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Radiation from the hot white dwarf excites the expelled gases, producing emission nebulae with spectra similar to those of emission nebulae found in star formation regions. [25] They are H II regions, because mostly hydrogen is ionized, but planetary are denser and more compact than nebulae found in star formation regions. [25]
The nebula measures around two light years long from end to end, and contains a central white dwarf with an apparent magnitude of 11. The inner layers of the nebula were formed some 1,500 years ago. [4] The two ends of the nebula are marked by FLIERs, lobes of fast moving gas often tinted red in false-color pictures. [5]
Jewel Bug Nebula, [citation needed] Gummy Bear Nebula [5] See also: Lists of nebulae NGC 7027, also known as the Jewel Bug Nebula or the Magic Carpet Nebula , [ 6 ] is a very young and dense planetary nebula [ 7 ] located around 3,000 light-years (920 parsecs ) from Earth in the constellation Cygnus .
In astronomy, Bok globules are isolated and relatively small dark nebulae containing dense cosmic dust and gas from which star formation may take place. Bok globules are found within H II regions, and typically have a mass of about two [1] to 50 solar masses contained within a region about a light year or so across (about 4.5 × 10 47 m 3). [2]
The closest and largest dark nebulae are visible to the naked eye, since they are the least obscured by stars in between Earth and the nebula, and because they have the largest angular size, appearing as dark patches against the brighter background of the Milky Way like the Coalsack Nebula and the Great Rift.
The Trifid Nebula was the subject of an investigation by astronomers using the Hubble Space Telescope in 1997, using filters that isolate emission from hydrogen atoms, ionized sulfur atoms, and doubly ionized oxygen atoms. The images were combined into a false-color composite picture to suggest how the nebula might look to the eye.
A 6" telescope with a magnification around 100x will reveal a slightly bluish disk, while telescopes with a primary mirror at least 16" in diameter may reveal slight color and brightness variations in the interior. [4] This nebula has an elliptical shape with a triple-shell structure. The brightest is the main shell, which spans 12″ × 18 ...
Planetary nebulae, represented here by the Ring Nebula, are examples of emission nebulae. An emission nebula is a nebula formed of ionized gases that emit light of various wavelengths. The most common source of ionization is high-energy ultraviolet photons emitted from a nearby hot star .