The source of the major solar energetic particle events from super active region 11944

Brooks, David H.; Yardley, Stephanie L.

doi:10.1126/sciadv.abf0068

Cited by 36 publications

(32 citation statements)

References 67 publications

(81 reference statements)

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“…Previous studies have tried to link these features to in situ measurements of the solar wind, and we are currently investigating their role in the production of solar energetic particles (SEPs). Plasma composition measurements are important for SEP connection studies (Brooks & Yardley 2021), and further work on this topic will be the focus of missions such as Solar Orbiter and Parker Solar Probe. In fact, Harra et al (2021) have already analysed a series of small type III bursts observed by Parker Solar Probe in order to identify the source of SEPs.…”

Section: Summary and Discussionmentioning

confidence: 99%

Widespread occurrence of high-velocity upflows in solar active regions

Yardley

Brooks

Baker

2021

A&A

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Aims. We performed a systematic study of 12 active regions (ARs) with a broad range of areas, magnetic fluxes, and associated solar activity in order to determine whether there are upflows present at the AR boundaries and, if these upflows exist, whether there is a high-speed asymmetric blue wing component present in them. Methods. To identify the presence and locations of the AR upflows, we derive relative Doppler velocity maps by fitting a Gaussian function to Hinode/EIS Fe XII 192.394 Å line profiles. To determine whether there is a high-speed asymmetric component present in the AR upflows, we fit a double Gaussian function to the Fe XII 192.394 Å mean spectrum that is computed in a region of interest situated in the AR upflows. Results. Upflows are observed at both the eastern and western boundaries of all ARs in our sample, with average upflow velocities ranging between −5 and −26 km s−1. A blue wing asymmetry is present in every line profile. The intensity ratio between the minor high-speed asymmetric Gaussian component compared to the main component is relatively small for the majority of regions; however, in a minority of cases (8/30) the ratios are large and range between 20 and 56 %. Conclusions. These results suggest that upflows and the high-speed asymmetric blue wing component are a common feature of all ARs.

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Section: Summary and Discussionmentioning

confidence: 99%

Widespread occurrence of high-velocity upflows in solar active regions

Yardley

Brooks

Baker

2021

A&A

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“…The suitability of this method for measurements of the solar coronal magnetic field has been recently demonstrated by Chen et al (2021) through a forward modeling approach. This technique has also been successfully applied to solar extreme ultraviolet (EUV) spectral observations (e.g., Si et al 2020;Landi et al 2020Landi et al , 2021Brooks & Yardley 2021). The measured field strengths in solar ARs are often several hundred Gauss, which is consistent with the typical field strengths in the lower corona as derived from magnetic field extrapolations (Landi et al 2020) and magnetohydrodynamic (MHD) models (Chen et al 2021).…”

Section: Introductionmentioning

confidence: 66%

Measurements of the magnetic field strengths at the bases of stellar coronae using the magnetic-field-induced transition theory

Chen,

Liu,

Tian

et al. 2021

Preprint

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Measurements of the magnetic field in the stellar coronae are extremely difficult. Recently, it was proposed that the magnetic-field-induced transition (MIT) of the Fe x 257 Å line can be used to measure the coronal magnetic field of the Sun. We performed forward modeling with a series of global stellar magnetohydrodynamics models to investigate the possibility of extending this method to other late-type stars. We first synthesized the emissions of several Fe x lines for each stellar model, then calculated the magnetic field strengths using the intensity ratios of Fe x 257 Å to several other Fe x lines based on the MIT theory. Finally, we compared the derived field strengths with those in the models, and concluded that this method can be used to measure at least the magnetic field strengths at the coronal bases of stars with a mean surface magnetic flux density about one order of magnitude higher than that of the Sun. Our investigation suggests the need of an extreme ultraviolet spectrometer to perform routine measurements of the stellar coronal magnetic field.

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“…More recently, Brooks & Yardley (2021) have identified the source region of the energetic particles during an eruption. Again, our model corroborates and explains those findings as it shows that the ICME can maintain a distinguished chemical composition during its motion in the interplanetary space with a limited mixing of the plasma.…”

Section: Discussionmentioning

confidence: 99%

“…Spectroscopy usually provides important information about element abundances (e.g. Lee & Raymond 2012), and it has been used, for instance, to track the presence of solar energetic particles (SEP) in ICMEs (Brooks & Yardley 2021), but in situ measurements would represent the best solution for directly measuring the composition of solar mass transported by ICMEs close to Earth. Studying the chemical composition of ICME plasma allows one to trace back its origin on the different layers of the solar atmosphere, also taking advantage of the so-called first ionisation potential (FIP) effect (see recent review by Song & Yao 2020).…”

Section: Introductionmentioning

confidence: 99%

Tracing the ICME plasma with a MHD simulation

Biondo

Pagano

Reale

et al. 2021

A&A

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The determination of the chemical composition of interplanetary coronal mass ejection (ICME) plasma is an open issue. More specifically, it is not yet fully understood how remote sensing observations of the solar corona plasma during solar disturbances evolve into plasma properties measured in situ away from the Sun. The ambient conditions of the background interplanetary plasma are important for space weather because they influence the evolutions, arrival times, and geo-effectiveness of the disturbances. The Reverse In situ and MHD APproach (RIMAP) is a technique to reconstruct the heliosphere on the ecliptic plane (including the magnetic Parker spiral) directly from in situ measurements acquired at 1 AU. It combines analytical and numerical approaches, preserving the small-scale longitudinal variability of the wind flow lines. In this work, we use RIMAP to test the interaction of an ICME with the interplanetary medium. We model the propagation of a homogeneous non-magnetised (i.e. with no internal flux rope) cloud starting at 800 km s−1 at 0.1 AU out to 1.1 AU. Our 3D magnetohydrodynamics (MHD) simulation made with the PLUTO MHD code shows the formation of a compression front ahead of the ICME, continuously driven by the cloud expansion. Using a passive tracer, we find that the initial ICME material does not fragment behind the front during its propagation, and we quantify the mixing of the propagating plasma cloud with the ambient solar wind plasma, which can be detected at 1 AU.

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The source of the major solar energetic particle events from super active region 11944

Cited by 36 publications

References 67 publications

Widespread occurrence of high-velocity upflows in solar active regions

Widespread occurrence of high-velocity upflows in solar active regions

Measurements of the magnetic field strengths at the bases of stellar coronae using the magnetic-field-induced transition theory

Tracing the ICME plasma with a MHD simulation

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