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利用者:Bluedot/sandbox

記事執筆時の参照先

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出典・参考文献の記述

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数式などの記述

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画像利用

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金子メモ

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https://twitter.com/alpe_terashima/status/1108743735553097729 『週刊こどもニュース』に出演歴があるらしい。

ジョンバール分岐点

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『Q.E.D.』12巻「銀河の片隅にて」にジョンバール分岐点への言及が出てくるらしい。アシモフ『永遠の終り』にも？

いつか翻訳したい

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535年から536年の異常気象現象。火山活動だけでなく、彗星や小惑星の衝突だったのではないかという説もある。以下は参考になりそうな資料。

超大質量ブラックホール

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超大質量ブラックホールに英語版の記述を反映したい。

In the Milky Way

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Inferred orbits of 6 stars around supermassive black hole candidate Sagittarius A* at the Milky Way galactic centre[1]

Astronomers are very confident that the Milky Way galaxy has a supermassive black hole at its center, 26,000 light-years from the Solar System, in a region called Sagittarius A*[2] because:

  • The star S2 follows an elliptical orbit with a period of 15.2 years and a pericenter (closest distance) of 17 light-hours (1.8×1013 m or 120 AU) from the center of the central object.[3]
  • From the motion of star S2, the object's mass can be estimated as 4.1 million M☉,[4][5] or about 8.2×1036 kg.
  • The radius of the central object must be less than 17 light-hours, because otherwise, S2 would collide with it. In fact, recent observations from the star S14[6] indicate that the radius is no more than 6.25 light-hours, about the diameter of Uranus' orbit. However, applying the formula for the Schwarzschild radius yields just about 41 light-seconds, making it consistent with the escape velocity being the speed of light.
  • No known astronomical object other than a black hole can contain 4.1 million M☉ in this volume of space.

The Max Planck Institute for Extraterrestrial Physics and UCLA Galactic Center Group[7] have provided the strongest evidence to date that Sagittarius A* is the site of a supermassive black hole,[2] based on data from ESO's Very Large Telescope[8] and the Keck telescope.[9]

On 5 January 2015, NASA reported observing an X-ray flare 400 times brighter than usual, a record-breaker, from Sagittarius A*. The unusual event may have been caused by the breaking apart of an asteroid falling into the black hole or by the entanglement of magnetic field lines within gas flowing into Sagittarius A*, according to astronomers.[10]

Detection of an unusually bright X-Ray flare from Sagittarius A*, a supermassive black hole in the center of the Milky Way galaxy[10]
  1. ^ Eisenhauer (2005). “SINFONI in the Galactic Center: Young Stars and Infrared Flares in the Central Light-Month”. The Astrophysical Journal 628: 246–259. arXiv:astro-ph/0502129. Bibcode: 2005ApJ...628..246E. doi:10.1086/430667. http://iopscience.iop.org/0004-637X/628/1/246/62163.text.html. 
  2. ^ a b Henderson, Mark (December 9, 2008). “Astronomers confirm black hole at the heart of the Milky Way”. London: Times Online. http://www.thetimes.co.uk/tto/news/world/article1967154.ece 2009年5月17日閲覧。 
  3. ^ Schödel, R. (17 October 2002). “A star in a 15.2-year orbit around the supermassive black hole at the centre of the Milky Way”. Nature 419 (6908): 694–696. arXiv:astro-ph/0210426. Bibcode: 2002Natur.419..694S. doi:10.1038/nature01121. PMID 12384690. 
  4. ^ Ghez, A. M. (December 2008). “Measuring Distance and Properties of the Milky Way's Central Supermassive Black Hole with Stellar Orbits”. Astrophysical Journal 689 (2): 1044–1062. arXiv:0808.2870. Bibcode: 2008ApJ...689.1044G. doi:10.1086/592738. 
  5. ^ Milky Way's Central Monster Measured
  6. ^ Ghez, A. M.; Salim, S.; Hornstein, S. D.; Tanner, A.; Lu, J. R.; Morris, M.; Becklin, E. E.; Duchêne, G. (May 2005). “Stellar Orbits around the Galactic Center Black Hole”. The Astrophysical Journal 620 (2): 744–757. arXiv:astro-ph/0306130. Bibcode: 2005ApJ...620..744G. doi:10.1086/427175. 
  7. ^ UCLA Galactic Center Group
  8. ^ ESO - 2002
  9. ^ “| W. M. Keck Observatory”. Keckobservatory.org. 2013年7月14日閲覧。
  10. ^ a b “RELEASE 15-001 - NASA’s Chandra Detects Record-Breaking Outburst from Milky Way’s Black Hole”. NASA (5 January 2015). 6 January 2015閲覧。
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