Preface: Workshop on matter,astrophysics, gravitation,ions and cosmology—MAGIC23

We outline our experience in organizing the first edition of the Workshop on Matter, Astrophysics, Gravitation, Ions and Cosmology, held in virtual and in-person format, denominated MAGIC23, held from 6 to 10 March, 2023, in Praia do Rosa, Santa Catarina, Brazil. The event aimed to bring together leading academic scientists, professors, students, and research scholars for exchanging experiences and discuss the most recent innovations, trends, practical challenges, and experimental and theoretical solutions adopted in the investigation fields within the scope of the meeting. The workshop offered to the participants a platform for scientific and academic projects, partnerships, and presentation of high-quality research contributions describing original and unpublished results on topics related to matter, astrophysics, gravitation, ions, and cosmology.     

The fusion crust of the Winchcombe meteorite: A preserved record of atmospheric entry processes

Fusion crusts form during the atmospheric entry heating of meteorites and preserve a record of the conditions that occurred during deceleration in the atmosphere. The fusion crust of the Winchcombe meteorite closely resembles that of other stony meteorites, and in particular CM2 chondrites, since it is dominated by olivine phenocrysts set in a glassy mesostasis with magnetite, and is highly vesicular. Dehydration cracks are unusually abundant in Winchcombe. Failure of this weak layer is an additional ablation mechanism to produce large numbers of particles during deceleration, consistent with the observation of pulses of plasma in videos of the Winchcombe fireball. Calving events might provide an observable phenomenon related to meteorites that are particularly susceptible to dehydration. Oscillatory zoning is observed within olivine phenocrysts in the fusion crust, in contrast to other meteorites, perhaps owing to temperature fluctuations resulting from calving events. Magnetite monolayers are found in the crust, and have also not been previously reported, and form discontinuous strata. These features grade into magnetite rims formed on the external surface of the crust and suggest the trapping of surface magnetite by collapse of melt. Magnetite monolayers may be a feature of meteorites that undergo significant degassing. Silicate warts with dendritic textures were observed and are suggested to be droplets ablated from another stone in the shower. They, therefore, represent the first evidence for intershower transfer of ablation materials and are consistent with the other evidence in the Winchcombe meteorite for unusually intense gas loss and ablation, despite its low entry velocity.     

Visualization-based analysis of structural and dynamical properties of simulated hydrous silicate melt

We have explored first-principles molecular dynamics simulation data for hydrous MgSiO₃ liquid (with 10 wt% water) to gain insight into its structural and dynamical behavior as a function of pressure (0–150 GPa) and temperature (2,000–6,000 K). By visualizing/analyzing a number of parameters associated with short- and mid-range orders, we have shown that the melt structure changes substantially on compression. The speciation of the water component at low pressures is dominated by the isolated structures (with over 90% hydrogen participated) consisting of hydroxyls, water molecules, O–H–O bridging and four-atom (O–H–O–H and H–O–H–O) groups, where every oxygen atom may be a part of polyhedron or free (i.e., bound to only magnesium atom). Hydroxyls favor polyhedral sites over magnesium sites whereas molecular water is almost entirely bound to magnesium sites, and also interpolyhedral bridging (Si–O–H–O–Si) dominates other types of bridging. Water content is shown to enhance and suppress, respectively, the proportions of hydroxyls and molecular water. As compression increases, these isolated structures increasingly combine with each other to form extended structures involving a total of five or more O and H atoms and also containing threefold coordination species, which together consume over 80% hydrogen at the highest compression studied. Our results show that water lowers the mean coordination numbers of different types including all cation–anion environments. The hydrous melt tends to be more tetrahedrally coordinated but with the Si–Si network being more disrupted compared to the anhydrous melt. Protons increase the content of non-bridging oxygen and decrease the contents of bridging oxygen as well as oxygen triclusters (present at pressures above 10 GPa). The calculated self-diffusion coefficients of all atomic species are enhanced in the presence of water compared to those of the anhydrous melt. This is consistent with the prediction that water depolymerizes the melt structure at all pressures. Our analysis also suggests that proton diffusion involves two processes—the transfer of H atoms (requiring the rupture and formation of O–H bonds) and the motion of hydroxyls as hydrogen carriers (requiring the rupture and formation of Si–O and/or Mg–O bonds). Both the processes are operative at low compression whereas only the first process is operative at high compression.     

Culture,demography and biogeography of sponge science: From past conferences to strategic research?

Perceived changes in the culture of sponge science and sponge conferences served as motivation for an evaluation of the sponge science community and research, over time and at present. Observed changes included a decrease in proceedings publications on sponge fossils and freshwater sponges, sponges from temperate environments, review papers and data syntheses, frequency of aquarium studies, and number of species investigated per publication. Publications on recent sponges, hexactinellids, calcareans, marine, Indo‐Pacific and warm‐water sponges increased, as well as the number of authors per publication and the proportion of field studies. Studies at the level of specimens and ultrastructure were gradually replaced by molecular approaches, but studies at the community level remained stable. The five sub‐disciplines morphology/taxonomy, phylogeny/evolution, physiology, ecology and faunistics also retained about equal proportions over time. Conference publications related to taxonomy, phylogeny and biodiversity prevailed, whereas those on management and conservation were rare, possibly because studies on sponge recovery, survival and mortality were also scarce. The community of sponge scientists has grown and become more diverse over time, presently representing 72 nations. The gender distribution evened out since the first sponge conference and presently favours women at early and men at late career stages. Although stated research interests are generally dominated by physiology and ecology, taxonomy and evolution are favoured after retirement. Sponge science has become more dynamic, but maybe also more competitive and less inclusive. We now face the dual challenge of safeguarding against the loss of some sub‐disciplines, and fostering the collaborative, helpful culture characteristic of sponge science.     

Assessing the Constrained Harmonic Mean Method for Deriving the Kinematics of ICMEs with a Numerical Simulation

In this study we use a numerical simulation of an artificial coronal mass ejection (CME) to validate a method for calculating propagation directions and kinematical profiles of interplanetary CMEs (ICMEs). In this method observations from heliospheric images are constrained with in-situ plasma and field data at 1 AU. These data are used to convert measured ICME elongations into distance by applying the harmonic mean approach, which assumes a spherical shape of the ICME front. We used synthetic white-light images, similar to those observed by STEREO-A/HI, for three different separation angles between remote and in-situ spacecraft of 30^°, 60^°, and 90^°. To validate the results of the method, the images were compared to the apex speed profile of the modeled ICME, as obtained from a top view. This profile reflects the “true” apex kinematics because it is not affected by scattering or projection effects. In this way it is possible to determine the accuracy of the method for revealing ICME propagation directions and kinematics. We found that the direction obtained by the constrained harmonic mean method is not very sensitive to the separation angle (30^° sep: ?=W7; 60^° sep: ?=W12; 90^° sep: ?=W15; true dir.: E0/W0). For all three cases the derived kinematics agree relatively well with the real kinematics. The best consistency is obtained for the 30^° case, while with growing separation angle the ICME speed at 1 AU is increasingly overestimated (30^° sep: ΔV _arr≈??50 km?s^?1, 60^° sep: ΔV _arr≈+?75 km?s^?1, 90^° sep: ΔV _arr≈+?125 km?s^?1). Especially for future L₄/L₅ missions, the 60^° separation case is highly interesting in order to improve space-weather forecasts.     

Evolution of the Fine Structure of Magnetic Fields in the Quiet Sun: Observations from Sunrise/IMaX and Extrapolations

Observations with the balloon-borne Sunrise/Imaging Magnetograph eXperiment (IMaX) provide high spatial resolution (roughly 100 km at disk center) measurements of the magnetic field in the photosphere of the quiet Sun. To investigate the magnetic structure of the chromosphere and corona, we extrapolate these photospheric measurements into the upper solar atmosphere and analyze a 22-minute long time series with a cadence of 33 seconds. Using the extrapolated magnetic-field lines as tracer, we investigate temporal evolution of the magnetic connectivity in the quiet Sun’s atmosphere. The majority of magnetic loops are asymmetric in the sense that the photospheric field strength at the loop foot points is very different. We find that the magnetic connectivity of the loops changes rapidly with a typical connection recycling time of about 3±1 minutes in the upper solar atmosphere and 12±4 minutes in the photosphere. This is considerably shorter than previously found. Nonetheless, our estimate of the energy released by the associated magnetic-reconnection processes is not likely to be the sole source for heating the chromosphere and corona in the quiet Sun.     

A Method to Determine the Solar Synodic Rotation Rate and the Height of Tracers

The dependence of the measured apparent synodic solar rotation rate on the height of the chosen tracer is studied. A significant error occurs if the rotation rate is determined by tracing the apparent position of an object above the photospheric level projected on the solar disc. The centre-to-limb variation of this error can be used to determine simultaneously the height of the object and the true synodic rotation rate. The apparent (projected) heliographic coordinates are presented as a function of the height of the traced object and the coordinates of its footpoint. The relations obtained provide an explicit expression for the apparent rotation rate as a function of the observed heliographic coordinates of the tracer, enabling an analytic least-squares fit expression to determine simultaneously the real synodic rotation rate and the height of the tracer.     

Differential rotation and giant cell circulation of solar Ca+-network

We report new results obtained from high precision computer controlled tracings of ca. 400 bright Ca⁺-mottles made during summer 1975 in continuation of our 1974 program (Schröter and Wöhl, 1975). In particular, we looked in 1975 for the existence of a giant circulation pattern in the equatorial zone. We find for the differential rotation: = 13.93 – 2.90 sin² B (deg/day, sidereal) when combining the new measurements with those obtained in 1974. Observations from 26th April until June 19th give strong evidence that at that time four giant circulation cells, crossing the solar equator, (i.e. a nonaxisymmetric velocity field pattern with respect to the solar equator) did exist. This yields two more rapid and two slower rotating sectors with v = ±80 m s^–1. These giant cells transport angular momentum towards the equator.     

An Ensemble Study of a January 2010 Coronal Mass Ejection (CME): Connecting a Non-obvious Solar Source with Its ICME/Magnetic Cloud

A distinct magnetic cloud (MC) was observed in-situ at the Solar TErrestrial RElations Observatory (STEREO)-B on 20?–?21 January 2010. About three days earlier, on 17 January, a bright flare and coronal mass ejection (CME) were clearly observed by STEREO-B, which suggests that this was the progenitor of the MC. However, the in-situ speed of the event, several earlier weaker events, heliospheric imaging, and a longitude mismatch with the STEREO-B spacecraft made this interpretation unlikely. We searched for other possible solar eruptions that could have caused the MC and found a faint filament eruption and the associated CME on 14?–?15 January as the likely solar source event. We were able to confirm this source by using coronal imaging from the Sun Earth Connection Coronal and Heliospheric Investigation (SECCHI)/EUVI and COR and Solar and Heliospheric Observatory (SOHO)/Large Angle and Spectrometric Coronograph (LASCO) telescopes and heliospheric imaging from the Solar Mass Ejection Imager (SMEI) and the STEREO/Heliospheric Imager instruments. We use several empirical models to understand the three-dimensional geometry and propagation of the CME, analyze the in-situ characteristics of the associated ICME, and investigate the characteristics of the MC by comparing four independent flux-rope model fits with the launch observations and magnetic-field orientations. The geometry and orientations of the CME from the heliospheric-density reconstructions and the in-situ modeling are remarkably consistent. Lastly, this event demonstrates that a careful analysis of all aspects of the development and evolution of a CME is necessary to correctly identify the solar counterpart of an ICME/MC.