Baker, D;
Van Driel-Gesztelyi, L;
Brooks, DH;
Valori, G;
James, AW;
Laming, JM;
Long, DM;
... Kovari, Z; + view all
(2019)
Transient inverse-FIP plasma composition evolution within a confined solar flare.
Astrophysical Journal
, 875
(1)
10.3847/1538-4357/ab07c1.
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Abstract
Understanding elemental abundance variations in the solar corona provides an insight into how matter and energy flow from the chromosphere into the heliosphere. Observed variations depend on the first ionization potential (FIP) of the main elements of the Sun’s atmosphere. High-FIP elements (>10 eV) maintain photospheric abundances in the corona, whereas low-FIP elements have enhanced abundances. Conversely, inverse FIP (IFIP) refers to the enhancement of high-FIP or depletion of low-FIP elements. We use spatially resolved spectroscopic observations, specifically the Ar XIV/Ca XIV intensity ratio, from Hinode’s Extreme-ultraviolet Imaging Spectrometer to investigate the distribution and evolution of plasma composition within two confined flares in a newly emerging, highly sheared active region. During the decay phase of the first flare, patches above the flare ribbons evolve from the FIP to the IFIP effect, while the flaring loop tops show a stronger FIP effect. The patch and loop compositions then evolve toward the pre-flare basal state. We propose an explanation of how flaring in strands of highly sheared emerging magnetic fields can lead to flare-modulated IFIP plasma composition over coalescing umbrae which are crossed by flare ribbons. Subsurface reconnection between the coalescing umbrae leads to the depletion of low-FIP elements as a result of an increased wave flux from below. This material is evaporated when the flare ribbons cross the umbrae. Our results are consistent with the ponderomotive fractionation model (Laming 2015) for the creation of IFIP-biased plasma.
| Type: | Article |
|---|---|
| Title: | Transient inverse-FIP plasma composition evolution within a confined solar flare |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.3847/1538-4357/ab07c1 |
| Publisher version: | http://doi.org/10.3847/1538-4357/ab07c1 |
| Language: | English |
| Additional information: | Copyright © 2019. The American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. |
| Keywords: | Sun: abundances - Sun: corona - Sun: magnetic fields |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Space and Climate Physics |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10068399 |
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