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Departmental Colloquium

The Quenching of CO: The Complex Story of an Almost Homonuclear Molecule  
Guest Speaker
Professor Phillip Stancil  
Guest Affiliation
UGA Physics and Astronomy  
Guest Affiliation Url  
Thursday, November 19, 2015 3:30 pm - 4:30 pm  
Physics Auditorium (Rm 202)  
Carbon monoxide (CO) is detected in nearly every astronomical source from comets to high redshift quasars. It is observed in absorption in the UV, and by emission due to rotational and vibrational transitions from the near IR to submillimeter wavelengths. In most environments, CO rovibrational levels have populations far from thermal equilibrium so that the populations are determined primarily by collisions with dominant neutral species (H2, He, H). While collisional excitation of CO has been studied theoretically and experimentally for many decades, it may seem surprising that large uncertainties, orders of magnitude in some cases, remained in our knowledge of key parameters until now. It is only in recent years that computational resources and algorithms have advanced sufficiently that nearly exact, full-dimensional calculations have become feasible. In this talk I will highlight our recent computational work on full-dimensional scattering calculations, focusing on the CO-H, CO-H2, and CO-He collision complexes for rotational and vibrational excitation. I will also discuss the role of collisional data in astrophysical modeling.