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Proxima Centauri (プロキシマ・ケンタウリ)


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プロキシマ・ケンタウリ (Proxima Centauri) は、ケンタウルス座に位置する恒星。
太陽から4.22光年と、太陽系に最も近い恒星として知られている。

特徴
プロキシマ・ケンタウリは赤色矮星であり、非常に暗い恒星であるため、地球からの観測は肉眼では不可能。発見当時、プロキシマ・ケンタウリは既知の恒星の中で最も暗い恒星であった。
ケンタウルス座α星(アルファ・ケンタウリ)の第2伴星である。地球からプロキシマ・ケンタウリおよびアルファ・ケンタウリAを観測したとき、プロキシマ・ケンタウリとアルファ・ケンタウリAの角距離は約2度です。
アルファ・ケンタウリAおよびアルファ・ケンタウリBからプロキシマ・ケンタウリを観測したときの見かけの等級は4.5である。プロキシマ・ケンタウリに最も近い恒星はアルファ・ケンタウリAおよびアルファ・ケンタウリBであり、いずれもプロキシマ・ケンタウリから0.21光年の距離にある。プロキシマ・ケンタウリから6.55光年の距離にはバーナード星が位置している。
2002年、VLTIが光干渉法を用いてプロキシマ・ケンタウリの角直径を計測したところ、プロキシマ・ケンタウリの角直径は1.02±0.08ミリ秒角であることが判明した。

プロキシマ・ケンタウリは、地球との近さから、しばしば恒星間航行の目的地として挙げられる。宇宙船に重力加速度と同等の等加速度運動が恒常的に可能であれば、速度だけならば減速を考慮しても約6年、10分の1の0.1Gでも減速込で約14年で到達可能となる。 しかし、ボイジャー1号 (17.3km/s) のような等速度運動では数万年単位(ボイジャー1号の場合は7.3万年以上)の年月を要する距離であり、21世紀初頭の技術で到達するには人間個人の時間スケールで考えれば膨大な時間が必要となる。

Proxima Centauri is a star located 4.3 light years from the Earth in the constellation Centaurus.

Proxima Centauri (プロキシマ・ケンタウリ) : Picture

Proxima Centauri
Proxima Centauri
(C) NASA/ESA
Shining brightly in this Hubble Space Telescope image is our closest stellar neighbor: Proxima Centauri.

Proxima Centauri lies in the constellation of Centaurus, just over four light-years from Earth. Although it looks bright through the eye of Hubble, as you might expect from the nearest star to the solar system, Proxima Centauri is not visible to the naked eye. Its average luminosity is very low, and it is quite small compared to other stars, at only about an eighth of the mass of the Sun.

However, on occasion, its brightness increases. Proxima is what is known as a "flare star," meaning that convection processes within the star's body make it prone to random and dramatic changes in brightness. The convection processes not only trigger brilliant bursts of starlight but, combined with other factors, mean that Proxima Centauri is in for a very long life. Astronomers predict that this star will remain middle-aged — or a "main sequence" star in astronomical terms — for another four trillion years, some 300 times the age of the current universe.

These observations were taken using Hubble's Wide Field and Planetary Camera 2 (WFPC2). Proxima Centauri is actually part of a triple star system — its two companions, Alpha Centauri A and B, lie out of frame.

Although by cosmic standards it is a close neighbor, Proxima Centauri remains a point-like object even using Hubble's eagle-eyed vision, hinting at the vast scale of the universe around us.

Proxima Centauri: The Closest Star
Proxima Centauri: The Closest Star
(C) David Malin, UK Schmidt Telescope, DSS, AAO
What is the closest star to our Sun? It is Proxima Centauri, the nearest member of the Alpha Centauri triple star system. Light takes only 4.22 years to reach us from Proxima Centauri. This small red star, captured in the center of the above image, is so faint that it was only discovered in 1915 and is only visible through a telescope. Stars of all types from our Milky Way Galaxy are visible in the background. The brightest star in the Alpha Centauri system is quite similar to our Sun, has been known as long as recorded history, and is the third brightest star in the night sky. The Alpha Centauri system is primarily visible from Earth's Southern Hemisphere.

Alpha Centauri: The Closest Star System
Alpha Centauri: The Closest Star System
(C) 1-Meter Schmidt Telescope, ESO
The closest star system to the Sun is the Alpha Centauri system. Of the three stars in the system, the dimmest -- called Proxima Centauri -- is actually the nearest star. The bright stars Alpha Centauri A and B form a close binary as they are separated by only 23 times the Earth- Sun distance - slightly greater than the distance between Uranus and the Sun. In the above picture, the brightness of the stars overwhelm the photograph causing an illusion of great size, even though the stars are really just small points of light. The Alpha Centauri system is not visible in much of the northern hemisphere. Alpha Centauri A, also known as Rigil Kentaurus, is the brightest star in the constellation of Centaurus and is the fourth brightest star in the night sky. Sirius is the brightest even thought it is more than twice as far away. By an exciting coincidence, Alpha Centauri A is the same type of star as our Sun, causing many to speculate that it might contain planets that harbor life.

Interstellar Distances - In Perspective
Interstellar Distances - In Perspective
(C) NASA
The Voyager spacecraft left the solar system at 37,000 miles per hour. At that speed, it would take Voyager 80,000 years to reach Proxima Centauri.

Proxima Centauri Proxima Centauri: The Closest Star
Proxima Centauri
(C) NASA/ESA
Proxima Centauri: The Closest Star
(C) David Malin, UK Schmidt Telescope, DSS, AAO
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Proxima Centauri (プロキシマ・ケンタウリ) : Movie

A journey to Alpha Centauri
This video shows an imaginary journey from Earth to the Alpha Centauri system. As we leave the Solar System we see the familiar constellation figures including the Southern Cross (Crux) and the bright stars Alpha and Beta Centauri. As we approach Alpha Centauri we pass a faint red star, this is Proxima Centauri, the closest star to Earth and the faintest component of a triple star system. The final part shows the bright double star Alpha Centauri A and B with the Sun visible in the background. Alpha Centauri B is known to be orbited by an Earth-mass planet, the closest exoplanet to the Solar System.

A fly-through of the Alpha Centauri system
This video shows a fly-through of the bright double star Alpha Centauri A and B. In the final sequence we close in on Alpha Centauri B and a newly discovered planet swims into view. This Earth-mass planet is the closest exoplanet known and the lightest ever found around a star like the Sun.
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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。
プロキシマ・ケンタウリ. (2013, March 24). In Wikipedia.
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