A solar flare is a swift flash of enhanced brightness on the Sun, normally observed near its surface and close to a sunspot group. Powerful bursts are often, but not always, followed by a coronal mass expulsion. Even the most potent flares are hardly detectable in the total solar irradiance.
Solar flares hit all layers of the solar atmosphere (chromosphere, photosphere, and also corona). The plasma medium is cooked to tens of millions of kelvins, while protons, electrons, and heavier ions are accelerated to near the speed of light. Flares compose electromagnetic radiation across the electromagnetic spectrum at all wavelengths, from gamma waves to radio rays.
Causes of Solar Flares
Flares are possible when accelerated charged particles, mostly electrons, communicate with the plasma medium. Data implies that the event of magnetic reconnection leads to this ultimate acceleration of charged particles. On our Sun, magnetic reconnection may transpire on solar arcades – a bunch of closely occurring rings following magnetic lines of force. These lines of force instantly reconnect into a quieter arcade of loops, leaving a helix of magnetic field disconnected from the rest of the arcade. The immediate release of energy in this reconnection is the source of the particle acceleration. The separated magnetic helical field and its material may abruptly expand outwards, forming a mass coronal ejection.
Detection of Solar Flares
Well, the scientists use two different types of detectors: Magnetoresistance and Doppler. A Doppler is used to detect the change in velocity that is caused by an object spinning fast or spinning slower than the speed of light. On the other hand, Magnetoresistance measures the difference in temperature between when the object is near the Earth and when it is far away from us. The difference in the temperature can be detected using the Doppler technique.
Doppler has been around for decades, but until recently, was not very effective. Radio telescopes have helped us detect many astronomical phenomena. One such phenomenon is the flares. Here is how they work:
Radio telescopes listen to radio waves. These waves are emitted by explosions, gamma bursts, or black holes. When a radio signal is received, the antenna will hear a difference in temperature that is caused by the explosion. If the signal is near Earth, the antenna will pick up the difference in temperature very quickly. This means that the explosion occurred very close to the Earth.
Using radio waves, an infrared telescope can look for differences in temperature that are caused by explosions. The infrared wavelength is able to penetrate the Earth’s atmosphere and thus can detect differences in temperature very quickly. When the radio signals bounce back to Earth, the difference in temperature can be detected by a radio or an infrared instrument.