Scientists in Japan have captured full-spectrum, two-dimensional (2D) auroral images using a newly developed Hyperspectral Camera for Auroral Imaging (HySCAI).
(a) All-sky camera and (b) HySCAI keograms, and (c) time evolution of the spatially averaged spectrum of auroral emission measured by HySCAI on October 20-21, 2023. Image courtesy of Yoshinuma others., doi: 10.1186/s40623-024-02039-y.
The aurora is a natural optical phenomenon caused by the interaction of precipitation particles with components of the upper atmosphere.
The majority of the observed spectrum consists of lines or bands of neutral and ionized nitrogen and oxygen atoms.
The aurora comes in a variety of distinctive colors, including green and red, but there are multiple theories about how the different auroras emit light, and understanding their colors requires breaking down the light.
To study the auroral radiation processes and colors in detail, comprehensive (temporal and spatial) spectral observations are required.
“We have observed light being emitted from plasma within the magnetic field of the Large Helical Device (LHD),” said Dr. Katsumi Ida of the National Institute for Fusion Science in Japan and his colleagues.
“Various systems have been developed to measure the spectrum of light emitted from plasmas, and the processes of energy transport and the emission of atoms and molecules have been studied.”
“By applying this technology and knowledge to auroral observations, we can contribute to our understanding of auroral luminescence and to research into the electron energy generation process that produces auroral luminescence.”
The newly developed camera, HySCAI, consists of an all-sky lens, a monitor camera, a galvanometer scanner, a grating spectrometer, and an electron-multiplying charge-coupled device.
“Aurora observations use optical filters to capture images of specific colors, but this has the drawback of limited wavelengths and low resolution,” the researchers said.
“On the other hand, hyperspectral cameras have the advantage of being able to obtain the spatial distribution of the spectrum with high wavelength resolution.”
“In 2018, we started a project to develop a high-sensitivity hyperspectral camera by combining an image sweeping optical system using a galvanometer mirror with the EMCCD camera and lens spectrometer used in the LHD.”
“It took five years of planning to develop a system with the sensitivity to measure auroras down to 1kR (1 kiloraylei).”
“The system was installed in May 2023 at the Swedish Space Corporation's Esrange Space Centre in Kiruna, Sweden, which is located directly below the auroral zone and where auroras can be observed frequently.”
“The system successfully captured hyperspectral images of the aurora, i.e. two-dimensional images resolved by wavelength.”
Team work Published in the journal Earth, planets, space.
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Masayuki Yoshinuma others2024: Development of a hyperspectral camera for photographing the aurora (HySCAI). Earth Planet Space 76, 96; doi: 10.1186/s40623-024-02039-y
Source: www.sci.news
