Formation of Solar System :
A new study by researchers at the University of Chicago challenges the notion that the force of an exploding star forced the formation of the solar system.
In this study, published online last month in Earth and Planetary Science Letters, authors and Nicholas Tang Haolan Dauphas found the radioactive isotope of iron 60 - the telltale sign of an exploding star - is not abundant and mix well the material of the solar system. As cosmochemists, looking for remnants of stellar explosions in meteorites to help determine the conditions under which the solar system was formed.
Some moieties are radioactive isotopes of atoms unstable energy disintegrate over time. Scientists in the past decade have found high amounts of radioactive iron isotope 60 in the early solar system materials. "If you have 60 iron abundance in the solar system, that's a" smoking gun "- evidence of the presence of a supernova," said Dauphas, professor of geophysical sciences.
Iron 60 can only come from a supernova, what scientists have tried to explain this apparent abundance by suggesting that a supernova occurred in the area of isotope diffusion through the explosion.
But the results of Tang and Dauphas "were different from the previous works: We found that 60 iron levels were uniform and low in the early solar system materials reached their conclusions by analyzing meteorite samples to measure the abundance of iron 60, looked .. with the same materials that previous researchers had worked, but used a different approach, more accurate than the evidence showed very low iron 60.
Previous methods meteorite samples remain intact and impurities not removed completely, which may have led to increased measurement error. Tang and Dauphas' approach, however, requires that "digest" meteorite samples in the solution before the measurement, allowing them to completely remove impurities.
This process eventually produced results with much smaller errors. "Haolan spent five years working very hard to reach these conclusions, so did these statements lightly. We have been very careful to get to a point where we are ready to go public in these measures," said Dauphas.
To determine if iron 60 was distributed widely and looked Tang Dauphas another isotope of iron, iron 58. Supernovas both isotopes produced by the same processes, so they were able to follow the distribution of iron 60 by measuring the distribution of iron 58.
"Both isotopes act as inseparable twins: Once you know that iron was 58, 60 iron knew he could not be far behind," said Dauphas.
There was little variation in iron 58 measuring samples of different meteorites, confirming the end of the plate 60 is distributed uniformly. To account for their findings Tang Dauphas unprecedented and suggest that low iron levels 60 probably came from the long-term accumulation of the plate 60 in the interstellar medium of the ashes of countless stars of the past, rather than a catastrophic event as a nearby supernova.
If this is true, Dauphas said, not after "no need to invoke any star near the iron 60". However, it is more difficult to explain the abundance of aluminum 26, which implies the presence of a nearby star.
Instead of explaining this abundance of supernova, Tang and Dauphas propose that a massive star (perhaps more than 20 times the mass of the sun) sheds its outer gaseous layers through winds, diffusion of aluminum 26 and eventually contaminate the material form the solar system, while iron 60 remained locked inside the massive star. If the solar system was formed from this material, this alternate scenario would explain the abundance of both isotopes.
"In the future, this study should be considered when people build their story about the origin of the solar system and training," said Tang.
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