Thursday, 11 Oct, 2007 Science

Computer Simulation Unveils Unexpected Process on the Surface of the Sun

Solar granulationsSolar granulations (the relatively light patterns) and sunspots (dark spots). Picture taken by the sun telescope of the Swedish Royal Science Academy. Courtesy of V. Zakharov / MPI Solar System Research

There is no other star that is observed and studies as much as the Sun - the center of solar system. However, no one could say that we know very much about it: its surface still hides many secrets, which are still to be discovered one day. A mathematician from the University of Vienna along with his colleagues astronomers has simulated the solar granulations and has made some surprising discoveries.

According to Herbert Muthsam, professor at the Mathematic Institute at the University of Vienna, the solar granulation is a process similar to the waves of boiling water in a kettle. It is a process during which torrents of water and helium are pushed out from under the surface of the sun to cool and then to sink back under the surface.

Professor Muthsam has been working on the modeling process for three years in order to provide the astronomers with a better, high-resolution picture of the granulation, since neither existing telescopes nor previous calculations were able to do this. Professor Muthsam said that even though the sun is being always under observation, there are certain limits to the possibilities of the astronomers.

Today's studies, which benefit from the best solar telescopes, can observe only the upper layers of the Sun and waves coming from under its surface, whereas many processes, such as those taking place deep under the star's crust or even in its atmosphere, remain a secret.

Thus, in order to analyze processes, events and their consequences on the surface of the Sun and to draw certain conclusions about them, which would boost up subsequent studies, scientists need a high-quality computer simulation of those processes. Professor Muthsam and his colleagues have developed special programs for torrents' simulation using various mathematical methods. The project benefited from three super computers, including the Schrödinger cluster from the University of Vienna, which were kept busy for a year running calculations on the possible models of the processes under the surface of the star.

In general, the modeling has showed something unexpected: the animation of the process depicted a sort of a wall, which moved relatively fast through the boiling surface of the sun. The professor explained that the moving walls were acoustic pulses, gigantic walls made of noise, which move across the surface of the star. He added that yet no one has ever had an opportunity of observing those pulses.

After the computer modeling showed that granulations are much more turbulent than they were initially thought to be, the researchers began to study the effects that granulations have on the heating of the chromosphere and the solar corona.

"This project made us come one step closer to answering the questions we are still to answer... and in addition, our schedules for the next few years include now much more work", the professor said.


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