APOD: The Cats Eye Nebula (2012 Aug 26)

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APOD: The Cats Eye Nebula (2012 Aug 26)

Post by APOD Robot » Sun Aug 26, 2012 4:07 am

Image The Cats Eye Nebula

Explanation: Three thousand light-years away, a dying star throws off shells of glowing gas. This image from the Hubble Space Telescope reveals the Cat's Eye Nebula to be one of the most complex planetary nebulae known. In fact, the features seen in the Cat's Eye are so complex that astronomers suspect the bright central object may actually be a binary star system. The term planetary nebula, used to describe this general class of objects, is misleading. Although these objects may appear round and planet-like in small telescopes, high resolution images reveal them to be stars surrounded by cocoons of gas blown off in the late stages of stellar evolution.

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Re: APOD: The Cats Eye Nebula (2012 Aug 26)

Post by Beyond » Sun Aug 26, 2012 4:17 am

I agree with the 'misleading' link. That's quite a s-t-r-e-t-c-h!!
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Re: APOD: The Cats Eye Nebula (2012 Aug 26)

Post by cpjhogan » Sun Aug 26, 2012 5:23 am

Is it my imagination or does the central star have an elongated look?

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Re: APOD: The Cats Eye Nebula (2012 Aug 26)

Post by Ann » Sun Aug 26, 2012 5:37 am

This is a golden oldie by Hubble, which revolutionized our understanding of planetary nebulae. It reveals wonderful structure.

For me, the color freak, the picture was mostly confusing the first time I saw it. Was the nebula really so red? And if so, why was it red? Was all of its interior filled with Ha emission, the favorite red emission of the universe?

Soon I realized that the coloring of planetary nebulae in modern astrophotography was up for grabs. A bewildering palette of freak-hued nebular star-shrouds started appearing everywhere. A sample of wildly colored celestial Cat's Eyes are here, here, here, here, here, here, here, here, here, here and here.

I also want to call attention to some space art inspired by the Cat's Eye Nebula here, here and here. I like the artwork - a lot, actually - but for a while I reacted so negatively to the bewildering flora of chromatics of the planetary nebulae that I decided that I could take no interest in planetary nebula whatsoever.

Now I realize that planetary nebulae typically are aqua-colored (or "teal") inside, from 500.7 nm OIII emission. The other parts of them are typically red from 656 nm Ha emission. So this picture by Adam Block probably gives you a good idea of the intrinsic color of the Cat's Eye Nebula.

Finally, I'd like to give you this Cat's Eye, too.

Ann
Last edited by Ann on Sun Aug 26, 2012 5:56 am, edited 1 time in total.
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Re: APOD: The Cats Eye Nebula (2012 Aug 26)

Post by Mohrweb » Sun Aug 26, 2012 5:45 am

Interesetingly, seems similar to the APOD post of November 12, 2006.

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Re: APOD: The Cats Eye Nebula (2012 Aug 26)

Post by Beyond » Sun Aug 26, 2012 6:17 am

Ann wrote:This is a golden oldie by Hubble, which revolutionized our understanding of planetary nebulae. It reveals wonderful structure.

For me, the color freak, the picture was mostly confusing the first time I saw it. Was the nebula really so red? And if so, why was it red? Was all of its interior filled with Ha emission, the favorite red emission of the universe?

Soon I realized that the coloring of planetary nebulae in modern astrophotography was up for grabs. A bewildering palette of freak-hued nebular star-shrouds started appearing everywhere. A sample of wildly colored celestial Cat's Eyes are here, here, here, here, here, here, here, here, here, here and here.

I also want to call attention to some space art inspired by the Cat's Eye Nebula here, here and here. I like the artwork - a lot, actually - but for a while I reacted so negatively to the bewildering flora of chromatics of the planetary nebulae that I decided that I could take no interest in planetary nebula whatsoever.

Now I realize that planetary nebulae typically are aqua-colored (or "teal") inside, from 500.7 nm OIII emission. The other parts of them are typically red from 656 nm Ha emission. So this picture by Adam Block probably gives you a good idea of the intrinsic color of the Cat's Eye Nebula.

Finally, I'd like to give you this Cat's Eye, too.

Ann
Ann... Dats a lotta here's :!: :!: The last one tells me that you've been reading certain APOD links toooo long :!: :lol2:
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Transparent with a swirl inside.

Post by neufer » Sun Aug 26, 2012 6:23 am

http://en.wikipedia.org/wiki/Marble_%28toy%29 wrote:


<<The Marble originated in Harappan civilization in Pakistan near the river Indus. Various marbles of stone were found on excavation near Mohenjo-daro. Marbles are also often mentioned in Roman literature, and there are many examples of marbles from ancient Egypt.

Marbles were originally made by hand. Stone or ivory marbles can be fashioned by grinding. Clay, pottery, ceramic, or porcelain marbles can be made by rolling the material into a ball, and then letting dry, or firing, and then can be left natural, painted, or glazed. Clay marbles, also known as crock marbles or commies (common), are made of slightly porous clay, traditionally from local clay or leftover earthenware ('crockery'), rolled into balls, then glazed and fired at low heat, creating an opaque imperfect sphere that is frequently sold as the poor boy's 'old timey' marble. Glass marbles can be fashioned through the production of glass rods which are stacked together to form the desired pattern, cutting the rod into marble-sized pieces using marble scissors, and rounding the still-malleable glass.

One mechanical technique is dropping globules of molten glass into a groove made by two interlocking parallel screws. As the screws rotate, the marble travels along them, gradually being shaped into a sphere as it cools. Color is added to the main batch glass and/or to additional glass streams that are combined with the main stream in a variety of ways. For example, in the "cat's-eye" style, colored glass veins are injected into a transparent main stream. Applying more expensive colored glass to the surface of cheaper transparent or white glass is also a common technique.

In 1903, Martin Frederick Christensen of Akron, Ohio made the first machine-made glass marbles on his patented machine. His company, The M.F. Christensen & Son Co., manufactured millions of toy and industrial glass marbles until they ceased operations in 1917. The next US company to enter the glass marble market was Akro Agate. This company was started by Akronites in 1911, but was located in Clarksburg, West Virginia. Today, there are only two American-based toy marble manufacturers: Jabo Vitro in Reno, Ohio, and Marble King, in Paden City, West Virginia.

One marble game involves drawing a circle in sand, and players will take turns knocking other players' marbles out of the circle with their own marble. This game is called ringer . Other versions involve shooting marbles at target marbles or into holes in the ground (such as rolly or rolley hole). A larger-scale game of marbles might involve taking turns trying to hit an opponent's marble to win. A useful strategy is to throw a marble so that it lands in a protected, or difficult location if it should miss the target. While the game of marbles was once ubiquitous and attracted widespread press to national tournaments, its popularity has dwindled in the television age.>>
Art Neuendorffer

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Re: APOD: The Cats Eye Nebula (2012 Aug 26)

Post by Beyond » Sun Aug 26, 2012 6:59 am

Well Art, i see you've got all your marbles. Don't play much, eh :?:
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Re: APOD: The Cats Eye Nebula (2012 Aug 26)

Post by Moonlady » Sun Aug 26, 2012 7:33 am

Beautiful Nebulae, nice collection of HEREs :kitty: and marbles, I love marbles! I am missing the sizes, yes there are bigger and smaller ones, and the metallic shining ones!
in my childhood, we played a lot with them, calling in Germany "Klickers" because the sound they make when two clash.
Today kids play with other "klicks"...click here ...click there.

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Re: APOD: The Cats Eye Nebula (2012 Aug 26)

Post by Psnarf » Sun Aug 26, 2012 2:35 pm

The black and white image from Hubbel, http://imgsrc.hubblesite.org/hu/db/imag ... ll_jpg.jpg, shows features that do not appear in color. Was the color image binned without a luminosity reference? Those jets shooting out of the nebula appear to have originated from one of the outer shells, early in the nebulation evolution, if nebulation is the word for which I'm searching.

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Re: APOD: The Cats Eye Nebula (2012 Aug 26)

Post by geckzilla » Sun Aug 26, 2012 2:40 pm

Psnarf wrote:The black and white image from Hubbel, http://imgsrc.hubblesite.org/hu/db/imag ... ll_jpg.jpg, shows features that do not appear in color. Was the color image binned without a luminosity reference? Those jets shooting out of the nebula appear to have originated from one of the outer shells, early in the nebulation evolution, if nebulation is the word for which I'm searching.
Could have been that the data used to produce this particular version did not include those features. A more complete one: http://apod.nasa.gov/apod/image/0705/ca ... st_big.jpg
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Re: APOD: The Cats Eye Nebula (2012 Aug 26)

Post by FLPhotoCatcher » Sun Aug 26, 2012 4:38 pm

I was hoping to see a tribute to Neil Armstrong today, or at least tomorrow.
R.I.P., Mr. Armstrong.

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Re: APOD: The Cats Eye Nebula (2012 Aug 26)

Post by bystander » Sun Aug 26, 2012 5:04 pm

FLPhotoCatcher wrote:I was hoping to see a tribute to Neil Armstrong today, or at least tomorrow.
R.I.P., Mr. Armstrong.
From today's APOD page:
Neil Armstrong, first human to walk on another world: 1930 - 2012
or perhaps you may wish to check out these missing links.
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Re: APOD: The Cats Eye Nebula (2012 Aug 26)

Post by Boomer12k » Sun Aug 26, 2012 10:38 pm

Ann wrote:This is a golden oldie by Hubble, which revolutionized our understanding of planetary nebulae. It reveals wonderful structure.

For me, the color freak, the picture was mostly confusing the first time I saw it. Was the nebula really so red? And if so, why was it red? Was all of its interior filled with Ha emission, the favorite red emission of the universe?

Soon I realized that the coloring of planetary nebulae in modern astrophotography was up for grabs. A bewildering palette of freak-hued nebular star-shrouds started appearing everywhere. A sample of wildly colored celestial Cat's Eyes are here, here, here, here, here, here, here, here, here, here and here.

I also want to call attention to some space art inspired by the Cat's Eye Nebula here, here and here. I like the artwork - a lot, actually - but for a while I reacted so negatively to the bewildering flora of chromatics of the planetary nebulae that I decided that I could take no interest in planetary nebula whatsoever.

Now I realize that planetary nebulae typically are aqua-colored (or "teal") inside, from 500.7 nm OIII emission. The other parts of them are typically red from 656 nm Ha emission. So this picture by Adam Block probably gives you a good idea of the intrinsic color of the Cat's Eye Nebula.

Finally, I'd like to give you this Cat's Eye, too.

Ann

Ann....YOUR Cat's Eye reminds me of the Bubble Nebula... :D

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Re: APOD: The Cats Eye Nebula (2012 Aug 26)

Post by j p harrington » Mon Aug 27, 2012 12:03 am

When we took those images many years ago, what we really got was a series of pictures through
narrow-band filters corresponding to wavelengths emitted by certain specific ions in the nebular gas.
We then choose three of the images, assign a different color (red, green & blue) to each and combine
them to make a color image. It's quite arbitrary. For example, the wavelength of hydrogen (H-alpha)
is nearly the same as nitrogen (N II) -- they are both red -- but they are distributed quite differently
in the nebula. So if you assign them both to red, you smear out the interesting structures. The one on
my webpage (http://www.astro.umd.edu/~jph/) uses three filters which apply to oxygen ions. The
most prevalent is the highly ionized O III, which at 5007A does fall in the green part of the spectrum,
and I have assigned that image to green in the color composite. So the colors tend to be pretty arbitrary
-- that's why we call it "false color". The Hubble doesn't have a set of filters that match the response
of the human eye, and even if it did, the results would be rather disappointing, not revealing the
information we see in the false color combinations.
By the way, when we (Harrington & Borkowski) released that original image, we picked a combination
that was put together by Zolt Levay at STScI. The black and white image is one from the nitrogen
filter that I processed to reveal the jets.

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Re: APOD: The Cats Eye Nebula (2012 Aug 26)

Post by Ann » Mon Aug 27, 2012 12:46 am

Thanks for your explanation, J. P. Harrington. I'm slightly but not very surprised that you chose the green channel for the OIII emission (these days, OIII is typically shown as blue). I'm more surprised at where the green OIII emission is located in the nebula. Typically, OIII emission is only found in extremely rarefied parts of a nebula - typically in the almost perfect vacuum close to the central star - but in today's APOD, green appears to be associated with comparatively dense parts of the nebula, where one gaseous structure meets another and gets piled up.

But I checked out your homepage, the one you gave us your address to, and it appears that today's APOD was made from exposures through filters tracing oxygen emission only. There is no hydrogen or nitrogen involved here. And indeed, in the original coloring of your picture, the Cat's Eye Nebula is filled with green light from OIII emission. In other words, the OIII emission is in the right place. The parts that look green in today's APOD are mostly red in your image from 630 nm reddish OI emission.

So showing blue-green OIII emission as red in today's APOD was a very arbitrary decision, and probably not your doing.

Ann
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Re: APOD: The Cats Eye Nebula (2012 Aug 26)

Post by j p arrington » Mon Aug 27, 2012 1:32 am

There could be some confusion here ... Today's APOD image, which dates from 1995! --- Did not use the O III image at all. The red is
hydrogen alpha (which we can agree is in fact red). Since hydrogen has only one ionization stage, you see this line from anywhere that
the gas is ionized, so it is the dominant color. The other two filters used were neutral oxygen (O I), which is blue here, and once ionized
nitrogen (N II), which is used for the green channel. But by the actual wavelengths, they would all be red.
In the image on my web page, I don't have H-alpha or N II, but use OI, OII & OIII. This is a high ionization nebula, and so, except
where the gas is very dense, the oxygen tends to be O III, all the way out to the edge. But there are dense, partly neutral clumps.
These show up in neutral oxygen, OI at 6300A. They are blue in the APOD image and red in my webpage image. The N II image also
shows lower ionization zones and for complex reasons is especially strong in jets and other outlying structures.
This nebula doesn't have any visible gas near the central star -- that region has been swept by the stellar wind and is filled with
million degree, low density gas that can be seen in X-ray images taken with Chandra.
I restrain myself from running on further about this wonderful object (too late! they cry ...).

Patrick

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Re: APOD: The Cats Eye Nebula (2012 Aug 26)

Post by bystander » Mon Aug 27, 2012 3:46 am

Ann wrote:it appears that today's APOD was made from exposures through filters tracing oxygen emission only. There is no hydrogen or nitrogen involved here.
APOD Robot wrote: This image from the Hubble Space Telescope
This color picture, taken with the Wide Field Planetary Camera-2, is a composite of three images taken at different wavelengths. (red, hydrogen-alpha; blue, neutral oxygen, 6300 angstroms; green, ionized nitrogen, 6584 angstroms). The image was taken on September 18, 1994.
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Re: APOD: The Cats Eye Nebula (2012 Aug 26)

Post by Psnarf » Fri Aug 31, 2012 3:10 pm

geckzilla wrote:
Psnarf wrote:The black and white image from Hubbel, http://imgsrc.hubblesite.org/hu/db/imag ... ll_jpg.jpg, shows features that do not appear in color. Was the color image binned without a luminosity reference? Those jets shooting out of the nebula appear to have originated from one of the outer shells, early in the nebulation evolution, if nebulation is the word for which I'm searching.
Could have been that the data used to produce this particular version did not include those features. A more complete one: http://apod.nasa.gov/apod/image/0705/ca ... st_big.jpg
Thank you, Geckzilla, for the link. Upon closer inspection, the colorized image published today (26Aug12) is cropped, probably to focus on the stunning bits in the center.

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Re: APOD: The Cats Eye Nebula (2012 Aug 26)

Post by bystander » Fri Aug 31, 2012 7:40 pm

Psnarf wrote:
geckzilla wrote:
Psnarf wrote:The black and white image from Hubbel, http://imgsrc.hubblesite.org/hu/db/imag ... ll_jpg.jpg, shows features that do not appear in color. Was the color image binned without a luminosity reference? Those jets shooting out of the nebula appear to have originated from one of the outer shells, early in the nebulation evolution, if nebulation is the word for which I'm searching.
Could have been that the data used to produce this particular version did not include those features. A more complete one: http://apod.nasa.gov/apod/image/0705/ca ... st_big.jpg
Thank you, Geckzilla, for the link. Upon closer inspection, the colorized image published today (26Aug12) is cropped, probably to focus on the stunning bits in the center.
An even more complete image: http://apod.nasa.gov/apod/ap120831.html
Know the quiet place within your heart and touch the rainbow of possibility; be
alive to the gentle breeze of communication, and please stop being such a jerk.
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