Program: GN-2017A-Q-14

Recent Pan-STARRS 1 discoveries of objects on long-period comet orbits that are inactive or minimally active at perihelion (the “Manx comets”) have suggested the intriguing possibility that these could represent inner solar system material that was ejected into the Oort cloud during planet migration. Our team is undertaking a program to characterize these. One of these objects has surface properties similar to rocky S-type asteroids. Our S-type Manx displays a very weak level of comet-like activity, 5-6 orders of magnitude less than typical ice-rich comets on similar orbits coming from the Oort cloud. The activity suggests the intriguing possibility that the S-type Manx has retained a tiny fraction of the water that is expected to be present at its formation distance in the inner solar system. We may be looking at fresh inner solar system Earth-forming material, preserved for billions of years in the Oort cloud. Small primitive bodies were witness to the solar system’s formative processes. When gas was present in the disk during the first 5 million years, a local chemical signature was imprinted on the planetesimals. The connection to today’s solar system relies on how this material was dynamically re-distributed during planet formation. Recent dynamical models are reproducing key characteristics of todays solar system, some of these require significant giant planet migration, while others do not. A key difference between these two classes of models is that the former models expel rocky material from the inner solar system into the Oort cloud while the latter do not. The existence and amount of rocky S-type material in the Oort cloud could verify this key prediction of the migration based dynamical models. Pan-STARRS1 and other surveys discover about 10-15 Manx candidates per year (PS1 gets 75% of these). We propose to obtain grizYJH photometry using GMOS+GNIRS to characterize their surface mineralogy. By characterizing the mineralogy of ∼50 Manx candidates, we will be able to set very strong constraints on the dynamical models explaining the redistribution of material in the early solar system. Some models will be categorically ruled out, others will be refined to the point of them becoming useful. We will deliver a homogeneously characterized sample of very early essentially unaltered planetesimals, preserved in the Oort Cloud over the ages of the Solar System, and probing the regions of the protoplanetary disc that were scattered by the giant planets. We will request a Gemini Large program through the US TAC at the next opportunity. This request for 13.0 hours is to observe 6 known targets and 2 targets of opportunity.