The Balmer jump in astrophysical hydrogen plasmas

It is shown that, according to accepted theoretical concepts, there should be no intensity jump at the edge of the Balmer continuum, nor at that of other hydrogen series. We point out three reasons for a fairly smooth increase of the intensity to occur at the continuum edge. As a result, the jump sometimes spreads over hundreds of ångstroms, due mainly to the electron density inhomogeneity of solar plasma. Furthermore, the Doppler and Stark effects also give rise to a considerable spread of the series edge. We point out that excess continuum emission over a relatively narrow spectral interval before the continuum edge can result from overlapping of line wings.