Major Flares Research Articles

Change Ratios of Magnetic Helicity and Magnetic Free Energy During Major Solar Flares

Magnetic helicity is an important concept in solar physics, with a number of theoretical statements pointing out the important role of magnetic helicity in solar flares and coronal mass ejections (CMEs). Here we construct a sample of 47 solar flares, which contains 18 no-CME-associated confined flares and 29 CME-associated eruptive flares. We calculate the change ratios of magnetic helicity and magnetic free energy before and after these 47 flares. Our calculations show that the change ratios of magnetic helicity and magnetic free energy show distinct different distributions in confined flares and eruptive flares. The median value of the change ratios of magnetic helicity in confined flares is −0.8%, while this number is −14.5% for eruptive flares. For the magnetic free energy, the median value of the change ratios is −4.3% for confined flares, whereas this number is −14.6% for eruptive flares. This statistical result, using observational data, is well consistent with the theoretical understandings that magnetic helicity is approximately conserved in the magnetic reconnection, as shown by confined flares, and the CMEs take away magnetic helicity from the corona, as shown by eruptive flares.

Flare Duty Cycle of Gamma-Ray Blazars and Implications for High-energy Neutrino Emission

Gamma-ray flares of blazars may be accompanied by high-energy neutrinos due to interactions of high-energy cosmic rays in the jet with photons, as suggested by the detection of the high-energy neutrino IceCube-170922A during a major gamma-ray flare from blazar TXS 0506+056 at the ∼3σ significance level. In this work, we present a statistical study of gamma-ray emission from blazars to constrain the contribution of gamma-ray flares to their neutrino output. We construct weekly binned light curves for 145 gamma-ray bright blazars in the Fermi Large Area Telescope Monitored Source List adding TXS 0506+056. We derive the fraction of time spent in the flaring state (flare duty cycle) and the fraction of energy released during each flare from the light curves with a Bayesian blocks algorithm. We find that blazars with lower flare duty cycles and energy fractions are more numerous among our sample. We identify a significant difference in flare duty cycles between blazar subclasses at a significance level of 5%. Then using a general scaling relation for the neutrino and gamma-ray luminosities, with a weighting exponent of γ = 1.0–2.0, normalized to the quiescent gamma-ray or X-ray flux of each blazar, we evaluate the neutrino energy flux of each gamma-ray flare. The gamma-ray flare distribution indicates that blazar neutrino emission may be dominated by flares for γ ≳ 1.5. The neutrino energy fluxes for 1 week and 10 yr bins are compared with the decl.-dependent IceCube sensitivity to constrain the standard neutrino emission models for gamma-ray flares. Finally, we present the upper-limit contribution of blazar gamma-ray flares to the isotropic diffuse neutrino flux.

Global Energetics of Solar Powerful Events on 2017 September 6

Abstract Solar flares and coronal mass ejections (CMEs) are thought to be the most powerful events on the Sun. They can release energy as high as ∼1032 erg in tens of minutes, and also can release solar energetic particles (SEPs) into interplanetary space. We explore global energy budgets of solar major eruptions that occurred on 2017 September 6, including the energy partition of a powerful solar flare, and the energy budget of the accompanying CME and SEPs. In the wavelength range shortward of ∼222 nm, a major contribution of the flare radiated energy is in the soft X-ray (SXR) 0.1–7 nm domain. The flare energy radiated at wavelengths of Lyα and mid-ultraviolet is larger than that radiated in the extreme ultraviolet wavelengths, but it is much less than that radiated in the SXR waveband. The total flare radiated energy could be comparable to the thermal and nonthermal energies. The energies carried by the major flare and its accompanying CME are roughly equal, and they are both powered by the magnetic free energy in the NOAA AR 12673. Moreover, the CME is efficient in accelerating SEPs, and the prompt component (whether it comes from the solar flare or the CME) contributes only a negligible fraction.

Deep neural networks of solar flare forecasting for complex active regions

Solar flare forecasting is one of major components of operational space weather forecasting. Complex active regions (ARs) are the main source producing major flares, but only a few studies are carried out to establish flare forecasting models for these ARs. In this study, four deep learning models, called Complex Active Region Flare Forecasting Model (CARFFM)-1, −2, −3, and −4, are established. They take AR longitudinal magnetic fields, AR vector magnetic fields, AR longitudinal magnetic fields and the total unsigned magnetic flux in the neutral line region, AR vector magnetic fields and the total unsigned magnetic flux in the neutral region as input, respectively. These four models can predict the production of M-class or above flares in the complex ARs for the next 48 h. Through comparing the performance of the models, CARFFM-4 has the best forecasting ability, which has the most abundant input information. It is suggested that more valuable and rich input can improve the model performance.

#4183 A PHENOTYPIC DRIVEN RITUXIMAB MAINTENANCE APPROACH IS EFFECTIVE AND SAFE IN PATIENTS WITH ANCA ASSOCIATED VASCULITIS

Abstract Background and Aims Rituximab (RTX) has emerged as the first-line treatment to maintain remission in ANCA-Associated Vasculitis (AAV). However, the ideal strategy to RTX re-dosing is still unclear [1]. Method In this monocentric and retrospective study we evaluated the efficacy and safety of two RTX-based maintenance regimens in patients with AAV. Fixed-dose (FD) RTX dosing, consisting of at least 3 pre-emptive RTX administrations every 6 months, was preferred in patients judged to be at high relapse risk. Instead, a biomarker-guided on-demand (OD) RTX dosing strategy was preferred for patients deemed at lower risk of relapse; this consisted in RTX re-treatment only in case of B-cell repopulation or rise in ANCA titer. The single patient relapse risk was assessed according to the disease phenotype (granulomatous vs vasculitic), the ANCA specificity and the disease status (onset vs relapse). Relapses were defined as increase of disease activity requiring escalation of immunosuppression; major relapses were defined in case of life/organ-threatening manifestations. Results The study included 100 patients followed for a median of 24 months (IQR 20-30), 51% treated with an OD and 49% with a FD strategy. The main baseline characteristics of our cohort are shown in the Table; patients treated with a FD strategy were more often GPA, PR3-ANCA positive, with relapsing disease and ENT involvement and less frequent renal involvement. The FD group received a median of 4 (IQR 4-4) administrations of RTX for a median cumulative dose of 2 g (IQR 2-2). Only 6 (11.8%) patients in the OD group received RTX as maintenance therapy with a median of 1 (IQR 1-3) administration of RTX for a median cumulative dose of 0.75 g (IQR 0.5-1.75). Thirteen relapses occurred, 6 in the FD group and 7 in the OD one. Remission rates were comparable in the two cohorts, with respectively 87.6% and 85.9% of the patients in remission at 24 months (Figure 1 - panel A). No significant differences in remission rates across the 2 groups were observed after considering only major flares or after stratification according to clinical diagnosis (MPA/GPA) and ANCA specificity (Figure 1 - panel B to F). Ten and 20 severe infections (p = 0.383) and 3 and 1 cancer (p = 0.581) occurred respectively in the FD and OD group. Conclusion In our case series, a phenotypic-driven approach to RTX maintenance showed comparable efficacy and safety between fixed and on-demand dosing, despite different baseline characteristics between the two groups. These results suggest that personalizing RTX maintenance may be a feasible and safe strategy.

Confinedness of an X3.1-class Solar Flare Occurred in NOAA 12192: Analysis from Multi-instrument Observations

The nonassociation of coronal mass ejections with high energetic flares is sparse. For this reason, the magnetic conditions required for the confinedness of major flares is a topic of active research. Using multi-instrument observations, we investigated the evolution and effects of confinedness in an X3.1 flare, which occurred in active region (AR) 12192. The decrease of net fluxes in the brightening regions near the footpoints of the multisigmoidal AR in the photosphere and chromosphere, indicative of flux cancellation favoring tether-cutting reconnection (TCR), is observed using the magnetic field observations of HMI/SDO and SOT/Hinode, respectively. The analysis of spectropolarimetric data obtained by the Interferometric Bidimensional Spectrometer over the brightening regions suggests untwisting of field lines, which further supports TCR. Filaments near the polarity inversion line region, resulting from TCR of low-lying sheared loops, undergo merging and form an elongated filament. The temperature and density differences between the footpoints of the merged filament, revealed by DEM analysis, cause streaming and counterstreaming of the plasma flow along the filament and unload at its footpoints with an average velocity of ≈40 km s−1. This results in a decrease of the mass of the filament (density decreased by >50%), leading to its rise and expansion outward. However, due to strong strapping flux, the filament separates itself instead of erupting. Further, the evolution of nonpotential parameters describes the characteristics of confinedness of the flare. Our study suggests that the sigmoid–filament system exhibits upward catastrophe due to mass unloading but gets suppressed by strong confinement of the external poloidal field.

Growing evidence for high-energy neutrinos originating in radio blazars

ABSTRACT Evidence for bright-radio blazars being high-energy neutrino sources was found in recent years. However, specifics of how and where these particles get produced still need to be determined. In this paper, we add 14 new IceCube events from 2020–2022 to update our analysis of the neutrino-blazars connection. We test and refine earlier findings by utilizing the total of 71 track-like high-energy IceCube events from 2009–2022. We correlate them with the complete sample of 3412 extragalactic radio sources selected by their compact radio emission. We demonstrate that neutrinos are statistically associated with radio-bright blazars with a post-trial p-value of 3 · 10−4. In addition to this statistical study, we confirm previous individual neutrino-blazar associations, find and discuss several new ones. Notably, PKS 1741 − 038 was selected earlier and had a second neutrino detected from its direction in 2022; PKS 0735 + 168 has experienced a major flare across the whole electromagnetic spectrum coincidently with a neutrino arrival from that direction in 2021.

COVID-19 vaccination experience in patients with rheumatoid arthritis treated at a single VA medical center

BackgroundFollowing the introduction of the COVID-19 vaccines, there has been uncertainty as to whether receiving the COVID-19 vaccine will result in overactivation of the immune system and subsequently lead to an autoimmune disease flare.The purpose of this study was to assess whether rheumatoid arthritis (RA) patients who received the mRNA COVID-19 vaccine are at increased risk for disease flare. MethodsWe conducted a single-center retrospective and prospective study at the Louis Stokes Cleveland VA Medical Center between 12/2021 and 2/2022. We included 100 patients with rheumatoid arthritis (RA) who were actively on immunosuppressive therapy and received three doses of thePfizer-BioNTech vaccine. A survey questionnaire was used to collect data about their RA and if they developed symptoms post vaccination. Our primary end point was to determine incidence of flare of RA after COVID-19 vaccine. Secondary end points were to estimate the side effect profile from the vaccine, and to check if patients developed a COVID-19 infection after they received the vaccine. ResultsNone of the patients reported symptoms of RA flare within two months of receiving the 3 doses of the vaccine. Most common vaccine side effects were soreness over the injection site (n = 14), headache (n = 11), fatigue(n = 7) and myalgias(n = 4). 5 patients developed a COVID-19 infection prior to receiving the vaccine, 8 after being vaccinated, 3 of the 8 within 5 months from the second dose and 5 out of the 8 within 3 months from the third vaccine dose. ConclusionRA patients receiving the COVID-19 Pfizer mRNA vaccine do not appear to commonly develop major symptoms, flares or side effects following the vaccine. Further research with larger numbers of patients with rheumatoid arthritis as well as those with other autoimmune disease is needed to better understand the safety and effectiveness of COVID-19 vaccine.

Magnetic helicity and free magnetic energy as tools for probing eruptions in two differently evolving solar active regions

Aims. We study the role of magnetic helicity and free magnetic energy in the initiation of eruptions in two differently evolving solar active regions (ARs). Methods. Using vector magnetograms from the Helioseismic and Magnetic Imager on board the Solar Dynamics Observatory and a magnetic connectivity-based method, we calculate the instantaneous relative magnetic helicity and free magnetic energy budgets for several days in two ARs, AR11890 and AR11618, both with complex photospheric magnetic field configurations. Results. The ARs produced several major eruptive flares while their photospheric magnetic field exhibited different evolutionary patterns: primarily flux decay in AR11890 and primarily flux emergence in AR11618. Throughout much of their evolution, both ARs featured substantial budgets of free magnetic energy and of both positive (right-handed) and negative (left-handed) helicity. In fact, the imbalance between the signed components of their helicity was as low as in the quiet Sun and their net helicity eventually changed sign 14−19 h after their last major flare. Despite this incoherence, the eruptions occurred at times of net helicity peaks that were co-temporal with peaks in the free magnetic energy. The percentage losses, associated with the eruptive flares, in the normalized free magnetic energy were significant, in the range of ∼10−60%. For the magnetic helicity, changes ranged from ∼25% to the removal of the entire excess helicity of the prevailing sign, leading a roughly zero net helicity, but with significant equal and opposite budgets of both helicity senses. Respective values ranged from (0.3 − 2)×1032 erg and (1.3 − 20)×1042 Mx2 for energy and helicity losses. The removal of the slowly varying background component of the free energy and helicity (either the net helicity or the prevailing signed component of helicity) time series revealed that all eruption-related peaks of both quantities exceeded the 2σ levels of their detrended time series above the removed background. There was no eruption when only one or none of these quantities exceeded its 2σ level. Conclusions. Our results indicate that differently evolving ARs may produce major eruptive flares even when, in addition to the accumulation of significant free magnetic energy budgets, they accumulate large amounts of both left- and right-handed helicity without a strong dominance of one handedness over the other. In most cases, these excess budgets appear as localized peaks, co-temporal with the flare peaks, in the time series of free magnetic energy and helicity (and normalized values thereof). The corresponding normalized free magnetic energy and helicity losses can be very significant at certain times.

Application of Deep Reinforcement Learning to Major Solar Flare Forecasting

In this study, we present the application of deep reinforcement learning to the forecasting of major solar flares. For this, we consider full-disk magnetograms at 00:00 UT from the Solar and Heliospheric Observatory/Michelson Doppler Imager (1996–2010) and the Solar Dynamics Observatory/Helioseismic and Magnetic Imager (2011–2019), as well as Geostationary Operational Environmental Satellite X-ray flare data. We apply Deep Q-Network (DQN) and Double DQN, which are popular deep reinforcement learning methods, to predict “Yes or No” for daily M- and X-class flare occurrence. The reward functions, consisting of four rewards for true positive, false positive, false negative, and true negative, are used for our models. The major results of this study are as follows. First, our deep-learning models successfully predict major solar flares with good skill scores, such as HSS, F1, TSS, and ApSS. Second, the performance of our models depends on the reward function, learning method, and target agent update time. Third, the performance of our deep-learning models is noticeably better than that of a convolutional neural network (CNN) model with the same structure: 0.38 (CNN) to 0.44 (ours) for HSS, 0.47 to 0.52 for F1, 0.53 to 0.59 for TSS, and 0.09 to 0.12 for ApSS.

A Study of Preflare Solar Coronal Magnetic Fields: Magnetic Energy and Helicity

Solar flares fall into two types, with eruptive ones associated with coronal mass ejection (CME) and confined ones without CME. To explore whether there are preflare conditions in terms of magnetic energy and helicity that can effectively determine the types of flares, here we analyzed a suite of related parameters of the reconstructed preflare coronal magnetic field of major solar flares, either eruptive or confined, from 2011 to 2017 near the solar disk center. The investigated parameters include extensive-type quantities such as the total magnetic energy E T , the potential energy E P , the free energy E F , the relative helicity H R , and the nonpotential helicity H J , as well as the intensive-type indices E F /E P , ∣H J /H R ∣, , and , where is half of the total unsigned magnetic flux. We have the following key findings: (1) None of the extensive parameters can effectively distinguish the eruptive and confined potential of the preflare coronal fields, though the confined events have averagely larger values. (2) All the intensive parameters have significantly larger average and median values for eruptive flares than the confined events, which indicates that the field for eruptive flares has overall higher degree of nonpotentiality and complexity than that of the confined flares. (3) The energy ratio E F /E P and the normalized nonpotential helicity , which are strongly correlated with each other, have among the highest capability of distinguishing the fields that possibly produce a major eruptive or confined flare, as over 75% of all the events are successfully discriminated between eruptive and confined flares by using critical values of E F /E P ≥ 0.27 and .

On the Connection between Rieger-type and Magneto-Rossby Waves Driving the Frequency of the Large Solar Eruptions during Solar Cycles 19–25

Global solar activity variation mainly occurs over about an 11 yr cycle. However, both longer and shorter periodicities than the solar cycle are also present in many different solar activity indices. The longer timescales may be up to hundreds of years, while the shorter timescales for global solar variability could be within 0.5–2 yr, which include, e.g., from the Rieger-type periods (150–160 days) to quasi-biennial oscillations of 2 yr. The most likely origin of this short-timescale quasi-periodicity is attributed to magnetic Rossby waves, which have periods of 0.8–2.4 yr. In this work, we present findings of a unique evolution of identified shorter periodicities, like the Rieger-type, arising from magnetic Rossby waves, throughout Solar Cycles 19–25. We report further observational evidence of the strong relationship between the Rieger-type periodicity, magneto-Rossby waves, and major solar flare activity. Moreover, this study also reveals that the global solar magnetic field has a continuous periodic longitudinal conveyor belt motion along the solar equator, together with an up-and-down movement in the latitudinal directions. We found that when these longitudinal and latitudinal movements have Rieger-type periodicity and magneto-Rossby waves during the same period of a solar cycle, major flare activity is present.

Short- and mid-term outcomes in systemic lupus erythematosus patients presenting with disease exacerbation after SARS-CoV-2 mRNA vaccination: A cohort study from Puerto Rico.

To determine if SARS-CoV-2 mRNA vaccination has an impact on the clinical course of systemic lupus erythematosus (SLE). Puerto Ricans with SLE who received mRNA COVID-19 vaccines were studied. Demographic parameters, clinical manifestations, disease activity (per Systemic Lupus Erythematosus Disease Activity Index (SLEDAI), disease damage (per Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index), emergency room visits, hospitalizations, and pharmacologic therapy were determined. Baseline variables (prior to vaccination) were compared between patients with and without exacerbation after SARS-CoV-2 vaccination. Among those with exacerbation, clinical outcomes were determined up to 1year after vaccination. Of the entire cohort (n = 247), 14 (5.7%) had post-vaccination exacerbations. Photosensitivity, oral ulcers, anti-Ro antibodies, higher SLEDAI score, and corticosteroids exposure were associated with post-vaccination flares. Among those with post-vaccination flares, 10 (71.4%) had major organ involvement. No significant differences were observed for mean SLEDAI scores, emergency room visits, hospitalizations, disease damage, and exposure to immunosuppressive drugs before and after SARS-CoV-2 mRNA vaccination. At 12months of follow-up, all patients were fully controlled without evidence of active disease. In our group of SLE patients, 5.7% had a disease flare after SARS-CoV-2 mRNA vaccination. Most had exacerbations involving major organs/systems. Mucocutaneous manifestations, anti-Ro antibodies, disease activity, and corticosteroids were associated with flares. Awareness of these factors and the possibility of a major lupus flare after vaccination with COVD-19 vaccines is critical to provide timely and effective therapy.

Changes of Magnetic Energy and Helicity in Solar Active Regions from Major Flares

Magnetic free energy powers solar flares and coronal mass ejections, and the buildup of magnetic helicity might play a role in the development of unstable structures that subsequently erupt. To better understand the roles of energy and helicity in large flares and eruptions, we have characterized the evolution of magnetic energy and helicity associated with 21 X-class flares from 2010 to 2017. Our sample includes both confined and eruptive events, with 6 and 15 in each category, respectively. Using the Helioseismic and Magnetic Imager vector magnetic field observations from several hours before to several hours after each event, we employ (a) the Differential Affine Velocity Estimator for Vector Magnetograms to determine the photospheric fluxes of energy and helicity, and (b) nonlinear force-free field extrapolations to estimate the coronal content of energy and helicity in source-region fields. Using superposed epoch analysis, we find, on average, the following: (1) decreases in both magnetic energy and helicity, in both photospheric fluxes and coronal content, that persist for a few hours after eruptions, but no clear changes, notably in relative helicity, for confined events; (2) significant increases in the twist of photospheric fields in eruptive events, with twist uncertainties too large in confined events to constrain twist changes (and lower overall twist in confined events); and (3) on longer timescales (event time +12 hr), replenishment of free magnetic energy and helicity content to near preevent levels for eruptive events. For eruptive events, magnetic helicity and free energy in coronal models clearly decrease after flares, with the amounts of decrease proportional to each region’s pre-flare content.

Tozinameran (Pfizer-BioNTech COVID-19 vaccine)-induced AGEP-DRESS syndrome

Dear Editor, A 40-year-old woman with scalp psoriasis was maintained on topical mometasone furoate therapy from 2019 with no major psoriatic flares until she presented with one week of an acute generalised pustular eruption and fever in June 2021. Physical examination revealed numerous discrete and confluent pustules studded on her scalp, trunk and limbs, on

Multimessenger Picture of J1048+7143* *Released xxxx 2022.

We draw a multimessenger picture of J1048+7143, a flat-spectrum radio quasar known to show quasiperiodic oscillations in the γ-ray regime. We generate the adaptively binned Fermi Large Area Telescope light curve of this source above 168 MeV to find three major γ-ray flares of the source, such that each of the three flares consists of two sharp subflares. Based on radio interferometric imaging data taken with the Very Large Array, we find that the kiloparsec-scale jet is directed west, while our analysis of 8.6 GHz very long baseline interferometry data, mostly taken with the Very Long Baseline Array, revealed signatures of two parsec-scale jets, one pointing east, one pointing south. We suggest that the misalignment of the kiloparsec- and parsec-scale jets is a revealing signature of jet precession. We also analyze the 5 GHz total flux density curve of J1048+7143 taken with the Nanshan (Ur) and RATAN-600 single-dish radio telescopes and find two complete radio flares, lagging slightly behind the γ-ray flares. We model the timing of γ-ray flares as a signature of the spin–orbit precession in a supermassive black hole binary, and find that the binary could merge in the next ∼60–80 yr. We show that both pulsar timing arrays and the planned Laser Interferometer Space Antenna lack sensitivity and frequency coverage to detect the hypothetical supermassive black hole binary in J1048+7143. We argue that the identification of sources similar to J1048+7143 plays a key role in revealing periodic high-energy sources in the distant universe.

The impact of time-dependent stellar activity on exoplanet atmospheres

ABSTRACTM-dwarfs are thought to be hostile environments for exoplanets. Stellar events are very common on such stars. These events might cause the atmospheres of exoplanets to change significantly over time. It is not only the major stellar flare events that contribute to this disequilibrium, but the smaller flares might also affect the atmospheres in an accumulating manner. In this study, we aim to investigate the effects of time-dependent stellar activity on the atmospheres of known exoplanets. We simulate the chemistry of GJ 876c, GJ 581c, and GJ 832c that go from H2-dominated to N2-dominated atmospheres using observed stellar spectra from the MUSCLES collaboration. We make use of the chemical kinetics code vulcan and implement a flaring routine that stochastically generates synthetic flares based on observed flare statistics. Using the radiative transfer code petitradtrans, we also simulate the evolution of emission and transmission spectra. We investigate the effect of recurring flares for a total of 11 d covering 515 flares. Results show a significant change in abundance for some relevant species such as H, OH, and CH4, with factors going up to three orders of magnitude difference with respect to the pre-flare abundances. We find a maximum change of ∼12 ppm for CH4 in transmission spectra on GJ 876c. These changes in the spectra remain too small to observe. We also find that the change in abundance and spectra of the planets accumulates throughout time, causing permanent changes in the chemistry. We conclude that this small but gradual change in chemistry arises due to the recurring flares.

Safety and efficacy of the SGLT2 inhibitor dapagliflozin in patients with systemic lupus erythematosus: a phase I/II trial

ObjectiveSodium-glucose cotransporter-2 inhibitors have been identified profound renal/cardiac protective effects in different diseases. Here, we assessed the safety and efficacy of dapagliflozin among adult patients with systemic lupus erythematosus (SLE).MethodsWe...

Conditions for arrival of solar energetic protons in Earth after strong solar flares

We analyze the Sun-to-Earth transport of energetic protons accelerated in solar flares. We use a model which assumes that protons move earthward in the Parker electromagnetic field. In this model, protons are shown to be recorded on Earth when they, moving away from the solar flare region, reach the vicinity of the heliospheric current sheet, while Earth is at a distance smaller than the proton Larmor radius from the current sheet neutral line. We present the analysis of experimental data on solar flares in August–September 2011. This analysis shows that the absence of energetic protons recording in the vicinity of Earth for some major solar flares can be explained by the proposed model.

Условия прихода солнечных энергичных протонов на Землю после мощных вспышек на Солнце

We analyze the Sun-to-Earth transport of energetic protons accelerated in solar flares. We use a model which assumes that protons move earthward in the Parker electromagnetic field. In this model, protons are shown to be recorded on Earth when they, moving away from the solar flare region, reach the vicinity of the heliospheric current sheet, while Earth is at a distance smaller than the proton Larmor radius from the current sheet neutral line. We present the analysis of experimental data on solar flares in August–September 2011. This analysis shows that the absence of energetic protons recording in the vicinity of Earth for some major solar flares can be explained by the proposed model.