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
Complex Organic Molecules (COMs) have been detected in objects across different stages of stellar evolution. Many of these COMs are expected to form on interstellar ice and transfer later to the... Show moreComplex Organic Molecules (COMs) have been detected in objects across different stages of stellar evolution. Many of these COMs are expected to form on interstellar ice and transfer later to the gas phase. However, due to the challenge of detecting and assigning molecules in interstellar ice observations, the only frozen COM that has been unambiguously identified is methanol. This scenario is about to change, as the exceptional capabilities of the James Webb Space Telescope (JWST) enable the observation of weak signatures of molecules in interstellar ice.This thesis has a main focus on laboratory studies to support interstellar ice observation with the JWST. The results of the spectroscopic characterization of three COMs, acetone, methylamine, and methyl cyanide mixed in interstellar ice analogs are presented in Chapters 3, 4, and 5, respectively. The potential of their absorption features to trace these species in JWST observations is also discussed. Chapter 6 presents a new experimental approach to studying morphological changes in frozen CO, which is important to understand its morphology in space. Chapter 7 presents a computational study that simulates the infrared spectra of small fullerenes (between 44-70 C atoms) and provides insights for future JWST searches for these molecules Show less
