A polarimetric study of ETA carinae and the carina nebula

Abstract

This thesis contains an account of some of the work undertaken by the author while a member of the Astronomy Group at the University of Durham. The work of the group involves the measurement and interpretation of the linear polarization in nebular astronomical objects. The initial chapters briefly describe the theory of polarized light and the. method of observing linear polarization, along with an indication of the techniques involved when analyzing the data. Chapter three is a review of recent work on interstellar grains with a summary of the present ideas on the nature of the grains. The next chapter summarizes the observations of the peculiar object Carinae and in the following chapter, a polarization map of the nebulosity around Carinae is presented and a model determined to account for the observed linear polarization. The model involves the assumption of a bipolar type geometry for η Carinae with a size distribution of silicate grains of the form and it is found that grains of .15µ contribute most to the scattering at optical wavelengths. Using the same distribution it is found that maximum emission at l0µ can be expected from grains of size .lµ .The final chapter contains observations of the linear polarization in the Carina Nebula in the region of n Carinae, and the results are interpreted in the light of present ideas concerning n Carinae and its relationship with the Carinae Nebula. It seems that the light from η Carinae is being reflected by clouds in the Carina Nebula.