Revealing the Multi-Color Image of the Aurora Borealis with Hyperspectral Imageries

 

For the first time in history, scientists have successfully taken the first 2D spectral image of the auroral oval using a hyperspectral camera recently created by the National Institute for Fusion Science. This has provided scientists with this highly advanced technology to explain the color variations of the aurora in detail.  

Auroras are impressive light phenomena that are observed when the particles are accelerated and start to interact with the upper atmosphere, exciting it to emit photons of different colors. These colors are mainly the raw emission lines of nitrogen and oxygen, NI and OI, and molecular bands. They, therefore, depend on the transition energy levels, molecular vibration, as well as rotations.  

Even though the aurora borealis is famous for its qualities of having green and red hues, there is much more to color than might meet the eye; a comprehensive spectral study is needed. Traditional methods of using filter optical show some restrictions when measuring the wavelengths. On the other hand, hyperspectral includes the spatial distribution of the spectrum with high WRS that acquires detailed images of auroras based on colors. 

This hyperspectral camera was the result of a process started in 2018 and was built using the techniques used in the plasma emission analysis of the Large Helical Device (LHD). Scientists were able to use a lens spectrometer, an EMCCD camera, and an image sweep optical system to come up with a system that detects auroras at low intensities.  

Pumped up at the KEOPS station in the Esrange Space Center of the Swedish Space Corporation in Kiruna, Sweden, this system was able to capture hyperspectral scenes of the auroras in May of the year 2023. These observations began in September 2023; data in Japan was remotely collected.   

This breakthrough has a wide-spread meaning for auroral analysis. Whereas previously scientists were only able to collect electron data based on the existing wavelengths, it has now become possible to specify the energy levels of the incoming electrons through the ratios of the intensities of a range of wavelengths. 

Hyperspectral camera (HySCAI) While imaging the auroral events, the scanner was able to estimate electron energy to be around 1,600 electron volts, which is consistent with the former data.  The advantages of the presented work lie in the fact that HySCAI enables one to make precise descriptions of the distribution of the auroral colors in space and thus constitutes a significant step in studying these natural manifestations.

In addition, it reveals information concerning the coupling of charged particles with waves in a magnetic field, a question asked in both auroral and fusion plasma physics sciences.  As we progress, more people will directly get interdisciplinary training apart from universities and research institutes in different parts of the world, accordingly enhancing the understanding of auroral science and, in general, energy transportation through space and plasma domains.