Searching for disc sub-structure in compact discs: high resolution ALMA observations of the wide binary Sz65 & Sz66

James Maxwell Miley

Observations using ALMA’s long baselines have been instrumental in revealing substructures related to the mechanisms for planet formation and disc evolution. The resulting data have revealed a plethora of different density sub-structures in young circumstellar discs related to the formation mechanisms of exoplanets. As well as these spectacular poster-children, there also exists a significant population of discs that appear radially compact for which no substructure is resolved at all. Are the large proportion of “compact” discs found in surveys of star forming regions scaled-down versions of the srturctured bright discs? Meaning we require improved sensitivity and resolution to see their fine features? Or are they simply discs without sub-structures, in which the dominant physical mechanisms lead to an alternative evolution of disc density? Here I will present an analysis of ALMA’s view of two compact discs in Lupus using new very high angular resolution observations (0.035”, ?5 au). Sz 65 and Sz 66 are a wide binary system (?1000 au separation) in which we search for density sub-structure and investigate the true nature of the previously unresolved compact discs.