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The growth of dust grains in protoplanetary disks is a necessary first step towards planet formation 1 . This growth has been inferred from observations of thermal dust emission 2 towards mature protoplanetary systems (age >2 million years) with masses that are, on average, similar to Neptune 3 . In contrast, the majority of confirmed exoplanets are heavier than Neptune 4 . Given that young protoplanetary disks are more massive than their mature counterparts, this suggests that planet formation starts early, but evidence for grain growth that is spatially and temporally coincident with a massive reservoir in young disks remains scarce. Here, we report observations on a lack of emission of carbon monoxide isotopologues within the inner ~15 au of a very young (age ~100,000 years) disk around the solar-type protostar TMC1A. By using the absence of spatially resolved molecular line emission to infer the gas and dust content of the disk, we conclude that shielding by millimetre-size grains is responsible for the lack of emission. This suggests that grain growth and millimetre-size dust grains can be spatially and temporally coincident with a mass reservoir sufficient for giant planet formation. Hence, planet formation starts during the earliest, embedded phases in the life of young stars. Evidence for the earliest phase of planet formation, dust grain growth, has been seen in the very young and massive circumstellar disk around low-mass protostar TMC1A. Such systems, still rich in gas, are responsible for the high-mass end of the exoplanet mass distribution.

Outflows and winds launched from young stars play a crucial role in the evolution of protostars and the early stages of planet formation. However, the specific details of the mechanism behind these phenomena, including how they affect the protoplanetary disk structure, are still debated. We present JWST NIRSpec integral field unit observations of atomic and H2 lines from 1 to 5.1 μm toward the low-mass protostar TMC1A. For the first time, a collimated atomic jet is detected from TMC1A in the [Fe ii] line at 1.644 μm along with corresponding extended H2 2.12 μm emission. Toward the protostar, we detected spectrally broad H i and He i emissions with velocities up to 300 km s−1 that can be explained by a combination of protostellar accretion and a wide-angle wind. The 2 μm continuum dust emission, H i, He i, and O i all show emission from the illuminated outflow cavity wall and scattered line emission. These observations demonstrate the potential of JWST to characterize and reveal new information about the hot inner regions of nearby protostars; in this case, a previously undetected atomic wind and ionized jet in a well-known outflow.

Observations of the outflow associated with the TMC1A protostellar system reveal that the ‘disk wind’ model correctly explains how material is ejected from protostars. A young star turns on the gas Observations of the young, solar-type protostar TMC1A, taken with the Atacama Large Millimeter/submillimetre Array (ALMA) in high-angular-resolution mode, provide new data on the outflows of molecular gas associated with such systems. Per Bjerkeli et al . report images of carbon monoxide gas that is ejected from a region extending up to a radial distance of 25 astronomical units from the central protostar. Their data also show that angular momentum is removed from an extended region of the disk. These findings are consistent with the 'disk wind' model, in which the outflowing gas is launched by an extended disk wind from a Keplerian disk. Young stars are associated with prominent outflows of molecular gas 1 , 2 . The ejection of gas is believed to remove angular momentum from the protostellar system, permitting young stars to grow by the accretion of material from the protostellar disk 2 . The underlying mechanism for outflow ejection is not yet understood 2 , but is believed to be closely linked to the protostellar disk 3 . Various models have been proposed to explain the outflows, differing mainly in the region where acceleration of material takes place: close to the protostar itself (‘X-wind’ 4 , 5 , or stellar wind 6 ), in a larger region throughout the protostellar disk (disk wind 7 , 8 , 9 ), or at the interface between the two 10 . Outflow launching regions have so far been probed only by indirect extrapolation 11 , 12 , 13 because of observational limits. Here we report resolved images of carbon monoxide towards the outflow associated with the TMC1A protostellar system. These data show that gas is ejected from a region extending up to a radial distance of 25 astronomical units from the central protostar, and that angular momentum is removed from an extended region of the disk. This demonstrates that the outflowing gas is launched by an extended disk wind from a Keplerian disk.

This thesis describes observations and analyses of water in molecular outflows from young stellar objects. The abundance of this molecule (with respect to molecular hy- drogen) is deduced from observations carried out with primarily the Odin and Herschel telescopes. The large spatial extents of molecular outflows allow for mapping obser- vations to be done with both facilities, but in addition to this, spectroscopy also allow for the investigation of the kinematics. The observations discussed in this thesis were acquired over the years 2002 to 2011.In the first appended research paper, observations of 15 different shocked regions are reported. The targets were primarily molecular outflows, but two supernova rem- nants were also observed. This study shows that the water abundance in the gas is elevated in the presence of shock waves. Furthermore, the water abundance seems to correlate with the maximum velocity of the shocked gas.In the second paper, previously published observations of the Herbig-Haro object HH 54 are followed up, using APEX, Odin and Herschel. In this work we investigate the relative cooling contribution from CO and H2O and we compare the results with most recent shock models. CO dominates the cooling and we conclude that planar shock models do not explain the observations satisfactorily. Instead we find that a curved geometry can completely account for the observed line profile shapes in the two species. The inferred water abundance is lower than what was previously expected.In the third paper, Herschel mapping observations of VLA 1623 are presented. The ground-state transitions of o-H2O were mapped using the HIFI and PACS instruments but also higher energy transitions were observed towards selected positions in the out- flow lobes. The observed H2O(110 −101) line profiles show a variety of shapes over the observed region and also from this work, we conclude that the water abundance is lower than expected. In addition to this, it is now clear that the regions responsible for the emission in water are warmer than the regions traced by CO. A comparison with H2 data obtained with Spitzer allows us to estimate the physical parameters of the flow. This leads us to conclude, that it does not matter which molecular tracer we use when we infer the force and the power of the VLA 1623 outflow. The analysis is followed up in a letter where we include also the L 1448 and L 1157 outflows.

Disks around young stars are the sites of planet formation. As such, the physical and chemical structure of disks have a direct impact on the formation of planetary bodies. Outflowing winds remove angular momentum and mass and affect the disk structure and therefore potentially planet formation. Until very recently, we have lacked the facilities to provide the necessary observational tools to peer into the wind launching and planet forming regions of the young disks. Within the framework of the Resolving star formation with ALMA program, young protostellar systems are targeted with ALMA to resolve the disk formation, outflow launching and planet formation. This contribution presents the first results of the program. The first resolved images of outflow launching from a disk were recently reported towards the Class I source TMC1A (Bjerkeli et al. 2016) where we also present early evidence of grain growth (Harsono et al. 2018).

(abridged) Magnetic fields are fundamental to the accretion dynamics of protoplanetary disks and they likely affect planet formation. Typical methods to study the magnetic field morphology observe the polarization of dust or spectral lines. However, it has recently become clear that dust-polarization in ALMA's spectral regime does not always faithfully trace the magnetic field structure of protoplanetary disks, which leaves spectral line polarization as a promising method for mapping the magnetic field morphologies of such sources. We aim to model the emergent polarization of different molecular lines in the ALMA wavelength regime that are excited in protoplanetary disks. We explore a variety of disk models and molecules to identify those properties that are conducive to the emergence of polarization in spectral lines and may therefore be viably used for magnetic field measurements in protoplanetary disks. We used PORTAL in conjunction with LIME. Together, they allowed us to treat the polarized line radiative transfer of complex three-dimensional physical and magnetic field structures. We present simulations of the emergence of spectral line polarization of different molecules and molecular transitions in the ALMA wavelength regime. We find that molecules that thermalize at high densities, such as HCN, are also the most susceptible to polarization. We find that such molecules are expected to be significantly polarized in protoplanetary disks, while molecules that thermalize at low densities, such as CO, are only significantly polarized in the outer disk regions. We present the simulated polarization maps at a range of inclinations and magnetic field morphologies, and we comment on the observational feasibility of ALMA linear polarization observations of protoplanetary disks.

Modern telescopes generate increasingly large and diverse datasets, often consisting of complex and morphologically rich structures. To efficiently explore such data requires automated methods that can extract and organize physically meaningful information, ideally without the need for extensive manual interaction. We aim to provide a user-friendly implementation of a self-supervised machine learning framework to explore morphological properties of large datasets, based on the BYOL (Bootstrap Your Own Latents) method. By enabling the generation of meaningful image embeddings without manually labelled data, the framework will enable key tasks such as clustering, anomaly detection, and similarity based exploration. In contrast to existing BYOL implementations, astromorph accommodates data of varying dimensions and resolutions, including both single-channel FITS images and multi-channel spectral cubes. The package is built with usability in mind, offering streamlined pipeline scripts for ease of use as well as deeper customization options via PyTorch-based classes. To demonstrate the utility of astromorph, we apply it in two contrasting science cases representing different astronomical domains: images of protoplanetary disks observed with ALMA, and infrared dark clouds observed with Spitzer and Herschel. In both cases, we demonstrate how astromorph produces scientifically meaningful embeddings that capture morphological differences and similarities across large samples. astromorph enables users to apply a robust, label-free approach for uncovering morphological patterns in astronomical datasets. The successful application to two markedly different datasets suggest that the pipeline is broadly applicable across a wide range of imaging-rich astronomical context, providing a user friendly tool for advancing discovery in observational astronomy.

Outflows and winds launched from young stars play a crucial role in the evolution of protostars and the early stages of planet formation. However, the specific details of the mechanism behind these phenomena, including how they affect the protoplanetary disk structure, are still debated. We present ıt JWST NIRSpec Integral Field Unit (IFU) observations of atomic and H\\(_2\\) lines from 1 -- 5.1 \\(\\)m toward the low-mass protostar TMC1A. For the first time, a collimated atomic jet is detected from TMC1A in the [Fe II] line at 1.644 \\(\\)m along with corresponding extended H\\(_2\\) 2.12 \\(\\)m emission. Towards the protostar, we detected spectrally broad H I and He I emissions with velocities up to 300 km/s that can be explained by a combination of protostellar accretion and a wide-angle wind. The 2\\(\\)m continuum dust emission, H I, He I, and O I all show emission from the illuminated outflow cavity wall and scattered line emission. These observations demonstrate the potential of ıt JWST to characterize and reveal new information about the hot inner regions of nearby protostars. In this case, a previously undetected atomic wind and ionized jet in a well-known outflow.

(abridged) Protostellar outflows exhibit large variations in their structure depending on the observed gas emission. This study analyzes the atomic jet and molecular outflow in the Class I protostar, TMC1A to characterize morphology and identify previously undetected spatial features with JWST's NIRSpec IFU. In addition to identifying a large number of Fe II and H2 lines, we have detected the bipolar Fe jet by revealing, for the first time, the presence of a red-shifted atomic jet. Similarly, the red-shifted component of the H2 slower wide-angle outflow is observed. Both Fe II and H2 red-shifted emission exhibit significantly lower flux densities compared to their blue-shifted counterparts. Additionally, we report the detection of a collimated high-velocity (100 km s-1), blue-shifted H2 outflow, suggesting the presence of a molecular jet in addition to the well-known wider angle low-velocity structure. The Fe II and H2 jets show multiple intensity peaks along the jet axis, which may be associated with ongoing or recent outburst events. In addition to the variation in their intensities, the H2 wide-angle outflow exhibits a \"ring\"-like structure. The blue-shifted H2 outflow also shows a left-right brightness asymmetry likely due to interactions with the surrounding ambient medium and molecular outflows. Using the Fe II line ratios, the extinction along the atomic jet is estimated to be between Av = 10-30 on the blue-shifted side, with a trend of decreasing extinction with distance from the protostar. A similar Av is found for the red-shifted side, supporting the argument for an intrinsic red-blue outflow lobe asymmetry rather than environmental effects such as extinction. This intrinsic difference revealed by the unprecedented sensitivity of JWST, suggests that younger outflows already exhibit the red-blue side asymmetry more commonly observed towards jets associated with Class II disks.

Previous observations of B335 have presented evidence of ongoing infall in various molecular lines, e.g., HCO\\(^+\\), HCN, CO. There have been no confirmed observations of a rotationally supported disk on scales greater than ~12~au. The presence of an outflow in B335 suggests that also a disk should be present or in formation. To constrain the earliest stages of protostellar evolution and disk formation, we aim to map the region where gas falls inwards and observationally constrain its kinematics. Furthermore, we aim to put strong limits on the size and orientation of any disk-like structure in B335. We use high angular resolution \\(^13\\)CO data from ALMA, and combine it with shorter-baseline archival data to produce a high-fidelity image of the infall in B335. We also revisit the imaging of high-angular resolution Band 6 continuum data to study the dust distribution in the immediate vicinity of B335. Continuum emission shows an elliptical structure (10 by 7 au) with a position angle 5 degrees east of north, consistent with the expectation for a forming disk in B335. A map of the infall velocity (as estimated from the \\(^13\\)CO emission), shows evidence of asymmetric infall, predominantly from the north and south. Close to the protostar, infall velocities appear to exceed free-fall velocities. 3D radiative transfer models, where the infall velocity is allowed to vary within the infall region, can explain the observed kinematics. The data suggests that a disk has started to form in B335 and that gas is falling towards that disk. However, kinematically-resolved line data towards the disk itself is needed to confirm the presence of a rotationally supported disk around this young protostar. The measured high infall velocities are not easily reconcilable with a magnetic braking scenario and suggest that there is a pressure gradient that allows the infall velocity to vary in the region.