High-contrast imaging and polarimetry at solar-system scales

Abstract

Direct imaging is a uniquely powerful technique for studying exoplanets and circumstellar disks, offering spatially resolved observations of planetary systems and the environments in which they form. This dissertation presents a comprehensive investigation of high-contrast imaging and polarimetry at solar-system scales, with applications ranging from the detection of planetary companions to the detailed analysis of planet-forming disks.I begin with a theoretical and technical overview of direct imaging, outlining the key challenges of contrast, angular resolution, and wavefront aberrations. I then present a direct imaging search for second-generation planets around the white dwarf Sirius B, placing new limits on planetary companions within the dynamically stable orbital region. Next, I describe and characterize upgrades to the visible-light high-contrast imaging polarimeter VAMPIRES at the Subaru Telescope. These upgrades included photon-counting CMOS detectors, a novel observing mode for multiband imaging, coronagraphic optics, and new polarimetric optics. I then discuss the development of a dedicated data processing pipeline for VAMPIRES that handles calibration, image analysis, image registration, flux calibration, and polarimetry. This pipeline is designed to accommodate the high data volumes and diverse observing modes of VAMPIRES. Finally, I present a multi-epoch polarimetric imaging study of the HD 169142 planet-forming disk. This analysis highlights long-lived scattered-light substructures that persist over a twelve year observational baseline. By tracking the evolution of azimuthal features, I place dynamical constraints on potential planet-disk interactions. This study demonstrates the scientific merit of multi-epoch high-contrast polarimetric imaging for probing disk evolution and planet formation over multi-year timescales.