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