open magnetic field line xatt-e bâz-e meydân-e meqnâtisi-ye Fr.: ligne ouverte de champ magnétique In the context of solar physics, a → magnetic field line when it crosses the solar surface only once, i.e., when it goes from surface to infinity. This is the case at a sufficiently large scale in → coronal holes. This is mostly not the case in → active regions. |