Hasil untuk "physics.space-ph"

L. C. R. Aaij, B. Adeva, M. Adinolfi et al.

The LHCb detector is a forward spectrometer at the Large Hadron Collider (LHC) at CERN. The experiment is designed for precision measurements of CP violation and rare decays of beauty and charm hadrons. In this paper the performance of the various LHCb sub-detectors and the trigger system are described, using data taken from 2010 to 2012. It is shown that the design criteria of the experiment have been met. The excellent performance of the detector has allowed the LHCb collaboration to publish a wide range of physics results, demonstrating LHCb's unique role, both as a heavy flavour experiment and as a general purpose detector in the forward region.

T. Remer, F. Manz

M. Kavtaradze, G. Mamatsashvili, G. Chagelishvili et al.

We investigate magnetohydrodynamic (MHD) turbulence in plane shear flows with a streamwise background magnetic field in the super-Alfvénic regime. We show that the large-scale velocity shear suppresses turbulence imbalance, driving the system toward a balanced state -- the energies of counter-propagating Alfvén waves become essentially equal, even at initially perfectly imbalanced Alfvénic turbulence. This balancing is due to the shear-induced linear non-modal dynamics of Alfvén waves, including their transient growth and over-reflection. This linear route to balancing turbulence is new -- fundamentally different from nonlinear ones operative in shearless MHD turbulence -- and have direct implications for understanding balanced/imbalanced MHD turbulence in the solar wind, which is modeled as a shear flow in a thermodynamically complex plasma.

Xinan Dai, Haiyang Fu, Zichong Yan et al.

Solar storms perturb Earth's magnetosphere, triggering geomagnetic storms that threaten space-based systems and infrastructure. Despite advances in spaceborne and ground-based observations, the causal chain driving solar-magnetosphere-ionosphere dynamics remains elusive due to multiphysics coupling, nonlinearity, and cross-scale complexity. This study presents an information-theoretic framework to decipher interaction mechanisms in extreme solar geomagnetic storms across intensity levels within space weather causal chains, using 1980-2024 datasets. Unexpectedly, we uncover auroral spatial causality patterns associated with space weather threats in the Arctic during May 2024 extreme storms. By integrating causal consistency constraints into spatiotemporal modeling, SolarAurora outperforms existing frameworks, achieving superior accuracy in forecasting May/October 2024 events. These results advance understanding of space weather dynamics and establish a promising framework for scientific discovery and forecasting extreme space weather events.

Luise Meyer-Hetling, Martin J. Losekamm, Stephan Paul et al.

We present a neural-network framework designed to reconstruct the properties of cosmic-ray nuclei traversing the scintillating-fiber tracking calorimeter of the RadMap Telescope. Employing the Geant4 simulation toolkit and a simplified model of the detector to generate training and test data, we achieve the spectroscopic capabilities required for an accurate determination of the biologically relevant dose that astronauts receive in space. We can reconstruct a particle's trajectory with an angular resolution of better than $1.4^\circ$ and achieve a charge separation of better than $95\%$ for nuclei with $Z\leq8$; specifically, we reach an accuracy of $99.8\%$ for hydrogen. The energy resolution is $<20\%$ for energies below 1 GeV/n and elements up to iron. We also discuss the limitations of our detector, the reconstruction framework, and this feasibility study, as well as possible improvements.

David Pelosi, Fernando Barão, Bruna Bertucci et al.

The study presents an effective approach for deriving and utilizing polarity-based cross-correlation functions to forecast Galactic Cosmic Ray (GCR) fluxes based on solar activity proxies. By leveraging a universal correlation framework calibrated with AMS-02 and PAMELA proton flux data under a numerical model, the methodology incorporates Empirical Mode Decomposition (EMD) and a global spline fit. These techniques ensure robust handling of short-term fluctuations and smooth transitions during polarity reversals. The results have significant potential for space weather applications, enabling reliable GCR flux predictions critical for radiation risk assessments and operational planning in space exploration and satellite missions.

Abigail Tadlock, Chuanfei Dong, Chi Zhang et al.

The Martian magnetosheath acts as a conduit for mass and energy transfer between the upstream solar wind and its induced magnetosphere. However, our understanding of its global properties remains limited. Using nine years of data from NASA's Mars Atmosphere and Volatile EvolutioN (MAVEN) mission, we performed a quantitative statistical analysis to explore the spatial distribution of the magnetic fields, solar wind and planetary ions in the magnetosheath. We discovered significant asymmetries in the magnetic field, solar wind protons, and planetary ions between the quasi-perpendicular and quasi-parallel magnetosheaths. The asymmetries in the Martian magnetosheath exhibit both similarities and differences compared to those in the Earth's and Venus' magnetosheaths. These results indicate that the Martian magnetosheath is distinctly shaped by both shock geometry and planetary ions.

Leonidas Askianakis

Although vital for life on Earth, solar activity poses questions and increasing threats to humanity due to the Sun's unknown dynamics, intensified by our dependence on terrestrial and space-based infrastructure. This situation is compounded by significant gaps in our understanding of space weather phenomena, the Sun's magnetic field, and the need for rapid responses to unpredicted solar events. To address these issues, an optimized heliocentric satellite constellation is proposed that leverages satellites in an Elliptical Walker Constellation. This system offers (among others) equally distributed arguments of periapsis separations and cross-coupled true anomalies with respect to the Sun-centric coordinate frame. In this paper it is also demonstrated that this strategic multi-spacecraft configuration makes it possible to distinguish spatial and temporal changes in solar wind phenomena, reconstruct, in 3D, Coronal Mass Ejections (CMEs), predict which space or ground-based infrastructure and when it will be affected by CMEs, maintain continuous coverage of the critical Sun-Earth line throughout the mission's duration, and protect future missions by providing simultaneously in-situ and remote measurements from small and cost-effective satellites.

Meihua Fang, Zheng liang, Yingkui Gong et al.

Relativistic charged particle beam can be used as destructive beam weapons in space for debris removal tasks. The trajectories of charged particles are affected by both electric and magnetic forces in the Earth's magnetic field. In this paper, we firstly analyzed the correlation parameters of the charged particle beam as a weapon when it propagated in the geomagnetic field. Then the models were constructed based on COMSOL Multiphysics and the IGRF model was adopted in the simulation. The gyro-radius and the related uncertainty were analyzed by simulation of the charged particle transport in the geomagnetic field at different altitudes. The charged beam spot radius divergency was also simulated. The magnetic field pinch effect can be found and can limit the beam spreading.

L. Rosso, J. Lobry, S. Bajard et al.

A. Bellacosa, T. Chan, N. N. Ahmed et al.

Pete Riley, M. A. Reiss, C. Mostl

Accurately predicting the z-component of the interplanetary magnetic field, particularly during the passage of an interplanetary coronal mass ejection (ICME), is a crucial objective for space weather predictions. Currently, only a handful of techniques have been proposed and they remain limited in scope and accuracy. Recently, a robust machine learning (ML) technique was developed for predicting the minimum value of Bz within ICMEs based on a set of 42 'features', that is, variables calculated from measured quantities upstream of the ICME and within its sheath region. In this study, we investigate these so-called explanatory variables in more detail, focusing on those that were (1) statistically significant; and (2) most important. We find that number density and magnetic field strength accounted for a large proportion of the variability. These features capture the degree to which the ICME compresses the ambient solar wind ahead. Intuitively, this makes sense: Energy made available to CMEs as they erupt is partitioned into magnetic and kinetic energy. Thus, more powerful CMEs are launched with larger flux-rope fields (larger Bz), at greater speeds, resulting in more sheath compression (increased number density and total field strength).

D. Emerson, C. Moyer

D. Nordstrom, C. Alpers, C. Ptacek et al.

M. Falasca, S. Logan, V. Lehto et al.

J. Pandolfino, J. Richter, T. Ours et al.

Skralan Hosteaux, Luciano Rodiguez, Stefaan Poedts

This paper studies ICMEs detected by both Voyager spacecraft during propagation from 1 to 10 AU, with observations from 1977 to 1980. ICMEs are detected by using several signatures in the in-situ data, the primary one being the low measured to expected proton temperature ratio. We found 21 events common to both spacecraft and study their internal structure in terms of plasma and magnetic field properties. We find that ICMEs are expanding as they propagate outwards, with decreasing density and magnetic field intensities, in agreement with previous studies. We first carry out a statistical study and then a detailed analysis of each case. Furthermore, we analyse one case in which a shock can be clearly detected by both spacecraft. The methods described here can be interesting for other studies combining data sets from heliospheric missions. Furthermore, they highlight the importance of exploiting useful data from past missions.

Serge Koutchmy

The main observations of 1761 by M. Lomonossov and those that followed are recalled by extending the discussion to other remarkable visual observations of the passages, then with more and more powerful imagers producing images in profusion. The modern treatment of parasitic effects is briefly recalled by focusing on the expert observation of 1761 which has recently been widely commented on and criticized. It included a spurious effect called the "black drop effect". The shell or aureole or atmospheric ring of Venus observed outside the solar disk is considered with reference to the today parameters of the Venus atmosphere. The contacts during the transit are discussed taking into account effects of scattering, absorption and the dominant effects of the refraction at the small angular distances found to be comparable to a fraction of the angular dimension of the planet. Modern observations of the 2004 and the 2012 transit are tentatively discussed to elucidate what is the arc of Lomonossov?

Peter Steigenberger, Zhiguo Deng, Jing Guo et al.

Within the Multi-GNSS Pilot Project (MGEX) of the International GNSS Service (IGS), precise orbit and clock products for the BeiDou-3 global navigation satellite system (BDS-3) are routinely generated by a total of five analysis centers. The processing standards and specific properties of the individual products are reviewed and the BDS-3 orbit and clock product performance is assessed through direct inter-comparison, satellite laser ranging (SLR) residuals, clock stability analysis, and precise point positioning solutions. The orbit consistency evaluated by the signal-in-space range error is on the level of 4-8 cm for the medium Earth orbit satellites whereas SLR residuals have RMS values between 3 and 9 cm. The clock analysis reveals sytematic effects related to the elevation of the Sun above the orbital plane for all ACs pointing to deficiencies in solar radiation pressure modeling. Nevertheless, precise point positioning with the BDS-3 MGEX orbit and clock products results in 3D RMS values between 7 and 8 mm.

O. I. Berngardt, J. -P. St. Maurice, J. M. Ruohoniemi et al.

Based on ray tracing in a smooth ionosphere described by the IRI-2016 model we have infered the seasonal-diurnal dynamics of radio noise observed by four mid-latitude HF radars. In the calculations, noise is assumed to propagate from the radar dead zone boundary. Noise absorption along the ray path is simulated from the IRI-2016 electron density, and from the molecular nitrogen density and electron temperatures obtained from the NRLMSISE-00 model. Model results are compared with experimental radar data, and good agreement between the two is demonstrated. The model makes it possible to estimate the amount of absorption in D- and E- layers under average undisturbed conditions. This is important for the retrieval of long term variations in the electron density in the lower ionosphere. The model also makes it feasible to interpret vertical absorption in experimental data, thereby significantly expanding the capability of HF radars to monitor the lower ionosphere.