Listed are all scientific papers resulting from an ISSI activity written or co-authored by ISSI Team members, Working Group members, Workshop participants, visitors or staff members.
S. D. von Fellenberg et al. reported the first mid-infrared detection of a flare from Sgr A*. The JWST/MIRI/Medium Resolution Spectrometer observations were consistent with an orbiting hotspot undergoing electron injection with a spectrum that subsequently breaks from synchrotron cooling. However, mid-infrared extinction measurements appropriate for these data were not yet determined, and, therefore, the temporal evolution of the absolute spectral index remained unknown.
Scaling laws in astrophysical systems that involve energy, geometry, and spatiotemporal evolution provide the theoretical framework for physical models of energy dissipation processes.
Solar radio noise storms are common phenomena, composed of broadband continuum emission embedded with diverse fine structures, yet their unusually compact apparent sizes remain unexplained. We present frequency-time-resolved imaging spectroscopy of a near-disk-center noise storm observed by the Low Frequency Array between 30 and 40 MHz, together with anisotropic radio-wave scattering simulations.
Current models predict that at distances beyond 80 kpc in the Milky Way halo, we can find the earliest escaped stars from the merging Sagittarius dwarf galaxy. However, observational data on the Sagittarius stream at these distances are limited. This study examines an overdensity of red giant branch (RGB) stars potentially linked to Sagittarius merger debris.
The origin of magnetic switchbacks—large-amplitude, spherically polarized magnetic-field fluctuations with local polarity inversions shown to be nearly ubiquitous in the inner heliosphere by Parker Solar Probe—is presently one of the most outstanding open questions in solar and heliospheric science.
The thermal lattice method (TLBM) offers an alternative to classical PDE-based numerical methods for modelling planetary dynamics. It solves the lattice Boltzmann equation on a unitary discrete lattice which requires no matrix operations, and hence scales extremely well on HPC clusters.
Solar radio bursts exhibit complex fine structures that reveal intricate coronal plasma dynamics. Here, we report detection of spike-like repeating burst pairs, characterized by two short-lived (0.1-2 s), narrowband components separated by about 4 s at frequencies 30-50 MHz. Using high-resolution dynamic spectra and spectroscopic imaging, we analyzed 613 burst pairs, measuring their durations, bandwidths, drift rates, flux densities, and spatial characteristics.
The mesosphere and lower thermosphere (MLT) dynamics play a crucial role in the vertical coupling of the whole atmosphere and are a key component of space weather processes. However, accurately representing the MLT in whole atmosphere models remains challenging due to sparse observational coverage and limited assimilation of high‐altitude wind data.
Magnetic switchbacks are fluctuations in the solar wind in which the interplanetary magnetic field sharply deflects away from its background direction so as to create folds in magnetic field lines while remaining of roughly constant magnitude. The magnetic field and velocity fluctuations are extremely well correlated in a way corresponding to Alfvénic fluctuations propagating away from the Sun. For a background field which is nearly radial this causes an outwardly propagating jet to form.
Global ideal magnetohydrodynamic models of the heliosphere typically predict a greatly exaggerated magnetic field pile-up in the inner heliosheath (IHS), the region between the termination shock and heliopause. However, Voyager 1 and 2 observations show only a gradual increase throughout this region.
