The Flame Nebula near Alnitak is a distinct orange-gold color, not even close to the same deep red of hydrogen alpha emission of the nearby IC 434.
Is this dramatic difference in color due to a different emission spectrum and gas composition? Or is it colored by intervening dust? Or what?
IC434 is a pretty pure Ha emitting source. The Flame combines Ha with reflection from dust. I can't think of another way to get orange, what would be the emission line, and how on Earth <grin> would it be strong enough?
The color thing becomes really interesting with imaging. Assume the camera passes Ha well, ie no unmodded DSLRs. LRGB images still tend to overemphasize the reflection component of the Flame. Sometimes people make the Flame white, and (I think inevitably) portray IC434 as orange. I don't think that's correct, although it has some charm.
You can see a wide range of interpretations in this thread. Or on astrobin or with Google images.
What I admire is people who capture varying shades of color in the Flame. Using HaRGB, I couldn't do that, it's a pretty uniform orange.
A great example of how the colors we portray are simply various interpretations of the data.
Edited by bobzeq25, 30 March 2019 - 09:27 AM.