Influence of Large-scale Interplanetary Structures on the Propagation of Solar Energetic Particles: The Multispacecraft Event on 2021 October 9

Lario, D.; Wijsen, Nicolas; Kwon, Ryun-Young; Sánchez‐Cano, Beatriz; Richardson, I. G.; Pacheco, Daniel; Palmerio, Erika; Stevens, Michael L.; Szabó, Á.; Heyner, Daniel; Dresing, Nina; Gómez-Herrero, R.; Carcaboso, Fernando; Aran, A.; Afanasiev, Alexandr; Vainio, R.; Riihonen, E.; Poedts, Stefaan; Brüden, M.; Xu, Zigong; Kollhoff, Alexander

doi:10.3847/1538-4357/ac6efd

Cited by 12 publications

(28 citation statements)

References 83 publications

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“…Hardly any large SEP event of the STEREO era has escaped a detailed analysis by the SEP research community. Some notable examples are studies focusing on individual SEP proton events carried out by Wiedenbeck et al (2013) Most recently, the addition of SEP detectors on Parker Solar Probe (PSP) and Solar Orbiter (SolO) allowed multiplespacecraft analyses of solar cycle-25 SEP events (Cohen et al 2021;Kollhoff et al 2021;Lario et al 2022). The SEP spatial distributions are inferred from direct comparisons of SEP intensity profiles at different spacecraft.…”

Section: Longitudinal Distributions Of Sep Eventsmentioning

confidence: 99%

Spatial Evolution of 20 MeV Solar Energetic Proton Events

Kahler

Ling

Reames

2023

ApJ

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The longitudinal extents of solar energetic (E > 10 MeV) particle (SEP) events in the heliosphere are a characteristic important for understanding SEP acceleration and transport as well as their space weather effects. SEP detectors on the STEREO A and B spacecraft launched in 2008, combined with those on Earth-orbiting spacecraft, have enabled recent studies of this characteristic for many events. Each SEP event distribution has been characterized by a single central longitude, width, and amplitude derived from Gaussian fits to peak intensities or fluences at each spacecraft. To capture dynamic changes of those parameters through SEP events, we apply Gaussian fits in solar-based Carrington longitude coordinates with 1 hr resolution to four selected large 20 MeV proton events. The limitations of single-Gaussian fits for very extended events is discussed. In all four examples the widths are increasing throughout the event, as expected, while the projected Gaussian centers at SEP onset start from 30° to 100° east of the associated flare, move westward, then remain stationary well east of the flare for several days before moving west as the event amplitudes decrease. Late decay phases can be characterized by eastward movements away from the flare longitudes. We introduce schematic Buffett plots to show successive snapshots of event longitudes and amplitudes.

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Section: Longitudinal Distributions Of Sep Eventsmentioning

confidence: 99%

Spatial Evolution of 20 MeV Solar Energetic Proton Events

Kahler

Ling

Reames

2023

ApJ

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“…The intensity-time profiles of the SEP event at SolO might be influenced by the arrival of a stream interaction region (SIR) during the SEP onset time. As discussed by Lario et al (2022), the high-speed stream driving the SIR was previously observed by STEREO-A and later also by near-Earth spacecraft, where it strongly affected the observed energetic ion intensity-time profiles. At SolO, the SIR and its associated magnetic compression might have acted as a magnetic mirror, reflecting some of the electrons back towards the inner heliosphere and the CMEdriven shock wave where the electrons may subsequently accelerate to higher energies.…”

Section: Phasementioning

confidence: 59%

“…We find that this is an interesting aspect of the event, hence, our analysis is focused on establishing an association between the energetic electrons and the different radio emissions during the impulsive phase of the flare and understanding the origin of the apparent second phase of electron energization after the flare maximum. Specifics on the energetic proton observations for this event can be found in Lario et al (2022).…”

Section: Introductionmentioning

confidence: 99%

Multiple injections of energetic electrons associated with the flare/CME event on 9 October 2021

Jebaraj¹,

Koulooumvakos²,

Dresing³

et al. 2023

Preprint

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Context. We study the solar energetic particle (SEP) event observed on 9 October 2021, by multiple spacecraft including Solar Orbiter (SolO). The event was associated with an M1.6 flare, a coronal mass ejection (CME) and a shock wave. During the event, high-energy protons and electrons were recorded by multiple instruments located within a narrow longitudinal cone.Aims. An interesting aspect of the event was the multi-stage particle energization during the flare impulsive phase and also what appears to be a separate phase of electron acceleration detected at SolO after the flare maximum. We aim to investigate and identify the multiple sources of energetic electron acceleration. Methods. We utilize SEP electron observations from the Energetic Particle Detector (EPD) and hard X-ray (HXR) observations from the Spectrometer/Telescope for Imaging X-rays (STIX) on-board SolO, in combination with radio observations at a broad frequency range. We focus on establishing an association between the energetic electrons and the different HXR and radio emissions associated with the multiple acceleration episodes. Results. We have found that the flare was able to accelerate electrons for at least 20 minutes during the nonthermal phase observed in the form of five discrete HXR pulses. We also show evidence that the shock wave has contributed to the electron acceleration during and after the impulsive flare phase. The detailed analysis of EPD electron data shows that there was a time difference in the release of low-and high-energy electrons, with the high-energy release delayed. Also, the observed electron anisotropy characteristics suggest different connectivity during the two phases of acceleration.

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“…In the left panels of Figure 9, we discern the region between the green vertical lines as the possible interval of the ICME by the below criteria: (1) lowered temperature, (2) continuously enhanced magnetic field strength, and (3) rotated magnetic field after October 13. Lario et al (2022) also use these signatures indicative of this ICME event. Throughout 2021 October 9-15, SolO did not record electron pitch angle, which brings uncertainty to the identification of the actual boundaries of the ICME.…”

Section: Evolution On the Ecliptic Planementioning

confidence: 99%

“…As the standoff distance between shock fronts and CME flux ropes increases from the nose to the flank, the long-duration sheath region can hint that the spacecraft likely observe the flank of CMEs (Chen et al 2022). (2) The relative location of the source region, SolO, and the L1 point, as shown by Lario et al (2022), implies that the left flank of the CME would arrive at SolO and the L1 point as a result of CME deflections caused by stream interaction regions (Liu et al 2019). The large differences between the observations at SolO and the L1 point could be explained by the radial and longitude separation at these two locations.…”

Section: Evolution On the Ecliptic Planementioning

confidence: 99%

Global Morphology Distortion of the 2021 October 9 Coronal Mass Ejection from an Ellipsoid to a Concave Shape

Yang

Hou

Feng

et al. 2023

ApJ

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This paper presents a study of a 2021 October 9 coronal mass ejection (CME) with multipoint imaging and in situ observations. We also simulate this CME from the Sun to Earth with a passive tracer to tag the CME’s motion. The coronagraphic images show that the CME is observed as a full halo by SOHO and as a partial halo by STEREO-A. The heliospheric images reveal that the propagation speed of the CME approaches about 1° hr−1, suggesting a slow CME. With simulated results matching these observation results, the simulation discloses that as the CME ejects from the Sun out to interplanetary space, its global morphology is distorted from an ellipsoid to a concave shape owing to interactions with the bimodal solar wind. The cross section of the CME’s flux rope structure transforms from a circular shape into a flat one. As a result of the deflection, the propagation direction of the CME is far away from the Sun–Earth line. This means that the CME flank (or the ICME leg) likely arrives at both Solar Orbiter and the L1 point. From the CME’s eruption to 1 au, its volume and mass increase by about two orders and one order of magnitude, respectively. Its kinetic energy is about 100 times larger than its magnetic energy at 1 au. These results have important implications for our understanding of CMEs’ morphology, as well as their space weather impacts.

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Influence of Large-scale Interplanetary Structures on the Propagation of Solar Energetic Particles: The Multispacecraft Event on 2021 October 9

Cited by 12 publications

References 83 publications

Spatial Evolution of 20 MeV Solar Energetic Proton Events

Spatial Evolution of 20 MeV Solar Energetic Proton Events

Multiple injections of energetic electrons associated with the flare/CME event on 9 October 2021

Global Morphology Distortion of the 2021 October 9 Coronal Mass Ejection from an Ellipsoid to a Concave Shape

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