Plasma composition measurements in an active region from Solar Orbiter/SPICE and Hinode/EIS

Abstract

A key goal of the Solar Orbiter mission is to connect elemental abundance measurements of the solar wind enveloping the spacecraft with EUV spectroscopic observations of their solar sources, but this is not an easy exercise. Observations from previous missions have revealed a highly complex picture of spatial and temporal variations of elemental abundances in the solar corona. We have used coordinated observations from Hinode and Solar Orbiter to attempt new abundance measurements with the SPICE (Spectral Imaging of the Coronal Environment) instrument, and benchmark them against standard analyses from EIS (EUV Imaging Spectrometer). We use observations of several solar features in AR 12781 taken from an Earth-facing view by EIS on 2020 November 10, and SPICE data obtained one week later on 2020 November 17; when the AR had rotated into the Solar Orbiter field-of-view. We identify a range of spectral lines that are useful for determining the transition region and low coronal temperature structure with SPICE, and demonstrate that SPICE measurements are able to differentiate between photospheric and coronal Mg/Ne abundances. The combination of SPICE and EIS is able to establish the atmospheric composition structure of a fan loop/outflow area at the active region edge. We also discuss the problem of resolving the degree of elemental fractionation with SPICE, which is more challenging without further constraints on the temperature structure, and comment on what that can tell us about the sources of the solar wind and solar energetic particles.

To be published in The Astrophysical Journal

References in corpus (14)

• The Solar Orbiter mission -- Science overview
• CHIANTI -- an atomic database for emission lines -- Paper XVI: Version 10, further extensions
• The elemental composition of the Sun II. The iron group elements Sc to Ni
• The elemental composition of the Sun I. The intermediate mass elements Na to Ca
• Flows and Non-thermal Velocities in Solar Active Regions Observed with the Extreme-ultraviolet Imaging Spectrometer on Hinode: A Tracer of Active Region Sources of Heliospheric Magnetic Fields?
• Element Abundances: A New Diagnostic for the Solar Wind
• Modelling of EIS spectrum drift from instrumental temperatures
• Generic magnetic field intensity profiles of interplanetary coronal mass ejections at Mercury, Venus and Earth from superposed epoch analyses
• The source of the major solar energetic particle events from super active region 11944
• The drivers of active region outflows into the slow solar wind
• Linking the Sun to the Heliosphere Using Composition Data and Modelling. A Test Case with a Coronal Jet
• Elemental composition in quiescent prominences
• Magnetic Field Geometry and Composition Variation in Slow Solar Winds: The Case of Sulfur
• Signature and escape of highly fractionated plasma in an active region