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
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
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 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
This thesis presents new insights of protoplanetary disk evolution. It focuses on the characterisation of several elements in the earliest phases of planet formation in protoplanetary disks: the... Show moreThis thesis presents new insights of protoplanetary disk evolution. It focuses on the characterisation of several elements in the earliest phases of planet formation in protoplanetary disks: the connection between the SED and disk gaps (Chapters 2, 3 and 4), PAHs in the gas flows in disk gaps (Chapter 5) and dust processing of forsterite in evolving protoplanetary disks (Chapter 6). Show less
This thesis focuses on the interplay of the young star and its protoplanetary disk, on the evolution of the dust particles that make up the protoplanetary disk surrounding the young star, and thus... Show moreThis thesis focuses on the interplay of the young star and its protoplanetary disk, on the evolution of the dust particles that make up the protoplanetary disk surrounding the young star, and thus on the very first stage of the formation of planets like those that compose our own Solar system. Show less
Star formation occurs when a dense cloud of interstellar gas and dust gravitationally collapses. Rotation during this collapse leads naturally to the formation of a flattened circumstellar disk... Show moreStar formation occurs when a dense cloud of interstellar gas and dust gravitationally collapses. Rotation during this collapse leads naturally to the formation of a flattened circumstellar disk around the forming star. These disks are additionally known as protoplanetary disks because the orbiting circumstellar dust and cold gas represent the building blocks for planets. How long this material survives and how it evolves in this time will determine the propensity for (and the diversity of) planetary systems. This thesis is split into three parts that analyze different aspects of disk evolution and the circumstellar environment. In part one, we use observations at millimeter wavelengths to probe (and then model and compare) the dust and gas properties around low-mass Sun-like stars. We conclude that high-resolution spatial and spectral imaging of optically thinner molecular lines will provide the most robust description of the disk structure and evolution using future instrumentation. During these routine observations, we report recurring millimeter flares resulting in part two. We attribute this phenomenon to synchrotron emission from relativistic electrons trapped in the (colliding) magnetospheres of a young binary system. Finally, we present a microgravity experiment to probe the collisional growth mechanism for the first steps of planet formation. Show less
