Testing, Comparing, and Validating an L1 Method for Abundances Derivations from EUV Spectra
Year: 2026
Type: article
Abstract: Element abundances found in the solar corona and solar wind are often different from those measured in the solar photosphere, and the fractionation mechanisms are thought to be intimately tied to the physical processes leading to coronal heating and acceleration of the solar wind. The complexity of the data and the methods used to invert underconstrained problems and thus estimate abundances make it challenging to identify and study these mechanisms. In this work, we present an L1-norm inversion method to derive abundances from coronal spectral observations. We explored a variety of approaches, considering different sets of inverted variables (e.g., including the abundance of Si, S, and Fe, as separate independent variables), and we tested and validated them using synthetic data from numerical radiative MHD models. In addition, we investigated the effects of bound-free absorption from neutral hydrogen and helium on the method and Poisson noise. We discuss the advantages and limitations of the various inversion approaches presented.
Source: The Astrophysical Journal
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $4,499
Awards: G1097075911, G1241265189, G1620805660, G407070428, G5645059712, THE PROPOSED INVESTIGATION ADDRESSES THE PROBLEM OF SOLAR ATMOSPHERIC HEATING VIA STUDYING NON-THERMAL DYNAMICS DURING SMALL SCALE MAGNETIC RECONNECTION IN THE TRANSITION REGION. NON-THERMAL ENERGY IS CONSIDERED TO BE A SUBSTANTIAL FRACTION OF THE TOTAL ENERGY RELEASED BY MAGNETIC RECONNECTION AND STUDIES OF LARGE-SCALE EVENTS SUCH AS SOLAR FLARES HAVE CONFIRMED THIS POINT. WITH THE UNPRECEDENTED SPATIAL AND TEMPORAL RESOLUTION OF IRIS WE ARE NOW ABLE TO INVESTIGATE NON-THERMAL DYNAMICS IN SMALL-SCALE RECONNECTION-DRIVEN EVENTS. SUCH EVENTS ARE UBIQUITOUS ON THE SUN AND CONSIDERED AS A POSSIBLE ENERGY SOURCE FOR HEATING THE LOW SOLAR ATMOSPHERE; AND NON-THERMAL ENERGY PRODUCED DURING THESE EVENTS COULD CONTRIBUTE ADDITIONALLY TO THE LOCAL THERMAL AND KINETIC ENERGY BALANCE. NON-THERMAL DYNAMICS OFTEN MANIFEST THEMSELVES AS IMPULSIVE BRIGHTENINGS. WE WILL USE THE IRIS INSTRUMENT TO IDENTIFY COLLIMATED BRIGHTENINGS ORIGINATED FROM SMALL-SCALE RECONNECTION SITES WHICH APPEAR TO BE JET LIKE WITH A PLANE-OF-THE-SKY APPARENT VELOCITY (MORE THAN 1000 KM/S) SIGNIFICANTLY HIGHER THAN THE LOCAL ALFVEN SPEED (ESTIMATED TO BE WITHIN 200-450 KM/S IN THE UPPER CHROMOSPHERETRANSITION REGION). THEY ARE POSSIBLY CONSEQUENCES OF NON-THERMAL DYNAMICS BECAUSE IT IS UNLIKELY FOR LOCAL PLASMA TO ACTUALLY MOVE AT SUCH HIGH SPEEDS. OBSERVATIONS OF SUCH SUPER-ALFVENIC JETS FROM IRIS DATA WERE REPORTED IN OUR PRELIMINARY WORK AND WE PROPOSED THAT THE OBSERVATION COULD BE DUE TO ENERGETIC ELECTRON BEAMS WHICH ORIGINATE IN RECONNECTION SITES AND DEPOSIT THEIR ENERGY IN SOLAR ATMOSPHERE. WE PROPOSE TO CONDUCT NUMERICAL EXPERIMENTS TO TEST THE PROPOSED SCENARIO OF NON-THERMAL HEATING. WE WILL USE HIGH-RESOLUTION MHD SIMULATIONS OF A THREE-DIMENSIONAL RECONNECTION SITE LARGE-SCALE RADIATIVE MHD SIMULATIONS BOTH ALONG WITH A PARTICLE TRACER CODE TO INVESTIGATE THE PRODUCTION OF ENERGETIC ELECTRON BEAMS. THE RESULTS OF THESE SIMULATIONS WILL THEN BE USED: (1) TO SYNTHESIZE SLIT-JAW AND SPECTRAL DATA AND COMPARE WITH IRIS OBSERVATIONS; AND (2) AS THE INPUT TO THE RADIATIVE-HYDRODYNAMIC RADYN CODE TO INVESTIGATE THE DEPOSITION OF THE NON-THERMAL ENERGY CARRIED BY ELECTRON BEAMS INTO THEIR SURROUNDING PLASMA AS THEY TRAVEL AND COMPARE RESULTS WITH IRIS OBSERVATIONS. WE WILL OBTAIN STATISTICS OF SUCH EVENTS BY COLLECTING AND ANALYZING OBSERVATIONS OF SUPER-ALFVENIC JETS. THE COMPARISON BETWEEN THESE OBSERVATIONS AND THE SIMULATIONS WILL PROVIDE INSIGHTS INTO THE OBSCURE NON-THERMAL PROCESS IN THE TRANSITION REGION., G8605206908
OpenAlex ID: W7225407090