remove color noise

[Steve NB]

I'm trying to remove color noise from a star trails picture.  The color noise is quite obvious when you blow up the image but I've tried many things to no avail. Using the noise filter/dust and scratches does the most but is far from perfect or even good.  I've included two small sections of the picture one for sky and one for foreground.  If there's a good solution for sky verses foreground that's fine.  Any ideas would be most appreciated.

[JaniceCA]

Hey guys, I found the tutorial on Adobe online help:https://helpx.adobe.com/in/lightroom-cc/how-to/reduce-noise-in-photos.html

It workes like a charm: