Astronomische Nachrichten最新文献

Prominences (PRs) are among the most common solar phenomena, yet their full physical picture, particularly their chromospheric mm emission, remains incomplete. The new Atacama Large Millimeter/submillimeter Array (ALMA) presents an opportunity to study PRs at mm and sub-mm wavelengths through a combination of measurements and theoretical modeling. We utilize ALMA single-dish measurements alongside data from other radio instruments to model the PR brightness temperature through adaptation and modification of the 1D semi-empirical Avrett–Tian–Landi–Curdt–Wülser (ATLCW) quiet-Sun (QS) model. The calculated and measured PR brightness temperatures were found to be lower than the measured QS value and predictions from the unperturbed ATLCW QS model across the ALMA wavelength range, consistent with PRs appearing in absorption. The PR density was found to be 60–163 times higher and temperature 155–163 times lower than the QS level, aligning with previous measurements. A key finding emerged with the non-hydrostatic equilibrium assumption, yielding a more physically consistent PR brightness temperature. This suggests that PR stability is most likely maintained by its magnetic field obeying magnetostatic conditions rather than by pure hydrostatic equilibrium, supporting recent studies. Additionally, our results confirm that thermal bremsstrahlung is the dominant radiation mechanism for PRs at mm and sub-mm wavelengths.

We study the spin evolution of the young X-ray pulsar PSR J0537-6910 in the Large Magellanic Cloud, the fastest-spinning isolated pulsar known to date with a rotation period of 16 ms, which provides a unique laboratory for probing the early angular momentum evolution of a neutron star. Motivated by the observed discrepancy that most pulsars exhibit less than three braking indices in contrast to what is predicted by a magnetospheric dipolar slow-down law, we propose a hybrid Magnetic Dipole Radiation and Wind (MDRW) model that incorporates both magnetic dipole radiation (MDR) and particle wind contributions. By assuming $��n�=�2�$, we derive analytical solutions for the spin evolution equations under different ages (1–4 kyr). We show that the initial spin period range (10.5–14.3 ms) predicted by the MDRW model significantly exceeds the values derived from the classical MDR framework (7.0–14.4 ms), which is in agreement with physical expectations for neutron star birth scenarios. Furthermore, the MDRW model reveals an equal partitioning of rotational energy loss between magnetic dipole radiation and particle wind components ($��d�=�f�=�0.5�$) when $��n�=�2�$, highlighting the interplay of the various mechanisms in the spin-down of young pulsars. This also provides a new approach to estimating the period evolution of pulsars.

Each asteroid pair demonstrates strikingly the similar heliocentric orbit elements, suggesting a dynamical association. To date, more than 200 asteroid pairs distributing across a vast extent range from the Near-Earth region to the outer Solar System have been discovered. The studies on them reveal the asteroidal formation and evolution mechanism and provide us with an opportunity to understand the ongoing process of rotational fission of an asteroid parent driven by YORP effect. Especially, the young asteroid pairs are getting more attention, and at present, we find that the (434936) 2006 TW124–2015 HB287 system may be an additional young pairs. Using the backward integration method, various indicators suggest that this system age is likely less than 1 kyr since they began evolving into the asteroid pair phase. Such these young asteroid pairs maybe provide a wealth of clues to study the effects of space weathering, the rotational properties of small asteroids, and the clues on the evolution mechanism of multiple asteroid systems.

A novel approach to cosmic inflation within the framework of a noncommutative Riemannian foliated quantum gravity, built upon a reverse Faddeev–Jackiw symplectic spacetime deformation of the conventional Poisson algebra, is investigated. Friedmann-type dynamical equations, analytically continued to a complex noncommutative framework, incorporate a modified energy-momentum Riemann tensor and a noncommutative matter-energy potential, highlighting the emergence of quantum gravity topological fluctuation effects on the expansion dynamics of the universe. In this realm, the coupling of UV and IR scales plays a central role, providing a natural topological mechanism for inflation and recursal evidence for the generation of relic gravitational waves. These predictions align with a self-consistent description of the transition between the primordial mirror-universe deceleration and present-universe acceleration phases as predicted by the Riemann foliated quantum gravity, offering potential connections to observational cosmology.

Dark matter constitutes approximately $��27�\%�$ of the universe's total matter-energy content, yet its fundamental nature remains unknown. Axions, initially proposed to solve the strong CP problem in quantum chromodynamics (QCD), emerge as leading dark matter candidates due to their attractive theoretical properties and compatibility with observational constraints. This paper explores the theoretical foundations of axions, their interactions with electromagnetic fields, and recent advancements in experimental detection methods. We provide an in-depth analysis of axion models, including the PQWW, KSVZ, DFSZ models, and axion-like particles (ALPs), highlighting their mass ranges, coupling strengths, and experimental implications. The potential for detecting axion dark matter via pulsar observations is also explored, offering a novel avenue to constrain axion parameter spaces. Finally, we discuss ongoing challenges and future research directions in axion physics, underscoring the transformative potential of axion detection for solving the dark matter puzzle and advancing fundamental physics.