It's not a dawn, it's STEVE

Aurora observers who watched spectacular displays during the Labor Day weekend may have seen more than the northern lights. STEVE may have dazzled them.

STEVE is an abbreviation for "Strong Thermal Emissions Velocity Enhancement", a celestial phenomenon for researchers, citizen-scientists, and dawn photography enthusiasts who introduced themselves to the world in 2016.

STEVE's narrow ribbon of light, to the naked eye, strangely resembles a dawn. However, there are distinct differences. First, its pink mauve color does not look like a dawn. In addition, the phenomenon is often associated with "palissade" emissions, which look like columns of green light crossing the ribbons at lower altitudes. Finally, STEVE appears in areas further south than auroral lights.

Scientists thought something was wrong.

This summer, researchers confirmed that STEVE was not a dawn, but a unique phenomenon. Their conclusions were published in the journal Geophysical Research Letters.

"The important thing is that we can clearly say that this is not a normal aurora," said Don Hampton, a researcher at the University of Alaska Fairbanks, co-author of the newspaper. "It's a new phenomenon, it's pretty exciting."

The project, led by DM researcher at the University of Calgary Gillies used a spectrograph to examine the light of the phenomenon and identify the type of emissions that it generates, as well as patterns and lengths d & # 39; wave. Hampton and his colleagues designed and built the spectrograph at the Institute of Geophysics of the UAF.

"We need to understand what the spectrum looks like and therefore understand the physics behind it," Hampton said. A spectrum acts as a definitive identification, such as a DNA test or a chemical formula for light.

When scientists looked at the spectrum of STEVE, they saw something unique. Aurora has individual wavelengths and acts as a neon sign. In the aurora, the electrons of our magnetosphere fly downwards, colliding with the atoms and molecules of our atmosphere, which excites them. Once the excited particles relax, they emit photons, which can be seen as specific wavelengths of light. Depending on the colors you see, you know that some lights come from a nitrogen molecule and some from other oxygen.

"When we looked at the spectrum of STEVE, it did not show any of these distinct wavelengths," Hampton said. "Instead, it's a very broad band of light, so all the wavelengths are as loud as one."

This means that light does not come from atoms and molecules colliding in the atmosphere, but from something very hot – perhaps thousands of degrees.

"When you turn on your electric stove, the coils get hot, no? If you look at it with a spectrograph, you will see broadband broadcasts," Hampton said. "So it's like a kind of show in a very, very hot atmosphere."

The research also concluded that picket fence emissions resemble a typical aurora structure. These are caused by the same types of particle precipitation that are usually observed with the auroras.

Like Aurora Borealis, the appearances of STEVE vary considerably, ranging from weeks to months apart.

Scientists have been studying the hot particles associated with STEVE since the 1970s. However, they have not realized until recently that they were producing a visible feature.

Confirming the existence of a celestial phenomenon is exciting, said Hampton. The next, more difficult step is to find out what causes it and how it affects us.

Any perturbation of the upper atmosphere, such as a dawn, can affect radio communications between the Earth and a spacecraft. STEVE is particularly interesting because it is an important input of local energy, but it is clearly not a normal aurora.

"As a new phenomenon, we want to understand not only why and how it is created, but also how it affects our infrastructure," said Hampton. "We do not think that if we understand how STEVE is created, we will cure cancer or produce a chain drive (although we never know it), but we want to understand how part of the ionosphere works, what which could help overall, as well as some practical understanding to reduce the impact on other aspects of our daily lives.