North America Nebula

The North America Nebula (NGC 7000 or Caldwell 20) is an emission nebula in the constellation Cygnus, close to Deneb (the tail of the swan and its brightest star). The shape of the nebula resembles that of the continent of North America.

North America Nebula
Emission nebula
H II region
This image layout reveals how the appearance of the North America nebula can change dramatically using different combinations of visible and infrared observations.
Observation data: J2000.0 epoch
Right ascension 20h 59m 17.1s[1]
Declination+44° 31′ 44″[1]
Distance1,600 ± 100[2] ly   (675 ± 30 pc)
Apparent magnitude (V)4
Apparent dimensions (V)120 × 100 arcmins
ConstellationCygnus
DesignationsNGC 7000, Sharpless 117, Caldwell 20

General information
Cygnus Wall

The North America Nebula covers an area of more than four times the size of the full moon, but its surface brightness is low, so normally it cannot be seen with the unaided eye. Binoculars and telescopes with large fields of view (approximately 3°) will show it as a foggy patch of light under sufficiently dark skies. However, using a UHC filter, which filters out some unwanted wavelengths of light, it can be seen without magnification under dark skies. Its shape and reddish color (from the hydrogen Hα emission line) show up only in photographs of the area.

The portion of the nebula resembling Mexico and Central America is known as the Cygnus Wall. This region exhibits the most concentrated star formation. The North America Nebula and the nearby Pelican Nebula (IC 5070) are parts of the same interstellar cloud of ionized hydrogen (H II region). Between the Earth and the nebula complex lies a band of interstellar dust that absorbs the light of stars and nebulae behind it, and thereby determines the nebula's apparent shape. The distance of the nebula complex is not precisely known, nor is the star responsible for ionizing the hydrogen so that it emits light. If the star inducing the ionization is Deneb, as some sources say, the nebula complex would be about 1,800 light-years' distance, and its absolute size (6° apparent diameter on the sky) would be 100 light-years.

The nebula was discovered by William Herschel, from Slough, England, on October 24, 1786 or by his son John Herschel before 1833.[3]

gollark: I can't sell you pronouns.
gollark: What of the "potato OS" vulnerabilities?
gollark: I'm pretty sure I fire more lasers without problems.
gollark: Remember, they literally restart every 6 hours due to memory leaks.
gollark: Minecraft and Minecraft mods are based upon layer upon layer of awful code.

See also

References
  1. "NASA/IPAC Extragalactic Database". Results for NGC 7000. Retrieved 2006-10-17.
  2. Shevchenko, V. S.; Grankin, K. N.; Nel'Nikov, S. Yu. (1988). "The structure of RSF 4 CYG B - Regions of star formation from an unusual point of view". Astronomicheskii Zhurnal. 65: Nov.–Dec. 1988, p. 1230–1243. In Russian. Bibcode:1988AZh....65.1230S. ISSN 0004-6299.
  3. "NGC 7000 – North America Nebula". SEDS – Students for the Exploration and Development of Space, The Messier Catalogs. Retrieved 25 August 2017.


This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.