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The Age of Comets What comets tell us about the the early solar system ! Carsten Dominik University of Amsterdam Radboud University Nijmegen The Rosetta mission to comet 67P/Churyumov-Gerasimenko 2004 2014 Image credits: ESA/ESO Bernard 68: ready for collapse Image credit: ESO Collapse and Rotation Real disks What are comets? • Small solar system body • Very hard to detect when far from Sun • Develop coma and tails when close to Sun Comet outgassing Image: ESA Comet coma Image credit: Vicent Peris and José Luis Lamadrid Comet tails Comet tails Gas small grains larger grains Key properties of comets • Size • Strength • Composition • Orbital properties Temple 1 7.6 km Size Hartley 2.25 km Wild 2 5.5 km Planet Formation Agglomeration Accretion ~1 µm ~1 km ~10000 km Preplanetary Planetesimals Planets dust Strength Comet SL9 1994 Tidal breakup Breakup to equal blocks requires very weak material Composition Mumma & Charnley 2011 • Dust (Silicates and Carbonaceous) • Ices H2O, CO, CO2, HCN, CH3CN, CS….. Amorphous Olivine Amorphous Pyroxene Crystalline Forsterite Crystalline Enstatite Silica PAH Comparison comet Hale-Bopp versus disk HD 100546 Malfait et al 1998 Deuterium in Comets Comet orbits Kay Gibson, Ball Aerospace & Technologies Corp Where comets come from, part I Öpik 1932, Oort 1950 Creating the Oort Cloud Circular orbits Far away Eccentric,! reaching to planets Comet orbits Kay Gibson, Ball Aerospace & Technologies Corp Pluto (1930) ClydeClyde TombaughTombaugh Orbit of Pluto 1992 QB1 ... en Kuipergordel objecten Orbit of Jupiter Orbit of Neptune 29-09-2009 LWSK 29 Origin of comet reservoirs Brett Gladmann Science 2005 Distribution of orbital elements Pluto’s resonant capture Pluto’s resonant capture Pluto’s resonant capture a Neptune P t=0 time e today time 1:1 3:2 2:1 i time The age of comets (Wag the dog) Credit: Sky & Telescope The End • Comets are ﬁrst class witnesses of the formation and early evolution of the solar system • Together with observations of planets and of protoplanetary disks, they can indeed be a Rosetta Stone for understanding our origins.

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The Blurring Distinction Between Asteroids and Comets
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