This thesis examines the link between simple molecules and the underlying structure and chemistry within protoplanetary disks - the birthplaces of planets. The chapters describe the analysis and... Show moreThis thesis examines the link between simple molecules and the underlying structure and chemistry within protoplanetary disks - the birthplaces of planets. The chapters describe the analysis and interpretation of data obtained with the Atacama Large Millimeter/submillimeter Array (ALMA) interferometer, primarily in two disks around the young stars HD 163296 and HD 169142. Observations of dust and molecular gas probe the relationship between the dust structure, the gas distribution, and the chemical processes that give rise to the gaseous species. In the disk around HD 169142, substructure in the millimeter dust and carbon monoxide gas strongly suggests the presence of giant planets sweeping up disk material. Meanwhile, molecular ions reveal previously hidden structure in the gas deep within the disk beyond the millimeter dust edge. In the disk around HD 163296, carbon monoxide and the simple organic molecule formaldehyde show radial variation connected to the millimeter dust edge. The organic molecule methanol is not detected in the disk, suggesting differences in the production of formaldehyde and methanol. This thesis concludes that the distribution of simple molecules is connected to the dust size distribution in disks, while more complex molecules remain elusive but can still provide constraints on disk chemistry. Show less
My work focuses on a class of astronomical objects called protoplanetary disks. These flattened structures rotating around young stars are made of gas and dust and are the places where planets,... Show moreMy work focuses on a class of astronomical objects called protoplanetary disks. These flattened structures rotating around young stars are made of gas and dust and are the places where planets, like our own Earth, are formed. One of the main properties needed to explain the process of planet formation is the mass of protoplanetary disks. There is however not yet a consensus on how such masses can be reliably measured from disk observations. In this thesis, I investigate weather less abundant isotopologues of carbon monoxide (CO) are good candidates for tracing disk masses. Initially I tackle the problem from a theoretical point of view by running a grid of physical-chemical disk models. Subsequently I compare my model predictions with recently acquired observations of protoplanetary disks in the Lupus star-forming region. The conclusion of my work is that CO isotopologues are good disk mass tracers, but they need to be calibrated. Observations of other molecules like hydrogen deuteride (HD), atomic carbon and hydrocarbons can serve this cause. Show less
To study how planetary systems come into existence we study much younger systems still in formation. Gas and dust rich disks surrounding young stars are thought to be the precursors of... Show moreTo study how planetary systems come into existence we study much younger systems still in formation. Gas and dust rich disks surrounding young stars are thought to be the precursors of planetary systems and therefore known as protoplanetary disks. In this thesis, I study large-scale structures in protoplanetary disks through high-contrast imaging of the scattering surfaces of these disks; and I calibrated two high-contrast imagers. To observe these disks at optical wavelengths, we need to take into account that the central star is much brighter than the (star)light reflected by the disk surface: i.e., high contrast between star and disk. Additionally, light coming from the star & disk is disturbed by the Earth’s atmosphere. Therefore, specialized high-contrast imaging instruments are required to correct for atmospheric disturbance of the stellar light in order to allow the highest possible spatial resolution and contrast between the star and its nearby surroundings. Improving our understanding of these high-contrast imagers will allow for a better interpretation of the data recorded with these instruments, while the interpretation of disk structures detected at high spatial resolution forms a crucial step in our understanding of the general principles that govern disk evolution and planet formation. Show less
