Study Shows How Sunspots Form

In a new investigation, researchers were able to gain more insight into the processes and phenomena that eventually lead to the formation of dark spots on the Sun. These so-called sunspots were mysterious until not long ago, but now experts say they known more about them than ever.

The research team that carried out the new work says that it was able to arrive at the new conclusions after an in-depth analysis of sunspot edges. This is what allowed them to derive key details of how these formations develop.

The most important thing that separates sunspots from their surroundings is their color. They appear darker when viewed through specialized instruments because they are cooler than other solar regions.

Past investigations have demonstrated that intense magnetic activity on and beneath the surface of the Sun can lead to this cooling, by isolating the region from the usual flow of hot matter. However, experts failed to explain the behavior and structure of sunspots until now.

What this study determined was that the explanations seeking to shed light on sunspots via convective flow theories are correct. Each of these solar structures is divided into a darker region called the umbra, and a brighter area around the edges, called the penumbra.

Throughout the latter, countless 1,200-mile (2,000-kilometer) long filaments alternate between bright and dark colors. Thus far, it has been difficult to analyze these structures, on account of the fact that they are only 150 kilometers (90 miles) wider.

Solar physicists have proposed years ago that a type of movement present in gases, called convective flow, may be driving the rapid motions these filaments are displaying. The structures themselves are produced by downflows and upflows of gas, hence the color.

In a study focused on a sunspot that appeared on the Sun in 2010, experts measured downflow speeds reaching 2,200 miles per hour (3,600 kilometers per hour), Upflows were determined to reach speeds of 6,600 miles per hour (10,800 kilometers per hour), Space reports.

“This is what we have been expecting to find, but we were maybe surprised about actually succeeding in seeing these flows,” Royal Swedish Academy of Sciences / Stockholm University solar physicist and researcher Göran Scharmer says.

The expert and his team published details of their work in the June 2 online issue of the top journal Science.