Optical Polarimetry in Undergraduate Education

Abstract

Polarimetry plays an important part in observational astronomy, but it is all too often given limited attention in astronomy textbooks. Coupled with a sometimes confusing mathematical introduction, students may feel that polarization is a difficult subject best left for study at a different time, or worse, not at all. Additionally, polarimetric observations and analysis are not typical exercises students are likely to engage in as part of an observational astronomy course. Over the past few years students at Virginia Military Institute have used an optical polarimeter, which was designed and constructed in-house, on the 20 cm Cassegrain telescope at the VMI Observatory to study the polarization of stars. These observations have enhanced their astronomical knowledge and allowed them the opportunity to gain valuable experience using this important technique. The subsequent analysis of stellar polarization has led to a better understanding of the mathematics of polarization, its interpretation, and statistical treatment. In this paper I describe the design and construction of an optical polarimeter suitable for a small college observatory and outline the observing and data analysis strategies. I will also present observations that range from brief introduction exercises that can be included as part of an observational astronomy course to longer programs suitable for undergraduate research projects.