APOD: Messier 76 (2010 Jul 23)

[APOD Robot]

Messier 76

Explanation: "Nebula at the right foot of Andromeda ... " begins the description for the 76th object in Charles Messier's 18th century Catalog of Nebulae and Star Clusters. In fact, M76 is one of the fainter objects on the Messier list and is also known by the popular name of the "Little Dumbbell Nebula". Like its brighter namesake M27 (the Dumbbell Nebula), M76 is recognized as a planetary nebula - a gaseous shroud cast off by a dying sunlike star. The nebula itself is thought to be shaped more like a donut, while the box-like appearance of its brighter central region is due to our nearly edge-on view. Gas expanding more rapidly away from the donut hole produces the fainter loops of far flung material. The fainter material is emphasized in this composite image, highlighted by showing emission from hydrogen atoms in orange and oxygen atoms in complementary blue hues. The nebula's dying star can be picked out in the sharp false-color image as blue-tinted star near the center of the box-like shape. Distance estimates place M76 about 3 to 5 thousand light-years away, making the nebula over a light-year in diameter.

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[/b]

[neufer]

Messier 76

Explanation: "Nebula at the right foot of Andromeda ... " begins the description
for the 76th object in Charles Messier's 18th century Catalog of Nebulae and Star Clusters.

Messy (Messier, Messiest) Being mucky, foul, sordid, smutty or muddy.

<<A blood blister is a type of blister that forms when subdermal tissues and blood vessels are damaged without piercing the skin. It consists of a pool of lymph, blood and other bodily fluids trapped beneath the skin. If punctured, it suppurates a dark red fluid. Sometimes the fluids are cut off from the rest of the body and dry up, leaving behind dead cell material inside the blister with a texture like putty. Some blood blisters can be extremely painful due to bruising where the blister occurred. Common areas that suffer from blood blisters include the hands and feet.
* Leave the blister alone. Elevate the injured area. Apply a cold pack.
* Soak the blister in epsom salts to reduce swelling.
* Keep the area cleanly bandaged, and replace the bandage daily or whenever necessary.
* If the blister breaks, quickly rinse the area and apply an antiseptic such as neosporin.>>

[owlice]

Art, dang it, I'm eating here!!!

[owlice]

(or was, anyway...)

[neufer]

Art, dang it, I'm eating here!!! (or was, anyway...)

Donuts?

[orin stepanek]

Distance estimates place M76 about 3 to 5 thousand light-years away, making the nebula over a light-year in diameter.

That's a pretty rangy estimate; meaning that the nebula could be close to 2 light-years across! I'm just going by that if it's over a LY at 3000LY distance that at 5000LY it must be closer to two LY across.

[owlice]

Donuts?

Black pudding and eggs with ketchup; clearly a doughnut would have been a better first choice!

[biddie67]

This little newbie does struggle at times - it took me a while to realize that the Andromeda Galaxy and the Andromeda constellation were two different things. Is Messier 76 considered to be in our Milky Way galaxy??

Art - I agree with owlice - ugh!!! If the APOD paragraph had listed Messier 76 at the LEFT foot of Andromeda, would you have horizontally flipped your offered picture -or- do you have a left-footed blood-blister picture in your archives????

[neufer]

This little newbie does struggle at times - it took me a while to realize that the Andromeda Galaxy and the Andromeda constellation were two different things. Is Messier 76 considered to be in our Milky Way galaxy??

Absolutely! Further than the Andromeda constellation but much closer than the Andromeda Galaxy.

Art - I agree with owlice - ugh!!! If the APOD paragraph had listed Messier 76 at the LEFT foot of Andromeda, would you have horizontally flipped your offered picture -or- do you have a left-footed blood-blister picture in your archives????

The Little Dumbbell Nebula, also known as Messier 76, NGC 650/651, the Barbell Nebula, or the Cork Nebula, is a planetary nebula in the constellation Perseus.

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I'm far too lazy to bother flipping pictures.

You may well be disgusted (and I'm sorry for that) but I'll bet the next time you see an image of Messier 76 you'll remember just where it lies in the sky....in the constellation Perseus.

<<The Ludovico technique is a fictional drug-assisted aversion therapy from the novel and film A Clockwork Orange. It involves the patient being forced to watch violent images for long periods of time, while under the effect of drugs that cause a near death experience. The Ludovico technique is an artistic semblance of the psychological phenomenon known as operant conditioning which is a form of associative learning that was first demonstrated by B.F. Skinner. The typical procedure for inducing operant conditioning involves presentation of a neutral stimulus along with either the presentation of a positive stimulus or the removal of an aversive stimulus. The neutral stimulus could be any event that does not result in an overt behavioral response from the organism under investigation. In the story of A Clockwork Orange, when the protagonist, Alex, is made the subject of the Ludovico technique, he is conditioned to associate his illness with violence.>>

[Ann]

Another false-color planetary nebula. Personally I can't stand them.

Normally, I really feel that I understand what the color of astronomical objects signifies. In other words, I understand why things are the color they are. But when it comes to planetary nebulae, I'm stumped. Yes, I understand that the central star is usually blue because it is so hot. (But I'm not sure about the very, very hottest and youngest central stars. Are they blue too? Or are they so hot that their visual spectrum is pretty "flat"?)

Gaaahhh. I hate not understanding the color of things. It makes some sort of sense to me that the central star of a planetary nebula should be blue due to its very high temperature. Similarly, the gas closest to the central star should be the hottest and in the highest state of excitation, so therefore the gas closest to the central star should be blue-green due to OIII emission. Further out, the ultraviolet radiation from the tiny burnt-out stellar core should not be enough to make oxygen flouresce, but instead we should see red hydrogen emission. There might be an intermediate stage where blue-green OIII emission and red hydrogen emission mingles to case a yellow glow. The Ring Nebula, M57, is extremely well-behaved as planetary nebulae go:



Thank you, M57, I understand, more or less, what you are all about. (Although I suspect that this Hubble image shows red HII emission as green, leaving only sulphur emission as red, causing the nebula to look a bit too blue, too green and too yellow and not sufficiently red. Still, I think I understand the image as well as the nebula, and we have a clear progression of temperatures from the highest to the lowest as we move away from the hot central star.)

But M76? Is that one well-behaved? No!!!! Take a look at those lobes blowing out from the boxy "bar" of the nebula. Why are those lobes blue???? What business do they have being blue? How can they be more highly excited that structures closer to the central star????

Gahhh!!!! I hate it!

Here is another picture of M76, which may be more true-colored, or at least I think so:



The lobes are still blue, and I still understand nada. <puke icon>

Ann

[owlice]

Ann, color can show things other than how hot something is. It makes perfect sense that one color should be used for hydrogen, another for oxygen. 'Tis a puzzlement to me that you are so flummoxed by that.

Why are those lobes blue????

I'll take a wild stab at this and suppose there are a lot of oxygen atoms in those lobes; that that's what this image shows -- the chemical (or physical, I suppose, if one prefers) structure of the nebula. Why you would "hate" that an image can convey such information ... well, you do, but wow. That seems incredibly narrow to me, but to each her own.

[geckzilla]

I'm just glad that it's possible to visualize a lot of things in space. Color be damned. I was annoyed to discover that you can't just get a really powerful microscope and take pictures of pieces of atoms.

[neufer]

Why are those lobes blue????

• I'll take a wild stab at this and suppose
  there are a lot of oxygen atoms in those lobes;
  that that's what this image shows--
  the chemical (or physical, I suppose,

if one prefers) structure of the nebula.

Code: Select all

Chemical:                         Oxygen
Chemical/Physical:   doubly ionized (by UV radiation from the star)
Physical:            a density from 100 to 10,000 particles per cc

Computer simulation of the formation of a planetary nebula from a star with a warped disk, showing the complexity which can result from a small initial asymmetry. Credit: Vincent Icke

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<<A planetary nebula is an emission nebula consisting of an expanding glowing shell of ionized gas ejected during the asymptotic giant branch phase of certain types of stars late in their life. Physicists showed in the 1920s that in gas at extremely low densities, electrons can populate excited metastable energy levels in atoms and ions which at higher densities are rapidly de-excited by collisions. Electron transitions from these levels in nitrogen and oxygen ions (O²⁺ or OIII, O⁺ and N⁺) give rise to the 500.7 nm (blue-green) spectral line and other lines. These spectral lines, which can only be seen in very low density gases, are called forbidden lines.

A typical planetary nebula is roughly one light year across, and consists of extremely rarefied gas, with a density generally from 100 to 10,000 particles per cm³. Young planetary nebulae have the highest densities, sometimes as high as 10⁶ particles per cm³. As nebulae age, their expansion causes their density to decrease. The masses of planetary nebulae range from 0.1 to 1 solar masses. Radiation from the central star heats the gases to temperatures of about 10,000 K. The gas temperature in central regions is usually much higher than at the periphery reaching 16,000–25,000 K. The volume in the vicinity of the central star is often filled with a very hot (coronal) gas having the temperature of about 1,000,000 K. This gas originates from the surface of the central star in the form of the fast stellar wind.

About 3000 planetary nebulae are now known to exist in our galaxy, out of 200 billion stars. Their very short lifetime compared to total stellar lifetime accounts for their rarity. They are found mostly near the plane of the Milky Way, with the greatest concentration near the galactic center. Planetary nebulae play a very important role in galactic evolution. The early universe consisted almost entirely of hydrogen and helium, but stars create heavier elements via nuclear fusion. The gases of planetary nebulae thus contain a large proportion of elements such as carbon, nitrogen and oxygen, and as they expand and merge into the interstellar medium, they enrich it with these heavy elements, collectively known as metals by astronomers.

Subsequent generations of stars which form will then have a higher initial content of heavier elements. Stars which formed very early in the universe and contain small quantities of heavy elements are known as Population II stars, while younger stars with higher heavy element content are known as Population I stars.>>

[owlice]

:: falls over laughing ::

neufer!!! Oh, that's funny!! Thank you!!

Thanks, too, for the info on nebulas! I need to find a lecture on nebulas that I can listen to in the car; I keep meaning to do that. SO much to learn!

I'm just glad that it's possible to visualize a lot of things in space. Color be damned. I was annoyed to discover that you can't just get a really powerful microscope and take pictures of pieces of atoms.

But you can get pictures of lots of other cool things! One of my favorite pictures of all time was in a textbook I had long ago. It was a greyscale scanning electron microscope image of a single red blood cell. It was elegant and beautiful; I so often wished I'd had a glossy copy of that image to frame! (RBCs are amazingly elegant to me, though I very much prefer they stay where they belong and don't spill out all over the place.) I will not put the image tags around it since there has been enough blood spilled, or at least blistered, on this thread already, but there is a nice color image of RBCs here: http://amadeo.blog.com/repository/84086/3980423.jpg

[moonstruck]

Wow! Owlice is that actual microscopic RBC's or some artist's depiction? I didn't know we had that in us

[Ann]

Owlice wrote:

I'll take a wild stab at this and suppose there are a lot of oxygen atoms in those lobes; that that's what this image shows -- the chemical (or physical, I suppose, if one prefers) structure of the nebula.

• I'll take a wild stab at this and suppose
  there are a lot of oxygen atoms in those lobes;
  that that's what this image shows--
  the chemical (or physical, I suppose,

if one prefers) structure of the nebula.

How did you do that, neufer? Amazing!!!!!

Ann

[owlice]

Wow! Owlice is that actual microscopic RBC's or some artist's depiction? I didn't know we had that in us

You have them in you, lots and lots and lots of them; about a quarter of the cells in your body are red blood cells. And you make lots of them (read: millions) every second, and your body culls lots of old cells out (read: millions) every second, recycling parts for building new cells. And when you need to, because you've been injured or are visiting the Alps or Andes, your body can ramp up production by, IIRC, a factor of 10. Makes me tired just thinking about it!! <g>

[neufer]

Wow! Owlice is that actual microscopic RBC's or some artist's depiction? I didn't know we had that in us

You have them in you, lots and lots and lots of them; about a quarter of the cells in your body are red blood cells. And you make lots of them (read: millions) every second, and your body culls lots of old cells out (read: millions) every second, recycling parts for building new cells.

Dang it, Owlice, I'm eating Cheerios here!!! (or was, anyway...)

[owlice]

Dang it, Owlice, I'm eating Cheerios here!!! (or was, anyway...)

With strawberries or raspberries, perchance?

[neufer]

Dang it, Owlice, I'm eating Cheerios here!!! (or was, anyway...)

With strawberries or raspberries, perchance?

Definitely with lots of raspberries!

[owlice]

Definitely with lots of raspberries!

Man. I set myself up for that, I did, I did indeed!

[Guest]

Raspberries are not always red or black

[Beyond]

Raspberries are not always red or black

Somehow a thundershower around here got me signed out and i didn't realize it until i posted, so i show up as a guest. Now, as you can tell, i am signed in again. Looks like the thundershower gave me a bowl of raspberries--no cheerios--just raspberries If you do not have enough, owlice, i can share

[neufer]

Raspberries are not always red or black

... Looks like the thundershower gave me a bowl of raspberries--no cheerios
--just raspberries If you do not have enough, owlice, i can share

[size=150][color=#BF00BF][b]The Cat's Eye Nebula[/b][/color] (NGC 6543)[/size]

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[size=150]The [color=#FF0000][b]Neuferchau[/b][/color] Coat of Arms.[/size]

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Neuferchau & Neuendorf are villages in Saxony-Anhalt, Germany.
On 1 January 2010, Neuferchau & Neuendorf merged into the town of Klötze (i.e., Klutz).

<<In the early days of telescopic astronomy, the word nebula was used to describe any fuzzy patch of light that did not look like a star. Many of these, such as the Andromeda Nebula, had spectra that looked like stellar spectra, and these turned out to be galaxies. Others, such as the Cat's Eye Nebula, had very different spectra. When William Huggins looked at the Cat's Eye, he found no continuous spectrum like that seen in the Sun, but just a few strong emission lines. The two [bluish green] lines at 495.9 nm and 500.7 nm were the strongest. These lines did not correspond to any known elements on Earth. The fact that helium had been identified by the emission lines in the Sun in 1868, and had then also been found on Earth in 1895, encouraged astronomers to suggest that the lines were due to a new element. The name nebulium (occasionally nebulum or nephelium) was first mentioned by the wife of Huggins in a short communication in 1898, although it is stated that Huggins occasionally used the term before. [However,] the development of the periodic table by Dimitri Mendeleev and the determination of the atomic numbers by Henry Moseley in 1913 left nearly no room for a new element.

Ira Sprague Bowen was working on UV spectroscopy and on the calculation of spectra of the light elements of the periodic table when he became aware of the [bluish green] lines discovered by Huggins. With this knowledge he was able to suggest that the [bluish green] lines might be forbidden transitions. They were shown as due to doubly ionized oxygen at extremely low density, rather than the hypothetical nebulium. As Henry Norris Russell put it, "Nebulium has vanished into thin air." Nebulae are typically extremely rarefied, much less dense than the hardest vacuums produced on Earth. In these conditions, lines can form which are suppressed at normal densities. These lines are known as forbidden lines, and are the strongest lines in most nebular spectra.>>

[Beyond]

To me, The Cat's Eye Nebula just does not look like a cat's eye no matter how i look at it.
However, The Neuferchau Coat of Arms does Greatly reveal definitive information about the Author.