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Abstract Coronal pseudostreamer flux systems have a specific magnetic configuration that influences the morphology and evolution of coronal mass ejections (CMEs) from these regions. Here we continue the analysis of the Wyper et al. magnetohydrodynamic simulation of a CME eruption from an idealized pseudostreamer configuration through the construction of synthetic remote-sensing and in situ observational signatures. We examine the pre-eruption and eruption signatures in extreme ultraviolet and white light from the low corona through the extended solar atmosphere. We calculate synthetic observations corresponding to several Parker Solar Probe–like trajectories at ∼10R_⊙to highlight the fine-scale structure of the CME eruption in synthetic WISPR imagery and the differences between the in situ plasma and field signatures of flank and central CME-encounter trajectories. Finally, we conclude with a discussion of several aspects of our simulation results in the context of interpretation and analysis of current and future Parker Solar Probe data. 

Abstract This study presents observations of a large pseudostreamer solar eruption and, in particular, the post-eruption relaxation phase, as captured by Metis, on board the Solar Orbiter, on 2022 October 12, during its perihelion passage. Utilizing total-brightness data, we observe the outward propagation of helical features up to 3 solar radii along a radial column that appears to correspond to the stalk of the pseudostreamer. The helical structures persisted for more than 3 hr following a jet-like coronal mass ejection associated with a polar crown prominence eruption. A notable trend is revealed: the inclination of these features decreases as their polar angle and height increase. Additionally, we measured their helix pitch. Despite the 2 minute time cadence limiting direct correspondence among filamentary structures in consecutive frames, we find that the Metis helical structure may be interpreted as a consequence of twist (nonlinear torsional Alfvén waves) and plasma liberated by interchange reconnection. A comparison was performed between the helix parameters as outlined by fine-scale outflow features and those obtained from synthetic white-light images derived from the high-resolution magnetohydrodynamics simulation of interchange reconnection in a pseudostreamer topology by P. F. Wyper et al. A remarkable similarity between the simulation-derived images and the observations was found. We conjecture that these Metis observations may represent the upper ends of the spatial and energy scales of the interchange reconnection process that has been proposed recently as the origin of the Alfvénic solar wind. 

Abstract The anisotropy of energetic particles provides essential information to help resolve the underlying fundamental physics of their spatial distributions, injection, acceleration, and transport processes. In this work, we report an energetic ion enhancement that is characterized by very large and long-lasting anisotropies observed by STEREO A and Solar Orbiter, which are nearly aligned along the same nominal Parker spiral. This ion enhancement appears at the rising phase of a widespread solar energetic particle event that was associated with the farside coronal mass ejection on 2022 February 15. According to our analysis, the long-lasting anisotropy resulted from the continuous injection of energetic ions from a well-connected particle source located beyond the STEREO A’s orbit. Solar Orbiter also observed an interval of very large anisotropy dominated exclusively by sunward streaming ions but with the additional implication that it detected the very early phase of ion injections onto magnetic field lines that newly connected to the particle source, which is likely the first reported event of this kind. These results further illustrate how energetic particle anisotropy information, in particular from multiple observer locations, can be used to disentangle the sources and transport processes of energetic ions, even when their heliospheric context is not simple. 

Abstract Connecting the solar wind observed throughout the heliosphere to its origins in the solar corona is one of the central aims of heliophysics. The variability in the magnetic field, bulk plasma, and heavy ion composition properties of the slow wind are thought to result from magnetic reconnection processes in the solar corona. We identify regions of enhanced variability and composition in the solar wind from 2003 April 15 to May 13 (Carrington Rotation 2002), observed by the Wind and Advanced Composition Explorer spacecraft, and demonstrate their relationship to the separatrix–web (hereafter, S-Web) structures describing the corona’s large-scale magnetic topology. There are four pseudostreamer (PS) wind intervals and two helmet streamer (HS) heliospheric current sheet/plasma sheet crossings (and an interplanetary coronal mass ejection), which all exhibit enhanced alpha-to-proton ratios and/or elevated ionic charge states of carbon, oxygen, and iron. We apply the magnetic helicity–partial variance of increments ( H m –PVI) procedure to identify coherent magnetic structures and quantify their properties during each interval. The mean duration of these structures are ∼1 hr in both the HS and PS wind. We find a modest enhancement above the power-law fit to the PVI waiting-time distribution in the HS-associated wind at the 1.5–2 hr timescales that is absent from the PS intervals. We discuss our results in the context of previous observations of the ∼90 minutes periodic density structures in the slow solar wind, further development of the dynamic S-Web model, and future Parker Solar Probe and Solar Orbiter joint observational campaigns. 

Abstract On 2022 February 15–16, multiple spacecraft measured one of the most intense solar energetic particle (SEP) events observed so far in Solar Cycle 25. This study provides an overview of interesting observations made by multiple spacecraft during this event. Parker Solar Probe (PSP) and BepiColombo were close to each other at 0.34–0.37 au (a radial separation of ∼0.03 au) as they were impacted by the flank of the associated coronal mass ejection (CME). At about 100° in the retrograde direction and 1.5 au away from the Sun, the radiation detector on board the Curiosity surface rover observed the largest ground-level enhancement on Mars since surface measurements began. At intermediate distances (0.7–1.0 au), the presence of stream interaction regions (SIRs) during the SEP arrival time provides additional complexities regarding the analysis of the distinct contributions of CME-driven versus SIR-driven events in observations by spacecraft such as Solar Orbiter and STEREO-A, and by near-Earth spacecraft like ACE, SOHO, and WIND. The proximity of PSP and BepiColombo also enables us to directly compare their measurements and perform cross-calibration for the energetic particle instruments on board the two spacecraft. Our analysis indicates that energetic proton measurements from BepiColombo and PSP are in reasonable agreement with each other to within a factor of ∼1.35. Finally, this study introduces the various ongoing efforts that will collectively improve our understanding of this impactful, widespread SEP event. 

Context. Coronal mass ejections (CMEs) on the Sun are the largest explosions in the Solar System that can drive powerful plasma shocks. The eruptions, shocks, and other processes associated to CMEs are efficient particle accelerators and the accelerated electrons in particular can produce radio bursts through the plasma emission mechanism. Aims. Coronal mass ejections and associated radio bursts have been well studied in cases where the CME originates close to the solar limb or within the frontside disc. Here, we study the radio emission associated with a CME eruption on the back side of the Sun on 22 July 2012. Methods. Using radio imaging from the Nançay Radioheliograph, spectroscopic data from the Nançay Decametric Array, and extreme-ultraviolet observations from the Solar Dynamics Observatory and Solar Terrestrial Relations Observatory spacecraft, we determine the nature of the observed radio emission as well as the location and propagation of the CME. Results. We show that the observed low-intensity radio emission corresponds to a type II radio burst or a short-duration type IV radio burst associated with a CME eruption due to breakout reconnection on the back side of the Sun, as suggested by the pre-eruptive magnetic field configuration. The radio emission consists of a large, extended structure, initially located ahead of the CME, that corresponds to various electron acceleration locations. Conclusions. The observations presented here are consistent with the breakout model of CME eruptions. The extended radio emission coincides with the location of the current sheet and quasi-separatrix boundary of the CME flux and the overlying helmet streamer and also with that of a large shock expected to form ahead of the CME in this configuration. 

Context. Coronal mass ejections (CMEs) are large eruptions of magnetised plasma from the Sun that are often accompanied by solar radio bursts produced by accelerated electrons. Aims. A powerful source for accelerating electron beams are CME-driven shocks, however, there are other mechanisms capable of accelerating electrons during a CME eruption. So far, studies have relied on the traditional classification of solar radio bursts into five groups (Type I–V) based mainly on their shapes and characteristics in dynamic spectra. Here, we aim to determine the origin of moving radio bursts associated with a CME that do not fit into the present classification of the solar radio emission. Methods. By using radio imaging from the Nançay Radioheliograph, combined with observations from the Solar Dynamics Observatory, Solar and Heliospheric Observatory, and Solar Terrestrial Relations Observatory spacecraft, we investigate the moving radio bursts accompanying two subsequent CMEs on 22 May 2013. We use three-dimensional reconstructions of the two associated CME eruptions to show the possible origin of the observed radio emission. Results. We identified three moving radio bursts at unusually high altitudes in the corona that are located at the northern CME flank and move outwards synchronously with the CME. The radio bursts correspond to fine-structured emission in dynamic spectra with durations of ∼1 s, and they may show forward or reverse frequency drifts. Since the CME expands closely following an earlier CME, a low coronal CME–CME interaction is likely responsible for the observed radio emission. Conclusions. For the first time, we report the existence of new types of short duration bursts, which are signatures of electron beams accelerated at the CME flank. Two subsequent CMEs originating from the same region and propagating in similar directions provide a complex configuration of the ambient magnetic field and favourable conditions for the creation of collapsing magnetic traps. These traps are formed if a CME-driven wave, such as a shock wave, is likely to intersect surrounding magnetic field lines twice. Electrons will thus be further accelerated at the mirror points created at these intersections and eventually escape to produce bursts of plasma emission with forward and reverse drifts. 

Abstract In this paper we examine a low-energy solar energetic particle (SEP) event observed by IS⊙IS’s Energetic Particle Instrument-Low (EPI-Lo) inside 0.18 au on 2020 September 30. This small SEP event has a very interesting time profile and ion composition. Our results show that the maximum energy and peak in intensity are observed mainly along the open radial magnetic field. The event shows velocity dispersion, and strong particle anisotropies are observed throughout the event, showing that more particles are streaming outward from the Sun. We do not see a shock in the in situ plasma or magnetic field data throughout the event. Heavy ions, such as O and Fe, were detected in addition to protons and 4He, but without significant enhancements in 3He or energetic electrons. Our analysis shows that this event is associated with a slow streamer blowout coronal mass ejection (SBO-CME), and the signatures of this small CME event are consistent with those typical of larger CME events. The time–intensity profile of this event shows that the Parker Solar Probe encountered the western flank of the SBO-CME. The anisotropic and dispersive nature of this event in a shockless local plasma gives indications that these particles are most likely accelerated remotely near the Sun by a weak shock or compression wave ahead of the SBO-CME. This event may represent direct observations of the source of the low-energy SEP seed particle population. 

Abstract The search for life in the Universe is a fundamental problem of astrobiology and modern science. The current progress in the detection of terrestrial-type exoplanets has opened a new avenue in the characterization of exoplanetary atmospheres and in the search for biosignatures of life with the upcoming ground-based and space missions. To specify the conditions favourable for the origin, development and sustainment of life as we know it in other worlds, we need to understand the nature of global (astrospheric), and local (atmospheric and surface) environments of exoplanets in the habitable zones (HZs) around G-K-M dwarf stars including our young Sun. Global environment is formed by propagated disturbances from the planet-hosting stars in the form of stellar flares, coronal mass ejections, energetic particles and winds collectively known as astrospheric space weather. Its characterization will help in understanding how an exoplanetary ecosystem interacts with its host star, as well as in the specification of the physical, chemical and biochemical conditions that can create favourable and/or detrimental conditions for planetary climate and habitability along with evolution of planetary internal dynamics over geological timescales. A key linkage of (astro)physical, chemical and geological processes can only be understood in the framework of interdisciplinary studies with the incorporation of progress in heliophysics, astrophysics, planetary and Earth sciences. The assessment of the impacts of host stars on the climate and habitability of terrestrial (exo)planets will significantly expand the current definition of the HZ to the biogenic zone and provide new observational strategies for searching for signatures of life. The major goal of this paper is to describe and discuss the current status and recent progress in this interdisciplinary field in light of presentations and discussions during the NASA Nexus for Exoplanetary System Science funded workshop ‘Exoplanetary Space Weather, Climate and Habitability’ and to provide a new roadmap for the future development of the emerging field of exoplanetary science and astrobiology.