APOD: A Sagittarius Triplet (2024 Jul 10)

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APOD: A Sagittarius Triplet (2024 Jul 10)

Post by APOD Robot » Wed Jul 10, 2024 4:06 am

Image A Sagittarius Triplet

Explanation: These three bright nebulae are often featured on telescopic tours of the constellation Sagittarius and the crowded starfields of the central Milky Way. In fact, 18th century cosmic tourist Charles Messier cataloged two of them; M8, the large nebula above center, and colorful M20 below and left in the frame. The third emission region includes NGC 6559, right of M8 and separated from the larger nebula by a dark dust lane. All three are stellar nurseries about five thousand light-years or so distant. Over a hundred light-years across the expansive M8 is also known as the Lagoon Nebula. M20's popular moniker is the Trifid. Glowing hydrogen gas creates the dominant red color of the emission nebulae. But for striking contrast, blue hues in the Trifid are due to dust reflected starlight. The broad interstellar skyscape spans almost 4 degrees or 8 full moons on the sky.

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Re: APOD: A Sagittarius Triplet (2024 Jul 10)

Post by Ann » Wed Jul 10, 2024 6:43 am

Yes, that's a nice upside down Sagittarius Triplet! :D

APOD 10 July 2024 annotated.png

Of course this skyscape is not really upside down, but most people that take a nerdy interest in astronomy tend to live in the northern hemisphere! 🌎

The Lagoon and Trifid Nebulas get a lot of attention, but there is so much going on in the vicinity of these two sky celebrities. What about the Footprint nebula? I love it! 👣

Footprint nebula Steve Mazlin Jim Misti.png
The Sagittarius footprint!

The Footprint is very clearly connecting the Lagoon Nebula and the NGC 6559 region.

And speaking of NGC 6559...

NGC 6559 is the nebula consisting of a bright red hydrogen alpha arc and a bright blue reflection nebula "inside" it. The two blue stars in the reflection nebula are early spectral class B, and it is perhaps unexpected that they should be able to snowplow such a magnificent arc. I don't think they are doing it all on their own, either, but they get help from a hot O-type star relatively nearby, 11 Sagittarius. I think that 11 Sgr and the two stars in the reflection nebula push the gas from opposite directions, creating this beautiful arc.

Note the Chinese Dragon Nebula connecting NGC 6559 with Sgr 11: 🐉

A lovely nebula in the NGC 6559 region is IC 1274:

IC 1274 gmadkat.png
IC 1274. Credit: gkmadkat.

A tiny forgotten gem in this overall region is IC 4678:

The little reflection nebula here is sweet, of course, but I love the red streaks of hydrogen alpha. And, of course, the lovely little black "bird of nebulosity" seemingly riding on a red beam and taking flight at right! 🕊

So yes, there is so much to see in this fantastic region of nebulosity in Sagittarius! But let's leave the nebulosity behind and end with an open and a globular cluster:

And that's all from me today!

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Re: APOD: A Sagittarius Triplet (2024 Jul 10)

Post by zendae » Wed Jul 10, 2024 4:31 pm

I hope APOD presents the new NASA Webb visualization of the Pillars Of Creation here. To see this in a 3D format is striking, since everything is basically 2D-looking otherwise. Even if it isn't actual, it certainly is dramatic, and I hope, helpful. It would be exciting for the rest of us to see other phenomena like this, even if it is rather boring and tedious for the professionals.