The formation of stars and planets happens over multiple scales, which can interact. In particular, planet formation happens in the dense, complex environment of star forming regions. This thesis... Show moreThe formation of stars and planets happens over multiple scales, which can interact. In particular, planet formation happens in the dense, complex environment of star forming regions. This thesis primarily explores the effects of high stellar density and presence of nearby massive stars (or a low density and absence of massive stars) on the evolution of protoplanetary disks, and their consequences for planet formation. Additionally, the dynamics of stellar feedback-driven shells is explored, and a novel operator splitting algorithm is introduced that allows for flexible coupling of a large number of physical models. Show less
The focus of this thesis is how stars like our Sun and planets like Jupiter, Saturn, and Earth are formed. With arrays of radio telescopes, I observed the environments where the first stages of... Show moreThe focus of this thesis is how stars like our Sun and planets like Jupiter, Saturn, and Earth are formed. With arrays of radio telescopes, I observed the environments where the first stages of star and planet formation occur. This thesis focuses on characterizing different components of young protostellar systems, most notably their jets and disks. Using interferometric radio observations with ALMA array, I provided information on key chemical tracers of different components of the protostellar systems. By characterizing the radio signal from young stars with ALMA and VLA interferometers, I was able to disentangle an emission from the jet and the disk. This led to an unexpected development: I was able to compare dust masses of young disks with those of older disks for the first time. By comparing this information with masses of the extrasolar planets detected so far I showed that the solid cores of gas giants must form in the first 0.1 Myr of stellar life. That is an important time constrain, that pushes the onset of planet formation earlier and highlights the importance of characterization of the youngest protostars in understanding the origin of Solar System and Earth. 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
Stars like our Sun are formed in large, tenuous clouds of gas and dust. As the star is formed at the centre, the remaining material collapses into a thick disk around it. The chemical composition... Show moreStars like our Sun are formed in large, tenuous clouds of gas and dust. As the star is formed at the centre, the remaining material collapses into a thick disk around it. The chemical composition of such a cloud changes dramatically during this process. Spherical models have always been used to model this chemical evolution, but they cannot properly describe the disk. This thesis presents the first model that follows the entire chemical evolution from a pre-stellar core to a circumstellar disk in two spatial dimensions. It follows material as it falls in from the cloud to the star and disk. The density, temperature and UV flux along these trajectories serve as input for a gas-phase chemical network -- including freeze-out onto and evaporation from cold dust grains. The model offers new insights into the chemical history of disks, in particular of the region where planets and comets are formed. Applications of the model include the gas/ice ratios of carbon monoxide and water (Chapter 2), the abundances of key gas-phase molecules (Chapter 3), the crystallinity of the dust (Chapter 4), the isotope-specific photodissociation of carbon monoxide (Chapter 5) and the charge balance of polycyclic aromatic hydrocarbons (PAHs; Chapter 6). Show less
