A study of birefringence in the interstellar medium in the direction of the Crab Nebula
Abstract
view Abstract Citations (13) References (28) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS A study of birefringence in the interstellar medium in the direction of the Crab nebula. Martin, P. G. ; Angel, J. R. P. Abstract The interstellar medium may be regarded as a weak wave plate, the linear birefringence arising from the aligned grains which produce interstellar linear polarization. Using the Crab Nebula as a background source of linearly polarized light we have investigated this birefringence by measurements of circular polarization. The circular component is found to vary with the intrinsic linear polarization in a sinusoidal fashion characteristic of a wave plate with the orientation expected from independent measurements of the interstellar linear polarization in the same direction. Measurements of the wavelength dependence, together with the sense and magnitude of the circular polarization are interpreted as evidence for the dielectric nature of the interstellar grain materials. These observations provide a firm basis for a similar interpretation of the circular polarization of reddened stars. The observations of the stars can then be used to study the grain composition and the structure of the magnetic field in many directions in the Galaxy. Publication: The Astrophysical Journal Pub Date: October 1974 DOI: 10.1086/153168 Bibcode: 1974ApJ...193..343M Keywords: Birefringence; Circular Polarization; Crab Nebula; Interstellar Matter; Polarized Light; Astronomical Maps; Interstellar Magnetic Fields; Interstellar Radiation; Lines Of Force; Magnetic Field Configurations; Milky Way Galaxy; Polarization Characteristics; Astrophysics full text sources ADS |
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