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| Where the missing helium went; A mystery solved | |
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| Tweet Topic Started: Jan 8 2007, 01:37 PM (101 Views) | |
| big al | Jan 8 2007, 01:37 PM Post #1 |
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Bull-Carp
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Found this while searching for a news item concerning a hydrogen explosion at a power plant this morning. Scientists solve missing helium mystery Astrophysicists found the answer while modeling a 'near explosion' By Andrea Thompson Space.com staff writer Space.com Updated: 7:36 p.m. ET Nov 6, 2006 For years, astrophysicists have tried to reconcile a cosmic discrepancy: The universe held much less helium-3 gas than was predicted by models of stellar evolution. But by using new three-dimensional models, scientists think they’ve discovered where all the helium-3 went — it was destroyed by the very stars that were thought to eject it into space, according to a new study. Just after the Big Bang, the gases that made up the universe were predominately hydrogen, with 10 percent helium-4 and just .001 percent helium-3. But astrophysicists thought that “several times that much [helium-3] ought to have come by later [stellar] evolution,” said Peter Eggleton, an astrophysicist at Lawrence Livermore National Laboratory and lead author of the study, which appeared Oct. 26 on the Science Express Web site. According to previous models of stellar evolution, low mass stars (about 1 to 2 times the size of our sun) should have produced large amounts of helium-3 and increased its percentage in the universe to .01. But observations showed that the amount of helium-3 in the universe still at .001 percent. “It was odd that the helium-3 didn’t seem to pile up,” Eggleton said. Astrophysicists had tried to come up with what Eggleton called “flimsy ideas” to explain the discrepancy. In what he described as a case of serendipity, he and his colleagues found the answer of the missing helium-3 while they were modeling a “near explosion” called a helium flash, which occurs when a star switches from burning hydrogen to burning helium. Stars like the Sun burn hydrogen at their cores for nearly 10 billion years. As the star ages, it exhausts all the hydrogen at its core to become a red giant and begins to burn helium. The star also loses much of its mass through stellar winds. The expelled material was thought to be rich in helium 3. (Heavier elements like carbon, nitrogen, and oxygen have accumulated in the universe through this same mechanism.) While modeling the helium flash, Eggleton and his colleagues found an unexpected instability elsewhere in the star that “seemed to explain two phenomena that had been a bother for several years,” Eggleton said. The instability mixed helium-3 in the outer layers of the star into deeper layers where it was hot enough for it to be burned up — solving the problem of where all the helium-3 went to. The instability also explained why older stars were observed to have increasing abundances of carbon-13 and nitrogen-14 when they weren’t expected to. Like the helium-3, carbon-12 and nitrogen-13 located nearer the surface were also mixed deeper into the star where they were converted into carbon-13 and nitrogen-14, respectively. “Now it seems that a perfectly respectable mechanism is” behind the discrepancies astrophysicists have been trying to explain for decades, Eggleton said. © 2006 Space.com. All rights reserved. Source: Scientists solve missing helium mystery Big Al |
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Location: Western PA "jesu, der simcha fun der man's farlangen." -bachophile | |
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| The 89th Key | Jan 8 2007, 02:08 PM Post #2 |
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Very interesting stuff, Big Al. |
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| Mark | Jan 8 2007, 02:11 PM Post #3 |
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HOLY CARP!!!
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Yes! that is very interesting. Thanks Al! |
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___.___ (_]===* o 0 When I see an adult on a bicycle, I do not despair for the future of the human race. H.G. Wells | |
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| ***musical princess*** | Jan 8 2007, 02:40 PM Post #4 |
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HOLY CARP!!!
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I find it funny when people read things like this and still try and dispute the Big Bang theory. x |
| x Caroline x | |
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| The 89th Key | Jan 8 2007, 02:46 PM Post #5 |
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You know what the funniest thing about it all will be? We'll get to heaven and I will be standing there next to Moonbat and we'll both say "God, which is correct, the Big Bang Theory or the Creation Theory?" And he'll say, "Yes." |
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| ***musical princess*** | Jan 8 2007, 02:48 PM Post #6 |
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HOLY CARP!!!
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![]() That's if he gets to heaven... ![]() JK!!! x |
| x Caroline x | |
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