Article
Astronomy & Astrophysics
N. Dresing, L. Rodriguez-Garcia, I. C. Jebaraj, A. Warmuth, S. Wallace, L. Balmaceda, T. Podladchikova, R. D. Strauss, A. Kouloumvakos, C. Palmroos, V. Krupar, J. Gieseler, Z. Xu, J. G. Mitchell, C. M. S. Cohen, G. A. de Nolfo, E. Palmerio, F. Carcaboso, E. K. J. Kilpua, D. Trotta, U. Auster, E. Asvestari, D. da Silva, W. Droge, T. Getachew, R. Gomez-Herrero, M. Grande, D. Heyner, M. Holmstroem, J. Huovelin, Y. Kartavykh, M. Laurenza, C. O. Lee, G. Mason, M. Maksimovic, J. Mieth, G. Murakami, P. Oleynik, M. Pinto, M. Pulupa, I. Richter, J. Rodriguez-Pacheco, B. Sanchez-Cano, F. Schuller, H. Ueno, R. Vainio, A. Vecchio, A. M. Veronig, N. Wijsen
Summary: On April 17, 2021, a complex and long-lasting solar eruption produced a widespread solar energetic particle event that was observed by five well-separated observers in the inner heliosphere. The event was the second of its kind in solar cycle 25 and produced relativistic electrons and protons. The aim of this study was to understand the reasons for the wide spread of elevated SEP intensities and identify the source regions of the observed particles.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
L. Rodriguez-Garcia, R. Gomez-Herrero, N. Dresing, D. Lario, I. Zouganelis, L. A. Balmaceda, A. Kouloumvakos, A. Fedeli, F. Espinosa Lara, I. Cernuda, G. C. Ho, R. F. Wimmer-Schweingruber, J. Rodriguez-Pacheco
Summary: This paper presents a study on the radial dependences of solar energetic electron (SEE) events measured by MESSENGER and Solar Orbiter missions. The results show that the electron peak intensity and energy spectrum exhibit radial dependencies, with the electron peak intensity following a power law dependence and the energy spectrum being harder than previous studies near 1 au. The findings have important implications for understanding the characteristics of SEE events.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
A. Kollhoff, A. Kouloumvakos, D. Lario, N. Dresing, R. Gomez-Herrero, L. Rodriguez-Garcia, O. E. Malandraki, I. G. Richardson, A. Posner, K-L Klein, D. Pacheco, A. Klassen, B. Heber, C. M. S. Cohen, T. Laitinen, I Cernuda, S. Dalla, F. Espinosa Lara, R. Vainio, M. Koeberle, R. Kuehl, Z. G. Xu, L. Berger, S. Eldrum, M. Bruedern, M. Laurenza, E. J. Kilpua, A. Aran, A. P. Rouillard, R. Bucik, N. Wijsen, J. Pomoell, R. F. Wimmer-Schweingruber, C. Martin, S. Boettcher, J. L. Freiherr von Forstner, J-C Terasa, S. Boden, S. R. Kulkarni, A. Ravanbakhsh, M. Yedla, N. Janitzek, J. Rodriguez-Pacheco, M. Prieto Mateo, S. Sanchez Prieto, P. Parra Espada, O. Rodriguez Polo, A. Martinez Hellin, F. Carcaboso, G. M. Mason, G. C. Ho, R. C. Allen, G. Bruce Andrews, C. E. Schlemm, H. Seifert, K. Tyagi, W. J. Lees, J. Hayes, S. D. Bale, V Krupar, T. S. Horbury, V Angelini, V Evans, H. O'Brien, M. Maksimovic, Yu Khotyaintsev, A. Vecchio, K. Steinvall, E. Asvestari
Summary: The first widespread solar energetic particle event of solar cycle 25 was observed on November 29, 2020, with particles spreading over more than 230 degrees in longitude near 1AU. The delay in particle onset at different spacecraft was found to be related to the flare-footpoint angle, consistent with previous observations. Anisotropic particle distributions observed at SolO, Wind, and STEREO-A suggest involvement of diffusive propagation processes near the Sun.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
D. E. Morosan, J. Pomoell, A. Kumari, E. K. J. Kilpua, R. Vainio
Summary: The Sun produces powerful solar flares and coronal mass ejections (CMEs) which can accelerate electron beams and generate radio bursts. This study investigates the physical mechanism responsible for a type II burst that occurs in the absence of a CME.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
D. Sudar, B. Vrsnak, M. Dumbovic, M. Temmer, J. Calogovic
Summary: The study reveals that under isotropic solar wind conditions, the distance between the apex and the flank of a CME increases monotonically with time, but never becomes fully circular. The velocity of the leading edge segments converges towards the solar wind speed, while the flank speed does not exceed that of the apex.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
Johan L. Freiherr von Forstner, Mateja Dumbovi, Christian Moestl, Jingnan Guo, Athanasios Papaioannou, Robert Elftmann, Zigong Xu, Jan Christoph Terasa, Alexander Kollhoff, Robert F. Wimmer-Schweingruber, Javier Rodriguez-Pacheco, Andreas J. Weiss, Juergen Hinterreiter, Tanja Amerstorfer, Maike Bauer, Anatoly Belov, Maria A. Abunina, Timothy Horbury, Emma E. Davies, Helen O'Brien, Robert C. Allen, G. Bruce Andrews, Lars Berger, Sebastian Boden, Ignacio Cernuda Cangas, Sandra Eldrum, Francisco Espinosa Lara, Raul Gomez Herrero, John R. Hayes, George C. Ho, Shrinivasrao R. Kulkarni, W. Jeffrey Lees, Cesar Martin, Glenn M. Mason, Daniel Pacheco, Manuel Prieto Mateo, Ali Ravanbakhsh, Oscar Rodriguez Polo, Sebastian Sanchez Prieto, Charles E. Schlemm, Helmut Seifert, Kush Tyagi, Mahesh Yedla
Summary: This study presents observations of the first coronal mass ejection (CME) observed by the Solar Orbiter spacecraft and the associated Forbush decrease (FD) measured by the High Energy Telescope (HET). The study emphasizes the importance of multi-spacecraft observations and data-based modeling for understanding space weather impacts in the inner heliosphere.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
M. Temmer, V. Bothmer
Summary: The plasma and magnetic field characteristics of the upstream regions of interplanetary coronal mass ejections (ICMEs) and their evolution as a function of distance to the Sun in the inner heliosphere were investigated. It was found that the sheath structure consists of compressed plasma following the shock and lies ahead of a region of compressed ambient solar wind. The sheath density starts to dominate over the density within the magnetic ejecta (ME) between 0.09 and 0.28 au, and the ME density falls below the ambient solar wind density over 0.45-1.18 au. The size of the sheath shows a weak positive correlation with distance from the Sun.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
S. N. A. Syed Zafar, R. Umar, N. H. Sabri, M. H. Jusoh, A. N. Dagang, A. Yoshikawa
Summary: Previous studies have shown that solar activities such as coronal mass ejections and solar flares can lead to the development of storms and high-speed streams. This study investigates the response of the geomagnetic index SYM/H to solar wind parameters, as well as the ground geomagnetic field responses at low-latitude stations. Findings suggest delayed response of the Earth's magnetosphere to weak geomagnetic storms, while strong solar wind and IMF variations can excite the Earth's H-component during geomagnetic storms caused by solar activities.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
L. Rodriguez-Garcia, R. Gomez-Herrero, I Zouganelis, L. Balmaceda, T. Nieves-Chinchilla, N. Dresing, M. Dumbovic, N. Nitta, F. Carcaboso, L. F. G. dos Santos, L. K. Jian, L. Mays, D. Williams, J. Rodriguez-Pacheco
Summary: The study aims to explain the reasons for the different intensity-time profiles observed by spacecraft and to identify the solar source related to the widespread SEP event. Analysis of in situ data and remote-sensing observations suggests that a shock driven by the CME is the solar source of the SEP event, while differences in intensity-time profiles can be attributed to particle scattering beyond Mercury's orbit.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
D. Telloni, C. Scolini, C. Moestl, G. P. Zank, L-L Zhao, A. J. Weiss, M. A. Reiss, R. Laker, D. Perrone, Y. Khotyaintsev, K. Steinvall, L. Sorriso-Valvo, T. S. Horbury, R. F. Wimmer-Schweingruber, R. Bruno, R. D'Amicis, R. De Marco, V. K. Jagarlamudi, F. Carbone, R. Marino, M. Stangalini, M. Nakanotani, L. Adhikari, H. Liang, L. D. Woodham, E. E. Davies, H. Hietala, S. Perri, R. Gomez-Herrero, J. Rodriguez-Pacheco, E. Antonucci, M. Romoli, S. Fineschi, M. Maksimovic, J. Soucek, T. Chust, M. Kretzschmar, A. Vecchio, D. Muller, I Zouganelis, R. M. Winslow, S. Giordano, S. Mancuso, R. Susino, S. L. Ivanovski, M. Messerotti, H. O'Brien, V Evans, V Angelini
Summary: Both data analysis and numerical simulations indicate that the passage of two distinct, dynamically and magnetically interacting ICMEs at Solar Orbiter is a possible scenario, supported by the numerous similarities between EUHFORIA time series at Solar Orbiter and Solar Orbiter data.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
K. Martinic, M. Dumbovic, M. Temmer, A. Veronig, B. Vrsnak
Summary: This study investigates different methods for determining the orientation of coronal mass ejections (CMEs) in the near-Sun environment and explores the non-radial flow in the sheath region of interplanetary CMEs (ICMEs). The results show that current methods are limited in accurately determining the orientation of CMEs, but most CMEs have a low inclination. Consistent estimations of the tilt between remote and in situ data were obtained for the majority of CME-ICME pairs. The observed non-radial flows suggest that the CME orientation may impact its propagation.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
Athanasios Papaioannou, Konstantin Herbst, Tobias Ramm, Edward W. Cliver, David Lario, Astrid M. Veronig
Summary: The potential impact of solar superflares on the radiation environment around Earth is assessed by studying the relationship between the peak proton flux and fluence of solar energetic particle (SEP) events and the solar flare soft X-ray peak photon flux.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
Susan W. Samwel, Rositsa Miteva
Summary: This study presents a comprehensive catalogue of solar energetic electron events observed during solar cycles 23 and 24 in the energy range of 103-315 keV. The analysis includes the correlation between electron enhancements and solar activities such as solar flares and coronal mass ejections, as well as their correlation with solar energetic protons. The catalogue aims to provide a publicly available service and is considered a novel tool for real-time particle forecasting systems to mitigate harmful space weather effects.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
L. Rodriguez-Garcia, T. Nieves-Chinchilla, R. Gomez-Herrero, I. Zouganelis, A. Vourlidas, L. A. Balmaceda, M. Dumbovic, L. K. Jian, L. Mays, F. Carcaboso, L. F. G. dos Santos, J. Rodriguez-Pacheco
Summary: The main objective of this study is to investigate the radial and longitudinal evolution of the interplanetary counterpart (ICME) in the inner heliosphere and to examine the different magnetic flux-rope configurations observed on the solar disk and in situ at various locations.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
Robert F. Wimmer-Schweingruber, Lars Berger, Alexander Kollhoff, Patrick Kuehl, Bernd Heber, Liu Yang, Verena Heidrich-Meisner, Andreas Klassen, Raul Gomez-Herrero, Javier Rodriguez-Pacheco, George C. Ho, Glenn M. Mason, Nils P. Janitzek, Athanasios Kouloumvakos, Linghua Wang, Alexander Warmuth, David Lario, Fernando Carcaboso, Christopher J. Owen, Radoslav Buik, Daniel Pacheco, Olga Malandraki, Robert C. Allen, Luciano Rodriguez, Daria Shukhobodskaia, Francisco Espinosa Lara, Ignacio Cernuda, Stephan I. Boettcher, Sandra Eldrum, Sebastian Fleth, Zigong Xu
Summary: This study observed an unusual solar particle event where the path length of electrons and ions was three times longer than the standard spiral length, yet they still followed the same magnetic field structures. This event offers important opportunities to study the transport of SEPs within interplanetary structures.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
G. M. Mason, G. C. Ho, R. C. Allen, A. Kouloumvakos, R. F. Wimmer-Schweingruber, J. Rodriguez-Pacheco
Summary: The Solar Orbiter spacecraft observed the suprathermal ion pool and its constituents during its close perihelion passes in 2022. By comparing data at different distances from the Sun, the differences in the suprathermal ion pool composition at different locations and times are revealed. The results show that the suprathermal ion pool is heavier and has characteristics of solar flare material when closer to the Sun. Throughout the mission, there is only a modest increase in the fluences in the inner heliosphere compared to farther distances.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
Immanuel. C. C. Jebaraj, A. Kouloumvakos, N. Dresing, A. Warmuth, N. Wijsen, C. Palmroos, J. Gieseler, A. Marmyleva, R. Vainio, V. Krupar, T. Wiegelmann, J. Magdalenic, F. Schuller, A. F. Battaglia, A. Fedeli
Summary: Researchers studied a solar energetic particle (SEP) event on 9 October 2021, which was associated with an M1.6 flare, a coronal mass ejection, and a shock wave. High-energy protons and electrons were recorded within a narrow longitudinal cone. The aim was to investigate and identify the multiple sources of energetic electron acceleration.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
L. Rodriguez-Garcia, L. A. Balmaceda, R. Gomez-Herrero, A. Kouloumvakos, N. Dresing, D. Lario, I. Zouganelis, A. Fedeli, F. Espinosa Lara, I. Cernuda, G. C. Ho, R. F. Wimmer-Schweingruber, J. Rodriguez-Pacheco
Summary: This study aims to identify potential correlations between solar energetic electron (SEE) events measured by the MESSENGER mission and the properties of parent solar activity phenomena. Statistical analysis reveals an asymmetry in the connection angles (CAs) for SEE events with the highest peak intensities, and moderate to strong correlations are found between the electron peak intensity and the maximum speed of CME-driven shock, flare peak intensity, and CME speed at apex for well-connected events. The correlations become blurred when including poorly connected events.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
R. Bucik, G. M. Mason, N. V. Nitta, V. Krupar, L. Rodriguez, G. C. Ho, S. T. Hart, M. A. Dayeh, J. Rodriguez-Pacheco, R. Gomez-Herrero, R. F. Wimmer-Schweingruber
Summary: We observed six recurrent solar energetic particle injections at around 0.5 au from March 3 to 6 in 2022 using Solar Orbiter. Five of these injections were associated with jets originating from a plage near a large sunspot in active region 12 957. Injections with high He-3 and Fe enrichments showed large jets, while injections with no or lower enrichments showed minor jets. The event with the highest enrichment also exhibited a more compact configuration of the underlying photospheric magnetic field. Extreme-ultraviolet images from Solar Orbiter revealed intersecting loops at the base of jets not visible from 1 au, which may be a precondition for the recurrent events.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
Wen Wang, Linghua Wang, Saem Krucker, Robert F. F. Wimmer-Schweingruber
Summary: We investigated the energy spectrum of 458 solar energetic electron (SEE) events and classified them into five spectral types: downward double-power-law (DDPL), upward double-power-law (UDPL), single-power-law (SPL), Ellison-Ramaty (ER), and logarithmic-parabola (LP) events. These events showed different spectral indices and exhibited variations during the solar cycle. The spectral shape of most SEE events appeared to be unrelated to the estimated electron path lengths, suggesting complex processes/sources involved in the formation of SEE events.
ASTROPHYSICAL JOURNAL
(2023)
Review
Astronomy & Astrophysics
Ilya G. Usoskin
Summary: In this article, the authors review the current understanding of long-term solar activity on a multi-millennial timescale through indirect proxy methods. The concept of solar activity is explained, along with an overview of indices used to quantify different aspects of variable solar activity, with a focus on sunspot numbers. The historical development and modern state of proxy-based reconstructions of past solar activity are discussed, emphasizing the use of cosmogenic isotopes C-14 and Be-10. The article concludes with the main features of long-term solar magnetic activity and their implications for solar/stellar dynamo theory.
LIVING REVIEWS IN SOLAR PHYSICS
(2023)
Article
Astronomy & Astrophysics
Nicholas Larsen, Alexander Mishev, Ilya Usoskin
Summary: We introduce a new open-source tool OTSO for modeling cosmic ray propagation in the Earth's geomagnetosphere and demonstrate its application in several events. Comparison with widely used tools and validation show good agreement. The tool is also used to provide necessary background for analyzing two notable ground-level enhancements.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2023)
Article
Astronomy & Astrophysics
Sergey Koldobskiy, Florian Mekhaldi, Gennady Kovaltsov, Ilya Usoskin
Summary: Extreme solar particle events (ESPEs) are rare and powerful processes of solar eruptive activity. This study presents a new method to reconstruct ESPE fluence based on advanced modeling techniques, combining different cosmogenic isotope (CI) data. The reconstructed ESPE fluences have a smoother spectral shape and significantly higher estimates of low-energy fluence, making ESPEs even more dangerous for modern technological systems than previously believed. The fitted modified Band function allows for the application of the obtained results in different fields.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2023)
Article
Astronomy & Astrophysics
Jan Gieseler, Nina Dresing, Christian Palmroos, Johan L. Freiherr L. von Forstner, Daniel J. Price, Rami Vainio, Athanasios Kouloumvakos, Laura Rodriguez-Garcia, Domenico Trotta, Vincent Genot, Arnaud Masson, Markus Roth, Astrid Veronig
Summary: Solar-MACH is an open-source tool written in Python that derives and visualizes the spatial configuration and solar magnetic connection of different observers in the heliosphere. It utilizes the Parker Heliospheric Magnetic Field model for magnetic connection in the interplanetary space and the Potential Field Source Surface model for connecting the magnetic field to the solar photosphere. Solar-MACH is designed for analyzing Solar Energetic Particle events and solar transients such as Coronal Mass Ejections.
FRONTIERS IN ASTRONOMY AND SPACE SCIENCES
(2023)
Article
Astronomy & Astrophysics
G. M. Mason, I. Roth, N. V. Nitta, R. Bucik, D. Lario, G. C. Ho, R. C. Allen, A. Kouloumvakos, R. F. Wimmer-Schweingruber, J. Rodriguez-Pacheco
Summary: In this study, Solar Orbiter observations of two He-3-rich events are presented, showing clearer features than previous studies. The data suggest that He-3-rich events have a single acceleration mechanism responsible for the unique abundance features of He-3, heavy ions, and ultraheavy ions. The study also calculates reasonable fits to observed abundances and the acceleration model proposed.
ASTROPHYSICAL JOURNAL
(2023)
Article
Astronomy & Astrophysics
Evangelos Paouris, Angelos Vourlidas, Athanasios Kouloumvakos, Athanasios Papaioannou, Vamsee Krishna Jagarlamudi, Timothy Horbury
Summary: The coronal mass ejection on September 5, 2022 was the fastest and one of the largest CMEs observed so far. It is of great significance for space weather studies, as it may result in a high-energy particle event that requires careful attention.
ASTROPHYSICAL JOURNAL
(2023)
Article
Astronomy & Astrophysics
A. Kouloumvakos, G. M. Mason, G. C. Ho, R. C. Allen, Robert F. Wimmer-Schweingruber, A. P. Rouillard, J. Rodriguez-Pacheco
Summary: Observations of Solar Energetic Particles using the Suprathermal Ion Spectrograph on the Solar Orbiter mission reveal extended time periods of high He-3 abundance, typically lasting seven days and coinciding with changes in the spacecraft's magnetic connection to active regions.
ASTROPHYSICAL JOURNAL
(2023)
Article
Geosciences, Multidisciplinary
Jingnan Guo, Xiaolei Li, Jian Zhang, Mikhail I. Dobynde, Yuming Wang, Zigong Xu, Thomas Berger, Jordanka Semkova, Robert F. Wimmer-Schweingruber, Donald M. Hassler, Cary Zeitlin, Bent Ehresmann, Daniel Matthiae, Bin Zhuang
Summary: On 28 October 2021, solar eruptions caused intense and long-lasting enhancements in solar energetic particle (SEP) flux observed by spacecraft across the heliosphere. The arrival of SEPs at Earth resulted in the 73rd ground level enhancement (GLE) event recorded by ground-based neutron monitors. Notably, this study presents the first GLE event detected on the surfaces of Earth, Moon, and Mars, using particle and radiation detectors. By analyzing data from near-Earth spacecraft, the event-integrated proton spectrum is determined, and particle transport models are employed to predict radiation levels on the lunar and martian surfaces. Additionally, previous GLE event doses on the Moon and Mars are modeled and compared with the current event, contributing to our understanding of potential radiation risks for future human exploration of these celestial bodies.
GEOPHYSICAL RESEARCH LETTERS
(2023)
Review
Astronomy & Astrophysics
Aimee Norton, Rachel Howe, Lisa Upton, Ilya Usoskin
Summary: This article describes the defining observations of the solar cycle and their constraints on the dynamo processes within the Sun. It covers topics such as sunspot numbers, active region flux ranges and lifetimes, bipolar magnetic region tilt angles, Hale and Joy's law, and various other aspects.
SPACE SCIENCE REVIEWS
(2023)