Outreach
Vortices from our daily lives
We see vortices in nature all the time. It might be the swirling motion that we create in the morning when stirring our spoon to prepare coffee/tea. Or when we see the water flow in a creek, creating small swirls. Vortices can also appear as gigantic structures, such as the tornados we observe on Earth which have a radius around thousand kilometers. The vortices can be defined as a rotating column of flow (air, water or other liquids). As they rotate, vortices can help mix the material in the flow, such as in the vortex case or can be so powerful that they destroy entires buildings when they cross a city. Once trapped in a vortex, it might not be easy to escape. And this leads to vortex as a way to carry material (for example seeds in the tornado case) across a state.
Vortices in the Solar System
Other planets also present tornadoes, one example is the so called Jupyter's Great Red Spot, which is a tornado so large that could encompass around 6 Earths and has been going on for at least 300 hundred years. The Great Red Spot rotates in the counter-clockwise direction and it takes 4.5 Earth's day to make a complete turn. And that is not the only tornado outside Earth.
On the left a close view of Jupiter's Great Red Spot and on the right vortices detected in Jupiter and other planets in our solar system. (Credit: Wikipedia)
The solar vortices
Our Sun also has tornadoes which are rotating column of plasma that can go from the solar surface all the way to the upper atmosphere. And we know solar tornadoes exist because they leave "signatures" at different heights of the solar atmosphere as illustrate in the image below.
Solar tornadoes: The first panel shows an observation of a solar tornado which consists on a rapidly rotating column of plasma. The middle column show how that tornado is observed across the solar atmosphere; close to the solar surface, it concentrates the magnetic field and it is rooted along the dark lanes. And in the chromosphere, the rotating column of plasma is observed as circular or elliptical darker rings. The third column shows a simulation made by Wedemeyer et al. 2012 and it depicts the rotating column of plasma as twisted velocity field lines connecting the solar surface on bottom to the upper atmosphere on the top of the tornado. (Credit: Solar Dynamic Observatory (SDO) satellite, Wedemeyer et al. 2012 )
The Sun also present smaller vortices that are not easy to directly observe. It is believed that almost 3% of the solar surface is covered by vortices. And at all times, there are around 11000 tornadoes in the solar atmosphere.
Solar vortices are important because they help to explain a long-standing question in the solar physics: The coronal heating problem. First, imagine you are close to a fireplace that is on and running on its maximum capacity. You would feel warm, right? Now, if you move away from the fireplace, the temperature drops. As you move away from the core of the Sun, where the heat is produced, initially the same thing happens, i.e., the temperature drops. Now, somewhere in the middle of the solar atmosphere the temperature start to rise dramatically, even though it is away from the source of energy. This is the coronal heating problem. The solar physicians are investigating the Sun to understand how the upper solar atmosphere is being heat up to temperatures more than a hundred times higher than the temperatures observed in the solar surface. And so far, studies have shown that the solar vortices are able to produce, transport and dissipate the necessary energy to explain such high temperatures.
Solar vs Earth Tornadoes
Average diameter size:
Sun: 120 to 2600 miles
Earth: between 60 and 1300 miles
Lifetime:
Sun: 0.29 min to a couple of hours
Earth: Usually 12 to 24 hours
Typical velocities:
Sun: 5,600 mph
Earth: Category 5: 157 mph or higher