The work presented in this thesis is based on ALMA surveys of protoplanetary disks in three star-forming regions: Lupus, OMC-2, and NGC 2024. The motivation for this thesis is to study the... Show moreThe work presented in this thesis is based on ALMA surveys of protoplanetary disks in three star-forming regions: Lupus, OMC-2, and NGC 2024. The motivation for this thesis is to study the evolution of protoplanetary disks from the population level.The first two chapters focus on the Lupus clouds, a low-mass star-forming region. It has been the subject of a large survey with ALMA, targeting bright gas lines and the emission from millimeter-sized grains. This allows us to answer important questions on disk evolution: how common are >200 AU-sized disks with continuum substructure, and how are these substructures formed? Do compact disks observed in the continuum also correspond to compact gas disks?The chapters focusing on Orion deal with the impact of massive stars on disks. OMC-2 provides a view of a population of disks that are formed in a massive cloud, but isolated from the radiation of massive stars. They link disks that do form near these massive stars to those in low-mass YSOs. NGC 2024 also hosts massive stars, and is the youngest region surveyed; the presence of multiple populations of young stars has been suggested. ALMA allows us to independently test the complexity of this environment. Show less
To address the fundamental questions of how life on Earth emerged and how common life may be in the Universe, it is crucial to know the chemical composition of the planet-forming material. Planets... Show moreTo address the fundamental questions of how life on Earth emerged and how common life may be in the Universe, it is crucial to know the chemical composition of the planet-forming material. Planets were originally thought to form in protoplanetary disks, but studies of both disks and our Solar System show that planet formation already starts much earlier, in disks that are still embedded in cloud material. These young disks, however, are largely uncharacterised. This thesis presents a number of case studies on the physical and chemical structure of young disks, including the first temperature measurements showing that young disks are too warm for CO ice, unlike protoplanetary disks. In addition, it is shown that young disks around outbursting stars are the ideal sources to probe the the chemical complexity in planet-forming material. Show less
