North America Nebula
From Wikipedia, the free encyclopedia
| Diffuse nebula | Lists of nebulae |
|---|---|
North America Nebula, including Pelican Nebula |
|
| Observation data (Epoch J2000.0) |
|
| Type | Emission |
| Right ascension | 20h 59m 17.1s[1] |
| Declination | +44° 31′ 44″[1] |
| Distance | 2,200 ± 100 ly (675 ± 30 pc)[2] |
| Apparent magnitude (V) | ?? |
| Apparent dimensions (V) | ~30 arcmins |
| Constellation | Cygnus |
| Physical characteristics | |
| Radius | - |
| Absolute magnitude (V) | - |
| Notable features | - |
| Other designations | NGC 7000 |
| edit | |
The North America Nebula (NGC 7000) is an emission nebula in the constellation Cygnus, close to Deneb (the tail of the swan and its brightest star). The remarkable shape of the emission nebula resembles that of the North American continent, especially along the southeast coast.
[edit] General information
The North America Nebula is large, covering an area of more than ten 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 by the naked eye under dark skies. Its prominent shape and especially its reddish color (from the hydrogen Hα emission line) only show up in photographs of the area.
The North America Nebula and the nearby Pelican Nebula, (IC 5070) are in fact 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 is responsible for the shape as we see it. 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 1800 light years distance, and its absolute size (6° apparent diameter on the sky) would be 100 light years.
The discovery of the North America Nebula is attributed to the famous 18th century astronomer William Herschel.
 Amateur photo |
 Amateur photo |
 Amateur photo |
 Amateur photo |
 (Amateur astronomer photo, Luc Viatour) |
[edit] External links
- NASA APOD: The North America Nebula (May 1, 2000)
- NASA APOD: The North America Nebula (June 6, 1996)
[edit] References
- ^ a b NASA/IPAC Extragalactic Database. Results for NGC 7000. Retrieved on 2006-10-17.
- ^ 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 (ISSN 0004-6299) 65: Nov.-Dec. 1988, p. 1230-1243. In Russian..
