The Japanese Spacecraft HINODE measured the strongest magnetic field ever recorded on the surface of the Sun. This magnetic field was the result of a gas outflow from the interaction between two sunspots.
As reported in the Astrophysical Journal, the two sunspots were really close to each other on February 4, 2014, and they began pushing against one another. Usually the magnetic field is strongest in the darkest part of the spots, the umbra, but in this case it was in the brighter area between the spots, the penumbra.
The umbra usually has vertical magnetic fields of the order of 3,000 gauss, between 10,000 and 5,000 times stronger than Earth’s own magnetic field, which is between 0.3 and 0.6 gauss. What HINODE recorded had the incredible strength of 6,250 gauss. Over the course of five days, the spacecraft monitored the area and discovered that the source was not inside the spots.
What the researchers realized was that there was a horizontal gas flow between the two spots, because the two spots had a different polarity. So the field lines from one were entering the other one, and the charged particles that make up the surface of the Sun started to migrate from one spot to the other. The researchers compare the process to the subduction zone between plate tectonics in the Earth’s crust. The moving plasma enhances the natural strength of the magnetism in the region pushing it towards the record-breaking value that was recorded.
"HINODE's continuous high-resolution data allowed us to analyze the sunspots in detail to investigate the distribution and time evolution of the strong magnetic field and also the surrounding environment," author Takenori Okamoto said in a statement.
"Finally, the longtime mystery of the formation mechanism of a stronger field outside an umbra than in the umbra has been solved.”
There have been a handful more instances of observations of what appeared to be extremely strong magnetic fields on the Sun, around similar strength. This is most definitely the strongest field observed parallel to the surface. Their analysis suggested that the gas in the magnetic field was moving at about 7 kilometers per second (15,700 miles per hour).