APOD: Cocoon Nebula Wide Field (2012 Sep 13)

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APOD: Cocoon Nebula Wide Field (2012 Sep 13)

Post by APOD Robot » Thu Sep 13, 2012 4:05 am

Image Cocoon Nebula Wide Field

Explanation: In this crowded starfield covering over 2 degrees within the high flying constellation Cygnus, the eye is drawn to the Cocoon Nebula. A compact star forming region, the cosmic Cocoon punctuates a long trail of obscuring interstellar dust clouds. Cataloged as IC 5146, the nebula is nearly 15 light-years wide, located some 4,000 light years away. Like other star forming regions, it stands out in red, glowing, hydrogen gas excited by the young, hot stars and blue, dust-reflected starlight at the edge of an otherwise invisible molecular cloud. In fact, the bright star near the center of this nebula is likely only a few hundred thousand years old, powering the nebular glow as it clears out a cavity in the molecular cloud's star forming dust and gas. But the long dusty filaments that appear dark in this visible light image are themselves hiding stars in the process of formation, seen at infrared wavelengths.

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Re: APOD: Cocoon Nebula Wide Field (2012 Sep 13)

Post by Boomer12k » Thu Sep 13, 2012 4:54 am


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Re: APOD: Cocoon Nebula Wide Field (2012 Sep 13)

Post by Ann » Thu Sep 13, 2012 4:59 am

What a great image! :D :D :D

I love the protrait of the nebulosity in this area. I have never before seen that ridge of red Ha emission directly behind the Cocoon, with the Cocoon sort of "sticking out of it". This structure makes the Cocoon very slightly similar to the Horsehead region. There, too, you have a conspicuous feature sticking out across a red ridge of nebulosity. And the prominent blue reflection nebula "below" the Horsehead is slightly similar to the Cocoon Nebula itself.

Note the long dusty filament which is light brown in color near the Cocoon, but becomes dark, almost pitch black, away from it. The Cocoon has formed at the end of this long string of dust. Fascinatingly, dust clouds often seem to be really quite elongated. Here is an example of an elongated star forming dust cloud in Corona Australis.

I don't have my software here - darn it! - so I can't check the central star of the Cocoon, but I have looked it up before. I know that this star has been classified as a relatively unremarkable star of cool class B, but that must be a misclassification. I don't see how this star could fill the Cocoon with red light if it wasn't at least of early class B, spectral class B2 or earlier.

Once again, this is a spectacular APOD! :D

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Re: APOD: Cocoon Nebula Wide Field (2012 Sep 13)

Post by starsurfer » Thu Sep 13, 2012 9:59 am

Amazing image, I love it when amateurs go deep and reveal familiar favourites in an almost completely new light! The extended reflection nebulosity is a wonderful surprise! The Ha streamers are part of a massive complex of background nebulosity that is unrelated to the Cocoon Nebula. The sky is literally filled with hydrogen and long Ha exposures of many regions show faint background nebulosity. In fact, the imager Fabian took a deep image of the area around the Double Cluster that reveals an epic web of Ha: http://www.starpointing.com/ccd/ngc869_ngc884.html

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Re: APOD: Cocoon Nebula Wide Field (2012 Sep 13)

Post by emc » Thu Sep 13, 2012 12:16 pm

Waking up from a deep sleep this morning I was delighted to find my Starship encountering yet another beautiful object filled cosmic scene…
There’s nothing I can recognize; this is nowhere that I’ve known.
With no sign of life at all, I guess that I’m alone.
And I feel so secure that I know this can’t be real…
But I feel good.
Cuckoo cocoon have I come to, too soon for you?

Genesis – Cuckoo Cocoon – Lamb Lies Down on Broadway - 1974
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