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NGC 6611 (Eagle Nebula, M16)


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NGC 6611, M16
Eagle Nebula (わし星雲)
Open Cluster (散開星団)
Emission Nebula (散光星雲)
OC II3mn


別名 (Other names)
OCL 54 with Eagle Nebula, IC 4703, Messier 16, Sharpless 49, Sh2-49, RCW 165, Gum 83, Star Queen Nebula

明るさ (Brightness)
6等級

星座 (Constellation)
へび座 (Ser) (Serpens)

距離 (Distance)
6,500光年 (6,500 light-years)

わし星雲(わしせいうん、M16、NGC6611、IC4703)は、へび座に位置する散開星団と散光星雲の複合した天体。散開星団の背景に散光星雲が広がっており、メシエ天体としての番号M16は散開星団の方に付けられた番号。
散光星雲にはIC4703という番号が付けられている。1745年にジャン=フィリップ・ロワ・ド・シェゾーによって星団が発見され、1764年にシャルル・メシエが背景の星雲を発見した。しかし、メシエは同時代の観測者と比較して貧弱な機材しか持っておらず、M15 などのように発見者が星団に分離できた場合でもメシエは星団を分離できず星雲状で見ている場合が多々ある。

わし星雲はへび座に属するが、観測する際にはたて座γ星から西へ約 2.5°の位置にあるとして探した方が見つけやすい。M16の南約2.5°には同じように散光星雲と散開星団が重なった天体であるオメガ星雲が存在し、双眼鏡では同一の視野内に見ることができる。赤い散光星雲(HII領域)の中央が象の鼻のような細長い暗黒星雲によって隠されており、全体が羽を広げた鷲のように見えることからこの名前が付けられている。

わし星雲は星形成が活発に行われている領域で、前景に見える星団M16もこの星雲から生まれたと考えられている。M16の中にはスペクトル型がO6型という高温の星が含まれており、こういった若い高温星からの紫外線によって背景の星雲が電離して輝いている。

1995年4月にはハッブル宇宙望遠鏡によって、星雲中央にある細長い暗黒星雲の画像が撮影された。この観測によって、暗黒星雲の柱の先端からさらに細い分子雲が伸びており、その先端に生まれたばかりの星が隠されている様子がはっきりと捉えられた。この暗黒星雲は後に「創造の柱」(Pillars of Creation )と名付けられた。

双眼鏡では星雲状に見えるが、条件がよければ数個の星が見える。口径10cmの望遠鏡では数十個の星が見え始める。散光星雲を見るためには口径20cm以上の望遠鏡が必要とされる。小さい口径の望遠鏡では星団を分離できず星雲状に見ている。大口径の望遠鏡でも人間の目には見えにくいHII領域の星雲部分をはっきり見るためには干渉フィルターを使用すると良い。
NGC 6611 (Eagle Nebula, M16) is an emission nebula located 6,500 light years from the Earth in the constellation Serpens.

NGC 6611 (Eagle Nebula, M16) : Picture

Eagle Nebula
The Eagle Nebula from Kitt Peak
(C) T. A. Rector & B. A. Wolpa, NOAO, AURA
From afar, the whole thing looks like an Eagle. A closer look at the Eagle Nebula, however, shows the bright region is actually a window into the center of a larger dark shell of dust. Through this window, a brightly-lit workshop appears where a whole open cluster of stars is being formed. In this cavity tall pillars and round globules of dark dust and cold molecular gas remain where stars are still forming. Already visible are several young bright blue stars whose light and winds are burning away and pushing back the remaining filaments and walls of gas and dust. The Eagle emission nebula, tagged M16, lies about 6,500 light years away, spans about 20 light-years, and is visible with binoculars toward the constellation of Serpens. This picture combines three specific emitted colors and was taken with the 0.9-meter telescope on Kitt Peak, Arizona, USA.

The Pillars of Eagle Castle
The Pillars of Eagle Castle
(C) Emanuele Colognato & Jim Wood
What lights up this castle of star formation? The familiar Eagle Nebula glows bright in many colors at once. The above image is a composite of three of these glowing gas colors. Pillars of dark dust nicely outline some of the denser towers of star formation. Energetic light from young massive stars causes the gas to glow and effectively boils away part of the dust and gas from its birth pillar. Many of these stars will explode after several million years, returning most of their elements back to the nebula which formed them. This process is forming an open cluster of stars known as M16.

The Fairy of Eagle Nebula
The Fairy of Eagle Nebula
(C) The Hubble Heritage Team, (STScI/AURA), ESA, NASA
The dust sculptures of the Eagle Nebula are evaporating. As powerful starlight whittles away these cool cosmic mountains, the statuesque pillars that remain might be imagined as mythical beasts. Pictured above is one of several striking dust pillars of the Eagle Nebula that might be described as a gigantic alien fairy. This fairy, however, is ten light years tall and spews radiation much hotter than common fire. The greater Eagle Nebula, M16, is actually a giant evaporating shell of gas and dust inside of which is a growing cavity filled with a spectacular stellar nursery currently forming an open cluster of stars. The above image in scientifically re-assigned colors was released in 2005 as part of the fifteenth anniversary celebration of the launch of the Hubble Space Telescope.

M16: Pillars of Creation
M16: Pillars of Creation
(C) J. Hester, P. Scowen (ASU), HST, NASA
It was one of the most famous images of the 1990s. This image, taken with the Hubble Space Telescope in 1995, shows evaporating gaseous globules (EGGs) emerging from pillars of molecular hydrogen gas and dust. The giant pillars are light years in length and are so dense that interior gas contracts gravitationally to form stars. At each pillars' end, the intense radiation of bright young stars causes low density material to boil away, leaving stellar nurseries of dense EGGs exposed. The Eagle Nebula, associated with the open star cluster M16, lies about 7,000 light years away. The pillars of creation were imaged again in 2007 by the orbiting Spitzer Space Telescope in infrared light, leading to the conjecture that the pillars may already have been destroyed by a local supernova, but light from that event has yet to reach the Earth.

The Eagle Nebula in Hydrogen, Oxygen, and Sulfur
The Eagle Nebula in Hydrogen, Oxygen, and Sulfur
(C) IAC, Daniel Lopez

M16 and the Eagle Nebula
M16 and the Eagle Nebula
(C) Johannes Schedler (Panther Observatory)

M16 and the Eagle Nebula
M16 and the Eagle Nebula
(C) Adam Block, Mt. Lemmon SkyCenter, Univ. Arizona

Inside the Eagle Nebula
Inside the Eagle Nebula
(C) Far-infrared: ESA/Herschel/PACS/SPIRE/Hill, Motte, HOBYS Key Programme Consortium;
X-ray: ESA/XMM-Newton/EPIC/XMM-Newton-SOC/Boulanger

Eagle Nebula Eagle Nebula
The Eagle Nebula from Kitt Peak
(C) T. A. Rector & B. A. Wolpa, NOAO, AURA
Inside the Eagle Nebula
(C) ESA
M16 and the Eagle Nebula The Pillars of Eagle Castle
M16 and the Eagle Nebula
(C) Johannes Schedler (Panther Observatory)
The Pillars of Eagle Castle
(C) Emanuele Colognato & Jim Wood
M16: Pillars of Creation The Eagle Nebula in Hydrogen, Oxygen, and Sulfur
M16: Pillars of Creation
(C) J. Hester, P. Scowen (ASU), HST, NASA
The Eagle Nebula in Hydrogen, Oxygen, and Sulfur
(C) IAC, Daniel Lopez
Sh2-49 (Eagle Nebula) Sh2-49 (Eagle Nebula)
Sh2-49 (Eagle Nebula)
(C) Image by Dean Salman -
http://www.sharplesscatalog.com
Sh2-49 (Eagle Nebula)
(C) http://galaxymap.org/
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NGC 6611 (Eagle Nebula, M16) : Movie

M16, the Eagle Nebula
This stunning movie shows the Eagle Nebula from the iconic 1995 Hubble image of the Pillars of Creation through to the latest multi-wavelength composite.
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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。
わし星雲. (2013, November 23). In Wikipedia.
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