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physical object > natural object > celestial body > nebula > H II region > gaseous nebula

gaseous nebula (emission nebula)
subject			fact

gaseous nebula	has catalog gaseous nebula catalog
	has synonym emission nebula
	has definition An H II region, a supernova remnant, or a planetary nebula. H II regions have an emission-line optical spectrum, and a thermal continuous spectrum declining in intensity as the wavelength increases (from maximum in the ultraviolet) through infrared and radio. Supernova remnants have an emission-line optical spectrum and a nonthermal radio spectrum. Temperatures of planetary nebulae are much higher than those of H II regions.
	is a kind of H II region
H II region	has composition ionized hydrogen
nebula	is a part of gas
celestial body	has spectra
physical object	has location or center of gravity
	has angular momentum
	has mass
	has velocity
	has momentum
	has temperature
	has volume
	has extent
	has material

Kinds of gaseous nebula :

• 30 Doradus Nebula (9 facts) (NGC 2070, Great Looped Nebula, Tarantula Nebula) - A giant H II region, at least 300 pc across - one of the largest known. It is larger and more luminous than any known in the Galaxy. It is the brightest object in the Large Magellanic Cloud at both optical and radio wavelengths, and contains the densest concentration of W-R stars. (The brightest object near the center is a O+ WN star of M_v = - 10.2.) It is characterized by very rapid, disordered, and complex motions.
• Carina Nebula (3 facts) (NGC 3372)
• Eagle Nebula (5 facts) (IC 4703)
• expanding emission nebula (37 kinds, 206 facts)
• Keyhole Nebula (2 facts)
• Lagoon Nebula (9 facts) (M 8, NGC 6523) - An emission nebula in Sagittarius 2 kpc distant.
• N 159 (4 facts)
• NGC 3603 (2 facts)
• NGC 604 (3 facts)
• North America Nebula (4 facts) (NGC 7000) - An emission nebula in Cygnus.
• Omega Nebula (11 facts) (Swan Nebula, M 17, NGC 6618) - A bright H II region. It is a double radio source.
• Orion Nebula (13 facts) (M 42) - A large cloud of gas and dust giving birth to young stars in the constellation Orion and visible to the naked eye. It is an HII region 1500 light-years away., An HII region about 500 pc distant, barely visible to the naked eye in the center of Orion's sword. It is undoubtedly a region where stars are being born; young O stars and many T Tauri variables are associated with it, and its members are extreme Population I. Probably no more than 20000 years old. It is also an X-ray source (3U 0527-05 and M42, NGC 1976)., The Orion Nebula, a star-forming region in the constellation Orion.
• Tarantula Nebula (3 facts)
• Trifid Nebula (10 facts) (M 20, NGC 6514) - An emission nebula in Sagittarius.

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