of the sky.

   Strobe: Enter fixed display interval (days) for strobe effect.

   Focus: Enter planet number for rotating coordinates.

  Method: Select integration method.

  Star is centralised on the screen.

 Baricentre is centralised on the screen.

Mandatory fields:

  • The File selected above must be in the format of a 'fit' file saved by the Systemic console.
  • The Mass should be that of the central star in solar masses. This is found from the star's data file in the Systemic Console. (Unfortunately this cannot be obtained from the fit file).
  • Press the GO button to start the simulation.

Options:

  • Inclination: The Inclination is the inclination of the plane of the planets' orbits relative to the plane of the sky. (Quote from Eugenio at Systemic: "For exoplanetary systems, the reference plane is the plane of the sky. An orbit with i=0 would appear face-on as seen from earth. For i=90, the orbit is edge-on. For i=60, the orbital plane is tilted 30 degrees from the line joining the Earth (or the Sun) and the distant star." The planet masses produced by the Systemic Console assume an inclination of 90 degrees and this is the default. If another value of inclination is provided then the planet masses are multiplied by 1/sin(inclination). Planet masses are in Jupiter masses.
  • Strobe: This will lock the display frequency to the number of days specified. Set this to the period of a planet and the planet will appear static. This can be used to show up resonance. You may need to adjust the period for best results because the actual period of a planet may vary or be different from that specified in the fit file.    
  • Focus: If a valid planet number is placed in this field then the coordinates will be rotated so that this planet is always in the same direction. This can reveal Trojan, Horseshoe or other 1:1 resonant behaviour. 
  • Method: Select the integration method. The default Yoshida 6th order will probably provide the best combination of speed and accuracy.
  • Star: If this is checked the star will remain static in the centre of the screen.
  • Barycentre: If this is checked the system barycentre will be in the centre of the screen. The star and planet orbits may 'wobble'.

Simulation Page:

  • The star will appear with the name "Star". The planets will appear with the names Planet1, Planet2 etc in the sequence they are defined in the fit file.
  • Click Stop to stop/start the motion.
  • Left/Right click Speed to increase/decrease simulation speed.
  • Left/Right click Zoom to zoom in/out.
  • Left/Right click Tilt to tilt the system up/down.
  • Left/Right click Rotate to rotate the system.
  • Click Back to reverse direction.
  • Click Orbits to see orbits drawn (from osculating elements calculated after each integration step). These may not always work especially if orbits are very unstable.
  • Click Info to toggle the top line information and planet names.

Information Line:

  • Int. Step is the size of the integration step in days.
  • body-body shows which two bodies are determining the integration step.
  • Display Step is the number of days between display updates.
  • Rel.Energy is the (change in energy)/(original energy) of the system.
  • J=nnnn.nnn is the Julian date, starting with the date in the fit file.

 

 

 

 
Tony Evans 2004-2009

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