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CO ro-vibrational emission

Tracing the geometry of the inner protoplanetary disc
PhD ceremony:Ms R.P. (Rosina) Hein-Bertelsen
When:February 13, 2015
Supervisors:I.E.E. (Inga) Kamp, Prof, prof. dr. R. Waters
Where:Academy building RUG
Faculty:Science and Engineering
CO ro-vibrational emission

When stars are born they are surrounded by discs containing dust and gas. Since we expect planets to form in these discs, we call them protoplanetary discs. During planet formation, we expect dynamical effects to lead to a gradual removal of material close to the orbit of the planet, possibly leading to gaps/holes in the disc.

CO (carbon monoxide) is the second most common molecule in the universe and it is therefore also abundantly present in these discs. The ro-vibrational line transitions of the CO molecule are frequently observed from the warm inner regions of protoplanetary discs. Hence, CO ro-vibrational emission lines could be excellent tracers of the presence of gaps/holes due to planet formation.

Using observed spectra collected at the VLT (Very Large Telescope) in Chile, and using detailed computer models of such discs, we have investigated how the CO ro-vibrational emission lines from protoplanetary discs can best be used to trace planet formation processes.

We find that CO ro-vibrational line profiles from high resolution and high signal to noise near-infrared spectra can reveal the location of gaps in protoplanetary discs. By studying the line fluxes, widths and shapes of these line profiles, dust gaps, dust and gas gaps, or unusually extended emitting regions can be identified. Hence, inner disc geometries that appear unclear from dust observations alone, can be characterized in much more detail by the analysis of CO ro-vibrational line profiles. Future ELT instruments like METIS would be an excellent tool for these studies.