Context. Evidence of magnetic interaction between late-type stars and close-in giant planets
is provided by the observations of stellar hot spots rotating synchronously with the planets …

Magnetic field topology frozen in ideal magnetohydrodynamics (MHD) and its breakage in
near-ideal MHD are reviewed in two parts, clarifying and expanding basic concepts. The first …

Context. Recent observations suggest that stellar magnetic activity may be influenced by the
presence of a close-by giant planet. Specifically, chromospheric hot spots rotating in phase …

A loss of magnetic field confinement is believed to be the cause of coronal mass ejections
(CMEs), a major form of solar activity in the corona. The mechanisms for magnetic energy …

Context. Giant planets orbiting main-sequence stars closer than 0.1 AU are called hot
Jupiters. They interact with their stars affecting their angular momentum. Aims. Recent …

Context. Stars interact with their close-in planets through radiation, gravitation and magnetic
fields. Aims. We investigate the energy input to a planetary atmosphere by reconnection …

This study is an observational search for evidence of prominence-associated magnetic flux
ropes at the photospheric level in plage regions away from sunspots. Although there are a …

Context. Late-type stars interact with their close-in planets through their coronal magnetic
fields. Aims. We introduce a theory for the interaction between the stellar and planetary fields …

Partial differential equations of mixed elliptic-hyperbolic type arise in diverse areas of
physics and geometry, including fluid and plasma dynamics, optics, cosmology, traffic …

Context. The interaction between the magnetic fields of late-type stars and their close-by
planets may produce stellar flares as observed in active binary systems. However, in spite of …