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Archive 2015 · Helix Nebula

  
 
StarNut
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p.1 #1 · p.1 #1 · Helix Nebula


Hi,

This is the Helix Nebula, a large, bright planetary nebula, the type of nebula which it is generally thought our Sun will produce as nuclear fusion slows and then dies in its core, and it expels its outer layers of gas. For obvious reasons, it has been called "The Eye of God" and "The Eye of Sauron." Estimates of its distance from Earth vary, but tend to be around 650 light years, making it the closest planetary nebula to Earth; it is about six light years across (including the fainter nebulosity).

The little blue star at the center of the nebula (in the middle of the blue/green disc) is the star that started this nebula when it shucked off its outer layers; that event is thought to have happened about 11,000 years ago. That "blue" star actually is a white dwarf, about the size of Earth, but has a mass very close to that of the original star; it's so dense that a teaspoon of a white dwarf would weigh as much as a few elephants! It's a very hot star, emitting most of its visible light in the blue spectrum (no, I don't know why they call a blue star a "white" dwarf!).

This image contains a bit over 26 hours of light-frame data, about half of which was taken through a hydrogen alpha filter.

Camera: Santa Barbara Instruments Group STL11000M
Telescope: RC Optical Systems 14.5" carbon-truss Ritchey-Chretien (Cassegrain)
Mount: Software Bisque Paramount ME

Enjoy!

http://www.de-regt.com/Astronomy/Helix.RCOS.40.jpg

Edited on Apr 11, 2015 at 11:54 AM · View previous versions



Apr 09, 2015 at 05:29 AM
dgdg
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p.1 #2 · p.1 #2 · Helix Nebula


"A great eye, lidless, wreathed in flame"
Very cool shot.

David



Apr 09, 2015 at 07:31 AM
Steve Perry
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p.1 #3 · p.1 #3 · Helix Nebula


Amazing work - love it!


Apr 09, 2015 at 09:25 AM
chasphoto2015
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p.1 #4 · p.1 #4 · Helix Nebula


Helps you realize how intricate the solar system really is, great shot !


Apr 09, 2015 at 11:31 AM
Maritan
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p.1 #5 · p.1 #5 · Helix Nebula


Amazing! Thanks for sharing. I love seeing pictures that like this that show us a glimpse of the wonders available outside this tiny planet.


Apr 09, 2015 at 01:34 PM
sasho_p
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p.1 #6 · p.1 #6 · Helix Nebula


This is truly astonishing and a lot of hard work went there (astrophotography requires lot's of it).
Is the white dwarf the star in the center? It looks almost blue - probably still "young"



Apr 09, 2015 at 01:37 PM
StarNut
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p.1 #7 · p.1 #7 · Helix Nebula


Thanks for the kind words!

sasho_p wrote:
Is the white dwarf the star in the center? It looks almost blue - probably still "young"


A white dwarf can be blue-white, or white. I couldn't find anything on this star, so I suspect that it's a blue-white, and I suspect that it being in the midst of all that blue-colored gas enhances the blue color.




Apr 09, 2015 at 04:25 PM
Sunny Sra
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p.1 #8 · p.1 #8 · Helix Nebula


DUUUUDE!!


Apr 09, 2015 at 04:29 PM
Tim Knutson
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p.1 #9 · p.1 #9 · Helix Nebula


Lets say for a minute, that I want to go down to Home Depot and get a hydrogen alpha filter. What isle do I look in?

Seriously, tell us more about the setup.



Apr 09, 2015 at 07:32 PM
StarNut
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p.1 #10 · p.1 #10 · Helix Nebula


Tim Knutson wrote:
Lets say for a minute, that I want to go down to Home Depot and get a hydrogen alpha filter. What isle do I look in?

Seriously, tell us more about the setup.


There's an outfit called New Mexico Skies, which operates a thriving business hosting people's fancy astronomy gear, for imaging. One is in the Sacramento Mountains in New Mexico, and the other is in the South Australia desert.

In the South Australia desert, my scopes, mount and camera are located in a large roll-off roof observatory owned by NMS, with the scopes, mounts and cameras of many others. Each of us has a server, connected to the internet and our equipment; I open up a connection to my server down there before I go to bed, tell it what I want my system to do that night (what target(s), what filters and how many subexposures), cue it up, and go to bed. If all goes well (which it normally--but not always--does), it's imaging away when I wake up in the morning. I download the data from the server in Australia to my home desktop each morning, examine the individual subexposures, and file them appropriately (many get tossed as not being good enough, so the 26 hours in this image probably represents 35 or 40 hours of active data collection).

To clarify, inside the camera is a filter wheel. The camera's chip is a monochrome chip; I take images using a variety of filters: At least a clear filter (for the details), and a red-pass filter, a green-pass filter, and a blue-pass filter. Combining the images taken through the color filters gives me a true color version of the object, and the images through the clear filter gives me the detail (very much like color TV worked in the analog days, with two signals broadcast, one low resolution carrying the color information, and one high resolution carrying the detail). If the object has interesting emissions in a particular narrow band for which I have a filter (hydrogen alpha, a very narrow piece of the red spectrum, is emitted by many nebulae; I also have filters for recording emissions from sulfur ions and oxygen ions), I'll take images through those filters, in addition to the LRGB filters.

Processing is very time-consuming, and often very difficult; this one was particularly difficult, for a variety of reasons (principally, it's very difficult to blend narrow-band data--hydrogen alpha in this case--with broadband data, since the narrow-band data are so dense; so it's tricky and painstaking to do that; also this is a very nuanced nebula, and I really struggled to find what I felt was an optimal point in the sharpening curve, so that the image shows many details, but doesn't look like it has had too many facelifts). I started processing this data set in November, gave up for a while, re-commenced in early March, worked on it for many, many hours (often working myself into a rat-hole, and starting over almost from scratch).

I finally decided that this was as good as I am going to get, declared victory, and posted it.

It's a labor of love; not for the faint of heart.



Mark



Edited on Apr 11, 2015 at 01:04 PM · View previous versions



Apr 09, 2015 at 10:12 PM
JimFox
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p.1 #11 · p.1 #11 · Helix Nebula


Hey Mark,

What a really cool looking shot. But one I have to say that I can never imagine doing! What an incredible amount of work it requires, I take my hat off to you for doing these.

Jim



Apr 09, 2015 at 10:29 PM
danws6
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p.1 #12 · p.1 #12 · Helix Nebula


As always I appreciate you posting both the image and the detailed explanations.


Apr 09, 2015 at 11:16 PM
Tim Knutson
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p.1 #13 · p.1 #13 · Helix Nebula


Mark, thanks for the detailed write up. I think your right, not for the faint of heart. But I do like the go to bed and let it happen part.

Nice job.



Apr 09, 2015 at 11:58 PM
srkbar
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p.1 #14 · p.1 #14 · Helix Nebula


As always, another master piece! Thanks for sharing your knowledge.


Apr 10, 2015 at 12:56 AM
ChrisKayler
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p.1 #15 · p.1 #15 · Helix Nebula


Always enjoy your star images and accompanying commentary. We are truly insignificant specks in this universe. Artistically, I want a bit more space all around the image as a whole, as the nebula feels quite cramped as is. This one also seems a tiny bit soft.

Edit: Just read your description on the setup. Wild!!



Apr 10, 2015 at 09:20 AM
StarNut
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p.1 #16 · p.1 #16 · Helix Nebula


Again, thanks: I do very much appreciate the responses!

ChrisKayler wrote:
Artistically, I want a bit more space all around the image as a whole, as the nebula feels quite cramped as is.


This is the entire frame, with a tiny bit of cropping for aligning the various subexposures and dithering (a necessity for reducing noise in the final combined images). For about US$14,000, I could get a camera with a larger chip; donations are being accepted!

This one also seems a tiny bit soft.

Ever hear the term "nebulous"? This is a nebula!

Seriously, one judges the softness of these images by looking at the smaller stars. The nebula is, by definition, soft and nebulous; the trick in processing one as large as this is to optimize the detail, without over-sharpening it (which looks horrible, IMO). I've processed these data many, many times; with "only" 14.5" of aperture, there a limit on the detail that it can captured, and I'm satisfied that this is as good as I can get it. The Hubble photos are more detailed, and a very few earth-based cameras have captured significantly more detail, because they're much larger instruments.



Edited on Apr 10, 2015 at 10:37 PM · View previous versions



Apr 10, 2015 at 10:35 AM
dbehrens
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p.1 #17 · p.1 #17 · Helix Nebula


Wow - WoW - WOW!
Dave



Apr 10, 2015 at 11:38 AM
wbrad
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p.1 #18 · p.1 #18 · Helix Nebula


This is really amazing. I find it hard to grasp that one little star, like our sun, "when it shucked off it's outer layers" could produce a nebula six light years across. Fantastic image.

Wayne



Apr 11, 2015 at 07:43 AM
DejanS
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p.1 #19 · p.1 #19 · Helix Nebula


Outta this world! Captured my "eye" and pun intended! ;-)

Dejan



Apr 11, 2015 at 07:56 AM
StarNut
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p.1 #20 · p.1 #20 · Helix Nebula


Again, thanks for the enthusiastic response; I think this is one of my best shots, and it's nice to see that others like it, also!

wbrad wrote:
This is really amazing. I find it hard to grasp that one little star, like our sun, "when it shucked off it's outer layers" could produce a nebula six light years across. Fantastic image.

Wayne


One of my favorite things about this hobby is that I learn lots about the universe as I research the objects I'm photographing. It is kind of mind-blowing that a little star like ours can create a nebula six light years across, while retaining almost all of its mass but shrinking to something with a diameter less than 1% of its original. It's an amazing universe!




Apr 11, 2015 at 01:13 PM
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