New astrophoto, the Firebird Nebula & the Dragon's Egg Nebula! (NGC 6188 and 6164)
Every now and then you get surprised. I'm dealing with a moon that's getting brighter, and hanging in the sky longer, each day and before I say "it's too much" I'm looking around the sky for places that are still relatively dark and in completely the opposite direction from that monthly light-polluter.
The constellation Ara is over there, up pretty high in the sky but I know nothing about it since it's a southern constellation. So I get out my Sky App (Sky Safari) and start scrolling around looking for anything that would qualify as a 'worthwhile target'.
Quite by accident I stumble on this nebula that seems relatively substantial, only identified by it's catalog number of NGC 6188. Sky Safari describes it as "an interstellar carnival of young blue stars, hot red gas, and cool dark dust." A 'carnival'? How could I resist that? So 'time's a-wastin'" so I wheel the scope to that part of the sky, get all up and running and shoot it for two nights.
What’s That?
As I was shooting I noticed there was this odd thing in the upper part of the frame but honestly when you're taking raw data in the form of the 3-4 minute exposures, they don't look all that great, you just need to verify that your mount is tracking well and you're in focus. So I didn't think too much more about it.
When I got the final photo processed in the computer I realized then what a complete gem of an object this is, and they were right, so many cool things going on in this one.
The center of the Ara O-B Association of super bright stars.
I found out that NGC 6188 is known as the Firebird Nebula, a glowing area of hydrogen located about 4,300 light years away in the southern constellation Ara. The bright open cluster NGC 6193 (right of center in the main image), is visible to the naked eye, and is responsible for a region of reflection nebulosity within NGC 6188. This cluster is the center of the "Ara O-B (the biggest, hottest star types) Association" and all the outpouring of energy from all these gigantic stars are the engine that is sculpting all the gas clouds in this giant area of star-forming area. These massive, young stars have recently formed there – some are only a few million years old. This spark of formation was probably caused when the last batch of stars went supernova. The two hottest stars in this 'association' are actually so close to each other as to nearly be touching, and the complicated mixing of their combined stellar winds cause this to be a bright object in X-Rays too!
The “Dragon’s Egg” Nebula – NGC 6164
Delayed Gratification
When I had the final high-resolution image processed I finally got a good look at that odd thing that showed up top of frame and I was gobsmacked at how cool this thing turned out to be! I knew it had to have it's own catalog number so I tracked that down and it turns out to be NGC 6164, known as the Dragon's Egg Nebula, and is just across the border in the constellation Norma. The nebula is approximately 3,870 light years away which puts it basically in the same neighborhood but slightly in front of the Firebird itself.
Its shape gives it the appearance of a planetary nebula resulting from the death of an old star similar to the Sun, but it turns out to be a glowing emission nebula instead. The gas from this nebula was ejected by the double star located at its center and when digging deeper, there's an intriguing story.
Astronomers studying this thing were confused by the fact that the two stars in the double star were so different in physical nature. Usually when you have stars that close together, they form at the same time and have similar ages and compositions but not these two. Why? Well it turns out they don't look the way we think they should because, once upon a time, they were three. It was found that two of the original stellar trinary merged, producing not just the beautiful Dragon's Egg nebula in which the stars are ensconced, but two mismatched stars each about 30 times more massive than the Sun, bound together in a gravitational dance, orbiting each other every 26 years. It's likely that each of these stars will end up as a black hole as their final state.
The larger of the two stars is interesting because previous research suggests that it has a magnetic field which is really strange, because stars larger than about seven times the mass of the Sun usually don't and this one is four times that!
But wait!…
And it gets weirder. The nebula itself is estimated to be around 7,500 years old. Its presence alone is strange enough; you usually see this kind of thing around old, dying stars, but both stars in the nebula's core are very much in the prime of their life. And then there's a whole lot of nitrogen, carbon, and oxygen in it. Usually these elements are sequestered inside stars, not billowing around outside them.
So the idea is that the two inner stars violently merged creating a magnetic star and throwing out some material, which created the nebula. The more distant star formed a new orbit with the newly merged, now-magnetic star, creating the binary we see today at the center of the nebula."