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The Ring Nebula

The Ring Nebula

The Ring Nebula, a classic planetary nebula located 2,300 light-years from Earth.

THIS IMAGE OF the Ring Nebula or Messier 57 was obtained using the Wide Field Camera on the Isaac Newton Telescope in the Canary Islands.

The Ring Nebula is often regarded as the prototype of a “planetary nebula“. But despite the name, a planetary nebula has nothing to do with planets. The moniker was given because such objects did not look sharp and star-like when seen through early telescopes; rather, they appeared as distinct blobs or discs, and in that sense their appearance resembled that of planets.

A planetary nebula forms when an elderly star puffs off its outer gas layers. Afterwards, intense radiation from the exposed core of the star heats up the gas, making it glow. It is the final stage in the life of Sun-like stars, and results in the remnant stellar core becoming a white dwarf.

Many planetary nebulae are full shells of gas surrounding the star on all sides. But observations have shown that the Ring Nebula is, most probably, actually a ring (torus) surrounding its central star, and not a spherical (or ellipsoidal) shell.

This nebula is located approximately 2,300 light-years from Earth. Astronomers estimate that the gas cloud has been expanding away from the star for about 1,600 years (plus or minus about 240 years).

The image is a three-colour composite made from data collected using filters to isolate the light emitted by hydrogen alpha (H-alpha), doubly ionised oxygen (OIII) and ionised sulphur (SII) atoms, and coded in the image as red, green and blue respectively.

See the full-size, high-resolution image here (will open in a new window or tab).

Text adapted from Information issued by IAC. Image obtained and processed by members of the IAC astrophotography group (A. Oscoz, D. López, P. Rodríguez-Gil and L. Chinarro).

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The striking Ring Nebula

The Ring Nebula

A colour-composite image of the Ring Nebula, M57, which is 2,300 light-years from Earth. The nebula is a torus, or donut, of gas surrounding a white dwarf star.

The Ring Nebula is often considered the leader of a class of celestial objects known as “planetary nebulae”. The image above was produced by astronomers from the Isaac Newton Group of Telescopes in the Canary Islands.

Despite the term, planetary nebulae have nothing to do with planets. They got their name from observations using early telescopes, through which they looked like small blobs instead of pinprick stars. In this respect, they resembled the discs or faces of planets, and the name has stuck ever since.

In reality, a planetary nebula is a huge cloud of gas that has been “puffed” off by a star in the final stages of its life. Our Sun will eventually go through this phase.

The Ring Nebula, also known as M57 (being the 57th entry in the catalogue compiled by the 18th-19th century French astronomer Charles Messier) is 2,300 light-years from Earth. At its centre is a white dwarf star…the “burned out” remains of a normal type of star.

Some planetary nebula are spherical-shaped clouds that completely surround their central star. The Ring Nebula, though, is thought instead to be a ring (or torus, like a donut) surrounding the white dwarf and fortuitously seen face-on by Earth-bound astronomers.

The image above is a false-colour composite that shows emission from certain specific types of gas in the nebula: hydrogen (shown as red), doubly ionised oxygen (green) and ionised sulphur (blue).

See the full-size, high-resolution version here (new window).

The photos below give two other views. First, a Hubble Space Telescope image that shows the nebula in approximately true colour; and second, an infrared view from the Spitzer Space Telescope.

The Ring Nebula

A Hubble Space Telescope image of the Ring Nebula, showing it in approximately true colours.

The Ring Nebula.

A Spitzer Space Telescope infrared image of the Ring Nebula gives a very different picture, bringing out lots of detail not seen at other wavelengths.

Top image courtesy of the Isaac Newton Group of Telescopes; image obtained and processed by members of the IAC astrophotography group (A. Oscoz, D. López, P. Rodríguez-Gil and L. Chinarro).

Middle image courtesy The Hubble Heritage Team (AURA / STScI / NASA).

Bottom image courtesy NASA / JPL-Caltech / J. Hora (Harvard-Smithsonian CfA).

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