3-D Ring Nebula Reveals Its “inner Jelly Doughnut”

How absolutely beautiful. This composite image of the Ring Nebula made combines views with the  Hubble Space Telescope with a picture of the nebula’s  outer halo from the Large Binocular Telescope (LBT) in Arizona. Click to enlarge. Credit: NASA, ESA, C. Robert O’Dell (Vanderbilt University), and David Thompson

After the moon and planets, the Ring Nebula must be one of the top three deep sky objects sought out by astronomers of all stripes. Many a spring and summer night I’ve made my “pilgrimage to the Ring”. And why not? It’s easy to spot not far from the brilliant star Vega in the constellation Lyra and looks like a smoke ring frozen in time.

To find the Ring Nebula, first locate Vega, the uppermost and brightest star of the Summer Triangle asterism. It’s well placed in the east at nightfall in late May. The Ring is midway between the two stars in the bottom of Lyra’s figure. Created with Stellarium

The Ring Nebula was discovered in a 2.5″ refracting telescope by Antoine Darquier de Pellepoix in 1779. He described it as “a very dull nebula, but perfectly outlined; as large as Jupiter and looks like a fading planet.” Not long after, famed French comet hunter Charles Messier stumbled on while tracking a new comet across the sky. Messier promptly added it to his catalog of fuzzy things that resemble comets, dubbing it M57.

In small telescopes, the Ring looks like a round, pale-gray smoke ring with a dark center. Larger amateur scopes show its elliptical shape and thin veil of gas across the dark opening. Credit: Jim Misti

Located about 2,000 light years from Earth and spanning nearly one light year (6 trillion miles) end to end, our entire solar system would fit inside the doughnut hole with room to spare. The Ring is one of many planetary nebulae, so called because their rounded shapes reminded early telescopic observers of planets.

Planetaries are the cast-off mantles and atmospheres of sun-sized stars when they run out of fuel in their cores. What’s left is an exceedingly hot, planet-sized core called a white dwarf star. The gassy remains fluoresce green, red and blue in the flood of energetic ultraviolet light radiating from the dwarf. Each color represents a different element; oxygen glows green, helium blue and nitrogen red.

The Ring Nebula is situated between Gamma and Beta Lyrae in the constellation Lyra the Harp. Its shape can be seen in almost any small telescope; binoculars show it as a slightly fuzzy “star”. Credit: NASA/ESA/Digitized Sky Survey 2

The nebula’s expanding at the fantastic speed of 43,000 mph (69,000 kph) but because of its great distance won’t show a whit of difference in size during a human lifetime. But 10,000 years from now, the Ring will have grown so large and faint it will merge with the interstellar medium, the thin soup of gas between the stars from which future generations of stars are born.

While the nebula looks like a bagel with a thick doughy exterior and empty center, it’s more like a jelly doughnut. In a small telescope, the center appears empty but larger scopes reveal that its interior is filled with less dense gas. Astronomers have combined ground-based telescopic views with new observations using the Hubble Space Telescope to give us a clear three-dimensional understanding of what we’re seeing.

We gaze directly down at the Ring Nebula from here on Earth (top perspective) and see the brightest part of the nebula as the colorful ring. This side-on view shows the nebula’s wide halo, inner region, lower-density “rugby ball” of material stretching towards and away from us, and the prominent, glowing disk. Credit: NASA, ESA, and A. Feild (STScI)

“We are gazing almost directly down one of the poles of this structure, with a brightly colored barrel of material stretching away from us. Although the center of this doughnut may look empty, it is actually full of lower density material that stretches both towards and away from us, creating a shape similar to a rugby ball slotted into the doughnut’s central gap,” says a recent NASA/ESA release on the topic.

In other words, there’s much more there than meets the eye. With only one perspective – we’re stuck on Earth after all – the nebula’s “inner jelly doughnut” self required careful observation and data-teasing to fathom. The next time we point our scopes in the Ring’s direction we can enjoy and appreciate it from a new perspective.

2 Responses

  1. Giorgio Rizzarelli

    Great pics and interesting article. M57 is one of my favorites, I already catched it also this year. In a clean day in the 8 inch I could see it in visual and from city, including it’s pale green-blue tint (it’s “green” you meant when you wrote “pale grey” under the amateur picture?)

    1. astrobob

      Hi Giorgio,
      No, I actually meant gray. That how it always looks to me. I’ve yet to see a green tint to it I (even though it shows so nicely in photos). Other planetaries are very colorful – like the one in Draco or the Cat’s Eye in Hydra.

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