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Accueil > Séminaires > Archive des séminaires d’Utinam > 2018

Michael Marsset

Deriving the shape, cratering history and density of the largest main-belt asteroids

mardi 6 mars 2018, 14h

Bibliothèque de l’observatoire


Queens University (Belfast)

Résumé :

Asteroids in our solar system are metallic, rocky and/or icy objects, ranging in size from a few meters to a few hundreds of kilometers. Whereas we now possess constraints for the surface composition, albedo and rotation rate for all D≥100 km main-belt asteroids, the 3-D shape, the crater distribution, and the density have only been measured for a very limited number of these bodies (N≤10 for the first two). Characterising these physical properties would allow us to address entirely new questions regarding the earliest stages of planetesimal formation and their subsequent collisional and dynamical evolution.

We are carrying out disk-resolved observations of the largest main-belt asteroids (sampling the main compositional classes) at high angular-resolution with VLT/SPHERE throughout their rotation in order to derive their 3-D shape, the size distribution of the largest craters, and their density. These measurements will allow investigating for the first time the following fundamental questions :

  • Does the asteroid belt effectively hosts a large population of small bodies formed in the outer solar system ?
  • Was the collisional environment in the inner solar system (at 2-3 AU) more intense than in the outer solar system (≥5AU) ?
  • What was the shape of planetesimals at the end of the accretion process ?