Orbital elements for HD 209458 b
Posted: 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:
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
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