We propose that extrasolar asteroid belts can be detected through their gravitational microlensing signatures. Asteroid belt + star lens systems create so-called "pseudo-caustics", regions in the source plane where the magnification exhibits a finite but discontinuous jump. These features allow such systems to generate distinctive signatures in the microlensing light curves for a wide range of belt configurations, with source trajectories as far as tenths of the Einstein ring radius from the centre of the lens. Sample light curves for a range of asteroid belt parameters are presented. In the near future, space-based microlensing surveys like WFIRST, which will have the power to detect percent-level changes in microlensing light curves even with sub-minute exposure times, may be able to discover extrasolar asteroid belts with masses of the order of an earth mass.
Extrasolar debris disks are the dust disks found around nearby main sequence stars arising from the break-up of asteroids and comets orbiting the stars. Far-IR surveys (e.g., with Herschel) showed that ~20% of stars host detectable dust levels. While dust temperatures suggest a location at 10s of au comparable with our Kuiper belt, orders of magnitude more dust is required implying a planetesimal population more comparable with the primordial Kuiper belt. High resolution imaging (e.g., with ALMA) has mapped the nearest and brightest disks, providing evidence for structures shaped by an underly…
Extrasolar planets found by gravitational microlensing often require assumptions on the source star distance and relative proper motion. Only in a few cases has it been possible to confirm these findings with space-based observations or high-resolution follow-up. 20 planetary microlensing events can be positionally cross-matched with the second Gaia data release containing parallax and proper motion measurements. In this work we subject all microlensing planets listed in NASA's Exoplanet Archive to an initial consistency check by comparing them with Gaia data release 2 measurements. The result…
Circumstellar debris disks are the extrasolar analogues of the asteroid belt and the Kuiper belt. They consist of comets and leftover planetesimals that continuously collide and produce circumstellar dust that can be observed as infrared excess or in resolved imaging. As an obvious outcome of the planet formation process, debris disks can help us constrain planet formation theories and learn about the history of our own solar system. This thesis presents observational studies of secondary gas in debris disks. It also discusses the astrobiological potential of debris disks created during impact…
We present VRI spectrophotometry of 1003 Main-Belt Asteroids (MBAs) observed with the Sutherland, South Africa, node of the Korea Microlensing Telescope Network (KMTNet). All of the observed MBAs were serendipitously captured in KMTNet's large 2deg $\times$ 2deg field of view during a separate targeted near-Earth Asteroid study (Erasmus et al. 2017). Our broadband spectrophotometry is reliable enough to distinguish among four asteroid taxonomies and we confidently categorize 836 of the 1003 observed targets as either a S-, C-, X-, or D-type asteroid by means of a Machine Learning (ML) algorith…
Debris disk is a catch-all term that can be used to refer to any component of a planetary system which is not an actual planet. In the Solar System this refers to the asteroids and comets in the Asteroid and Kuiper belts as well as the dust and gas derived from them, such as the zodiacal cloud. Studying the structure of extrasolar debris disks provides unique constraints on the underlying planetary system and on the processes of planet formation and protoplanetary disk evolution. Debris disks also have important implications for processes affecting the planets, such as impact events that may s…
