NGC-7538 is located about 9100 light-years away in the constellation Cephius. It is an active star-forming region and while it's not an especially popular imaging target, it is well-known to researchers. NGC-7538 contains a number of young -- 1-4 million years old -- stars, and a number of forming "protostars", including the largest yet detected. Protostars are not yet dense enough to begin the fusion process which powers a star, but are clearing and consolidating dust and gasses (in this case, in a region over 300 times the diameter of our solar system) as they gather mass. Image composed of 15 hours of narrowband exposures, processed in the Hubble pallette. Oranges and yellows are primarily sulfur and hydrogen emissions; blues and greens are primarily hydrogen and oxygen emissions. There is also a substantial amount of dust in the region, illuminated by the numerous bright stars in the region.
I processed this roughly following J-P Metsavainio's technique of separating the stars from the nebulosity at the linear stage, stretching and adjusting them independently, then recombining them for the final image. So the star colors, like the nebula colors, aren't "natural" but they're somewhat more consistent than would result from overlaying RGB stars on the SHO nebula. Along the way, learned a technique for histogram-stretching and then unstretching an image (returning it to linear form), and about the GAME script for making fancy masks. Thanks to
@Brian Sweeney for showing me the latter and helping make a mask for a bit of desaturation on the stars in the nebula core.
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