(abrupt change in stellar spectrum at end of Balmer series)
The Balmer jump (or Balmer discontinuity)
is an abrupt change in the intensity of some stars' spectra
for wavelengths shorter than the Balmer limit,
the "infinity" end of the Balmer series spectral lines,
i.e., 364.6 nm.
It occurs when the star is sufficiently hot that hydrogen atoms
with electrons at electron shell II are generally being
than moving to a higher level of atomic excitation.
Photons of sufficient energy can be absorbed,
lowering the continuum at the above-mentioned wavelength,
and the sufficiently-hot star produces enough such photons
to do this significantly.
The shape of the jump is an indication of the star's density and
The jump is strongest in early stars, e.g., A-type stars.
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Referenced by pages:
Balmer-break galaxy (BBG)
blue horizontal branch (BHB)