Solar Flare Irradiance: Observations and Physical Modeling
arXiv:2110.06310 · doi:10.3847/1538-4357/ac4784
Abstract
We examine SDO/EVE data to better understand solar flare irradiance, and how that irradiance may vary for large events. We measure scaling laws relating GOES flare classes to irradiance in 21 lines measured with SDO/EVE, formed across a wide range of temperatures, and find that this scaling depends on the line formation temperature. We extrapolate these irradiance values to large events, exceeding X10. In order to create full spectra, however, we need a physical model of the irradiance. We present the first results of a new physical model of solar flare irradiance, NRLFLARE, that sums together a series of flare loops to calculate the spectral irradiance ranging from the X-rays through the far ultraviolet (~ 0 to 1250 Angstroms), constrained by GOES/XRS observations. We test this model against SDO/EVE data. The model spectra and time evolution compares well in high temperature emission, but cooler lines show large discrepancies. We speculate that the discrepancies are likely due to both a non-uniform cross section of the flaring loops as well as opacity effects. We then show that allowing the cross-sectional area to vary with height significantly improves agreement with observations, and is therefore a crucial parameter needed to accurately model the intensity of spectral lines, particularly in the transition region from 4.7 < log T < 6.0.
Accepted to ApJ
References in corpus (17)
- CHIANTI -- an atomic database for emission lines -- Paper XVI: Version 10, further extensions
- CHIANTI - an atomic database for emission lines - Paper XV: Version 9, improvements for the X-ray satellite lines
- Magnetic Properties of Solar Active Regions that Govern Large Solar Flares and Eruptions
- RH 1.5D: a massively parallel code for multi-level radiative transfer with partial frequency redistribution and Zeeman polarisation
- The Atmospheric Response to High Nonthermal Electron Beam Fluxes in Solar Flares I: Modeling the Brightest NUV Footpoints in the X1 Solar Flare of 2014 March 29
- Statistical Study of GOES X-ray Quasi-Periodic Pulsations in Solar Flares
- KAPPA: A Package for Synthesis of optically thin spectra for the non-Maxwellian kappa-distributions based on the CHIANTI database
- Inference of Heating Properties from "Hot" Non-flaring Plasmas in Active Region Cores I. Single Nanoflares
- Gas-dynamic shock heating of post-flare loops due to retraction following localized, impulsive reconnection
- Pulsations in the Earth's Lower Ionosphere Synchronized with Solar Flare Emission
- What determines the X-ray intensity and duration of a solar flare?
- The Lightweaver Framework for NLTE Radiative Transfer in Python
- Measurements of Coronal Magnetic Field Strengths in Solar Active Region Loops
- The direct relation between the duration of magnetic reconnection and the evolution of GOES light curves in solar flares
- Signatures of the non-Maxwellian -distributions in optically thin line spectra. II. Synthetic Fe XVII--XVIII X-ray coronal spectra and predictions for the Marshall Grazing-Incidence X-ray Spectrometer (MaGIXS)
- On the Area Expansion of Magnetic Flux-Tubes in Solar Active Regions
- Quantifying the Influence of Key Physical Processes on the Formation of Emission Lines Observed by IRIS: I. Non-Equilibrium Ionization and Density-Dependent Rates