Planetary Science Seminar

Abstract: The 2015 consensus view is that the presence of elements heavier than helium in the atmosphere of an isolated white dwarf is a signpost for a planetary system in orbit about that star. This interpretation was a long time in coming -- roughly 90 years! -- but by now the evidence is overwhelming. The relative elemental abundances in these otherwise-pristine stellar atmospheres reveal the bulk elemental composition of the building blocks of rocky planets. Using the Solar System as a model, one can deduce a past history of differentiation and collisions for some of these rocky exoplanet precursors, a history that can inform us about the origins of our own Solar System. Interpretation of the white dwarf data indicates the presence of closely-packed major planets around single main sequence stars and a history of gravitational interactions of such (complex) planetary systems with the secondaries in binary star systems.