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RE: Ring nebula
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The Ring Nebula, a medium-sized ring of gas resulting from an exploding star as seen through the Astrochannels 14" telescope and video camera.



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Expand (112kb, 1024 x 996)
Object Name: The Ring Nebula
Exposure Time: 90 seconds
Filter Type: Blue
Time : 04:40 UT on Wednesday 10 May 2006

-- Edited by Blobrana at 12:07, 2006-05-10

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Located in the radiant little constellation of Lyra high overhead during mid-summer you will find one of the most enchanting of all deep-sky objects, the Ring Nebula. The Ring formed largely from an expanding shell of material cast off by a star as it ages. M57 is one of the brightest and best of these.
Unlike many deep-sky objects that often require just a bit of imagination to make out, this comes close to actually looking like the photographs. A stark, slightly elongated loop of material standing out against the darkness of the sky, the ninth magnitude ring is very easy to find, located right in between the two end stars of the constellation.
Located about 1400 light years distant the Ring is estimated to be about 1/2 light year in diameter, expanding at 12 miles per second.


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This image shows the M57 planetary nebulae, the famous Ring Nebula.
The wide view is a composite of three exposures; one to record the details of the inner roughly one light-year span of the familiar nebula, one to record the surprisingly intricate but faint outer rings of glowing hydrogen gas, and one to pick up the rich assortment of distant background galaxies.
By chance, one of the background galaxies, IC 1296 at the upper left, is close enough to show its barred, spiral structure making an attractive visual comparison with M57. IC 1296 is 200 million light-years away compared to only 1400 light years for M57, a faint ring is also apparent around the outer reaches of the distant spiral galaxy.

Planetary nebulas are the results of a star casting off its outer layers during periods of transformation. Not at all unlike "shedding its skin". The word nova, simply means "new star". From time to time out of nowhere astronomers will spot a star where one had not existed before. Two or three novas are discovered each year, typically by amateur astronomers. A nova will brighten up very rapidly increasing its luminosity by a factor of hundreds or thousands, frequently in less than a day before fading over a period of up to a year or more. Nova are typically binary stars, two stars orbiting around each other. One will draw material from the other only to lose it's structural stability with all of the extra stuff piled on top of it. This leads it to a sudden flare up or eruption, casting off the extra material into space. While dramatic, the total material lost in cases like these is typically 0.00001 % of the entire mass, in other words, not a whole lot.

The central star that illuminates the material is a real challenge for amateur telescopes. Shining at a feeble 15th magnitude, it is well beyond the range of smaller instruments. If you have a large pair of binoculars you may be able to just make it out under very dark skies. But even in smaller telescopes it is unmistakable.
There are three main ways to locate objects in the sky. The cheaters use a computer-driven telescope. They would simply say "find me M57", and the scope is automatically slewed to the proper position. Those with a bit of astronomical honour to their names will use "setting circles", simple indicators that will let them locate by hand an object based on its coordinates. But if you like the thrill of the pursuit, there is the "star hopping" method. Using star hopping one locates objects by finding a series of stars as "landmarks". And hopping from a bright one to a dimmer one to a dimmer one yet until the desired object comes into view.
The Ring Nebula is one of the easiest to find. It is nearly exactly on a line between Beta Lyrae and Gamma Lyrae, the two bright stars along the bottom of the constellation, . Simply locate Beta Lyrae in the telescopes viewfinder and move it about 1/3rd the distance to the other star and M57 should be right in view looking like a ghost planet.

Colour photos show the outer edges to be red, while the inner portions are green and yellow. Not exactly a lovely colour combination. In very large instruments a bluish-green colour is revealed.


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