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Interrogating Solar Flare Loop Models with IRIS Observations 2: Plasma Properties, Energy Transport, and Future Directions
Kerr, Graham S.
During solar flares a tremendous amount of magnetic energy is released and transported through the Sun's atmosphere and out into the heliosphere. Despite over a century of study, many unresolved questions surrounding solar flares are still present. Among those are how does the solar plasma respond to flare energy deposition, and what are the impor…
Chromospheric thermodynamic conditions from inversions of complex Mg II h & k profiles observed in flares
De Pontieu, Bart; Sainz Dalda, Alberto
The flare activity of the Sun has been studied for decades, using both space- and ground-based telescopes. The former have mainly focused on the corona, while the latter have mostly been used to investigate the conditions in the chromosphere and photosphere. The Interface Region Imaging Spectrograph (IRIS) instrument has served as a gateway betwee…
Non-thermal Broadening of IRIS Fe XXI Line Caused by Turbulent Plasma Flows in the Magnetic Reconnection Region During Solar Eruptions
Reeves, Katharine K.; Polito, Vanessa; Chen, Bin +3 more
Magnetic reconnection is the key mechanism for energy release in solar eruptions, where the high-temperature emission is the primary diagnostic for investigating the plasma properties during the reconnection process. Non-thermal broadening of high-temperature lines has been observed in both the reconnection current sheet (CS) and flare loop-top re…
Multi-wavelength observations and modeling of a microflare: constraining non-thermal particle acceleration
Reeves, Katharine K.; Polito, Vanessa; Yu, Sijie +5 more
In this work we analyze a small B-class flare that occurred on 29 April 2021 and was observed simultaneously by the Interface Region Imaging Spectrograph (IRIS) and the Nuclear Spectroscopic Telescope Array (NuSTAR) X-ray instrument. The IRIS observations of the ribbon of the flare show peculiar spectral characteristics that are typical signatures…
The universality of power law slopes in the solar photosphere and transition region observed with HMI and IRIS
Aschwanden, Markus J.; Nhalil, Nived Vilangot
We compare the size distributions of self-organized criticality (SOC) systems in the solar photosphere and the transition region, using magnetogram data from Helioseismic and Magnetic Imager (HMI) and Interface Region Imaging Spectrograph (IRIS) data. For each dataset we fit a combination of a Gaussian and a power law size distribution function, w…
Multi-Scale Variability of Coronal Loops Set by Thermal Non-Equilibrium and Instability as a Probe for Coronal Heating
Antolin, Patrick; Froment, Clara
Solar coronal loops are the building blocks of the solar corona. These dynamic structures are shaped by the magnetic field that expands into the solar atmosphere. They can be observed in X-ray and extreme ultraviolet (EUV), revealing the high plasma temperature of the corona. However, the dissipation of magnetic energy to heat the plasma to millio…
Interrogating Solar Flare Loop Models with IRIS Observations 1: Overview of the Models, and Mass flows
Kerr, Graham S.
Solar and stellar flares are transient yet dramatic events in the atmospheres of the Sun or stars, during which vast amounts of magnetic energy is liberated. This energy is subsequently transported through the solar atmosphere or into the heliosphere, and together with coronal mass ejections flares comprise a fundamental component of space weather…
Solar Jets: SDO and IRIS Observations in the Perspective of New MHD Simulations
Schmieder, Brigitte
Solar jets are observed as collimated plasma beams over a large range of temperatures and wavelengths. They have been observed in H α and optical lines for more than 50 years and called surges. The term "jet" comes from X-ray observations after the launch of the Yohkoh satellite in 1991. They are the means of transporting energy through the helios…
Near-Ultraviolet Continuum Modeling of the 1985 April 12 Great Flare of AD Leo
Kowalski, Adam F.
White-light stellar flares are now reported by the thousands in long-baseline, high-precision, broad-band photometry from missions like \emph{Kepler}, K2, and TESS. These observations are crucial inputs for assessments of biosignatures in exoplanetary atmospheres and surface ultraviolet radiation dosages for habitable zone planets around low-mass …
Rapid variations of Si IV spectra in a flare observed by interface region imaging spectrograph at a sub-second cadence
Polito, Vanessa; Yu, Sijie; De Pontieu, Bart +2 more
We report on observations of highly-varying Si IV 1402.77 Å line profiles observed with the Interface Region Imaging Spectrograph (IRIS) during the M-class flare from 2022 January 18 at an unprecedented 0.8 s cadence. Moment analysis of this line observed in flare ribbon kernels showed that the intensity, Doppler velocity, and non-thermal broadeni…