The Sun often produces eruptive events on different energetic and temporal scales. It might, however, also produce events, so-called extreme solar events, whose energy could be orders of magnitude greater than anything we have observed during recent decades. But what is an extreme solar event? How strong can they be and how often do they occur?
In a novel cross-disciplinary effort, the ISSI Team around Erika Palmerio and David Barnes is revolutionizing our understanding of Coronal Mass Ejections (CMEs), powerful solar eruptions with significant space weather impacts on Earth. Focusing on the often-overlooked tomography technique, the team utilizes state-of-the-art magnetohydrodynamic simulations and synthetic white-light data to overcome observational limitations. By placing virtual spacecraft strategically, they generate synthetic images, reconstructing CME structures through discrete tomography.
The findings based on their modelling reveal a complex, irregular front in contrast to traditional assumptions. The team aims to evaluate the impact of 3D reconstructions on space weather predictions, comparing them with conventional forward-modelling techniques. With plans to extend analyses to heliospheric imagery, their work promises groundbreaking insights into CME behavior and improved forecasting methods. Stay tuned for further revelations from this innovative endeavor tackled at ISSI Bern!
See the full team report here: “Tomographic Inversion of Synthetic White-Light Images: Advancing Our Understanding of CMEs in 3D“
The standard cosmological model states that massive galaxies contain a large fraction of dark matter. Dark matter is a transparent substance that does not interact through regular baryonic matter and is only detected through its gravitational pull over the stars and the gas.
The Earth’s magnetosphere shields our planet from hazardous space weather effects caused by solar disturbances and energetic particles. However, the global structure of the magnetosphere is still extremely difficult to describe. Major challenges include the scarcity of data sets, as well as the breadth of physical processes that need to be taken into account. Our ISSI Team explores various approaches that help to mitigate these challenges. Recent publications from our ISSI Team provide new insights into how to extract information about global magnetospheric and ionospheric structures, and how to combine global data analysis and global modeling in meaningful ways. The new results suggest potentially transformative ways to work with global datasets, develop new global models, and improve the accuracy of the current global models.
Earth’s magnetic environment is filled with a symphony of sound that we cannot hear. All around our planet, ultralow-frequency waves compose a cacophonous operetta portraying the dramatic relationship between Earth and the Sun. Now, a new citizen science project called HARP – or Heliophysics Audified: Resonances in Plasmas – has turned those once-unheard waves into audible whistles, crunches, and whooshes. Early tests have already made surprising finds, and citizen scientists can join the journey of sonic space exploration to decipher the cosmic vibrations that help sing the song of the Sun and Earth.
Report from the ISSI Team #447 Cold Plasma of Ionospheric Origin at the Earth’s Magnetosphere led by Sergio Toledo-Redondo (ES)
Above the neutral atmosphere, space is filled with charged particles, which are tied to the Earth’s magnetic field. The particles come from two sources, the solar wind and the Earth’s upper atmosphere. Most of the solar wind particles are deflected by the Earth´s magnetic field, but some can penetrate into near-Earth space. The ionized layer of the upper atmosphere is continuously ejecting particles into space, which have low energies and are difficult to measure. We investigate the relative importance of the two charged particle sources for the dynamics of plasma processes in near-Earth space. In particular, we consider the effects of these sources in magnetic reconnection.
Report from the ISSI Team #448 “Global study of the transmission of foreshock ULF waves into the magnetosheath and the magnetosphere” led by L. Turc and M. Palmroth
Plasma waves forming in the turbulent foreshock upstream of Earth’s bow shock have long been known to transmit into Earth’s magnetosphere. Yet the exact mechanism allowing their propagation through the shock remained unknown. A recent paper published in Nature Physics, led by Lucile Turc and initiated within the ISSI Team #448, proposes a new scenario to explain the wave transmission.
Report from ISSI Team #472 on Closing The Gap Between Ground Based And In-Situ Observations Of Cometary Dust Activity: Investigating Comet 67P To Gain A Deeper Understanding Of Other Comets led by R. Marschall (FR) & O. Ivanova (SK)
ESA’s Comet Interceptor mission (launch in 2029) will, for the first time, visit a long period or dynamically new comet (LPC/DNC), one the most pristine objects in our Solar System. DNCs have been stored in the outermost part of our planetary system since they formed 4.5 billion years ago. From there, they enter the inner Solar System for the first time to reveal their primitive structure and composition.
Report from the ISSI Team #535 “Unraveling Surges: a joint perspective from numerical models, observations, and machine learning” led by D. Nóbrega-Siverio
A numerical experiment – performed by Daniel Nóbrega Siverio and Fernando Moreno Insertis – has shown for the first time how one of the most abundant structures in the solar atmosphere, the Coronal Bright Points, can be formed, acquire energy, and be disrupted through the action of solar granulation.
When the Sun is observed from space with X-ray or extreme ultraviolet detectors, its atmosphere is seen to be full of roundish bright points with sizes similar to our planet Earth. These Coronal Bright Points (CBPs) are found to be consisted of sets of bright magnetic arcs that confine very hot plasma and emit enormous amounts of energy for hours and even days, typically disappearing after a series of eruptive phenomena.
Report from ISSI Team #469 Using Energetic Electron And Ion Observations To Investigate Solar Wind Structures And Infer Solar Wind Magnetic Field Configurations led by G. Li and L. Wang
Coronal mass ejections (CMEs) represent some of the most energetic processes in the entire solar system. They are often associated with Solar Energetic Particle Events (SEP events) and are major concerns of space weather studies. When CMEs happen, they drive shock waves in front of them and charged particles are accelerated at the shock front through the diffusive shock acceleration mechanism. Protons and ions can be accelerated to the energy beyond 1 GeV/nuc in some of the most energetic SEP events. Understanding how particles are accelerated in these events and how these accelerated particles propagate to the Earth has been a central problem for space plasma physics.
Report from ISSI/ISSI-BJ Team #444 “Chemical Abundances in the ISM: The Litmus Test of Stellar IMF Variations in Galaxies Across Cosmic Time” led by D. Romano and Z.-Y. Zhang
Astronomers have known for a long time that large galaxies grow through accretion and merging of smaller systems. A recent study published in Nature Astronomy demonstrates that this fundamental pattern of structure formation also applies to galactic satellites on small scales. A team of Italian researchers and members of the ISSI/ISSI-BJ Team #444 has discovered an old star cluster in the Large Magellanic Cloud (LMC) whose chemical composition is unambiguously pointing to an external origin.
Report from ISSI Team #415 Understanding the Origins of Problem Geomagnetic Storms led by N.V. Nitta and T. Mulligan
Coronal mass ejections (CMEs) are large eruptions from the Sun that are often powerful drivers of space weather effects at Earth. Being able to predict their behaviour in interplanetary space is one of the main goals of space weather forecasting. However, there is a class of CMEs that are particularly hard to observe and, therefore, forecast. These eruptions are known as “stealth CMEs” and they were first reported by Robbrecht et al. [2009], who used the twin STEREO spacecraft (in orbit around the Sun) that were separated by ~50° in longitude to observe a clear ejection off the solar limb from one perspective, but no corresponding eruptive signatures against the solar disc from the other. The lack of indications that an eruption has occurred makes it particularly challenging to establish whether a CME is Earth-directed, especially when imagery from secondary viewpoints is not available. Nitta & Mulligan [2017] analysed a number of stealth CMEs that, in fact, caused unexpected space weather effects at Earth, also known as “problem geomagnetic storms”.
Report from the ISSI Team #408 Low Frequency Imaging Spectroscopy with LOFAR – New Look at Non-Thermal Processes in the Outer Corona led by E. Kontar
The combination of kinetic simulations with LOFAR telescope observations published in a paper in Nature Astronomy shows that the fine structures are caused by the moving intense clumps of Langmuir waves in a turbulent medium.
Report from the ISSI Team #477 “Radiation Belt Physics From Top To Bottom: Combining Multipoint Satellite Observations And Data Assimilative Models To Determine The Interplay Between Sources And Losses” led by led by J.-F. Ripoll (CEA, France), G. D. Reeves (Los Alamos National Laboratory, USA) & D. L. Turner (Applied Physics Laboratory, USA)
Lightning superbolts are the most powerful and rare lightning events with intense optical emission, first identified from space by the Vela satellites at the end of the 70s. Recently, radio frequency superbolts were geographically localized by the very low frequency (VLF) ground stations of the World-Wide Lightning Location Network (WWLLN). Interestingly, the distribution of superbolt locations and occurrence times was not equivalent to that of ordinary lightning: instead, superbolts were found to occur over oceans and seas at a much higher rate, and more often in winter [Holzworth et al., 2019].
Report from ISSI Team #397 Comet 67P/Churyumov-Gerasimenko Surface Composition as a Playground for Radiative Transfer Modeling and Laboratory Measurements” led by M. Ciarniello
Recent investigations of the surface composition of comet 67P/Churyumov-Gerasimenko, by means of observations provided by the VIRTIS imaging spectrometer onboard the Rosetta mission, revealed the presence of aliphatic organics and ammonium salts, which characterize the ubiquitous 3.2 µm absorption band in the comet’s infrared spectrum.
