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NGC 7023 (Iris Nebula)


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NGC 7023
Iris Nebula (アイリス星雲)
Emission Nebula (散光星雲)
Nb EN+OCL


別名 (Other names)
LBN 487, OCL 235, Caldwell 4

星座 (Constellation)
ケフェウス座 (Cep) (Cepheus)


距離 (Distance)
1,300光年 (1,300 light-years)

アイリス星雲(LBN 487、Caldwell 4)は、ケフェウス座の明るい散光星雲。
1794年10月18日、ウィリアム・ハーシェルによって発見された。
星雲は+7等星の星SAO 19158によって輝いている。ミラ型変光星であるケフェウス座T星や、明るい変光星(+3.23等)であるケフェウス座β星(アルフィルク)の近くに位置する。大きさは6光年。

なお、NGC 7023は、LBN 487内の散開星団を指す。

NGC 7023 (Iris Nebula) is an emission nebula located 1,300 light years from the Earth in the constellation Cepheus.

NGC 7023 (Iris Nebula) : Picture

NGC 7023: The Iris Nebula
NGC 7023: The Iris Nebula
(C) Jimmy Walker
These clouds of interstellar dust and gas have blossomed 1,300 light-years away in the fertile star fields of the constellation Cepheus. Sometimes called the Iris Nebula, NGC 7023 is not the only nebula in the sky to evoke the imagery of flowers, though. Still, this deep telescopic view shows off the Iris Nebula's range of colors and symmetries in impressive detail. Within the Iris, dusty nebular material surrounds a hot, young star. The dominant color of the brighter reflection nebula is blue, characteristic of dust grains reflecting starlight. Central filaments of the dusty clouds glow with a faint reddish photoluminesence as some dust grains effectively convert the star's invisible ultraviolet radiation to visible red light. Infrared observations indicate that this nebula may contain complex carbon molecules known as PAHs. The pretty blue petals of the Iris Nebula span about six light-years.

NGC7023 (Iris Nebula)
NGC 7023 (Iris Nebula)
(C) NASA

NGC7023 (Iris Nebula)
NGC 7023 (Iris Nebula)
(C) NASA

NGC 7023 (Iris Nebula)
The Iris Nebula in a Field of Dust
(C) Mikel Martínez
What flowers in this field of dark star dust? The Iris Nebula. The striking blue color of the Iris Nebula is created by light from the bright star SAO 19158 reflecting off of a dense patch of normally dark dust. Not only is the star itself mostly blue, but blue light from the star is preferentially reflected by the dust -- the same affect that makes Earth's sky blue. The brown tint of the pervasive dust comes partly from photoluminescence -- dust converting ultraviolet radiation to red light. Cataloged as NGC 7023, the Iris Nebula is studied frequently because of the unusual prevalence there of Polycyclic Aromatic Hydrocarbons (PAHs), complex molecules that are also released on Earth during the incomplete combustion of wood fires. The bright blue portion of the Iris Nebula spans about six light years. The Iris Nebula, pictured above, lies about 1,300 light years distant and can be found with a small telescope toward the constellation of Cepheus.

NGC7023 (Iris Nebula) NGC7023 (Iris Nebula)
NGC 7023 (Iris Nebula)
(C) NASA
NGC 7023 (Iris Nebula)
(C) NASA
NGC7023 (Iris Nebula) NGC7023 (Iris Nebula)
NGC 7023 (Iris Nebula)
(C) NASA
NGC 7023 (Iris Nebula)
(C) NASA
NGC7023 (Iris Nebula) NGC7023 (Iris Nebula)
NGC 7023 (Iris Nebula)
(C) NASA
NGC 7023 (Iris Nebula)
(C) NASA
NGC 7023
NGC 7023: The Iris Nebula
(C) Jimmy Walker
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「ウィキペディア(wikipedia):フリー百科事典」より文章引用。
アイリス星雲. (2012, October 27). In Wikipedia.
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