APOD: Ring Nebula Drawn (2012 Sep 15)

[APOD Robot]

Ring Nebula Drawn

Explanation: A planetary nebula with a simple symmetry familiar to telescopic sky gazers, the Ring Nebula (M57) is some 2,000 light-years away in the musical constellation Lyra. Hints of changing colors and subtle details are brought out in this remarkable sketch of the cosmic ring. The sketch was made with 800x magnification and excellent seeing conditions directly at the eyepiece of a 40 inch reflecting telescope. Colored pencils on white paper were used to create the original drawing, shown here digitally scanned with an inverted palette applied. About one light-year across, the nebula is composed of outer layers expelled from a dying, once sun-like star. Intense ultraviolet light from the hot central star ionizes atoms in the gas and powers the nebular glow. Ionized hydrogen adds a reddish tint. Ionized oxygen produces a characteristic blue-green color. Difficult to see under average conditions with small telescopes, the Ring Nebula's central star was visible at all times during the artist's study.

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[Beyond]

Looks like Art to me. No reflections.

[Ann]

APOD Robot wrote:
Colored pencils on white paper were used to create the original drawing, shown here digitally scanned with an inverted palette applied.

Inverted palette? I was just about to say that the colors here are truly excellent. The only thing that can be inverted here is the color of the background sky, which must of course have been changed from white to black.

Otherwise, the colors are just achingly good. Note the strikingly blue color of the central star. This is to be expected, since the central stars of planetary nebulae are among the hottest known, and therefore the visually bluest, as long as they can be seen at all and are relatively unreddened. (Admittedly, there may not be a linear relationship between temperature and ever-bluer optical color. The neutron star Geminga, whose surface temperature may be about half a million Kelvin, is not dominated by blue light in the optical part of the spectrum.)

But when it comes to typical temperatures of the central stars of planetary nebulae, typically 30,000K to 100,000K, blue color is to be expected. According to Professor Emeritus Jim Kaler, the temperature of the central star of the Ring Nebula is as high as 150,000 Kelvin, and its blue color makes good sense.

Note the greenish-blue color of the Ring Nebula in Frédéric Burgeot's drawing. This is the color of OIII emission at 500.7 nm and Hβ light at 486.1 nm. The human eye is quite good at detecting faint light at a wavelength of about 500 nm, and both our color-blind rods as well as our color-detecting cones react well to this wavelength. This, in other words, is the color we will see, if we are able to spot color at all in the Ring Nebula when looking at it through a telescope.

By contrast, our eyes need a lot of light to see a wavelength of red light at 656.3 like Ha emission, or 658.4 nm, like singly ionized nitrogen. However, the red light of the Ring Nebula is particularly strong at its edges, and Frédéric Burgeot's drawing does indeed show a hint of pink at the nebula's edges.

Fantastic!!!

Ann

[Boomer12k]

My M57...

From Wikipedia...

250px-M57_The_Ring_Nebula.JPG (8.13 KiB) Viewed 4956 times

Imagine my embarassment....I have been telling people it is 7500 ly away.....ERRRGGGHHH I HATE THAT!!!!!!

I am so embarassed...to be so wrong...but I swear, I read it somewhere.....I read it somewhere....but it was wrong...AAAARRRRGGGHHHHH!!!!! (HEAVY SIGH in exasperation!!!!) Stupid brain....can't hold a thought any more....UUUUGGGGHHHH!!!!


Well, this APOD is very interesting, as all I see in my telescope is a black and white smoke ring....God's Smoke Ring, I call it...And then there is the very large outer area around it that you don't generally see.

I think the artist got it pretty close....he must have either used a picture, or had a really good scope to see the wispy central area...wish I could draw...but I COULD make a painting....

Do you notice the second photo? The central area? The two stars? They look like EYES, and the rest of the central area looks like a BABY'S HEAD???? Probably just...MY STUPID BRAIN AGAIN!!!! AAAAARRRRRGGGGHHH!!!!!

:---[===] *

[neufer]

<<Der Ring des Nibelungen is a cycle of four epic operas by the German composer Richard Wagner (1813–83). The works are based loosely on characters from the Norse sagas and the Nibelungenlied. The operas, which the composer described as a trilogy with a Vorabend ("preliminary evening"), are often referred to as the Ring Cycle, Wagner's Ring, or simply the Ring. Wagner wrote the libretto and music over the course of about twenty-six years, from 1848 to 1874. The four operas that constitute the Ring cycle are, in sequence:

• Das Rheingold (The Rhine Gold)
  Die Walküre (The Valkyrie)
  Siegfried
  Götterdämmerung (Twilight of the Gods)

Wagner's title is most literally rendered in English as The Ring of the Nibelung. The Nibelung of the title is the dwarf Alberich, and the ring in question is the one he fashions from the Rhinegold. The title therefore denotes "Alberich's Ring". In German the "-en" ending of "Nibelungen" and the article "des" preceding it denote the possessive (genitive) singular case. "Nibelungen" is occasionally mistaken as a plural.>>

[orin stepanek]

Very good drawing! Kudos to the artist!

[NoelC]

Very nice drawing, but some of what it implies is even more interesting...

He has a 40 inch telescope with optics good enough to see the central star of the Ring, under skies dark enough and with enough light gathering ability to sense color in the Ring, and finally, the ability to be comfortable for long enough at the eyepiece to draw a significantly good picture... Mmmmm!

Observational astronomer nirvana has been achieved.

-Noel

[neufer]

He has a 40 inch telescope with optics good enough to see the central star of the Ring, under skies dark enough and with enough light gathering ability to sense color in the Ring, and finally, the ability to be comfortable for long enough at the eyepiece to draw a significantly good picture... Mmmmm! Observational astronomer nirvana has been achieved.

• In a 40" telescope: just a 5th magnitude star!

[b][color=#0000FF]Reconstructed tower of Hahn's private Remplin Observatory Friedrich II. Graf von Hahn (July 27, 1742 – October 9, 1805) was a German nobleman, a philosopher and astronomer. In 1800, he discovered the central star in M57, the Ring Nebula.[/color][/b]

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<<The famous Ring Nebula (also catalogued as Messier 57, M57 or NGC 6720) appears in the northern constellation of Lyra. It is a prominent example of a planetary nebula. This is a shell of ionized gas expelled into the surrounding interstellar medium by a red giant star, which was passing through the last stage in its evolution before becoming a white dwarf.

The nebula disk has an angular size of 1.5 × 1 arcminutes, making it too small to be resolved with 10×50 binoculars. It is best observed using a telescope with an aperture of at least 8 in, but even a 3 in telescope will reveal its elliptical ring shape. The interior hole can be resolved by a 4 in instrument at a magnification of 100×. Larger instruments will show a few darker zones on the eastern and western edges of the ring, and some faint nebulosity inside the disk. The central star, at magnitude 14.8, is difficult to spot.

M57 has a visual magnitude of 8.8v and photographic magnitude of 9.7p. Photographs taken over a period of 50 years show the rate of nebula expansion is roughly 1 arcsecond per century, which corresponds to spectroscopic observations as 20–30 km s−1. M57 is illuminated by a central white dwarf or planetary nebula nucleus (PNN) of 15.75v visual magnitude, whose mass is ~1.2 M_☉.

All the interior parts of this nebula have a blue-green tinge that is caused by the doubly ionized oxygen emission lines at 495.7 and 500.7 nm. These observed so-called "forbidden lines" occur only in conditions of very low density containing a few atoms per cubic centimeter. In the outer region of the ring, part of the reddish hue is caused by hydrogen emission at 656.3 nm, forming part of the Balmer series of lines. Forbidden lines of ionized nitrogen or [N II] contributes to the reddishness at 654.8 and 658.3 nm.

This nebula was discovered by the French astronomer Antoine Darquier de Pellepoix in January 1779, who reported that it was "...as large as Jupiter [~ 50"] and resembles a planet which is fading." Later the same month, fellow French astronomer Charles Messier independently found the same nebula while searching for comets. It was then entered into his catalogue as the 57th object. Messier and German-born astronomer William Herschel speculated that the nebula was formed by multiple faint stars that were unresolvable with his telescope. In 1800, German Count Friedrich von Hahn announced that he had discovered the faint central star at the heart of the nebula a few years earlier. He also noted that the interior of the ring had undergone changes, and said he could no longer find the central star. In 1864, English amateur astronomer William Huggins examined the spectra of multiple nebulae, discovering that some of these objects, including M57, displayed the spectra of bright emission lines characteristic of fluorescing glowing gases. Huggins concluded that most planetary nebulae were not composed of unresolved stars, as had been previously suspected, but were nebulosities. The nebula was first photographed by the Hungarian astronomer Eugene von Gothard in 1886.>>

[Psnarf]

Further investigation reveals rarely-seen outer structures - http://messier.seds.org/more/m057_jac.html

It was only recently that astronomers determined that we are looking down the barrel of a cylinder from one of the poles, not a ring.
http://messier.seds.org/m/m057.html

I have to wonder about the magnitude of the probability that the pole just happens to be pointed in our direction so that we can see down the barrel (or torus). Is this serendipitous orientation similar for all ring nebulae?

The age determined by winding back the clock of the known expansion rate suggests that folks living between 6,000BCE - 4,000BCE could have witnessed the explosion. Might there be glyphs, pictographs or neolithic symbols that chronicle the event?

[neufer]

Click to play embedded YouTube video.

It was only recently that astronomers determined that we are looking down the barrel of a cylinder from one of the poles, not a ring. http://messier.seds.org/m/m057.html

I have to wonder about the magnitude of the probability that the pole just happens to be pointed in our direction so that we can see down the barrel (or torus). Is this serendipitous orientation similar for all ring nebulae? The age determined by winding back the clock of the known expansion rate suggests that folks living between 6,000BCE - 4,000BCE could have witnessed the explosion. Might there be glyphs, pictographs or neolithic symbols that chronicle the event?

[KarelVreeburg]

I wonder why you name objects like this Ring Nebula's , because they are not, is is a Hour Glass Nebula seen from the top, ( or the bottom). It has a huge 3-D shape nothing like a ring. Karel Sculptor

[Chris Peterson]

I have to wonder about the magnitude of the probability that the pole just happens to be pointed in our direction so that we can see down the barrel (or torus). Is this serendipitous orientation similar for all ring nebulae?

Well... yes. Otherwise they wouldn't be ring nebulas, would they? But planetary nebulas in general are seen from all orientations, just as probability predicts, and as a result we have rings, bubbles, hourglasses, and all manner of suggestive names.

[neufer]

I wonder why you name objects like this Ring Nebula's , because they are not, is is a Hour Glass Nebula
seen from the top, ( or the bottom). It has a huge 3-D shape nothing like a ring. Karel Sculptor

But no one knew it's 3-D shape until recently.

And no one is totally certain about it's 3-D shape now.

[Czerno 1]

The sketch was made with 800x magnification and excellent seeing conditions directly at the eyepiece of a 40 inch reflecting telescope.

Beautiful and admirable ! What would be the physical size of the actual image at the eypiece (and original drawing) ?
Does someone know how long it took, or might have taken, the artist-astronomer to draw this
remarkable sketch ?

[neufer]

The sketch was made with 800x magnification and excellent seeing conditions directly at the eyepiece of a 40 inch reflecting telescope.

What would be the physical size of the actual image at the eypiece (and original drawing) ?

The nebula disk has an angular size of 1.5 × 1 arcminutes, making it 20 x 13 degrees at 800x magnification.

This would constitute much of the field of view in the eyepiece and about the size it appears to you on the screen.

[TNT]

Amazing how well the nebula was drawn! Beautiful!

[Anthony Barreiro]

This is a beautiful drawing. I am in awe of the time, patience, concentration, and skill involved.