AuthorPENNING, WILLIAM ROY.
AdvisorBurks, Thomas F.
MetadataShow full item record
PublisherThe University of Arizona.
RightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
AbstractThe magnetic rotator model has long been the favored explanation for coherent photometric modulations in the DQ Herculis class of cataclysmic variables. However, to date, all evidence supporting this model has been of the indirect variety. Unlike their synchronously rotating cousins, the AM Herculis objects, DQ Herculis stars have not yet been discovered to emit polarized radiation. Therefore, in light of this crucial lack, the evidence used to place these objects in the magnetic cataclysmic variable category has been strictly circumstantial, based primarily on the coherence of the photometric periodicities. In this work, time-resolved spectroscopy of four long-period DQ Herculis stars is performed. In addition, two of the same objects are observed with a new, sensitive circular polarimeter. Chapters II and III describe these observations and the results of each. To summarize, coherent variations in the wavelength of emission lines were found with the spectroscopic observations. A model is put forth, explaining this phenomenon as being due to varying illumination from a bright spot on the primary. This, of course, adds strength to the magnetic rotator model. Secondly, circular polarization was definitely found in one object studied, and possibly in a second. Therefore, for the first time, there is direct evidence of the magnetic nature of these binaries. In Chapter IV, the model of the rotating bright spot illuminating the disk is explored in further detail, including modeling with a minicomputer. Afterward, a problem brought out by the low polarization coupled with large amplitude photometric variations and a cool spectrum is investigated, namely, is it possible to produce large amounts of cyclotron radiation without producing large amounts of circular polarization? The results tend to show that, for a large emitting area, the answer is yes. Chapter V is a summary of the rest of the work.