Observations of Slow Elemental Abundance Decay in Association to CME
| Nugget | |
|---|---|
| Number: | 524 |
| 1st Author: | Saara TAKALA |
| 2nd Author: | |
| Published: | April 27, 2026 |
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Introduction
The abundances of the elements constituting the solar atmosphere can vary with position, and vary with time as well. The causes of these variations depend upon physical conditions, and precise measurements of the elemental distribution can help to understand these structures and their dynamics. See Figure 1 for a snapshot of the complexity of the corona); this shows the state of the corona after the flare/CME event discussed here.
The most powerful perturbations of the solar atmosphere are [solar flares] and coronal mass ejections. Over the past decades, notable relationships have been reported between these phenomena. Flares are known to affect the plasma composition near the flare site, temporarily reducing or increasing the abundances of certain elements during the event (Ref. [1]), but the effects of associated CMEs on these spectral signatures have yet to be determined.
The focus of our study (Ref. [2]) was the eruptive event SOL2024-06-24 from Active Region (AR) 13712, where a CME was observed in association with a long-duration M1 flare. The event was characterized by long-lasting post-eruption loops rising high above the solar surface. We investigate the temporal evolution of elemental abundances during the event from spectral fits to SUNSTORM 1 data, and analyze the results in relation to the CME.
Observations
SUNSTORM 1 was a two-unit low-Earth orbit CubeSat carrying the XFM-CS instrument, a spectrometer measuring solar X-ray emission in a wide dynamic range [3]. These data clearly resolve K-shell emissions from several elements. These direct 2->1 transitions directly reflect the elemental abundances. We analyzed the spectra from the flare in the 1-12 keV range via a two-temperature model with variable abundances. SUNSTORM observations are complemented by EUV observations from SDO AIA, Solar Orbiter FSI/EUI and STEREO-A EUVI (Figure 1). Additionally, we use imaging results from Solar Orbiter STIX to investigate the evolution of the X-ray source during the event.
Results
Spectral fitting results show a depletion in elemental abundances for Al, Ca, Mg, Fe, Si and S after CME liftoff, while Ar increased slightly. Hours after the eruptive event, recovery back to pre-eruption levels was not observed for any of the elements (Figure 2).
The STIX 6-10 keV images reveal the dominant source of emission during the event to have been a large, expanding coronal loop-top source (Figure 3). Prominent emission can be observed at the top of the loops for hours after the CME eruption.
References
[1] "The FIP and Inverse-FIP Effects in Solar Flares"
[3] "SUNSTORM 1/X-ray Flux Monitor for CubeSats (XFM-CS): Instrument characterization and first results"