New Theory for Mystery of Sunspots

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The sunspots are the dark and magnetic blemishes on the surface of our nearest star. These sunspots are thought to occur when increased magnetic activity inhibits the flow of heat onto a patch of the sun, causing it to darken. But the ultimate source of that boost of magnetism has remained unclear. Now researchers say the formation of hydrogen molecules may decrease the pressure on certain areas of the sun’s surface, allowing runaway magnetic fields to form and intensify. The sun is mostly made of hydrogen, the element makes up 90 percent of the sun’s mass, while helium contributes about 10 percent, and only 0.13 percent is everything else. Because the sun is so extremely hot (an average of 9944 degrees Fahrenheit, or 5,500 degrees Celsius) this hydrogen is generally in the form of single ionized atoms floating around in gaseous form.

However, inside sunspots the surface of the sun can cool enough to allow two hydrogen atoms to bond together to form hydrogen molecules. When two atoms combine into one molecule, the pressure it exerts is about half the pressure of the two particles it used to be. And when the pressure decreases like this, the magnetic fields can further intensify. To test this theory scientists observed the sun with the Dunn Solar Telescope at Sunspot, N.M. So they found evidence that significant quantities of hydrogen molecules form in sunspots that are able to maintain magnetic fields stronger than 2,500 Gauss. For comparison, Earth’s magnetic field is about one-half Gauss. The researchers plan to compare their observations to computer simulations. They also hope to gather more observations as the sun ramps up in its 11-year cycle toward a maximum of magnetic activity in 2013, which should provide many more examples of sunspots to behold.