Radio Observations of Discs around Young Stellar Objects
In this thesis we study the disc surrounding the Young Stellar Object DG Tau B. We present observations at both cm and mm wavelengths using e-MERLIN and the EVLA respectively. We study the cold dust in the disc of DG Tau B by looking at its spectral energy distribution (SED). We also analyse the proper motions of DG Tau B and the classical T Tauri star DG Tau A to determine if they are a binary. We fit a modified blackbody to the DG Tau B SED and model the dust using a temperature of T=9.6±0.6K and a mass of M=0.30±0.03M . We see a radio excess which is found to have a spectral index of α = 1.4 ± 0.2, which is indicative of free-free or synchrotron emission. The emission from DG Tau B at cm wavelengths is studied at two epochs. The jet of DG Tau B is resolved with e-MERLIN in both the 2014 and 2016 data, whilst the disc of DG Tau B is only marginally resolved in 2016. The lack of cm blackbody emission from the DG Tau B disc, and shallow spectral index of the radio excess, may indicate that there are no cm-sized dust grains in the disc of DG Tau B. However, the disc of DG Tau B is resolved at mm wavelengths whilst the jet is not. This could either be attributed to mm-sized dust grains in the disc of DG Tau B or be an indication of the dust temperature in the disc. We study the proper motions of DG Tau A and B and find them to be consistent with each other. This could be explained if they have formed from the same star-forming region. Further investigation would need to be conducted in order to confirm if the two Young Stellar Objects are part of a binary system.
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