A solar flare which occurred in a huge sunspot group, as captured by the Solar Observation Satellite “HINODE.” These sunspots appeared in the latter half of October last year and their size, large enough to be seen with the naked eye, became a topic of conversation. The time they reached the center of the solar disk coincided perfectly with NAOJ’s Open House Day. I’m sure there were people who viewed them through eclipse glasses. A solar flare is an explosive phenomenon on the solar surface. When a flare occurs, vast quantities of x-rays and high energy particles are generated, some of which fly to the Earth. The strength of solar flares is usually ranked using 5 classes. This is a picture of an X-class flare, which is the strongest class.

Aiming to Clarify the Trigger Mechanism of Solar Flares

When the electrically-charged high-energy particles accompanying a solar flare reach the Earth, they can disrupt communications and have effects on artificial satellites and astronaut extravehicular activities. There have also been widespread blackouts in high altitude areas caused by especially large flares. Very large solar flares are not irrelevant to our daily lives. Through the results from things like the Yohkoh satellite we came to reasonably understand how this vast energy is discharged in solar flares. But the flare trigger mechanism, i.e. “when and where will a flare occur?” is an important unresolved question. With the “HINODE” satellite we have been able to acquire high quality data which can be compared directly to numerical simulation data. Vigorous research continues into the phenomena which precede a flare and the magnetic field structures at the solar surface which give rise to a flare. This time, the flares which occurred in a huge sunspot group are an important sample. Many types of research using data from the “HINODE” observations are starting.

Text by: Masahito Kubo (Hinode Science Center)
Translation by: Ramsey Lundock (NAOJ)