The Helix is a planetary nebula located about 650 light years away in the constellation Aquarius.  It is the remains of a star that once looked a lot like our own sun—which, incidentally, will also create a planetary nebula when it dies in about five billion years.  When this happens, the hydrogen that fuels a star’s fusion reaction exhausts itself, and the star turns to helium for a fuel source, burning it into an even heavier mix of carbon, nitrogen and oxygen. Eventually, the helium will also be exhausted, and the star dies, puffing off its outer gaseous layers and leaving behind the tiny, hot, dense core, called a white dwarf. When these layers expand into space, they sweep with them planets, comets, asteroids, and anything else that was originally in the star’s orbit. The cloud of hot gas then glows from the energy of the intense ultraviolet radiation emitted from the white dwarf, and it’s this glowing, expanding cloud of gas and debris that creates the planetary nebula. 

There are tons of planetary nebulae out there, and almost all of them have really interesting, unique structure.  What’s interesting about the Helix is a) its proximity, at only 650 light years, and b) it is very young, at only 10,000 years old—this happened barely a minute ago, on a stellar time scale. 

From a processing perspective, this one was one of the trickier images I've ever done, owing to both the dynamic range as well as the detailed structure. 

First, it's got very faint extended nebulosity in Ha coupled with a really bright inner core that contains all the interesting structure.  To effectively show both elements, I used the same data but had to effectively do two different stretches and then blend them using masking and pixelmath to create an HDR effect.  The difficult part was being careful not to overdo it, otherwise I felt like the extended areas just looked flat and distracted from the party in the core. 

Second, regarding that core, this wasn't a narrowband image where you can just apply Ha as luminance and call it a day.  Both Ha and Oiii had very unique structures that were totally different.  I wanted both of these pieces to not only show up, but be accentuated. To create Oiii and Ha images that do this, first I used HDRMT to create exaggerated versions of each (to me, HDRMT undiluted is too much), and blended those with "normal" stretches to effectively attenuate the HDRMT effect but still bring out the detail.  I then used these for the core in the final pixelmath blend. 

This is definitely a target that could use more integration time, which I'll be sure and do next season.  Given everything going on, from the faint outer areas to the detailed inner areas, I think it's something more time will only help with.  For now, though, I'm going pencils down and moving on to the next thing.  Hope folks enjoy: critiques and commentary welcome as always.