Photoelectric polarization maps of two bipolar reflection nebulae

Abstract

view Abstract Citations (55) References (31) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Photoelectric polarization maps of two bipolar reflection nebulae. Schmidt, G. D. ; Angel, J. R. P. ; Beaver, E. A. Abstract A rapidly chopping polarimeter equipped with a large-aperture Pockels cell and 200-element digicon detector was used to obtain high-resolution maps of the optical polarization and surface brightness in the bipolar nebulae CRL 2688 and M 1-92. Both nebulae show radially symmetric polarization patterns characteristic of reflection and, except for the northwest lobe of M 1-92, are apparently optically thin to scattering. The very high polarization in CRL 2688 indicates small scattering grains, and the stellar spectrum is substantially blued upon reflection. Values of a color excess produced by circumstellar and interstellar extinction and of the visual extinction along the optical path of a scattered photon are estimated. The existence of small grains, optical thinness, and symmetric geometry indicates that scattering by or transmission through a medium of aligned grains is responsible for the circular polarization observed in CRL 2688. One possibility is that alignment by an interstellar magnetic field at an angle to the axis of the nebula provides the necessary skew geometry. Publication: The Astrophysical Journal Pub Date: January 1978 DOI: 10.1086/155803 Bibcode: 1978ApJ...219..477S Keywords: Astronomical Maps; Linear Polarization; Nebulae; Polarization Characteristics; Interstellar Magnetic Fields; Interstellar Matter; Magnetic Effects; Planetary Nebulae; Astrophysics; Polarization:Reflection Nebulae full text sources ADS | data products SIMBAD (7)