Encyclopedia of Astrobiology

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

Extinction, Interstellar or Atmospheric

  • Daniel Rouan
Living reference work entry
DOI: https://doi.org/10.1007/978-3-642-27833-4_563-2


The extinction is the decrease of the light intensity of a celestial object due to scattering and/or absorption by an intervening medium. The medium can be of telluric origin (molecules, aerosol in the atmosphere) or astrophysical (small dust particles in the interstellar medium); in the later case one speaks of interstellar extinction. Extinction is measured in magnitudes and the wavelength at which it applies should be indicated. The interstellar extinction is larger in the blue than in the red and becomes less and less important as the wavelength increases in the infrared domain. Because of this differential effect, extinction is responsible for the so-called reddening of distant stars. Reddening is characterized by the color excess. The radio domain is essentially not affected by extinction. Interstellar extinction is generally noted AF, where F is the symbol of the wavelength considered (U, B, V, etc.), defined by a passband filter. When no indication is given, it is...


Light Intensity Bioorganic Chemistry Differential Effect Dust Particle Color Index 
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Copyright information

© Springer-Verlag Berlin Heidelberg 2014

Authors and Affiliations

  1. 1.LESIAObservatoire Paris-Site de MeudonMeudonFrance