Ditched some of the old revisions, since they were put in because of my misguided fears of problems with stretch. Also, put the old "final" version in a second time to force the site to accept the current revision as the "original" so that the mouse over would work. It would be nice for Astrobin to create some flexibility around this issue...
I wasn't sure I was going to redo this one, especially since I got much satisfaction from just doing the
NGC 7023. Iris Cropped to the Core
with a considerable increase in added data. But I am running out of data to reprocess and I thought that I might get better stars and improve the color and some artifacts. It ended up being more work than I wanted. DNALinearfit kind of failed me on this one. So I had to do some manual stretching to match the 2 panels better. Still, not perfect. I also had to work on fixing some stitch related color artifacts and the big star, which I may return to to fix. But nothing too difficult. Reoriented this one to North up and East right, as if I was looking at this in my location. At full page, it might not look all that different, but I think the stars are noticeably better. Pixel peeping willl show some better sharpness and little residual noise. Though some large scale chrominance noise in areas. Added a Starless version for interest. This is a commonly posted field. As per my style, I did not go overboard on stretching the clouds.
While the data for this was collected mid June this year, the theme for me seems to continue with regard to my attraction to clouds of dust. (I have noticed that dust is also attracted to me!) Both NGC 7023 and SH2-136 are highlights to a vast area of dust. While they are visually close, from our perspective I really cannot say if they are really related to each other spatially. The Iris cloud to me seems much more explosive, almost radiating out from the apparent core while the ghosts appear much more tranquil, somehow being impacted from above from some unknown pressure that is compressing the dust. Perhaps they are distant to each other with the closer Iris superimposed by the less dramatic ghost clouds beyond...
But what is striking to me, and to continue a theme (at least in my mind, along with my NGC 1333 image is the fact that there is so much dust in what is clearly star forming regions yet we see so little hydrogen, by way of Ha emissions. It may well be there, hidden by some mechanism that quenches its Ha signal. Maybe the dust itself poisons that reaction. But there appears to be a perfectly hot blue star at the heart of the Iris that should emit plenty of UV light to fire up that hydrogen and show us. Maybe someone with an Ha filter can find it. To be sure, I can detect a bit of pink light on the surface of some of the illuminated clouds near the hot blue star. But it is weak and could be simple black body light from simple heating. A NASA site describes the red hues in the Iris as due to some unknown chemical compound fluorescing. In fact, the Iris hosts many Young Stellar Objects and IR sources along with Cepheid variables, etc. So there ought to be some hydrogen!
Upon starting this hobby and seeing these types of objects by my own hand, this has raised a whole host of questions as to what is going on. Hydrogen, oxygen and the other gases typically found in the universe are transparent. When we see dark clouds in the galaxy, these are not gas clouds. Yes, there no doubt is true gas associated with these, but they are neutral gas and not visible in our gear. The beautiful colors we see from these gases is because they can become excited by UV light emitted by large hot stars. We know that the universe as a whole is becoming more metal-rich as time goes by. If the Big Bang models are correct, there was no dust at all when the first stars lit up. And through various mechanisms of stellar destruction, more and more dust is accumulating in our universe as time goes by. (Think of this implication as it relates to life as we know it! That means the odds for life arising should increase with time, not just for statistical reasons, but for mechanistic reasons.) These molecular dust clouds stand in stark contrast to the vast star forming "bubble" nebula such as the Rosette, Misty Clover, Heart, Soul, etc.
One question I have for a star expert, is if there are clouds of dust, blown clean of gas by solar winds and extreme illumination, what becomes of those? Would we not expect these clouds of particles to also condense into large bodies through gravitational forces? We hear so much of star formation, either isolated or in clusters, but rarely or never of non-stellar large (stellar) mass bodies consisting less of gas and more of metals. What is the theory on those? If they are thought not to exist, then why? A body condensing of mostly dust but of stellar mass (by my meaning bodies otherwise large enough to have fusion if it was mostly hydrogen) should be very hot from heat of condensation and even significant fission radioactivity. What are these called? Brown dwarfs are just stars of insufficient mass to fuse. These would be potentially bigger.
The Iris was one of the first objects that I did last year (2019) with my new setup. I had wanted to return to it at a better time, so I did this mid June and when I learned that the ghost was close by, I decided that I had to have the two in the same frame, so made this a 2 panel mosaic. 30 subs on the Iris side and 32 on the Ghost side. I had taken a lot more, but most were not satisfactory. I guess that I can say that I got it, but I am not too satisfied with the result. So either I eventually I go back and work on this some more, or better yet, collect more and better subs. Either way, I do not intend to rush to do either.