This is generally a difficult area to process. Quite a vast dynamic range and colour complexity. The orange/yellow hues are difficult to obtain well. I'm not too certain the correct color balance on the Astrodon’s. They are not exactly a 1:1:1 ratio, but close. You still need to take into consideration the blue extinction factor as well.
I settled on a R:G:B of 1:1:0.8 for the final RGB combine.
As red and green make yellow, this emphasises the orange/yellow hues. I only used 20% saturation. Could have gone higher, but lacking sufficient data would result in more noise. I used the R channel with minor sharpening applied, this was then layered onto the RGB image with 80% opacity. RGB was Gaussian blurred (very mild). I've clipped in green and blue which I expected as I should have raised other colour levels instead. Getting rid of the green halo around Antares was a pain. I used the colour selection tool then dropped the green channel using curves - this needs more work in particular greater feathering.
This is a good example of what the area is suppose to look like with good colour balance and processing -
http://www.starryscapes.com/nebula/rho_ophiuchus.html