Rosette  Nebula Caldwell 49 NGC2237 NGC 2238 NGC 2239, NGC 2244 HRGB Composition. Quattro 200mm f4, ZWO ASI294MMPro / Skywatcher HEQ6 / Skywatcher Coma Corrector/Asiair Plus/ZWO OAG 
26/12/2022, 26/1/2023Ha 97x120s120x-5degBin2 ; R G B each 20x60s120x-5degBin2 ; (254 minutes total)Bortle 5
Its all about O stars!
The stars all start in a molecular cloud but the O stars win, at least to start with. They start big and bright, burn out quickly, then blow up dramatically and so spread their nucleosynthesised heavy elements all around the cluster so that much less aspiring G stars like our sun can use them for useful things like making humans (sic).
Their bright light, and probably their explosions as well, carve out the hollow in the cloud and release the stars from their cocoon.
The two shells at centre of this composition look like the work of Wolf-Rayet type stars (Not O stars but near enough that some overlap with O stars features: then they are known as Slash Stars). (Or maybe just supernova shells, but a bit rough, more like Thor's helmet.) I can't find any references to the shells or identifying names. Anyone know?
And just two O stars (HD 46223 and HD 46150 - the bright stars to the lower right and directly above the bubbles in the centre) are said to have carved out most of the ionised nebular cavity apparent in the photo. The cavity itself is suggested to be only about 100,000 y old (https://iopscience.iop.org/article/10.1088/0004-637X/719/2/1872) but the cavity is already 50 LY across!
There's even a diffuse Xray emission between the stars in the bubble attributed to the O star shock waves heating the interstellar medium to 1-10 Million degrees Kelvin.
The red periphery is due to their exciting hydrogen. The blue core is also due to the excitation of dust and Oxygen from these stars. (Admittedly creative license came in there with the blue centre - it was red in uniformly processed RGB (no LinearFit before HistogramTransformation) and green when LF preceded HT).
Anyway the Blue centre is a salute to O stars!
(The Bok globules from 9-12 oclock are a different story!)

https://apod.nasa.gov/apod/ap230206.html is an apod of the same area. (127mm refractor! Impressive!)