Here's a description (from the included "readme" file) :
This addon is simply an exposition of several sprites based models for Celestia. Use the models to build accretion disks, planetary nebulae or for fantasy SF sceneries. The models are free, but can't be used for any commercial activities.
There are several sorts of shapes which can be combined to make more complex systems : rings, tori, a few jets, lobes, shells and a few dejections. There's also a dipolar magnetic field model included (not made of sprites), specially fitted for the tori and the dejections. All the models were produced with Mathematica, a maths software.
Disclaimer : the models may be CPU/GPU intensive, depending on the computer/video card you have. I'm not responsible for any trouble you may experience with your computer ! All the models have been tested on two recent Macs (Mac mini 2009 and 13" MacBook Pro 2010), under OS X Snow Leopard 10.6.8.
To see the models in Celestia, just type the following names followed by a number :
The user can edit the files to change some material properties (especially the opacity and the blend mode).
http://fsgregs.startlogic.com/Public_Fi ... models.zip (10.2 MB)
If you do use the models in your virtual universe, please post some pictures here. It could inspire me to build better models !
Have fun !