Electronic Thesis and Dissertation Repository

Degree

Doctor of Philosophy

Program

Astronomy

Supervisor

Metchev, Stanimir A.

Abstract

Debris disks are gas-poor evolved circumstellar disks that show decreased near- to mid- infrared thermal excess emission because of lack of material close to the star. Regarded as massive analogues to the Main Asteroid or Kuiper Belts in the Solar System, these often young dust-rich disks comprise second-generation dust created by disruptive collisions of planetesimals and the decay products of asteroids and comets. Of the dozen or so directly imaged planets to date many share a distinctive characteristic: they reside in stellar systems known to also possess circumstellar dust. High-angular resolution characterization of debris disks, whose morphology is thought to be affected by embedded orbiting planets, offers an important offers an important pathway for probing planet-disk interaction. I used polarimetric differential imaging (PDI) to characterize debris disk at 0.042” resolution with the Gemini Planet Imager (GPI) on the Gemini South 8 m telescope. For the first project, I determined the photometric response of polarimetric observations with GPI leading to the flux calibration of the instrument. In my second and third project, I demonstrated the utility of PDI with radiative transfer modeling tools to characterize the morphology and grain properties of two debris disks at solar system scales. I reported the first PDI observations of the inner Kuiper Belt-analog HD 141569A disk and revealed the presence of an spiral arm. I also determined the existence of a putative unseen innermost disk inwards of 30 AU around HD 141569A through the analysis of the predicted thermal emission of the disk. Finally, I mapped the structure of the 82 AU ring-shaped HD 157587 debris disk. Our multi-wavelength high-contrast polarimetry reveals that even this unusually old (> 1 billion years) debris disk contains short-lived small grains: evidence of an active collisional cascade in this system. The combined power of extreme contrast (∼ 1 : 1, 000, 000 at 1 arc second), high angular resolution, and differential polarimetry with the Gemini Planet Imager reveals previously unseen disk structures, and is of great value for studying dynamically perturbed disks.

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