Search Publications
Radial evolution of interplanetary coronal mass ejection-associated particle acceleration observed by Solar Orbiter and ACE
Li, Gang; Kouloumvakos, Athanasios; Wimmer-Schweingruber, Robert F. +5 more
On 2022 March 10 a coronal mass ejection erupted from the Sun, resulting in Solar Orbiter observations at 0.45 au of both dispersive solar energetic particles arriving prior to the interplanetary coronal mass ejection (ICME) and locally accelerated particles near the ICME-associated shock structure as it passed the spacecraft on 2022 March 11. Thi…
Solar energetic particles injected inside and outside a magnetic cloud: The widespread solar energetic particle event on 2022 January 20
Palmerio, E.; Jebaraj, I. C.; Laitinen, T. +22 more
Context. On 2022 January 20, the Energetic Particle Detector (EPD) on board Solar Orbiter measured a solar energetic particle (SEP) event showing unusual first arriving particles from the anti-Sun direction. Near-Earth spacecraft separated by 17° in longitude to the west of Solar Orbiter measured classic anti-sunward-directed fluxes. STEREO-A and …
Deconstructing the Properties of Solar Super Active Region 13664 in the Context of the Historic Geomagnetic Storm of 2024 May 10–11
Nandy, Dibyendu; Jaswal, Priyansh; Sinha, Suvadip
Active regions (ARs) are sites of strong magnetic fields on the solar surface whose size can be several times that of Earth. They spawn dynamic activity, sometimes resulting in severe space weather. Some ARs characterized by extraordinary magnetic properties and exhibiting extreme activity are termed as super active regions (SARs). Recently, solar…
Shock and SEP Modeling Study for the 2022 September 5 SEP Event
Lario, D.; Jebaraj, I. C.; Mitchell, D. G. +10 more
On 2022 September 5, during Parker Solar Probe's (PSP) 13th encounter, a fast shock wave and a related solar energetic particle (SEP) event were observed as the spacecraft approached the perihelion of its orbit. Observations from the Integrated Science Investigation of the Sun (IS⊙IS) instrument suite show that SEPs arrived at the spacecraft with …
Determining the acceleration regions of in situ electrons using remote radio and X-ray observations
Jebaraj, I. C.; Vainio, R.; Kilpua, E. K. J. +13 more
Context. Solar energetic particles in the heliosphere are produced by flaring processes on the Sun or by shocks driven by coronal mass ejections. These particles are regularly detected remotely as electromagnetic radiation (X-rays or radio emission), which they generate through various processes, or in situ by spacecraft monitoring the Sun and the…
Differentiating the Acceleration Mechanisms in the Slow and Alfvénic Slow Solar Wind
D'Amicis, Raffaella; Reeves, Katharine K.; Stawarz, Julia E. +18 more
In the corona, plasma is accelerated to hundreds of kilometers per second and heated to temperatures hundreds of times hotter than the Sun's surface before it escapes to form the solar wind. Decades of space-based experiments have shown that the energization process does not stop after it escapes. Instead, the solar wind continues to accelerate, a…
Using the STIX background detector as a proxy for GOES
Volpara, Anna; Krucker, Säm; Dickson, Ewan C. M. +4 more
Context. The Spectrometer/Telescope for Imaging X-Rays (STIX) on board Solar Orbiter was designed to observe solar flares in the X-ray range of 4‑150 keV, providing spectral, temporal, and spatial information. Besides 30 imaging detectors, STIX has two additional detectors: the coarse flare locator (CFL) and the background (BKG) detector, which ar…
Stereoscopic observations reveal coherent morphology and evolution of solar coronal loops
Peter, H.; Chitta, L. P.; Plaschke, F. +2 more
Coronal loops generally trace magnetic lines of force in the upper solar atmosphere. Understanding the loop morphology and its temporal evolution has implications for coronal heating models that rely on plasma heating due to reconnection at current sheets. Simultaneous observations of coronal loops from multiple vantage points are best suited for …
Coronal hole picoflare jets are progenitors of both fast and Alfvénic slow solar wind
Livi, S.; Peter, H.; Chitta, L. P. +19 more
Solar wind, classified by its bulk speed and the Alfvénic nature of its fluctuations, generates the heliosphere. The elusive physical processes responsible for the generation of the different types of this wind are a topic of active debate. Recent observations reveal intermittent jets, with kinetic energy in the picoflare range, emerging from dark…
Transonic Turbulence and Density Fluctuations in the Near-Sun Solar Wind
Li, H.; Zank, G. P.; Zhao, L. -L. +2 more
We use in situ measurements from the first 19 encounters of Parker Solar Probe and the most recent five encounters of Solar Orbiter to study the evolution of the turbulent sonic Mach number Mt (the ratio of the amplitude of velocity fluctuations to the sound speed) with radial distance and its relationship to density fluctuations. We fo…