Binary and multiple systems?

[Alcoraiden]

Is there an add-on to allow multiple star systems, like Albireo or Mizar, to orbit their centers of gravity? Or an add-on for an individual multiple star system?

[selden]

Consider installing Celestia v1.4.0pre6.

[t00fri]

Consider using the forum's powerful SEARCH engine! There is plenty of stuff, notably also by myself. Like hundreds of highly accurate binary orbits (from scientific publications) for testing...

Bye Fridger

[Evil Dr Ganymede]

Is there an add-on to allow multiple star systems, like Albireo or Mizar, to orbit their centers of gravity? Or an add-on for an individual multiple star system?

To actually answer your question, yes there is. It's only available in 1.4.0pre6 - you can download that from this link

This supports multiple light sources, and also allows users to create systems that orbit barycentres. 'course, now I look I can't seem to find any files for you to look at that have barycentre code in them... maybe someone else can demonstrate how it works.

[t00fri]

All my hundreds of posted binary orbits have 'barycenter' code in them. They all use measured data on the component masses, orbiting around the common barycenter.

The respective stc orbit files may be downloaded from here:
http://www.shatters.net/forum/viewtopic.php?t=6312&postdays=0&postorder=asc&start=0

Bye Fridger

[Evil Dr Ganymede]

Knew I was forgetting something obvious...

This is one of fridger's binaries, from his file that he's linked to now, just to show you the general format:

Barycenter "13 Cet"
{
RA 8.811004
Dec -3.592758
Distance 68.652286
}


2762 "13 Cet A" # component A
{
OrbitBarycenter "13 Cet"
SpectralType "F8V..."
AppMag 5.61

EllipticalOrbit {
Period 6.890
SemiMajorAxis 1.933 # mass ratio 1.49 : 0.99
Eccentricity 0.760
Inclination 79.762
AscendingNode 229.234
ArgOfPericenter 12.768
MeanAnomaly 310.885
}
}

"13 Cet B" # component B
{
OrbitBarycenter "13 Cet"
SpectralType "G2V"
AppMag 6.88

EllipticalOrbit {
Period 6.890
SemiMajorAxis 2.885 # mass ratio 1.49 : 0.99
Eccentricity 0.760
Inclination 79.762
AscendingNode 229.234
ArgOfPericenter 192.768
MeanAnomaly 310.885
}
}

This is saved as an .stc file (you can have more than one binaries or multiple system per stc file). This particular example shows the 13 Ceti binary system.

First you need to define the location of the barycentre in space using RA/Dec/distance. Then you define the components and their orbits. If the primary component has a HIP number, put it on the top line of the code for that star (as shown here - 2762 is 13 Cet A's HIP number).

I'm not sure why there's a '...' after the spectral type for the first star in this case though.