Infrared photometry of binary stars

This thesis presents a description of the design and construction of an Infrared photometer for astronomical use, and its application, and that of another photometer, to study close binary systems. Initially a background to the relevant infrared technology is given. A low-level discussion of the mode of operation of the two common types of detector employed in this work, the bolometer and the photoconductor, is included. Also discussed is the relevant system electronics associated with the final data output. Next is a brief review of the current research and progress in the general field of infrared astronomy. A summary of the interesting and relevant features of binary systems and in particular close binaries, concludes the introductory section. Following this is a description of the photometer, its construction and operation. Details of several problems, such as chopping mechanisms, photometer alignment and detector cooling, are covered, together with their adopted solutions. Photometer performance in the laboratory and on the British infrared flux-collector at Tenerife was satisfactory, but plans to include a polarimetric facility were not completed. Finally, infrared observations of some close binary systems are presented and discussed. Infrared light curves from 1.25u to 11.3u were obtained for the prototype eclipsing binaries B Per and B Lyr. An analysis of the curves led to a model for B Per of a gas stream running from the secondary to the primary star. The mean density of the stream is 1012 electrons cm-3, mean temperature about 10,000K - 15,000K. A mass transfer rate for the stream of 1.8.10-8 Mg/yr is suggested. For B Lyr, a gaseous envelope round the secondary of approximately constant (spatially) electron density of 1.4.1012 cm-3 and a temperature of about 17,500K is proposed. As the temperature of the secondary component is of the same order as that of the stream, the important conclusion is drawn that the secondary is intrinsically more luminous than the primary. Incomplete data is also presented for a number of other potentially interesting eclipsing binari stars.