An Etymological Dictionary of Astronomy and Astrophysics
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The dividing point in a galaxy's spectrum at wavelengths shorter than the → Lyman limit. Galaxies contain large amounts of → neutral hydrogen which is very effective at absorbing radiation shortward of 912 Å. Hence galaxies are virtually dark at these wavelengths.

→ Lyman; → break.

A star-forming galaxy at → high redshift affected by the → Lyman break. Such a galaxy is detected in the red (R, → photometric band) but not in the blue (U and B bands). At those high redshfits (above 2.5), the → Lyman limit at 912 Å is shifted between the U and B bands.

→ Lyman; → break; → galaxy.