A Multiwavelength Perspective of the Rho-Ophiuchus Star-forming Region

Planet formation requires the growth of solid bodies over 12 orders of magnitude in size, from micron-sized interstellar dust grains to thousands of kilometre-sized planetary bodies. However, due to the strong wavelength dependence of dust emissivity, no single observation can accurately characterise the full size distribution of dust grains, necessitating a multiwavelength approach. Fortunately, the complementary capabilities of the James Webb Space Telescope (JWST), Atacama Large (sub-)millimetre Array (ALMA) and Jansky Very Large Array (VLA) can provide high resolution observations from near-infrared to centimetre wavelengths, probing dust evolution from ISM-like grains to cm-sized pebbles for the first time.

This thesis employs high resolution multiwavelength JWST, ALMA, and VLA observations for a sample of 20 low mass Class 0-III young stellar objects (YSOs) in the L1688 core of the Ophiuchus star-forming region. The unique morphological and energetic perspectives provided by each facility grant an unprecedented insight into the dust, disk, and outflow properties of YSOs across multiple evolutionary stages and spatial scales, under the same environmental conditions. In addition, employing physically motivated models of the millimetre-centimetre spectral energy distribution allows for the simultaneous characterisation of dust emission and ionised gas emission arising from protostellar jets, disk winds, and magnetospheric processes.

Characterisation of the spectral behaviour and underlying physical properties of dust and ionised gas emission reveals evidence for dust growth towards mm- and cm-sizes alongside tens to thousands of Earth masses in dust, available at the earliest stages of protostellar evolution (Class 0). In addition, the combination of mm- and cm-wave observations unveils a unique discontinuity between 40-10 GHz, explained by the transition from optically thick (sub-)mm emission to optically thin cm-wave emission. Comparison of VLA 10 GHz continuum and JWST NIRCam reveals a morphological connection between ionised gas emission in the innermost disk regions (10s au) and extended (100-1000s au) outflow features such as cavities, knots and bow shocks.

Ultimately, this thesis represents one of the highest resolution, multiwavelength perspectives of YSOs in Ophiuchus, spanning four orders of magnitude in wavelength. This work lays the foundations for multiple follow-up investigations with JWST, ALMA, and the VLA, as well as providing an observational framework for studies of planet formation using next-generation interferometers like the Square Kilometre Array.