NGC 7023. It's not an Iris Iris Nebula.

If you know me, you know how much I love the blue Type O stars and the stories of their lives. Not far behind are some of the blue-hot Type B stars (Type B, B0, B1) that have similar characteristics. All these stars have in common temperatures hot enough to ionize nearby interstellar hydrogen, creating the glorious red emission nebulae that we are familiar with. 

But what if the Type B star isn't hot enough to ionize surrounding hydrogen? Well, if it isn't hot enough, then you obviously don't have an emission nebula. However, if the Type B star is close to hot enough, and is situated in the right environment, then we can get a reflection nebula, where the intense luminosity of the Type B blue star is reflected off of the surrounding interstellar gas and dust. 

That is what is happening here. The star is also generating strong stellar winds, so there is the additional component of the reflection seeming to lie among earth-like clouds, modeled by the winds coming off the star.

The star at work in the image is named HD 200775, a "B2Ve C" star. Here's a rundown on all those cryptic stellar identifiers:

HD 200775 B2Ve C

B = Type B star
2 = Pretty darn hot, but not quite hot enough to ionize hydrogen.
V = Main Sequence
e  = Emission lines are present (Herbig Be star)
C = Some Carbon emission lines

Incidentally, for those with an interest in astro-history, the astronomer George Herbig, who studied these Be stars considers them to be pre Main Sequence stars. That is, they haven't evolved yet to full-fledged star status. In fact, in his 1959 paper on the subject, Herbig classified this star as a pre Main Sequence B3e star with a hydrogen shell, and not as a Main Sequence B2e star. So is it PMS or MS?  It would seem that there is some debate over the classification of the star...or the star has evolved...or instrumentation and stellar surveys have become more precise in the intervening decades.

It doesn't matter. It shouldn't trouble you. What matters here is that the luminosity of this (baby or adult) star is immense enough to light up the surround interstellar gas. Blue star. Blue reflection. 

As a final note on aesthetics, many imagers of the Iris work very hard to bring out the surrounding interstellar dust and gas. When they do, it has a distinctly reddish or brown color. That is their artistic choice and I respect the decision. I have, with intention, not done that and have cropped the FOV to restrict the visibility of the surrounding interstellar field. What I would like is for the viewer to focus on the reflection and how it fades into the darkness. In this case, focusing on bringing out the larger field only serves, in my opinion, to diminish the beauty of what this magnificent star is doing. Enough said.

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I will keep my description short today. I'll close with the comment that I did the entire image in PixInsight (except for my .sig, which I did in Photoshop). I am not completely happy with various aspects of the image and know that with more experience it would be a bit more nuanced. Perhaps one day I'll post a revision, but all told I am very happy with what I accomplished with PI. Thank you to my numerous astro-friends (eg. @Mark Germani, @wsg, @pcyvr, et al.,  who have been encouraging me to give PI a try.