Speedie, Jessica2025-08-072025-08-072025https://hdl.handle.net/1828/22566The assembly of planetary systems unfolds within the reservoir of 'leftover' material surrounding newborn stars. This thesis explores the use of interferometric observations at millimeter wavelengths to provide clues for unseen protoplanets at the earliest stages of formation, and to reveal the physical processes at play. First we identify how the tell-tale wake driven by an embedded protoplanet manifests in the midplane dust layer of its host circumstellar disk, and quantify the observing requirements to recover the signal in mm continuum emission with ALMA. These constraints establish the feasibility of mm dust wakes as a protoplanet-detection technique. Next, we apply our framework to a sample of ten circumstellar disks exhibiting kinematic evidence of wakes in 12CO molecular line emission. Such applications are a vital ingredient to distinguishing protoplanetary velocity disturbances from those of non-planetary origin. We also present the first direct measurement of gravitational instability in a planet-forming disk using 13CO and C18O molecular line emission. Our quantitative constraints on the kinematic structure in a disk with directly-imaged protoplanets demonstrates the physical mechanisms driving planet formation. Finally, the 12CO emission from AB Aurigae exhibits multiple infalling spiral streamers on 1000-au scales. Kinematic modeling pinpoints the region of impact with the disk to be near to candidate protoplanets, suggesting that planet formation cannot be understood without con- sideration of the surrounding star formation environment.enAvailable to the World Wide WebRadio astronomyPlanet formationThesisSpeedie, J., Booth, R. A., & Dong, R. 2022, Observing Planet-driven Dust Spirals with ALMA. The Astrophysical Journal, 930, 40, doi:10.3847/1538-4357/ac5cc0Speedie, J. & Dong, R. 2022, Testing Velocity Kinks as a Planet Detection Method: Do Velocity Kinks in Surface Gas Emission Trace Planetary Spiral Wakes in the Midplane Continuum? The Astrophysical Journal Letters, 940, 2, L43, doi:10.3847/2041-8213/aca074Speedie, J., Dong, R., Hall, C., et al. 2024, Gravitational instability in a planet-forming disk. Nature, 633, 8028, doi:10.1038/s41586-024-07877-0Speedie, J., Dong, R., Teague, R., et al. 2025, Mapping the Merging Zone of Late Infall in the AB Aur Planet-forming System. The Astrophysical Journal Letters, 981, 2, L30, doi:10.3847/2041-8213/adb7d5