How to make a particle static (bake)

I’m making a big solar system and for the beauty of the game i added some space dust and stuff using 10 big particles but the game if for phones and the particles don’t need to move or anything is there a way to just bake a particle and make it static ?
My idea is to put it on a plane as an image but that way it will lose its volumetric feel is there a better way?

in 2018.2 we added BakeMesh for particles: Unity - Scripting API: ParticleSystemRenderer.BakeMesh