An Etymological Dictionary of Astronomy and Astrophysics

A bump appearing in the plot of stellar → opacity versus temperature. The ionization of the heaviest → chemical elements, especially → iron, which is the most abundant heavy metal, produces a large number of weak spectral → absorption lines. These lines dominate the stellar opacity in the temperature range 10⁵-10⁶ K and furnish two local opacity peaks: a large peak around 2 × 10⁵ K and a smaller one around 1.5 × 10⁶ K (Rogers & Iglesias, 1992, ApJS 79, 507;
Iglesias et al. 1992, ApJ, 397, 717).

See also: → iron; → opacity; → peak.