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On Wednesday, February 11, 2015 at 10:48:16 AM UTC-8, a425couple wrote:
So, the stars had to make the heavier elements. Then burn out or blow up to disperse these elements into space to renain, or form up in planets, or into other stars. Do any stars only live 2.8 Billion years (13.8B - 11 B) ? The heaviest stars can complete their life cycles in just a few million years... http://en.wikipedia.org/wiki/Star#Massive_stars Scroll about 1/3 the way down and look for the "AGE" heading... "The more massive the star, the shorter its lifespan, primarily because massive stars have greater pressure on their cores, causing them to burn hydrogen more rapidly. The most massive stars last an average of a few million years, while stars of minimum mass (red dwarfs) burn their fuel very slowly and can last tens to hundreds of billions of years." \Paul A |
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"palsing" wrote in message...
- a425couple wrote: - So, the stars had to make the heavier elements. - Then burn out or blow up to disperse these elements into - space to renain, or form up in planets, or into other stars. - - Do any stars only live 2.8 Billion years (13.8B - 11 B) ? - The heaviest stars can complete their life cycles in just a few million years... - http://en.wikipedia.org/wiki/Star#Massive_stars - Scroll about 1/3 the way down and look for the "AGE" heading... - "The more massive the star, the shorter its lifespan, primarily because -massive stars have greater pressure on their cores, causing them to -burn hydrogen more rapidly. The most massive stars last an average -of a few million years, while stars of minimum mass (red dwarfs) -burn their fuel very slowly and can last tens to hundreds of billions of years." Thanks. and here is something more, also relevant How Old are the First Planets? By Keith Cooper - Aug 30, 2012 http://www.astrobio.net/news-exclusi...first-planets/ Heavy Metal Planets Earth was born out of the debris of a protoplanetary disc around a nascent Sun 4.54 billion years ago - a serious chunk of time in anybody's book. Yet the Universe is 13.7 billion years old - the Solar System has been around for just the last third of cosmic history. Is it possible that rocky planets could have formed around other stars much earlier? Are we the new kids on the block by comparison? "Until recently, we didn't think so. The prevailing wisdom had been that the magic of stellar alchemy didn't produce enough useful "star-stuff" to build terrestrial worlds until at least six or seven billion years after the Big Bang." ""A typical massive star that exploded and released heavy elements 10 to 12 billion years ago had a metallicity of about a tenth of the Sun," One of the favorite counter-arguments to the Fermi Paradox was that the threshold metallicity takes time to build up, resulting in the Sun being one of the first stars at the required level and hence Earth would be one of the first planets with life. !!---- Now we see that planets and possibly life could have arisen at practically any point in cosmic history, undermining this counter-argument and once again forcing us to ask, where is everybody? If life did first appear on worlds 12 to13 billion years ago, then intelligent civilizations (if indeed they survived all this time) would now billions of years ahead of us and their concerns may no longer include the happenings on a damp mudball somewhere in the galactic hinterlands. - (I think that idea is nonsense. How long can any one species live? If you have evolution, and survival of the fittest, there will always, and regularly be changes, and the best will survive and flourish. Even if it existed, any species 1 B years ago will have been vanquished long before now. No single civilization will last billions of years.) |
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