The charge-exchange collision frequency is enhanced by the attractive polarization force at ionospheric temperatures

This enhancement has been ignored in classic ionospheric studies, due to confusion and lack of a theoretical form

We derive a theoretical form to express this enhancement using the curved particle trajectory effect

An automated detection algorithm has been developed to identify transpolar arcs (TPAs) in DMSP/SSUSI data

There is a seasonal dependence in the occurrence of TPA such that they are detected more often in the winter hemisphere

The orbital plane of DMSP leads to a UT bias in the polar cap sampling of DMSP/SSUSI

Energetic ion fluxes form tailward beams surrounding the plasmoid but multiple separate branches near the equatorial plane

Boundary beams are primarily accelerated near x-line, equatorial acceleration occurs anywhere across tailward propagating plasmoid

Origins of accelerated ions are primarily in the dawnward central plasma sheet

A Monte Carlo model was developed to investigate the contributions of precipitating electrons and protons to the diffuse auroral emission

Proton-induced CO₂⁺ UVD emissions have lower peak altitudes than electron-induced emissions

The MAVEN/IUVS limb emission profiles of CO₂⁺ UVD during two SEP events were reproduced by considering the contribution of SEP protons

For fixed value thresholds annual mean burst duration-return period ratio tracks solar cycle for SMR but peaks near cycle decline for AE

Parameters of bursts in AE and SMR with thresholds at fixed quantile share the same distributions for successive solar cycle maxima

Tails of AE and SMR empirical distributions follow a solar cycle invariant functional form for solar cycle maximum, minimum and decline

We use POES data to analyze the relativistic electron precipitation (REP) near midnight (22–02 MLT), which is found to occur over L ∼ 4–7

We study REP events due to a single driver: waves (isolated REP) or current sheet scattering (energy-dependent precipitation)

Both mechanisms drive precipitation during field line stretching and most wave-driven events occur in association with EMIC waves

Atomic oxygen in MLT from SABER and WACCM-X has an SAO with maxima at solstices and at summer mid-high latitudes, opposite to that of MSIS

GITM reproduces the T-I SAO with equinoctial maxima using MSIS [O] at lower boundary and with solstitial maxima using WACCM-X [O]

GITM does not change the SAO phase between MLT and upper thermosphere on a seasonal scale

Electrons precipitate to the surface of Mercury and induce X-ray fluorescence

By filtering selectively based on the simultaneous level of solar X-ray flux, we can isolate electron-induced fluorescence on the dayside

Dayside fluorescence is organized by location, with a strong enhancement south of the equator at dawn

MHD modelling shows FLRs outside the plasmasphere move earthward from the initial to main phase of geomagnetic storms

Caused by (a) decreased field line eigenfrequencies due to enhanced plasma densities and weaker magnetic fields

(b) Higher fast waveguide frequencies, due to changes in density/boundary locations, which drive the FLRs

A simple predictor-corrector algorithm based on magnetic field data is presented to locate the bow shock position in spacecraft data

The method, biased towards quasi-perpendicular crossings, is general and applicable to all planetary bodies including Mars, Venus and Earth

More than 14, 900 bow shock crossings are identified with MAVEN for Mars Years 32-35, with 2D/3D fits revealing North-South asymmetries

A Chandra ACIS observation reveals a 10.3 sigma detection of X-rays from Uranus with a probability of chance occurrence of 10⁻⁶–10⁻⁷

Uranus' X-rays are concentrated between 0.6 and 1.1 keV, consistent with emission observed from Jupiter and Saturn

The X-ray fluxes seem to exceed scattered solar emission alone, which may suggest X-ray aurora and/or X-ray fluorescence from the rings