The Toronto Expedition – Log 02: Summary

Captain’s log, Stardate: 61226.5

The one-month expedition has come to an end much faster than expected, but it has been an incredibly rewarding journey.

One of the highlights of the visit was having several in-depth scientific discussions with the Admiral. Working closely with a theorist also gave me a valuable opportunity to better understand how theorists look at problems—sometimes from rather different perspectives than observers do.

During the visit, we began exploring a seemingly simple but surprisingly fundamental question: how reliably can we infer dust properties from multi-band ALMA continuum observations? By constructing synthetic observations of a single protoplanetary disk ring with prescribed dust properties and then attempting to recover them through SED fitting under different observing conditions, we found that the answer is not always straightforward.

Our preliminary experiments suggest that when the shorter wavelengths (such as ALMA Bands 6 and 7) become optically thick while the observations are only marginally resolved, recovering the intrinsic dust sizes can become unexpectedly challenging—even if longer-wavelength data (e.g., Band 3) remain optically thin. The result raises interesting questions about the robustness of some commonly adopted assumptions in dust-property studies, and there is still much to understand.

Beyond my own project, conversations with the students in the group introduced me to another fascinating topic: the possibility that shadows cast within protoplanetary disks may actively shape disk morphology and even influence the local dust properties. It is a compelling idea that I hope to explore further in the future.

This expedition may have been short, but it opened several new directions that I had not anticipated before arriving. The best outcome of a scientific visit is not necessarily finishing a paper—it is leaving with more interesting questions than when you arrived.

Until the next expedition. Captain out.