Understanding how elemental abundances vary with time in the solar atmosphere

Elemental abundance patterns are tracers of physical processes throughout the universe, with the cosmic reference standard being the solar chemical composition. Understanding how the Sun's chemical composition varies in time and space provides insight into how mass and energy flow through the Sun's atmosphere into the solar wind, and in turn, through the atmospheres of solar-like stars into stellar winds. The Sun mainly consists of hydrogen and helium, with trace amounts of heavier elements. Although its atmosphere (corona) should have the same elemental abundances as the surface (photosphere), easily ionized elements are enhanced by a factor 2-4 in the corona compared to their photospheric abundances; behavior known as the first ionisation potential (FIP) effect. Recent spectroscopic observations of the Sun have shown that the spatial and temporal variability of coronal composition is intrinsically linked to the evolution of the solar magnetic field. How variations in the coronal composition relate to changes in the magnetic field provides clues to the origin of solar activity (flares, jets) and the solar wind. One of the primary goals of the upcoming Solar Orbiter mission (due to launch in 2020) will be to establish the origin of the solar wind using these plasma properties.

The aim of this project is to exploit the more than 12 years of spectroscopic observations of the solar corona from the joint UK-NASA-JAXA (Japanese Aerospace Exploration Agency) Extreme-ultraviolet Imaging Spectrometer (EIS) instrument onboard the Hinode ("Sunrise" in Japanese) spacecraft. This unprecedented, yet underutilised, archive provides a unique opportunity to conduct the first statisticallysignificant study of the physical processes which govern variation in composition and elemental abundance across a range of spatial and temporal scales. The project will involve learning spectroscopic analysis techniques, analysing "big data" from a large archive, proposing and obtaining new observations with Hinode/EIS in Japan and combining the spectral data with imaging and magnetic field data using state-of-the-art techniques. This will provide an opportunity to advance scientific understanding and techniques in preparation for the launch of Solar Orbiter, an ESA-led mission with strong involvement from UCL/MSSL and the Solar-C mission currently being proposed to JAXA. The project will also involve close collaboration with international experts from Japan and the USA.