Polarized Brightness Distribution over Cassiopeia A, the Crab Neubla, and Cygnus A at 1.55-cm Wavelength.

Abstract

view Abstract Citations References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Polarized Brightness Distribution over Cassiopeia A, the Crab Neubla, and Cygnus A at 1.55-cm Wavelength. Mayer, Cornell H. ; Hollinger, James P. Abstract Observations with 1; 7 resolution were made of Cassiopeia A, the Crab Xebula, and Cygnus A using the 140-ft reflector of the Xational Radio Astronomy Observatory and a polarimeter at 1.55-cm wavelength which measured directly the intensity with linear polarization oriented N-S, and the Stokes parameters Q and U on three separate scans. These data were combined to determine the distribution of total intensity, polarized intensity, and degree and position angle of linear polarization for scans across the sources spaced at o; 8 intervals of declination. Cassiopeia A at 1.55-cm wavelength is a nearly circular source with enhanced regions of emission around the rim, and remarkably symmetrical linear polarization of about 4.5% around the rim and zero at the center of the source. The electric field is oriented circumferentially defining a radial magnetic field associated with the polarized radiation. The total intensity contours of the Crab Xebula source are roughly ellpitical, but the intensity of polarized radiation is concentrated in a smaller region centered about 0,5 south and o; 25 east of the center of the nebula with a maximum degree of polarization of about 16% at position angle 1540. Both the total intensity and polarized intensity of Cygnus A are consistent with two point sources separated by 1;9 along position angle 1090. The total intensity of the east component is 12% greater than of the west component. The intensities of linearly polarized radiation from the two comQonents are equal, but the polarization is nearly `opposite; 8.6+1.3% at 41+40 for the east component, and 9.7+1.3% at 151+40 for the west component. Additional observations of lower accuracy and lower resolution of 2'.6 which were made with the 85-ft reflector of the Xaval Research Laboratory to measure the circularly polarized component of radiation gave negative results with values for circular polarization of less than 2+2% for all three sources. Publication: The Astronomical Journal Pub Date: September 1967 DOI: 10.1086/110553 Bibcode: 1967AJ.....72S.815M full text sources ADS |