This research focuses on the distribution of chemical elements in protoplanetary disks, the birthplaces of planets. These disks form around young stars and contain gas and dust, from which planets... Show moreThis research focuses on the distribution of chemical elements in protoplanetary disks, the birthplaces of planets. These disks form around young stars and contain gas and dust, from which planets grow. Ice plays a crucial role in planet formation, aiding the clumping of dust particles and influencing the chemical makeup of both planets and their atmospheres. Using advanced observational techniques, including the James Webb Space Telescope (JWST) and the Atacama Large (sub-)Millimeter Array (ALMA), both direct observations of ice and indirect methods were employed to map the distribution of frozen carbon and other elements. The study offers new insights into how chemical compositions evolve during planet formation, explaining the vast diversity of planets observed across the universe. The societal relevance of these findings lies in enhancing our understanding of planet formation and the potential habitability of exoplanets. For example, the results show that carbon and oxygen are distributed differently in protoplanetary disks than previously thought, which has significant implications for exoplanet atmospheres. By combining physical and chemical models with future observations, this research deepens our understanding of how planets like Earth acquire their unique characteristics, contributing to a broader understanding of planetary diversity in the cosmos. Show less
This thesis focusses on the temperature structure in protoplanetary disks. The relation between structures seen in the dust and gas-phase molecules is investigated. This is crucial to understand... Show moreThis thesis focusses on the temperature structure in protoplanetary disks. The relation between structures seen in the dust and gas-phase molecules is investigated. This is crucial to understand the chemical composition of the planet forming material as well as to quantify the amount of gas present in the disk, a crucial parameter to determine if planets are likely present in the disk. One of the important regions in the disk is the water snowline, the midplane location where water freezes-out onto the dust grains. In this thesis, chemical modelling is used to infer the snowline location in a hot disk. This result is confirmed in the next chapter by 2D imaging of the water snow surface, the 2D equivalent of the water snowline. Additionally, the temperature structure across transition disk cavities is investigated to determine the mass of the planets that may be carving that cavity. Finally, the relation between the structures traced in the gas by different molecules and the dust is investigated to show that the chemical composition at the location of the dust rings and dust trap in the HD 100546 and OPH-IRS 48 disks, respectively, are different than in the other disk regions. Show less
A dense region of a gaseous and dusty cloud collapses to form a protostar surrounded by a disk and an envelope. This thesis uses both observations and models to study physical and chemical... Show moreA dense region of a gaseous and dusty cloud collapses to form a protostar surrounded by a disk and an envelope. This thesis uses both observations and models to study physical and chemical conditions of these protostellar systems which are likely where planets start to form. From the observational side, ALMA is used to quantify abundance ratios of complex organic molecules (COMs) in the gas around young protostars. These ratios are found to be remarkably constant for various nitrogen-bearing COMs which points to formation of these molecules under similar conditions, likely in ices of the prestellar phase. Moreover, observations of JWST are used to tentatively detect molecules such as methyl cyanide and ethyl cyanide in interstellar ices for the first time. In addition, high angular resolution ALMA observations of a protostellar system are analyzed to report the first detection of a disk wind candidate in methanol and hydrogen cyanide. From the modeling side, radiative transfer models are used to investigate how physical conditions such as source structure can change the molecular emission and molecular abundances. These models show that disk and optically thick dust can decrease the emission from COMs and change the correlations among their column densities. Show less
Detecting planets during their formation stages is crucial for understanding the history and diversity of fully developed planetary systems like our own. However, observing young planets directly... Show moreDetecting planets during their formation stages is crucial for understanding the history and diversity of fully developed planetary systems like our own. However, observing young planets directly is challenging because they are often deeply embedded within their host protoplanetary discs, rich in gas and dust. To overcome this limitation, this thesis introduces a novel methodology for identifying coherent kinematic perturbations in discs induced by giant planets orbiting stars with a mass similar to that of the Sun. This approach not only allows us to investigate the presence of planets but also to determine their most likely radial and azimuthal positions in a statistically robust manner. Moreover, it offers the additional benefit of enabling a three-dimensional reconstruction of the physical and dynamical structure of these planet-forming environments by simultaneously modelling the emission of multiple molecular tracers.The methodology is applied to various protoplanetary discs observed using the world-class interferometer ALMA, revealing a wide variety of kinematic and temperature features. These features include large-scale substructures with spiral and ring-like morphologies, as well as localised perturbations, some of which span coherently across the vertical extent of the disc indicating meridional circulation of material. Among the eight discs analysed, five exhibit signatures in the outer regions that could potentially be associated with massive embedded planets, suggesting that the interaction between discs and wide-orbit giant planets may represent a common early mechanism with a fundamental role in shaping the evolution of discs and, as a result, in the assembly and composition of planetary systems. Show less
