Use this URL to cite or link to this record in EThOS: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.660741
Title: Measurements of the polarization of starlight
Author: Pratt, Neil M.
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 1968
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Abstract:
A computer catalogue of photoelectric measurements of the polarization of starlight is being compiled, together with other relevant data about the measured. stars. There is a deficiency of measurements of the fainter stars due to the large amounts of telescope time required. A new photographic method, potentially very rapid with the advent of automatic measuring engines, is described. This method, using a polaroid filter, allows also the simultaneous measurement of brightness differences between successive star images at different orientations of the analyser not due to polarization effects, and hence the polarization can be isolated. Overlapping of star images limits the use of the method, with the Edinburgh Schmidt telescope, to areas of sky with < 6000 stars per square degree, or V =16 on average at the galactic equator. 527 stars in h and chi Persei to V = 13 have been measured. Using the Stokes parameters, comparison with published photoelectric measures for 54 stars gives an r.m.s. deviation of ± Om.029 per star, and the photoelectric and photographic means agree to within Om.003 and 1 degree. Proper motions from the literature and original photographic UBV photometry of the 527 stars has allowed the separation of the measured stars into groups within the local and Perseus spiral arms. From the mean polarization parameters for these groups of stars, it is concluded that the observed polarization towards h and chi Persei is largely produced within the local arm; that the orientation of the presumed magnetic field in the Perseus arm is different to that in the local arm; and that there is a possibility of local magnetic fields associated with the star clusters themselves.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.660741  DOI: Not available
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