There are many observational methods for studying debris disks because of constraints imposed on observing their predominately infrared wavelength emission close to the host star. Two methods which are discussed here are ground-based high contrast imaging and space-based far-IR emission. The Gemini Planet Imager (GPI) is a high contrast near-IR instrument designed to directly image planets and debris disks around other stars by suppressing star light to bring out faint sources nearby. Because debris disks are intrinsically polarized, polarimetry offers a useful way to enhance the scattered light from them while suppressing the diffracted, unpolarized noise. I discuss the characterization of GPI's microlens point spread function (PSF) in polarization mode to try to improve the quality of the processed data cubes. I also develop an improved flux extraction method which takes advantage of an empirically derived high-resolution PSF for both spectral and polarization modes. To address the instrumental effects of flexure, which affect data quality, I develop methods to counteract the effect by using the science images themselves without having to take additional calibrations. By reducing the number of calibrations, the Gemini Planet Imager Exoplanet Survey (GPIES) can stand to gain ~66 hours of additional on-sky time, which can lead to the discovery of more exoplanetary systems. The Herschel Space Observatory offers another method for observing debris disks which is ideally suited to measure the peak dust emission in the far-IR. Through a careful analysis, we look at 100/160 μm excess emission around λ Boo stars, to differentiate whether the emission is from a debris disk or a bowshock with the interstellar medium. It has been proposed that the stars' unusual surface abundances are due to external accretion of gas from those sources. We find that the 3/8 stars observed are well resolved debris disks and the remaining 5/8 were inconsistent with bowshocks. To provide a causal explanation of the phenomenon based on what we now know of their debris disks, I explore Poynting-Robertson (PR) drag as a mechanism for secondary accretion via a debris disk. However, I find that the accretion rates are too low to cause the surface abundance anomaly. Further study into the debris disks in relation to stellar abundances and surfaces are required to rule out or explain the λ Boo phenomenon through external accretion. / Graduate / 0606 / zhd@uvic.ca

HD 106906 is a young, binary stellar system, located at ~103.3 parsecs away in the Lower Centaurus Crux (LCC) group. This system is completely unique among known systems in that it contains an asymmetrical debris disk, as well as an 11 M(Jup) planet companion, at a separation of ~735 AU. Only 4 other systems are known to contain both a disk and detected planet, where HD 106906 is the only one in which the planet has apparently been ejected. Furthermore, the debris disk is nearly edge on, and extends roughly from 70 AU to >500 AU, where previous polarimetric studies with HST have shown the outer regions to have high asymmetry. The presence of a planet companion sparks questions about the origin of this asymmetry. To better understand the structure and composition of the disk, deeper data have been taken with the Gemini Planet Imager (GPI), which we have used to perform a deep polarimetric study of HD 106906’s asymmetrical debris disk. The data were taken in the H-band, and were supplemented with both J- and K1-band polarimetric data which have been obtained through one of GPI’s Large and Long Programs (LLP). Polarimetry is important in the study of debris disks in scattered light, as it helps us constrain their dust grain characteristics, as well as allowing us to obtain high-contrast images. Modelling the disk, along with an empirical analysis of our data, supports a disk that is asymmetrical in surface brightness and structure, as well as a disk that is highly eccentric. These results will be discussed in terms of possible sources of asymmetry, such as dynamical interaction with the planet companion HD 106906b. / Graduate / 2021-07-26