KMC Forums - Deep Sky

For you who like astronomy, I annotated 24 deep sky objects. The other 14 are at my site. Click on the Trifid Nebula for images.
http://jimcolyer.com/papers/entry?id=421;fa=3

Deep sky objects fascinate both amateur and professional astronomers. Star-hoppers aim their telescopes at nebulas (interstellar clouds of hydrogen gas and dust) and planetary nebulas (which are dying stars, not nebulas at all). They target supernova remnants, star clusters (open & globular) and galaxies. Nomenclature is sometimes confusing as early astronomers had only vague ideas about what they were seeing.

..1 TRIFID NEBULA (M20) - The three-lobed Trifid Nebula combines an open cluster, an emission nebula, a reflection nebula and a dark nebula. An emission nebula glows on its own when excited by nearby stars. This is the pink part of the Trifid. A reflection nebula merely reflects the light of nearby stars. This is the blue part. It looks to me like the dark dust lanes split the Trifid into four parts instead of three. The Trifid is a stellar nursery in Sagittarius above the spout of the teapot.

..2 ORION NEBULA (M42) - Stars are forming in M42, one of the most popular targets in astronomy. It has taught us much about how stars form from collapsing clouds of dust and gas. The Hubble Space Telescope has observed protoplanetary disks around young stars, suggesting that solar systems are common. Nebulas like M42 form from clouds of compressed hydrogen to eventually become open clusters like the Pleiades.

There is an open cluster within the Orion Nebula called the Trapezium. There is considerable ultraviolet radiation. M42 is seen as the middle object in the sword hanging from Orion's belt. Its nebulosity is plain through binoculars. The famous Horsehead Nebula is near the star Alnitak in the belt. I may be the only one who sees a turkey in the nebula's shape!

..3 NORTH AMERICA NEBULA (NGC 7000) - This is an emission nebula in Cygnus the Swan. Its shape is remarkable. We can picture the United States and Canada, Mexico and Central America as well as Florida and the Gulf of Mexico.

..4 PILLARS OF CREATION - These columns of interstellar dust and gas were imaged by Hubble in the Eagle Nebula in the constellation Serpens. The picture became famous. New stars are being "created." The pillars may actually be gone because of the enormous distance their light has to travel.

..5 HORSEHEAD NEBULA (Barnard 33) - The Horsehead is the dark nebula in Orion. It passes for a chess piece, a black knight.

..6 DUMBBELL NEBULA (M27) - Yes! It looks like an apple core! M27 was the first known "planetary nebula," and again I will stress that this is a terrible name because it has nothing to do with planets. What we see is an expanding gas cloud resulting from the death of a sun-like star. A white dwarf resides at the center of the cloud. The Dumbbell is located in Vulpecula the Fox.

..7 RING NEBULA (M57) - Probably the most photographed deep sky object, the infamous Ring Nebula is found in Lyra. Karen calls it "the eye." In reality, it is a "planetary nebula." A shell of gas is expanding into space at a tremendous speed although we cannot detect its movement because it is so far away. A star ended its life as a red giant, leaving behind a white dwarf. The Ring is 2300 light-years away. The central white dwarf is dim at magnitude 15, illuminating the gas cloud by ultraviolet radiation. Our sun will undergo a similar process.

..8 OWL NEBULA (M97) - The Owl is a "planetary nebula" just below the Big Dipper. Features in the expanding gas resemble the eyes of a wise owl. Use your imagination! The dying white dwarf at its center is magnitude 16.

..9 ETA CARINAE - This is a double star marked by balloon-shaped gas clouds. It is located in the southern constellation Carina, and we observed it at the Southern Skies Star Party in Bolivia. Eta Car A is massive. It is burning its fuel quickly and is expected to go supernova in a million years. Its brightness doubled in the late 1990s. It is classified as a variable and notorious for outbursts. Should Eta Carinae go hypernova, its shock waves may affect Earth. Earth's atmosphere, however, protects it from gamma rays.

10 CRAB NEBULA (M1) - The Crab Nebula has the distinction of being first on Charles Messier's list. It is a supernova remnant in Taurus. This exploding star was recorded by the Japanese in 1054. The Crab is expanding at the rate of 1500 kilometers per second. We would never know it by looking! A pulsar lies at its center. A pulsar is a neutron star that spins. The Crab Pulsar spins 30 times a second while emitting electromagnetic radiation in the form of radio waves, X-rays and gamma rays. The Earl of Rosse named this remnant because he thought his drawing looked like a crab.