Search Publications
Patches of Magnetic Switchbacks and Their Origins
de Wit, Thierry Dudok; Velli, Marco; Bale, Stuart D. +18 more
Parker Solar Probe (PSP) has shown that the solar wind in the inner heliosphere is characterized by the quasi omnipresence of magnetic switchbacks ("switchback" hereinafter), local backward bends of magnetic field lines. Switchbacks also tend to come in patches, with a large-scale modulation that appears to have a spatial scale size comparable to …
Solar Flare Heating with Turbulent Suppression of Thermal Conduction
Gordon Emslie, A.; Kerr, Graham S.; Allred, Joel C.
During solar flares, plasma is typically heated to very high temperatures, and the resulting redistribution of energy via thermal conduction is a primary mechanism transporting energy throughout the flaring solar atmosphere. The thermal flux is usually modeled using Spitzer's theory, which is based on local Coulomb collisions between the electrons…
Another Look at Erupting Minifilaments at the Base of Solar X-Ray Polar Coronal "Standard" and "Blowout" Jets
Panesar, Navdeep K.; Moore, Ronald L.; Sterling, Alphonse C.
We examine 21 solar polar coronal jets that we identify in soft X-ray images obtained from the Hinode/X-ray telescope (XRT). We identify 11 of these as blowout jets and four as standard jets (with six uncertain), based on their X-ray-spire widths being respectively wide or narrow (compared to the jet's base) in the XRT images. From corresponding e…
SolO/EUI Observations of Ubiquitous Fine-scale Bright Dots in an Emerging Flux Region: Comparison with a Bifrost MHD Simulation
Tiwari, Sanjiv K.; De Pontieu, Bart; Berghmans, David +2 more
We report on the presence of numerous tiny bright dots in and around an emerging flux region (an X-ray/coronal bright point) observed with SolO's EUI/HRIEUV in 174 Å. These dots are roundish and have a diameter of 675 ± 300 km, a lifetime of 50 ± 35 s, and an intensity enhancement of 30% ± 10% above their immediate surroundings. About h…
A Comparative Analysis of Machine-learning Models for Solar Flare Forecasting: Identifying High-performing Active Region Flare Indicators
Brandenburg, Axel; Nandy, Dibyendu; Srivastava, Nandita +9 more
Solar flares create adverse space weather impacting space- and Earth-based technologies. However, the difficulty of forecasting flares, and by extension severe space weather, is accentuated by the lack of any unique flare trigger or a single physical pathway. Studies indicate that multiple physical properties contribute to active region flare pote…
An Improved Magnetohydrodynamic Simulation of the 2006 December 13 Coronal Mass Ejection of NOAA Active Region 10930
Fan, Yuhong
We present a magnetohydrodynamic simulation of the coronal mass ejection on 2006 December 13 in the emerging δ-sunspot NOAA Active Region 10930, improving upon a previous simulation by Fan as follows. (1) Incorporate an ambient solar wind instead of using a static potential magnetic field extrapolation as the initial state. (2) In addition to impo…
The Rotation of Magnetic Flux Ropes Formed during Solar Eruption
Wang, Yuming; Liu, Rui; Jiang, Chaowei +3 more
Eruptions of solar filaments often show rotational motion about their rising direction, but the mechanism governing such rotation, and how the rotation is related to the initial morphology of the preeruptive filament (and cospatial sigmoid), filament chirality, and magnetic helicity, remains elusive. The conventional view of rotation as a result o…
Plasma Composition Measurements in an Active Region from Solar Orbiter/SPICE and Hinode/EIS
Teriaca, Luca; Schmutz, Werner; Warren, Harry P. +28 more
A key goal of the Solar Orbiter mission is to connect elemental abundance measurements of the solar wind enveloping the spacecraft with extreme-UV (EUV) spectroscopic observations of their solar sources, but this is not an easy exercise. Observations from previous missions have revealed a highly complex picture of spatial and temporal variations o…
Simultaneous Observations of Chromospheric Evaporation and Condensation during a C-class Flare
Li, Dong; Hong, Zhenxiang; Ning, Zongjun
We explored simultaneous observations of chromospheric evaporation and condensation during the impulsive phase of a C6.7 flare on 2019 May 9. The solar flare was simultaneously observed by multiple instruments, i.e., the New Vacuum Solar Telescope (NVST), the Interface Region Imaging Spectrograph, the Atmospheric Imaging Assembly (AIA), Fermi, the…
Diagnostics of Non-Maxwellian Electron Distributions in Solar Active Regions from Fe XII Lines Observed by the Hinode Extreme Ultraviolet Imaging Spectrometer and Interface Region Imaging Spectrograph
Mason, H. E.; Del Zanna, G.; Testa, P. +3 more
We present joint Hinode Extreme Ultraviolet Imaging Spectrometer (EIS) and Interface Region Imaging Spectrograph (IRIS) observations of Fe XII lines in active regions, both on-disk and off-limb. We use an improved calibration for the EIS data, and find that the 192.4 Å/1349 Å observed ratio is consistent with the values predicted by CHIANTI and th…