Scientists continue to fight over one of the most fascinating mysteries of the history of the solar system - a weak young sun paradox.
The standard model of stellar evolution indicate that with age, solar-type stars begin to glow brighter. Accordingly, four billion years ago the sun would have to emit a third less energy than today. Simple calculation shows that while on Earth it would be quite cold, and all the water on its surface would be completely frozen.
However, geologists confidently show that at that time reigned on earth moist and warm climate, which contributed to the emergence of life. The same, incidentally, applies to the nearby Mars, which then could also boast of a very vast ocean of water. This problem is well known as the weak young sun paradox.
Trying to resolve the paradox, involving a variety of mechanisms. Thus, some authors believe that the Earth warmed a powerful greenhouse effect caused by the high content of volcanic gases in the atmosphere - primarily carbon dioxide and methane. Others believe that the Earth itself at the time was far closer to the Sun. Still others - that the young Sun was more active than it is now. None of these explanations has not been made final, and we do not just write about the debate around this issue.
Engaged to her and the team of American researchers Stein Sigurdsson (Steinn Sigurdsson). They plan to simulate various scenarios of evolution of the Sun and compare simulation results with the available evidence.
In fact, until all of the proposed hypotheses are rather dubious. Take, for example, today the most popular version of the greenhouse effect. On Earth, such a result would give the availability of sufficient quantities of ammonia in the atmosphere, but this gas is rapidly degraded under the influence of solar radiation. And the necessary amount of carbon dioxide are extremely great - hundreds of times greater than today's values - and not consistent with the data paleogeology.
In the end, for Mars, located farther from the sun, the greenhouse effect should be stronger and the. Calculations show that for a desired temperature in the Martian atmosphere would have to appear dense clouds of carbon dioxide, which would not only warmed the planet, as it would have cooled, reflecting a significant part of the sunlight back into space.
Therefore, Sigurdsson and his colleagues are guided by a hypothesis. According to her, to the young sun was bright enough to maintain liquid oceans on Earth and Mars at that time it was supposed to be heavier than usual calculations show - about 2-5%. Less weight will not create enough energy would result in large to the fact that the sun would have evolved as the star of a different type.
To rethink the history of our stars, the scientists intend to use the new, much more sophisticated computer models of stellar evolution. It will carry out the calculations by varying not only the mass, but also other important parameters - such as the original content of various chemical elements, the intensity of turbulent processes in the plasma and t. n.
The main task the authors see the harmonization of the then and the present mass of the Sun. After all, it must lose 2-5 % more mass than we expected so far. Volatilization occurs with the mass flow of solar wind particles. However, the calculation carried out on the basis of modern solar wind intensity, gives a figure of 0.5 %. Perhaps in the past, he was several times stronger - but why?. In addition, to all in this puzzle came together, the sun was supposed to get rid of ... To do this, the solar wind at that time was to be a thousand times stronger than today.
To our knowledge, such stars emit powerful winds either large or small sizes, but the middling sort of our sun, these do not differ. But maybe we are wrong?. Solve this problem could be new studies of asteroids. The bodies are formed at the dawn of the solar system, and has since remained virtually unchanged, carrying the memories of that distant era. Indeed, some of which are crystals with injuries that are likely associated with a more powerful influence of the solar wind. On the other hand, this is not yet possible to say definitely, but even more so - to estimate the intensity of the solar wind, based on studies of asteroids.
Nevertheless, Sigurdsson almost certain that the solution to the paradox lies precisely in the ... Some traces of it found five years ago, scientists who studied the orbital dynamics of the major solar system bodies. They showed that in an era of youth the world could be closer to the star due to its slightly higher weight. However, these numbers are too small to serve as a reliable indication of.
Perhaps the new data will bring in-depth studies of the Sun. Perhaps it still bears some traces of the past - and they can occur when we learn to better understand what is going on deep below the surface of the star, and be able to closely monitor these processes.
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