Physics of the Sun and the heliosphere — solar interior, magnetic activity cycle, corona and solar wind, interplanetary magnetic field (Parker spiral), magnetospheric coupling, space weather. Sits between plasma physics (the underlying…
heliophysics
Solar wind
Continuous outflow of magnetised plasma from the solar corona — slow component (~400 km/s, dense) from streamers, fast component (~750…
Parker spiral
Geometry of the heliospheric magnetic field carried by the radially-flowing solar wind in combination with solar rotation: in the…
Earth's magnetosphere
Region around Earth dominated by the geomagnetic field, carved by the solar wind into a tear-drop cavity (~10 R_E sunward dayside,…
Magnetopause
Boundary at which solar-wind dynamic pressure balances geomagnetic pressure, ρ v² ≈ B²/(2μ₀). Standoff distance contracts during solar…
Earth's bow shock
Standing collisionless shock upstream of the magnetopause where the supersonic, super-Alfvénic solar wind decelerates to subsonic flow.…
Coronal mass ejection (CME)
Eruptive expulsion of ~10¹²–10¹³ kg of coronal plasma and embedded magnetic flux rope at 100s–3000 km/s. The principal driver of severe…
Solar flare
Sudden, localised release of 10²²–10²⁵ J of magnetic energy in the solar atmosphere via reconnection, observed as bright multi-wavelength…
Heliosphere
Bubble of solar-wind plasma and embedded heliospheric field carved out of the local interstellar medium, bounded by the heliopause at ~120…
Solar modulation of cosmic rays
Galactic cosmic-ray flux at Earth varies anti-correlated with the solar cycle: outward-convecting solar-wind magnetic field expels…
Space weather
Operational discipline forecasting solar-driven disturbances of the geospace environment — geomagnetic storms (Dst, Kp indices),…
Solar MHD
Single-fluid magnetohydrodynamic description of solar plasma — induction equation ∂B/∂t = ∇×(v×B) + η∇²B, frozen-in flux limit (η→0),…
Van Allen radiation belts
Two toroidal regions of energetic charged particles trapped by the geomagnetic field: inner belt (~1.5 R_E, protons up to 100s MeV), outer…
Helioseismic p-mode sound-speed inversion as Abel transform (heliophysics)
Heliophysics application of L0 numerical-quadrature and spline-interpolation theory. Solar p-mode oscillation frequencies observed at the…
Linear adiabatic wave equation and Eddington's homogeneous-sphere pulsation (heliophysics)
Heliophysics application of L0 Runge–Kutta and finite-difference theory. The linear adiabatic wave equation (LAWE) is the coupled…