Structure Of Magnetosphere Research Articles

An Adaptive X‐Ray Dynamic Image Estimation Method Based on OMNI Solar Wind Parameters and SXI Simulated Observations

AbstractObservations of the overall interactions between solar wind and the Earth's magnetosphere are crucial for space weather monitoring. Upcoming missions like the Solar Wind Magnetosphere Ionosphere Link Explorer (SMILE) and the Lunar Environment heliosphere X‐ray Imager (LEXI) aim to make comprehensive global imaging of Earth's magnetosphere using soft X‐ray imager (SXI) in order to understand its dynamic response to solar wind impact. Short‐duration X‐ray images have a low signal‐to‐noise ratio (SNR), limited by cosmic background and Poisson noise. Longer integration times provide better SNR of magnetospheric structures but fail to capture the short‐term dynamics during the integration. Our study introduces a neural network method which is able to estimate the short‐term dynamics during a long integration, driven by OMNI solar wind data and simulated soft X‐ray images. Specifically, an adaptive X‐ray image estimator and a spatio‐temporal discriminator are used. It leverages X‐ray models like Magnetohydrodynamic (MHD) and Jorgensen & Sun model, driven by OMNI data to provide high‐temporal‐resolution prior information on magnetosphere motion, with SXI observation images acting as a posterior constraint on the magnetosphere's state. Experimental validation demonstrates apparent improvements in Peak signal‐to‐noise ratio (PSNR) and Structural Similarity (SSIM) compared to traditional linear and optical flow interpolation methods. The method's flexibility, considering input‐output consistency, enables easy extension to any interval (>3 min), meeting diverse application needs. In conclusion, our study presents a new approach to soft X‐ray image estimation based on neural networks, providing insights into magnetospheric dynamics as observed in soft X‐rays.

Coherent Radio Emission from “Main-sequence Radio Pulse Emitters”: A New Stellar Diagnostic to Probe 3D Magnetospheric Structures

Main-sequence radio pulse emitters (MRPs) are magnetic early-type stars that produce coherent radio emission observed in the form of periodic radio pulses. The emission mechanism behind this is the electron-cyclotron maser emission (ECME). Among all kinds of magnetospheric emission, ECME is unique due to its high directivity and intrinsically narrow bandwidth. The emission is also highly circularly polarized and the sign of polarization is opposite for the two magnetic hemispheres. This combination of properties makes ECME highly sensitive to the three-dimensional structures in the stellar magnetospheres. This is especially significant for late-B and A-type magnetic stars that do not emit other types of magnetospheric emission such as Hα, the key probe used to trace magnetospheric densities. In this paper, we use an ultra-wideband observation (0.4–2 GHz) of a late B-type MRP HD 133880 to demonstrate how we can extract information on plasma distribution from ECME. We achieve this by examining the differences in pulse arrival times (“lags”) as a function of frequencies and qualitatively comparing those with lags obtained by simulating ECME ray paths in hot stars’ magnetospheres. This reveals that the stellar magnetosphere has a disk-like overdensity inclined to the magnetic equator with a centrally concentrated density that primarily affects the intermediate frequencies (400–800 MHz). This result, which is consistent with the recent density model proposed for hotter centrifugally supported magnetospheres, lends support to the idea of a unifying model for magnetospheric operations in early-type stars, and also provides further motivation to fully characterize the ECME phenomenon in large-scale stellar magnetospheres.

In situ evidence of the magnetospheric cusp of Jupiter from Juno spacecraft measurements

The magnetospheric cusp connects the planetary magnetic field to interplanetary space, offering opportunities for charged particles to precipitate to or escape from the planet. Terrestrial cusps are typically found near noon local time, but the characteristics of the Jovian cusp are unknown. Here we show direct evidence of Jovian cusps using datasets from multiple instruments onboard Juno spacecraft. We find that the cusps of Jupiter are in the dusk sector, which is contradicting Earth-based predictions of a near-noon location. Nevertheless, the characteristics of charged particles in the Jovian cusps resemble terrestrial and Saturnian cusps, implying similar cusp microphysics exist across different planets. These results demonstrate that while the basic physical processes may operate similarly to those at Earth, Jupiter’s rapid rotation and its location in the heliosphere can dramatically change the configuration of the cusp. This work provides useful insights into the fundamental consequences of star-planet interactions, highlighting how planetary environments and rotational dynamics influence magnetospheric structures.

A phase-resolved Fermi-LAT analysis of the mode-changing pulsar PSR J2021+4026 shows hints of a multipolar magnetosphere

Context. The radio-quiet γ-ray pulsar PSR J2021+4026 is a peculiar Fermi-LAT pulsar showing repeated and quasi-periodic mode changes. Its γ-ray flux shows repeated variations between two states at intervals of ∼3.5 years. These events occur over timescales < 100 days and are correlated with sudden changes in the spin-down rate. Multiwavelength observations also revealed an X-ray phase shift relative to the γ-ray profile for one of the events. PSR J2021+4026 is currently the only known isolated γ-ray pulsar showing significant variability, and thus it has been the object of thorough investigations. Aims. The goal of our work is to study the mode changes of PSR J2021+4026 with improved detail. By accurately characterizing variations in the γ-ray spectrum and pulse profile, we aim to relate the Fermi-LAT observations to theoretical models. We also aim to interpret the mode changes in terms of variations in the structure of a multipolar dissipative magnetosphere. Methods. We continually monitored the rotational evolution and the γ-ray flux of PSR J2021+4026 using more than 13 years of Fermi-LAT data with a binned likelihood approach. We investigated the features of the phase-resolved spectrum and pulse profile, and from these we inferred the macroscopic conductivity, the electric field parallel to the magnetic field, and the curvature radiation cutoff energy. These physical quantities are related to the spin-down rate and the γ-ray flux and therefore are relevant to the theoretical interpretation of the mode changes. We introduced a simple magnetosphere model that combines a dipole field with a strong quadrupole component. We simulated magnetic field configurations to determine the positions of the polar caps for different sets of parameters. Results. We clearly detect the previous mode changes and confirm a more recent mode change that occurred around June 2020. We provide a full set of best-fit parameters for the phase-resolved γ-ray spectrum and the pulse profile obtained in five distinct time intervals. We computed the relative variations in the best-fit parameters, finding typical flux changes between 13% and 20%. Correlations appear between the γ-ray flux and the spectral parameters, as the peak of the spectrum shifts by ∼10% toward lower energies when the flux decreases. The analysis of the pulse profile reveals that the pulsed fraction of the light curve is larger when the flux is low. Finally, the magnetosphere simulations show that some configurations could explain the observed multiwavelength variability. However, self-consistent models are required to reproduce the observed magnitudes of the mode changes.

Radio Polarization of Millisecond Pulsars with Multipolar Magnetic Fields

NICER has observed a few millisecond pulsars where the geometry of the X-ray-emitting hotspots on the neutron star have been analyzed in order to constrain the mass and radius from X-ray light-curve modeling. One example, PSR J0030 + 0451, has been shown to possibly have significant multipolar magnetic fields at the stellar surface. Using force-free simulations of the magnetosphere structure, it has been shown that the radio, X-ray, and γ-ray light curves can be modeled simultaneously with an appropriate field configuration. An even more stringent test is to compare predictions of the force-free magnetosphere model with observations of radio polarization. This paper attempts to reproduce the radio polarization of PSR J0030 + 0451 using a force-free magnetospheric solution. As a result of our modeling, we can reproduce certain features of the polarization well.

Signatures of Open Magnetic Flux in Jupiter's Dawnside Magnetotail

AbstractJupiter's magnetosphere exhibits notable distinctions from the terrestrial magnetosphere. The structure and dynamics of Jupiter's dawnside magnetosphere can be characterized as a competition between internally driven sunward flow and solar wind‐driven tailward flow. During the prime mission, Juno acquired extensive data from dawn to midnight, sampling the magnetodisc and higher latitude regions. Numerical moments from the Jovian Auroral Distributions Experiment (JADE‐I) plasma (ion) instrument revealed a mid‐latitude region of anticorotational (−vϕ) flow. While the magnitude of the flow is subject to uncertainty due to low count rates in these rarefied regions, we demonstrate in the raw JADE‐I data that the sign of vϕ is a robust measurement. Global Grid Agnostic Magnetohydrodyamics for Extended Research Applications simulations show a similar region of strongly reduced flow in proximity to open field lines. Additionally, we use Jupiter Energetic‐particle Detector Instrument integral moments to determine the Hen+/H+ ratio (where n refers to He+ or He++) and show that a transition to solar wind‐like composition occurs in the same region as the anticorotational flow. We conclude that the global simulations are consistent with the Juno data, where the simulations show a crescent of open magnetic flux that is bounded by the magnetodisc and a closed high‐latitude polar region (nominally the polar cap), which is never observed in the terrestrial magnetosphere. The distinct distribution of open flux in Jupiter's dawnside magnetosphere suggests the significance of planetary rotation and may represent a characteristic feature of rotating giant magnetospheres for future exploration.

Science return of probing magnetospheric systems of ice giants

The magnetospheric systems of ice giants, as the ideal and the unique template of a typical class of exoplanets, have not been sufficiently studied in the past decade. The complexity of these asymmetric and extremely dynamic magnetospheres provides us a great chance to systematically investigate the general mechanism of driving the magnetospheres of such common exoplanets in the Universe, and the key factors of influencing the global and local magnetospheric structures of this type of planets. In this paper, we discuss the science return of probing magnetospheric systems of ice giants for the future missions, throughout different magnetospheric regions, across from the interaction with upstream solar wind to the downstream region of the magnetotail. We emphasize the importance of detecting the magnetospheric systems of ice giants in the next decades, which enables us to deeply understand the space enviroNMent and habitability of not only the ice giants themselves but also the analogous exoplanets which are widely distributed in the Universe.

Revised Magnetospheric Model Reveals Signatures of Field‐Aligned Current Systems at Mercury

AbstractMercury is the smallest and innermost planet of our solar system and has a dipole‐dominated internal magnetic field that is relatively weak, very axisymmetric and significantly offset toward north. Through the interaction with the solar wind, a magnetosphere is created. Compared to the magnetosphere of Earth, Mercury's magnetosphere is smaller and more dynamic. To understand the magnetospheric structures and processes we use in situ MESSENGER data to develop further a semi‐empiric model of the magnetospheric magnetic field, which can explain the observations and help to improve the mission planning for the BepiColombo mission en‐route to Mercury. We present this semi‐empiric KTH22‐model, a modular model to calculate the magnetic field inside the Hermean magnetosphere. Korth et al. (2015, https://doi.org/10.1002/2015JA021022, 2017, https://doi.org/10.1002/2017gl074699) published a model, which is the basis for the KTH22‐model. In this new version, the representation of the neutral sheet current magnetic field is more realistic, because it is now based on observations rather than ad‐hoc assumptions. Furthermore, a new module is added to depict the eastward ring shaped current magnetic field. These enhancements offer the possibility to improve the main field determination. In addition, analyzing the magnetic field residuals allows us to investigate the field‐aligned currents and their possible dependencies on external drivers. We see increasing currents under more disturbed conditions inside the magnetosphere, but no clear dependence on the z‐component of the interplanetary magnetic field nor on the magnetosheath plasma β.

The Optically Thick Rotating Magnetic Wind from a Massive White Dwarf Merger Product. II. Axisymmetric Magnetohydrodynamic Simulations

We numerically construct a series of axisymmetric rotating magnetic wind solutions, aiming at exploring the observation properties of massive white dwarf (WD) merger remnants with a strong magnetic field, a fast spin, and an intense mass loss, as inferred for WD J005311. We investigate the magnetospheric structure and the resultant spin-down torque exerted to the merger remnant with respect to the surface magnetic flux Φ*, spin angular frequency Ω* and the mass-loss rate Ṁ . We confirm that the wind properties for σ≡Φ*2Ω*2/Ṁvesc3≳1 significantly deviate from those of the spherical Parker wind, where v esc is the escape velocity at stellar surface. For such a rotating magnetic wind sequence, we find (i) a quasiperiodic mass eruption triggered by magnetic reconnection along with the equatorial plane and (ii) a scaling relation for the spin-down torque T≈(1/2)×ṀΩ*R*2σ1/4 . We apply our results to discuss the spin-down evolution and wind anisotropy of massive WD merger remnants, the latter of which could be probed by a successive observation of WD J005311 using Chandra.

Design and construction of the near-earth space plasma simulation system of the Space Plasma Environment Research Facility

Our earth is immersed in the near-earth space plasma environment, which plays a vital role in protecting our planet against the solar-wind impact and influencing space activities. It is significant to investigate the physical processes dominating the environment, for deepening our scientific understanding of it and improving the ability to forecast the space weather. As a crucial part of the National Major Scientific and Technological Infrastructure–Space Environment Simulation Research Infrastructure (SESRI) in Harbin, the Space Plasma Environment Research Facility (SPERF) builds a system to replicate the near-earth space plasma environment in the laboratory. The system aims to simulate the three-dimensional (3-D) structure and processes of the terrestrial magnetosphere for the first time in the world, providing a unique platform to reveal the physics of the 3-D asymmetric magnetic reconnection relevant to the earth's magnetopause, wave–particle interaction in the earth's radiation belt, particles’ dynamics during the geomagnetic storm, etc. The paper will present the engineering design and construction of the near-earth space plasma simulation system of the SPERF, with a focus on the critical technologies that have been resolved to achieve the scientific goals. Meanwhile, the possible physical issues that can be studied based on the apparatus are sketched briefly. The earth-based system is of great value in understanding the space plasma environment and supporting space exploration.

PENELLOPE

HM Lup is a young M-type star that accretes material from a circumstellar disk through a magnetosphere. Our aim is to study the inner disk structure of HM Lup and to characterize its variability. We used spectroscopic data from HST/STIS, X-shooter, and ESPRESSO taken in the framework of the ULLYSES and PENELLOPE programs, together with photometric data from TESS and AAVSO. The 2021 TESS light curve shows variability typical for young stellar objects of the “accretion burster” type. The spectra cover the temporal evolution of the main burst in the 2021 TESS light curve. We compared the strength and morphology of emission lines from different species and ionization stages. We determined the mass accretion rate from selected emission lines and from the UV continuum excess emission at different epochs, and we examined its relation to the photometric light curves. The emission lines in the optical spectrum of HM Lup delineate a temperature stratification along the accretion flow. While the wings of the H I and He I lines originate near the star, the lines of species such as Na I, Mg I, Ca I, Ca II, Fe I, and Fe II are formed in an outer and colder region. The shape and periodicity of the 2019 and 2021 TESS light curves, when qualitatively compared to predictions from magnetohydrodynamic models, suggest that HM Lup was in a regime of unstable ordered accretion during the 2021 TESS observation due to an increase in the accretion rate. Although HM Lup is not an extreme accretor, it shows enhanced emission in the metallic species during this high accretion state that is produced by a density enhancement in the outer part of the accretion flow.

Concerning the detection of electromagnetic knot structures in space plasmas using the wave telescope technique

Abstract. The wave telescope technique is broadly established in the analysis of spacecraft data and serves as a bridge between local measurements and the global picture of spatial structures. The technique is originally based on plane waves and has been extended to spherical waves, phase-shifted waves and planetary magnetic field representation. The goal of the present study is the extension of the wave telescope technique using electromagnetic knot structures as a basis. As the knots are an exact solution of Maxwell's equations they open the door for a new modeling and interpretation of magnetospheric structures, such as plasmoids.

Unsolved problems: Mesoscale polar cap flow channels’ structure, propagation, and effects on space weather disturbances

Dynamic mesoscale flow structures move across the open field line regions of the polar caps and then enter the nightside plasma sheet where they can cause important space weather disturbances, such as streamers, substorms, and omega bands. The polar cap structures have long durations (apparently at least ∼1½ to 2 h), but their connections to disturbances have received little attention. Hence, it will be important to uncover what causes these flow enhancement channels, how they map to the magnetospheric and magnetosheath structures, and what controls their propagation across the polar cap and their dynamic effects after reaching the nightside auroral oval. The examples presented here use 630-nm auroral and radar observations and indicate that the motion of flow channels could be critical for determining when and where a particular disturbance within the nightside auroral oval will be triggered, and this could be included for full understanding of flow channel connections to disturbances. Also, it is important to determine how polar cap flow channels lead to flow channels within the auroral oval, i.e., the plasma sheet, and determine the conditions along nightside oval/plasma sheet field lines that interact with an incoming polar cap flow channel to cause a particular disturbance. It will also be interesting to consider the generality of geomagnetic disturbances being related to connections with incoming polar cap flow channels, including the location, time, and type of disturbances, and whether the duration and expansion of disturbances are related to flow channel duration and to multiple flow channels.

Stable accretion and episodic outflows in the young transition disk system GM Aurigae

Context. Young stellar systems actively accrete from their circumstellar disk and simultaneously launch outflows. The physical link between accretion and ejection processes remains to be fully understood. Aims. We investigate the structure and dynamics of magnetospheric accretion and associated outflows on a scale smaller than 0.1 au around the young transitional disk system GM Aur. Methods. We devised a coordinated observing campaign to monitor the variability of the system on timescales ranging from days to months, including partly simultaneous high-resolution optical and near-infrared spectroscopy, multiwavelength photometry, and low-resolution near-infrared spectroscopy, over a total duration of six months, covering 30 rotational cycles. We analyzed the photometric and line profile variability to characterize the accretion and ejection processes. Results. The optical and near-infrared light curves indicate that the luminosity of the system is modulated by surface spots at the stellar rotation period of 6.04 ± 0.15 days. Part of the Balmer, Paschen, and Brackett hydrogen line profiles as well as the HeI 5876 Å and HeI 10830 Å line profiles are modulated on the same period. The Paβ line flux correlates with the photometric excess in the u′ band, which suggests that most of the line emission originates from the accretion process. High-velocity redshifted absorptions reaching below the continuum periodically appear in the near-infrared line profiles at the rotational phase in which the veiling and line fluxes are the largest. These are signatures of a stable accretion funnel flow and associated accretion shock at the stellar surface. This large-scale magnetospheric accretion structure appears fairly stable over at least 15 and possibly up to 30 rotational periods. In contrast, outflow signatures randomly appear as blueshifted absorption components in the Balmer and HeI 10830 Å line profiles. They are not rotationally modulated and disappear on a timescale of a few days. The coexistence of a stable, large-scale accretion pattern and episodic outflows supports magnetospheric ejections as the main process occurring at the star-disk interface. Conclusions. Long-term monitoring of the variability of the GM Aur transitional disk system provides clues to the accretion and ejection structure and dynamics close to the star. Stable magnetospheric accretion and episodic outflows appear to be physically linked on a scale of a few stellar radii in this system.

Periodicities and Plasma Density Structure of Jupiter's Dawnside Magnetosphere

AbstractAbility to quantify variations in magnetic field topology and density within Jupiter's magnetosphere is an important step in understanding the overall structure and dynamics. The Juno spacecraft has provided a rich data set in the dawnside magnetosphere. The recent Grid Agnostic MHD for Extended Research Applications (GAMERA) global simulation study by Zhang et al. (2021, https://doi.org/10.1126/sciadv.abd1204) showed a highly structured plasmadisc with closed magnetic field lines mapped between the outer dawn‐tail flank and the high‐latitude polar region. To test these model predictions, we examined Juno's magnetic field data and electron/energetic particle data to categorize portions of orbits 1–15 into one of three regions based on plasma confinement: the flux pileup region, the intermediate region, and the plasmadisc region. For each region we examined periodicities from magnetic field fluctuations and particle density fluctuations on the 1–10 hr time scale. Periodicities on this time scale could relate to internal (e.g., plasmadisc structure) or external processes (e.g., Kelvin‐Helmholtz vortices). Similar analysis was performed on the GAMERA simulation with the data split into two regions, an outer (150 > R > 60) region and an inner (R < 60) region. Finally, using published density moments from Huscher et al. (2021, https://doi.org/10.1029/2021JA029446), we compared the relative density variations of the Juno moments and the GAMERA simulation to further understand the overall structure and dynamics of the plasmadisc. The agreement between data and simulation supports the existence of such a highly structured plasmadisc.

Exploring the Solar Wind-Planetary Interaction at Mars: Implication for Magnetic Reconnection.

The Martian crustal magnetic anomalies present a varied, asymmetric obstacle to the imposing draped interplanetary magnetic field (IMF) and solar wind plasma. Magnetic reconnection, a ubiquitous plasma phenomenon responsible for transferring energy and changing magnetic field topology, has been observed throughout the Martian magnetosphere. More specifically, reconnection can occur as a result of the interaction between crustal fields and the IMF, however, the global implications and changes to the overall magnetospheric structure of Mars have yet to be fully understood. Here, we present an analysis to determine these global implications by investigating external conditions that favor reconnection with the underlying crustal anomalies at Mars. To do so, we plot a map of the crustal anomalies' strength and orientation compiled from magnetic field data collected throughout the Mars Atmosphere and Volatile EvolutioN (MAVEN) mission. Then, we create "shear maps" which calculate and plot the angle of shear between the crustal fields and a chosen external field orientation. From there we define a "shear index" to quantify the susceptibility of a region to undergo reconnection based on a given overlaid, external field orientation and the resulting shear map for that region. We demonstrate that the shear analysis technique augments analysis of local reconnection events and suggests southward IMF conditions should favor dayside magnetic reconnection on a more global scale at Mars.

A 3D Magnetospheric CT Reconstruction Method Based on 3D GAN and Supplementary Limited‐Angle 2D Soft X‐Ray Images

AbstractSoft X‐ray imaging is a new method used to observe the structure of the Earth's magnetosphere. Reconstruction of the Earth's three‐dimensional (3‐D) magnetospheric structure from 2‐D soft X‐ray images is an important research topic in astronomical imaging and exploration. In this study, computed tomography (CT) is investigated for application to the planned Solar wind Magnetosphere Ionosphere Link Explorer (SMILE), where resulting images are collected at varying small angles. The restricted geometry of SMILE results in sparse projection data and reduced reconstruction quality. As such, a new algorithm is proposed, based on cone‐beam computed tomography (CBCT) and utilizing 3‐D generative adversarial networks (GAN) to supplement the 2‐D soft X‐ray images and increase the angular coverage of the projections. A complement optimization backpropagation network (COBN) is then used to reconstruct high‐quality 3‐D X‐ray emissivity profiles in the magnetosphere. A series of validation experiments were conducted in which the reconstructions were compared with synthetic results generated by the PPMLR‐MHD (an extended LagRangian version of the Piecewise Parabolic Method –MagnetoHydroDynamic) model under varying solar wind conditions. Results showed the supplemented profiles were more complete and accurate than the direct reconstructions, as measured by the peak signal‐to‐noise ratio (PSNR) and structural similarity (SSIM). This suggests the proposed technique could be a viable approach to observing magnetosphere structure and variability.

Structure of the Martian Dayside Magnetosphere: Two Types

A set of scientific instruments capable of high temporal resolution measurements onboard the Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft made it possible to study the structure and properties of the dayside Martian magnetosphere. The Mars plasma envelope on the dayside of the planet was discovered based on observations on the first orbiters of Mars (Vaisberg et al., 1976; Gringauz et al., 1976). The high temporal and mass resolution of MAVEN instruments made it possible to study the structure and processes in the plasma of the dayside magnetosphere, the plasma layer that exists between the solar wind heated by the shock wave and the ionosphere (Vaisberg et al., 2017). It is shown that, under different external conditions, two different types of plasma layers are formed between the ionosphere and magnetosheath on the dayside of the planet: (1) mixture of heated ionospheric ions and picked-up exospheric ions and (2) a layer of ionospheric ions accelerated by the solar wind motional electric field called “plume” (Dong et al., 2015). The first type of the Martian daytime magnetosphere is formed as a result of the interaction of oxygen exospheric ions captured and accelerated by the solar wind with the upper part of the Martian ionosphere (Vaisberg and Shuvalov, 2021). The second type of the Martian dayside magnetosphere is formed by the acceleration of an ion beam from the outer ionosphere, which then passes into a more energetic plume beam in the magnetosheath. This article discusses typical plasma populations, their properties and conditions that lead to the formation of the daytime magnetosphere from the material of the upper ionosphere.

Pulsar Magnetospheres and Their Radiation

The discovery of pulsars opened a new research field that allows studying a wide range of physics under extreme conditions. More than 3,000 pulsars are currently known, including especially more than 200 of them studied at gamma-ray frequencies. By putting recent insights into the pulsar magnetosphere in a historical context and by comparing them to key observational features at radio and high-energy frequencies, we show the following: ▪ Magnetospheric structure of young energetic pulsars is now understood. Limitations still exist for old nonrecycled and millisecond pulsars. ▪ The observed high-energy radiation is likely produced in the magnetospheric current sheet beyond the light cylinder. ▪ There are at least two different radio emission mechanisms. One operates in the inner magnetosphere, whereas the other one works near the light cylinder and is specific to pulsars with the high magnetic field strength in that region. ▪ Radio emission from the inner magnetosphere is intrinsically connected to the process of pair production, and its observed properties contain the imprint of both the geometry and propagation effects through the magnetospheric plasma. We discuss the limitations of our understanding and identify a range of observed phenomena and physical processes that still await explanation in thefuture. This includes connecting the magnetospheric processes to spin-down properties to explain braking and possible evolution of spin orientation, building a first-principles model of radio emission and quantitative connections with observations.

A Statistical Investigation of Factors Influencing the Magnetotail Twist at Mars.

The Martian magnetotail exhibits a highly twisted configuration, shifting in response to changes in polarity of the interplanetary magnetic field's (IMF) dawn‐dusk (B Y) component. Here, we analyze ∼6000 MAVEN orbits to quantify the degree of magnetotail twisting (θ Twist) and assess variations as a function of (a) strong planetary crustal field location, (b) Mars season, and (c) downtail distance. The results demonstrate that θ Twist is larger for a duskward (+B Y) IMF orientation a majority of the time. This preference is likely due to the local orientation of crustal magnetic fields across the surface of Mars, where a +B Y IMF orientation presents ideal conditions for magnetic reconnection to occur. Additionally, we observe an increase in θ Twist with downtail distance, similar to Earth's magnetotail. These findings suggest that coupling between the IMF and moderate‐to‐weak crustal field regions may play a major role in determining the magnetospheric structure at Mars.