Almost 80 years have passed since Bengt Edlén identified the strong Fe X red line in the spectrum of the solar corona. This discovery gave rise to an entirely new field of the solar physics – physics of the solar corona, which is advancing today owing, in particular, to the space-borne observations in EUV and X-ray spectral ranges. In contrast with imaging observations, spectroscopic observations are capable of almost directly inferring the information about plasma parameters, such as temperatures, densities, abundances, and so on. During more than 50 years of space experiments, various coronal structures have been analyzed in detail, from quiet coronal loops with one-million Kelvin plasma, to dynamic flaring plasma with temperatures of tens of million Kelvin. However, these observations turned out to be important not only for the fundamental understanding of solar processes but also had their impact on understanding the planetary and interplanetary environment, supported the progress in atomic and plasma physics.
Every spectroscopic instrument is based on a particular combination of optical elements and layout, each with its own advantages and limitations. As an example, for the X-ray spectral region well suitable for diagnostics of flaring plasma, a crystal-based or solid-state resolving elements are often used. Limited imaging capabilities of these instruments are compensated by the rare occurrence of flares and their spatial compactness. The slit spectrometers and spectrographs operating in the UV and EUV passbands were usually based on diffraction gratings and equipped with feeding telescopes, making it possible to study small-scale and not-so-bright structures of the solar corona. Full-Sun spectrographs and photometers, with no spatial resolution, usually covered a large spectral region and provide high temporal cadence, allowing the study of the connection between different layers of the solar atmosphere during dynamic events such as flares. This classification of instruments was dictated by the technical capabilities available at that time.
Recent advances in the field of instrumentation, such as availability of high spatial-resolution detectors, advances in the optical systems and high-performance mirrors, increased on-board computational capabilities, as well as rapid growth and affordability of cube-sats, etc., provide further possibilities to build spectroscopic devices with better characteristics and of new types. These new instruments have the potential to be definite improvements over the traditionally used instrumentation, giving the openings to new discoveries.
This Research Topic is devoted to the new spectroscopic instruments, approaches, and accompanying technologies under preparation. We invite researchers to publish Original Research and Review articles on the key themes that include, but are not limited to:
i) Advanced concepts and designs of new spectroscopic instrumentation, which have been recently launched, are scheduled to be launched or are in a planning phase.
ii) Description of technologies and/or design solutions that provide new possibilities for spectroscopic observations.
iii) Scientific questions that can be tackled with the use of spectroscopic approach/spectroscopic data, potential direction for further progress.
iv) New theoretical models and approaches which can provide further progress in solar physics and adjacent fields.
Almost 80 years have passed since Bengt Edlén identified the strong Fe X red line in the spectrum of the solar corona. This discovery gave rise to an entirely new field of the solar physics – physics of the solar corona, which is advancing today owing, in particular, to the space-borne observations in EUV and X-ray spectral ranges. In contrast with imaging observations, spectroscopic observations are capable of almost directly inferring the information about plasma parameters, such as temperatures, densities, abundances, and so on. During more than 50 years of space experiments, various coronal structures have been analyzed in detail, from quiet coronal loops with one-million Kelvin plasma, to dynamic flaring plasma with temperatures of tens of million Kelvin. However, these observations turned out to be important not only for the fundamental understanding of solar processes but also had their impact on understanding the planetary and interplanetary environment, supported the progress in atomic and plasma physics.
Every spectroscopic instrument is based on a particular combination of optical elements and layout, each with its own advantages and limitations. As an example, for the X-ray spectral region well suitable for diagnostics of flaring plasma, a crystal-based or solid-state resolving elements are often used. Limited imaging capabilities of these instruments are compensated by the rare occurrence of flares and their spatial compactness. The slit spectrometers and spectrographs operating in the UV and EUV passbands were usually based on diffraction gratings and equipped with feeding telescopes, making it possible to study small-scale and not-so-bright structures of the solar corona. Full-Sun spectrographs and photometers, with no spatial resolution, usually covered a large spectral region and provide high temporal cadence, allowing the study of the connection between different layers of the solar atmosphere during dynamic events such as flares. This classification of instruments was dictated by the technical capabilities available at that time.
Recent advances in the field of instrumentation, such as availability of high spatial-resolution detectors, advances in the optical systems and high-performance mirrors, increased on-board computational capabilities, as well as rapid growth and affordability of cube-sats, etc., provide further possibilities to build spectroscopic devices with better characteristics and of new types. These new instruments have the potential to be definite improvements over the traditionally used instrumentation, giving the openings to new discoveries.
This Research Topic is devoted to the new spectroscopic instruments, approaches, and accompanying technologies under preparation. We invite researchers to publish Original Research and Review articles on the key themes that include, but are not limited to:
i) Advanced concepts and designs of new spectroscopic instrumentation, which have been recently launched, are scheduled to be launched or are in a planning phase.
ii) Description of technologies and/or design solutions that provide new possibilities for spectroscopic observations.
iii) Scientific questions that can be tackled with the use of spectroscopic approach/spectroscopic data, potential direction for further progress.
iv) New theoretical models and approaches which can provide further progress in solar physics and adjacent fields.
