North America Nebula
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Constellation | Cygnus |
Designations | NGC 7000, Sharpless 117, Caldwell 20 |
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). It is named because its shape resembles North America.
History
On October 24, 1786, William Herschel observing from Slough, England, noted a “faint milky nebulosity scattered over this space, in some places pretty bright.” [4] The most prominent region was catalogued by his son John Herschel on August 21, 1829. It was listed in the New General Catalogue as NGC 7000, where it is described as a "faint, most extremely large, diffuse nebulosity.” [5]
In 1890, the pioneering German
In his study of nebulae on the
General information
The North America Nebula covers a region more than ten times the area of the full
The portion of the nebula resembling the north-east of North America is known as the Cygnus Wall. This region exhibits the most concentrated star formation.[8]
At optical wavelengths, the North America Nebula and the Pelican Nebula (
Distance and size
The distances to the North America and Pelican nebulae were controversial, because there are few precise methods for determining how far away an HII region lies. Until 2020, most astronomers accepted a value of 2,000 light years, though estimates ranged from 1,500 to 3,000 light years.[10] But in 2020, the Gaia astrometry spacecraft measured the distances to 395 stars lying within the HII region, giving the North America and Pelican nebulae a distance of 2,590 light years (795±25 parsecs). The entire HII region Sh2-117 is estimated to be 140 light years across, and the North America nebula stretches 90 light years north to south.[2]
Ionising star
HII regions shine because their hydrogen gas is ionised by the
Later observations have revealed J205551.3+435225 is a
Although the light from the Bajamar Star is dimmed by 9.6 magnitudes (almost 10,000 times) by the dark cloud L935, it is faintly visible at optical wavelengths, at magnitude 13.2. If we saw this star undimmed, it would shine at magnitude 3.6, almost as bright as Albireo, the star marking the swan's head.[11]
See also
References
- ^ a b "NASA/IPAC Extragalactic Database". Results for NGC 7000. Retrieved 2006-10-17.
- ^ S2CID 219708730.
- ^ Frommert, Hartmut; Kronberg, Christine (2020). "NGC 7000". SEDS. Archived from the original on 18 May 2021. Retrieved 26 August 2020.
- S2CID 221006656. Retrieved 26 August 2020.
- ^ Seligman, Courtney (2020). "NGC 7000, The North America Nebula". Celestial Atlas. Retrieved 26 August 2020.
- ^ a b French, Sue (2004). "Navigating North America" (PDF). Sky & Telescope. Sky Publishing Corp. Retrieved 26 August 2020.
- ^ Jardine, Kevin. "Sh 2-117". Galaxy Map. Retrieved 26 August 2020.
- ^ Wager, Sara (2016). "The Cygnus Wall of Star Formation". Astronomy Picture of the Day. NASA. Retrieved 2 September 2020.
- ^ Rebull, Luisa (2011). "Changing Face of the North America Nebula". Spitzer Space Telescope. NASA-JPL. Retrieved 26 August 2020.
- S2CID 18046553. Archived from the original(PDF) on 2019-03-08. Retrieved 2 September 2020.
- ^ a b Comerón, Fernando; Pasquali, Anna (2005). "Discovery of the star that ionizes the North America and Pelican nebulae". Centro Astronómico Hispano-Alemán Newsletter. Centro Astronómico Hispano-Alemán. Retrieved 26 August 2020.
- S2CID 55658165.)
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External links
- Media related to North America Nebula at Wikimedia Commons
- The North America Nebula (NGC 7000) at the astro-photography site of Mr. T. Yoshida.
- NASA APOD: The North America and Pelican Nebulae (June 30, 2009)
- NASA APOD: The North America Nebula (May 1, 2000)
- starpointing.com – Central part of the North America Nebula: The Great Wall
- Creative Commons North America Nebula Data North America Nebula – Creative Commons data Download & editing guide
- North America Nebula on