I recommend the Cool Worlds Utube video which sets out the astrophysics reasons detailing why there are no green stars visible to us.
Find it here:
https://youtu.be/vXOYbzQ4jDA?si=6D1aLgG5I-KYoRLO
I do not dispute that green stars cannot Exist in the Universe. However, I have many narrowband images taken over many years, which do appear to include significant green emissions. So where does the interstellar green come from? Generally, my green captures come from nebula areas, and likely stem from heavy Oii presence the gas mix, (which tend into the turquoise segment of the visible spectrum.
The Statue of Liberty object area shows tendrils of green light, so to the Tarantula Nebula; and various super nova remants in various locations.
A glance at the histogram of some of these areas definitely shows the presence of light in the green band, yes it is often well below the red and blue, but it it there.
Of course, our intervention in processing, can create some truly garish colour saturation, so that doesn't count in this question.
Now for observational astronomy green light cannot be detected, as the human eye cannot do long exposures, nor detect specific spectra bands; but for you narrowband imagers, let hear what you think on the subject of green spectra rarity?
