Powering the Solar Wind
"Intelligence is in asking the right question."
Yet another question has been answered in our pursuit to understand our star, the Sun. One of the prominent area of study regarding sun is the solar wind. It is a stream of charged particles released from the upper atmosphere of the Sun. We now understand how it has originated.
Solar wind is thought to originate in the sun's corona, the outermost layer of its atmosphere. The corona is much hotter than the surface of the sun, with temperatures reaching millions of degrees Celsius. This extreme heat is thought to be caused by the presence of magnetic fields in the corona, which trap and heat the charged particles.
Learning about the solar wind is crucial for one reason: aurora. The Carrington event was one such incidence. It was a solar geomagnetic storm in the year 1859 that caused severe damage to communication worldwide. We need to know its origin to predict and prevent such an event again. Earlier it was not easy to observe with the amount of accuracy and resolution that is available today.
Solar wind is steadily generated. This suggests that there must be a steady source for it. New findings show that the stream is generated by individual jetlets in the lower part of the corona. Each jetlet ranges to about several hundred kilometers long and has enough mass and energy to be a continuous source for the winds.
Jetlets are caused by a process called magnetic reconnection. Reconnection is commonly found throughout the universe and it is no surprise that it is the source for these jetlets. This also explains why the solar winds do not wax and wane with each solar cycle but remains constant.
Magnetic reconnection occurs when the magnetic field lines come close enough to trigger an explosive realignment. This phenomenon is observed when plasma is present. The amount of energy released is huge enough that an explosion on the Sun would impact the Earth.
- Namitha (MS22118)
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