Concept information
Terme préférentiel
Seyfert 2 galaxy
Définition(s)
- Type II Seyfert galaxies have the characteristic bright core, as well as appearing bright when viewed at infrared wavelengths. Their spectra contain narrow lines associated with forbidden transitions, and broader lines associated with allowed strong dipole or intercombination transitions. NGC 3147 is considered the best candidate to be a true Type II Seyfert galaxy. In some Type II Seyfert galaxies, analysis with a technique called spectro-polarimetry (spectroscopy of polarised light component) revealed obscured Type I regions. In the case of NGC 1068, nuclear light reflected off a dust cloud was measured, which led scientists to believe in the presence of an obscuring dust torus around a bright continuum and broad emission line nucleus. When the galaxy is viewed from the side, the nucleus is indirectly observed through reflection by gas and dust above and below the torus. This reflection causes the polarisation. (Wikipedia, The Free Encyclopedia, https://en.wikipedia.org/wiki/Seyfert_galaxy#Type_II_Seyfert_galaxies)
Concept(s) générique(s)
Traductions
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français
URI
http://data.loterre.fr/ark:/67375/MDL-SF7XR59T-P
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