http://www.asyura2.com/09/nature4/msg/519.html
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(回答先: ニュース - 科学＆宇宙 - 生命が存在できる初の惑星発見？ - ナショナルジオグラフィック 公式日本語サイト 投稿者 卍と十と六芒星 日時 2010 年 10 月 02 日 14:37:48)
宏観亭見聞録: グリーゼ 581 星系から謎の光パルス
http://macroanomaly.blogspot.com/2010/10/581.html
2010年10月1日金曜日
グリーゼ 581 星系から謎の光パルス
地球によく似た惑星が見つかったグリーゼ 581 星系。そこから発せられたと考えられる正体不明の光パルスが見つかっていたとのことです：
記事によると、光パルスを観測したのはウェスタン･シドニー大学の科学者で、SETI オーストラリア支部のメンバーである Ragbir Bhathal 博士。光パルスが観測されたのは 2008年 12月のこと。レーザーかそれに類似した技術を使って発せられたと考えられるスパイク状の非常に明瞭なシグナルだったとのことです。
Gliese 581g mystery: Scientist spotted 'mysterious pulse of light' from direction of new'Earth planet last year | Mail Online
http://www.dailymail.co.uk/sciencetech/article-1316538/Gliese-581g-mystery-Scientist-spotted-mysterious-pulse-light-direction-newEarth-planet-year.html
Does ET live on Goldilocks planet? How scientists spotted 'mysterious pulse of light' from direction of newly-discovered '2nd Earth' two years ago
By Niall Firth
Last updated at 8:03 AM on 1st October 2010
Dr. Ragbir Bhathal received a signal from the direction of Gliese 581 - but has heard nothing since
An astronomer picked up a mysterious pulse of light coming from the direction of the newly discovered Earth-like planet almost two years ago, it has emerged.
Dr Ragbir Bhathal, a scientist at the University of Western Sydney, picked up the odd signal in December 2008, long before it was announced that the star Gliese 581 has habitable planets in orbit around it.
A member of the Australian chapter of SETI, the organisation that looks for communication from distant planets, Dr Bhathal had been sweeping the skies when he discovered a 'suspicious' signal from an area of the galaxy that holds the newly-discovered Gliese 581g.
The remarkable coincidence adds another layer of mystery to the announcement last night that scientists had discovered another planet in the system: Gliese 581g - the most Earth-like planet ever found.
Dr Bhathal's discovery had come just months before astronomers announced that they had found a similar, slightly less habitable planet around the same star 20 light years away. This planet was called Gliese 581e.
When asked about his discovery at the time Dr Bhathal admitted he had been really excited about what he had possibly stumbled across.
He said: 'Whenever there’s a clear night, I go up to the observatory and do a run on some of the celestial objects. Looking at one of these objects, we found this signal.
'And you know, I got really excited with it. So next I had to analyse it. We have special software to analyse these signals, because when you look at celestial objects through the equipment we have, you also pick up a lot of noise.'
He went on: 'We found this very sharp signal, sort of a laser lookalike thing which is the sort of thing we’re looking for - a very sharp spike. And that is what we found. So that was the excitement about the whole thing.'
For months after his discovery Dr Bhathal scanned the skies for a second signal to see whether it was just a glitch in his instrumentation but his search came to nothing.
But the discovery of Earth-like planets around Gliese 581 - both 581e and 581d, which was in the habitable zone - has also caught the public imagination.
Documentary-maker RDF and social-networking site Bebo used a radio telescope in Ukraine to send a powerful focused beam of information - 500 messages from the public in the form of radiowaves - to Gliese 581.
And the Australian science minister at the time organised 20,000 users of Twitter to send messages towards the distant solar system in the wake of the discoveries.
This artist's conception shows the inner four planets of the Gliese 581 system and their host star, a red dwarf star only 20 light years away from Earth. The four tiny planets in the background are the planets that have already been discovered. The closer, blue and green planet is 581G, the most Earth-like planet ever discovered
And Dr Steven Vogt who led the study at the University of California, Santa Cruz, today said that he was '100 per cent sure ' that there was life on the planet.
The planet lies in the star's 'Goldilocks zone' - the region in space where conditions are neither too hot or too cold for liquid water to form oceans, lakes and rivers.
The planet also appears to have an atmosphere, a gravity like our own and could well be capable of life. Researchers say the findings suggest the universe is teeming with world like our own.
'If these are rare, we shouldn't have found one so quickly and so nearby,'
'The number of systems with potentially habitable planets is probably on the order of 10 or 20 per cent, and when you multiply that by the hundreds of billions of stars in the Milky Way, that's a large number. There could be tens of billions of these systems in our galaxy.'
GLIESE 581g FACT FILE
Diameter - 1.2 to 1.4 times that of the Earth
Mass - 3.1 and 4.3 times that of the Earth
Average surface temperature - between -24F and 10F (-31C and -12C)
Distance from the Earth - 20 light years or 118,000,000,000,000 miles
Time needed to travel to Gliese 581g in a rocket travelling one tenth the speed of light, or 19,000 miles per second - 200 years
One of six planets to orbit the star Gliese 581
Length of year - 37 Earth days
Gravity - similar or slightly higher than Earth
Distance from its sun - around six million miles
The planet orbits a red dwarf which is 50 times cooler and a third the size of our Sun
Composition - rocky with liquid water and atmosphere.
He told Discovery News: 'Personally, given the ubiquity and propensity of life to flourish wherever it can, I would say that the chances for life on this planet are 100 percent. I have almost no doubt about it'.
The planet is so far away, spaceships travelling close to the speed of light would take 20 years to make the journey. If a rocket was one day able to travel at a tenth of the speed of light, it would take 200 years to make the journey.
Planets orbiting distant stars are too small to be seen by telescopes. Instead, astronomers look for tell-tale gravitational wobbles in the stars that show a planet is in orbit.
The findings come from 11 years of observations at the W. M. Keck Observatory in Hawaii.
The planet orbits a small red star called Gliese 581 in the constellation of Libra. The planet, named Glieseg, is 118,000,000,000,000 miles away - so far away that light from its start takes 20 years to reach the Earth.
It takes just 37 days to orbit its sun which means its seasons last for just a few days. One side of the planet always faces its star and basks in perpetual daylight, while the other is in perpetual darkness.
The most suitable place for life or future human colonists would be in the 'grey' zone - the band between darkness and light that circles the planet.
'Any emerging life forms would have a wide range of stable climates to choose from and to evolve around, depending on their longitude,' said Dr Vogt who reports the find in the Astrophysical Journal.
If Gliese 581g has a rocky composition similar to the Earth's, its diameter would be about 1.2 to 1.4 times that of the Earth. It's gravity is likely to be similar - allowing a human astronaut to walk on the surface upright without difficulty.
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- グリーゼ 581g が姿を消す！ - メモ・独り言・戯言 - Yahoo!ブログ 卍と十と六芒星 2010/10/20 22:28:38
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