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Colours of the Outer Solar System Origins Survey

Physics/Astro Auditorium

Wes Fraser (Herzberg Institute of Astrophysics)

October 10 @ 4:00 PM - 5:00 PM

The orbital structure of the Kuiper Belt is dynamically excited, with most objects found on highly inclined and eccentric orbits. It is this orbital structure that has provided the main evidence for the early migrations of the gas-giant planets, and the violent dispersal of the outer proto-planetesimal disk. Many observational properties have been used as constraints on numerical efforts to uncover the details of the migratory history, including the detailed orbital distribution of Kuiper Belt Objects (KBOs), and the compositional classes KBOs which are known to correlate with the different orbital classes in which KBOs reside. This chemo-dynamical structure appears to be the result of the dynamical processes experienced by KBOs during the dispersal of the early disk, and the compositional heterogeneity of that disk. As a dynamical tracer however, the chemo-dynamical structure of the Kuiper Belt remains largely untapped. It was around this idea that the Col-OSSOS project was created. The Colours of the Outer Solar System Origins Survey is a large program that is nearly done executing on the Gemini-North and CFHT telescopes aimed to gather high quality optical-NIR colours of ~100 KBOs, in a brightness complete sample, and has designed to overcome various weaknesses of colour surveys that came before it. Col-OSSOS has been running since 2014 and has resulted in many exciting findings to date. With some anecdote about working very closely with Gemini and the excellent work they have done, I will present some of the main results of the Col-OSSOS, including a discussion about what the observed colour distribution informs us of the chemical structure of the early disk. Our results have provided some critical context for a number of otherwise curious objects, including the first silicate bearing objects in the Kuiper Belt, some odd blue binary KBOs found where no blue objects should be, and a compositional interpretation that implies most KBOs share a primordial source with the C-type asteroids. I will present a cosmogonic history that draws all of these disparate pieces together.