Encyclopedia of Astrobiology

Living Edition
| Editors: Muriel Gargaud, William M. Irvine, Ricardo Amils, Henderson James Cleaves, Daniele Pinti, José Cernicharo Quintanilla, Michel Viso

Opacity

  • Sylvia Ekström
Living reference work entry
DOI: https://doi.org/10.1007/978-3-642-27833-4_1109-3

Definition

Opacity measures the property of a medium to attenuate light. The opacity depends on the composition of the medium, its density, and temperature, but also on the wavelength considered. The absorption coefficient aν (with units [cm−1]) enters into the definition of the optical depth. More often in astronomy, it is the mass absorption coefficient \( {\kappa}_{\nu }={a}_{\nu }/\rho \)

Keywords

Absorption Coefficient Essential Role Bioorganic Chemistry Free Path Electronic Transition 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.
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Copyright information

© Springer-Verlag Berlin Heidelberg 2014

Authors and Affiliations

  1. 1.Observatoire astronomique de l’Université de Genève, Faculté des SciencesUniversité de GenèveVersoixSwitzerland