Wednesday 03 Dec 2014: Seminar: CO snowline migration through planet-forming regions
Dr Olja Panic - University of Cambridge
Physics, 4th floor 14:00-15:00
The location in a protoplanetary disc where the temperature drops below freezing for the CO molecule (20K), is the proposed location for the formation of planets like Uranus and Neptune. This snowline is expected to host a build-up of ices and sharp chemical gradients in both gas and ice composition. In contrast to the H2O snowline where viscous heating may be dominant, CO snowline location is dictated by irradiative heating of the disc by the central star. The migration of the CO snowline is intimately linked to the gas pressure, efficiency with which dust is coupled to the gas, and dust optical properties.
We investigate the effects that the key evolution processes have on disc temperature, and find that over the few-10 Myr lifetime of a disc, the temperature decreases drastically as a result of gas and dust loss. This causes the CO snowline to migrate by as much as 100~AU around intermediate-mass stars. For disc evolution studies this result means that the disc temperature is a proxy for the combined effect of gas and dust evolution, and one that can be observationally constrained (e.g., through CO snowline imaging). For planet formation our results imply that Neptune could have formed at higher densities and dust/gas ratios, i.e., closer in, and nonetheless under the specific chemical conditions provided by the CO snowline.
As a second part of my talk, I will include a short presentation on the Square Kilometre Array and The Cradle of Life science theme.