A break in the spectrum of a star or galaxy at 364.6 nm; also known as the Balmer jump. It arises at the termination of the Balmer series of hydrogen, at which point the atom becomes ionized. The size of this jump (i.e. the level of the continuum on either side of the break) is an important indicator of the physical conditions in the emitting region, particularly the pressure.
Subjects: Astronomy and Astrophysics.