| 单词 | surface brightness |
| 释义 | > as lemmassurface brightness surface brightness n. Astronomy the luminosity of a celestial object per unit area on the sky, typically expressed as the magnitude per square arc second. ΚΠ 1910 Science 3 June 878/1 With the latest determinations of temperature and surface brightness, it appears that the fainter red stars are somewhat smaller, and presumably denser, than the sun. 1940 G. Gamow Birth & Death of Sun vi. 124 Estimate stellar temperatures even when we do not know their surface brightness. 2010 R. H. Sanders Dark Matter Probl. iv. 55 The visible radius is taken to be that point at which the surface brightness falls to a certain faint level (25 magnitudes per square arc second, or, roughly 5 solar luminosities per square parsec). < as lemmas |
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