Orbital elements for HD 209458 b

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granthutchison
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Orbital elements for HD 209458 b

Post #1by granthutchison » 12.09.2003, 20:42

HD 209458 b is the only nearby extrasolar planet with observed transits of its parent star.
If you want to observe these transits in Celestia, overwrite the entry for HD 209458 b in extrasolar.ssc with the following definition, derived from published orbital elements:

Code: Select all

"b" "HD 209458"
{
   Texture "gasgiant.jpg"
   Mass      220
   Radius    102000

   InfoURL "http://www.obspm.fr/encycl/HD209458.html"

   # orbital data
   EllipticalOrbit {
      Period          0.0096502
      SemiMajorAxis   0.045
      Eccentricity    0.0
      Inclination     71.7
      AscendingNode   325   #true plane-of-sky node unknown
      ArgOfPericenter 205
      MeanAnomaly     148
   }
}


The position angle of the planet's ascending node on the plane of the sky is unknown (because the orbit orientation hasn't been directly observed) so the exact orientation of the orbital ellipse when projected on to the sky has to be chosen at random; but otherwise this definition reproduces the transit durations and timings, as described at http://www.obspm.fr/encycl/papers/hd209458-iauc.html, pretty well.

Grant

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