APOD: A Sagittarius Triplet (2013 Aug 30)

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APOD: A Sagittarius Triplet (2013 Aug 30)

Post by APOD Robot » Fri Aug 30, 2013 4:06 am

Image A Sagittarius Triplet

Explanation: These three bright nebulae are often featured in 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 left of center, and colorful M20 on the right. The third, NGC 6559, is above M8, separated from the larger nebula by a dark dust lane. All three are stellar nurseries about five thousand light-years or so distant. The expansive M8, over a hundred light-years across, 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, with contrasting blue hues, most striking in the Trifid, due to dust reflected starlight. The colorful skyscape recorded with telescope and digital camera also includes one of Messier's open star clusters, M21, just above the Trifid.

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Re: APOD: A Sagittarius Triplet (2013 Aug 30)

Post by Beyond » Fri Aug 30, 2013 4:22 am

What a difference distance makes. In today's APOD, the Trifid looks more like Duofid. In the Trifid link, the picture looks more like a Quadfid. So i guess Trifid is an average, or it just goes with the movie... Day of the Trifids, of which, there was a lot more than one.
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Re: APOD: A Sagittarius Triplet (2013 Aug 30)

Post by Ann » Fri Aug 30, 2013 4:50 am

It's so nice to see a lovely deep-sky RGB image by great astrophotographer Tony Hallas! :D :D :D

Note how the Lagoon Nebula and the NGC 6559 complex are clearly part of one and the same large starforming region. There is even a dark dust lane running from the "top" of the Lagoon Nebula all the way over to and "around" the NGC 6559 complex.

Next to active star formation regions at top left, the dark dust lane takes on a bluish hue. It becomes a mixture of an absorption nebula and a reflection nebula, reflecting the blue light of hot newborn stars.

This picture is a fine illustration of the fact that it takes dust to make gas clouds cool and condense enough to form stars. If you want to see star formation, follow the dust.

Speaking of reflection nebulae, very faint bluish reflection nebulae can be seen at the "top" and "bottom" of the Lagoon Nebula.

So the Lagoon Nebula and the NGC 6559 complex are linked. The Trifid Nebula and M21, the cluster of blue stars to the upper left of the Trifid, are likely also linked. But M21 has used up and then blown away all the gas and dust that it was born from. No red or blue nebulae can be seen here, and no sign of ongoing star formation.

But all the nebulae in the picture are busy producing and hatching new stars.

What a great picture this is! :D

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Re: APOD: A Sagittarius Triplet (2013 Aug 30)

Post by Boomer12k » Fri Aug 30, 2013 9:49 am

GREAT JOB, TONY HALLAS....he helped me with my post processing...

Really nice wide field portrait. My M-20 comes out very close in...." I am ready for my closeup, Mr. DeMille."
I toned down the large stars a bit, and took out a tad bit of glare.

Going to have to get me a wide angle telescope some day. I can use my Deep Ski Imager with a wide angle eyepiece, but I don't have a solid connection..just hand held, so things cannot be very long exposures. And I am just experimenting.

Keep up the great work! :D

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Re: APOD: A Sagittarius Triplet (2013 Aug 30)

Post by starsurfer » Fri Aug 30, 2013 11:55 am

Wow that's really good resolution for a wide angle lens image! I really like the globular cluster NGC 6544 near the Lagoon Nebula.

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Re: APOD: A Sagittarius Triplet (2013 Aug 30)

Post by Psnarf » Fri Aug 30, 2013 1:37 pm

Bigfoot the Pirate. Bigfoot footprint on left, wooden leg impression on right?

Must be time for my medication....

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Re: APOD Retrospective: August 30

Post by merrymargaret » Tue Sep 03, 2013 3:46 pm

Everyone is blind. This is Bigfoot with a stump for a leg! ;) Really - have another look! :lol2: