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Deep image of the Cocoon Nebula

Started by rwodaski, 10/06/2002 12:08AM
Posted 10/06/2002 12:08AM Opening Post
I took a 50-minute RGB image (50:50:80 minutes in RGB) of the Cocoon just the other night at New Mexico Skies. I have been trying to get a good color picture that would reveal the structure of the various layers of nebulosity that are present in this area. By chance, one of my fellow imagers walked in a moment ago and helped me understand what is going on in this image.

First, he suggests that this is a "Stromgren" sphere (spelling uncertain). That is a sphere of Hydrogen gas that is ionized by a central star, emitting deep red (H-alpha). Outside the sphere, the radiation from the star isn't bright enough to ionize the Hydrogen, so it glows with light reflected from the star. In this image, you can see the deep red of the ionized hydrogen, and a faint white glow around this (with a slight blue cast) that is reflected light.

Second, the dust lane that extends outward from the Cocoon is dark but also bright enough to be imaged. The dust is a deep rust-red color. An analysis of the individual R, G, and B images shows that there is a thick cloud of dust at lower right (perhaps a Bok Globule?), a lane of dust that is thinner and shows some stars through it, and a light haze of red dust generally over the lower half of the image.

My goal is always to use color to reveal structure in an image, and this example is one that really does that well. This a roughly half-size version of the image. I am on the road, and I cannot post a full-size version to my web site until I return home.

Ron Wodaski
author of "The New CCD Astronomy"

Attached Image:

rwodaski's attachment for post 1837

Ron Wodaski
New Astronomy Press
Posted 10/06/2002 12:10AM #1
Here is a version of the image with boosted brightness, that I hope will reveal more of the subtle dust regions in the image.

Ron Wodaski
author of "The New CCD Astronomy"

Attached Image:

rwodaski's attachment for post 62855

Ron Wodaski
New Astronomy Press
Posted 10/06/2002 02:40AM #2
Hi Ron,

Millions of perfectly guided stars! Wow!

Here is my close-up version which has the same blueish faint nebula on the outer parts.

Gute Nacht
mehr freude. 49° 13' 54" N
Posted 10/06/2002 07:04AM #3

here's a link to some info about this.

Here's another cocoon. Took it last week Ha:Ha:G:B 80:30:30:30 mins with Tak Mewlon 250 at f 13 St8e 2x2 bin. I think you can see some of the blue face on. I have a 6" mak-newt f 5.5, I think I'll try it with that scope for a ddeper image.

clear skies,

Larry Citro

Attached Image:

Larry Citro's attachment for post 62859
Posted 10/06/2002 01:22PM #4

Very nice image. I took a long exposure with my FSQ of that area last year, and the dust lane is really quite long. It sort of reminds me of a snake or caterpillar, with the Cocoon as the head.


Jeff 8O
Posted 10/08/2002 07:01PM #5
Keep up the great work!


Ivan Gastaldo 8)
Coconut Creek, FL

Ivan's Observatory
Lat 26N 16' 48" Long 80W 10' 48"
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