NASA images shed light on origin of solar winds

New images from NASA funded telescopes board a Japanese satellite have shed light about the suns agnetic field and the origin of solar winds, which disrupts ower grids, satellites and communications on Earth.

Washington, Dec 7 : New images from NASA funded telescopes board a Japanese satellite have shed light about the sun's agnetic field and the origin of solar winds, which disrupts ower grids, satellites and communications on Earth.

The solar wind is a stream of electrically charged gas that is ropelled away from the sun in all directions at speeds of almost million miles per hour.

Now, new data from the Hinode satellite shows that magnetic waves lay a critical role in driving the solar wind into space.

Better understanding of the solar wind may lead to more accurate rediction of damaging radiation waves before they reach atellites.

How the solar wind is formed and powered has been the subject of ebate for decades.

Powerful magnetic Alfven waves in the electrically charged gas ear the sun have always been a leading candidate as a force in he formation of solar wind since Alfven waves in principle can ransfer energy from the sun's surface up through its atmosphere, r corona, into the solar wind.In the solar atmosphere, Alfven waves are created when convective otions and sound waves push magnetic fields around, or when ynamic processes create electrical currents that allow the agnetic fields to change shape or reconnect."Until now, Alfven waves have been impossible to observe because f limited resolution of available instruments," said Alexei evtsov, Hinode program scientist, NASA Headquarters, Washington. With the help of Hinode, we are now able to see direct evidence f Alfven waves, which will help us unravel the mystery of how he solar wind is powered," he added.

Using Hinode's high resolution X-ray telescope, a team led by onathan Cirtain, a solar physicist at NASA's Marshall Space light Center, Huntsville, Ala., was able to peer low into the orona at the sun's poles and observe record numbers of X-ray ets.

The jets are fountains of rapidly moving hot plasma. Previous esearch detected only a few jets daily.With Hinode's higher sensitivity, Cirtain's team observed an verage of 240 jets per day. They conclude that magnetic econnection, a process where two oppositely charged magnetic ields collide and release energy, is frequently occurring in the ow solar corona. This interaction forms both Alfven waves and he burst of energized plasma in X-ray jets."These observations show a clear relationship between magnetic econnection and Alfven wave formation in the X-ray jets," said irtain. "The large number of jets, coupled with the high speeds f the outflowing plasma, lends further credence to the idea that -ray jets are a driving force in the creation of the fast solar ind," he added.

Another research team led by Bart De Pontieu, a solar physicist t Lockheed Martin's Solar and Astrophysics Laboratory, Palo lto, Califorina, focused on the sun's chromosphere, the region andwiched between the solar surface and its corona. sing extremely high-resolution images from Hinode's Solar ptical Telescope, De Pontieu's team found that the chromosphere s riddled with Alfven waves. When the waves leak into the orona, they are strong enough to power the solar wind."We find that most of these Alfven waves have periods of several inutes, much longer than many theoretical models have assumed in he past," said De Pontieu.

Comparisons with advanced computer simulations from the niversity of Oslo, Norway, indicate that reconnection is not the nly source of the Alfven waves.

"The simulations imply that many of the waves occur when the un's magnetic field is jostled around by convective motions and ound waves in the low atmosphere," said De Pontieu.

ANI