A linear feature in the H alpha chromosphere of the Sun, occurring near strong sunspots and plages or in filament channels Fibrils parallel strong magnetic fields, as if mapping the field direction
{i} tiny fiber, small hairlike structure; tiny fiber on a root (Botany); small hairlike structure outside of a cell wall (Anatomy)
A linear pattern in the H-alpha chromosphere of the Sun, as seen through an H-alpha filter, occurring near strong sunspots and plages or in filament channels