Volume 583, November 2015
Rosetta mission results pre-perihelion
|Number of page(s)
|Planets and planetary systems
|30 October 2015
Comets as collisional fragments of a primordial planetesimal disk
1 Département Lagrange, University of Nice–Sophia Antipolis, CNRS, Observatoire de la Côte d’Azur, 06304 Nice, France
2 P.A.S. Space Research Center, Bartycka 18A, 00-716 Warszawa, Poland
3 Dept. of Physics and Astronomy, Uppsala University, Box 516, 75120 Uppsala, Sweden
Received: 17 March 2015
Accepted: 16 April 2015
Context. The Rosetta mission and its exquisite measurements have revived the debate on whether comets are pristine planetesimals or collisionally evolved objects.
Aims. We investigate the collisional evolution experienced by the precursors of current comet nuclei during the early stages of the solar system in the context of the so-called Nice model.
Methods. We considered two environments for the collisional evolution: (1) the transplanetary planetesimal disk, from the time of gas removal until the disk was dispersed by the migration of the ice giants; and (2) the dispersing disk during the time that the scattered disk was formed. We performed simulations using different methods in the two cases to determine the number of destructive collisions typically experienced by a comet nucleus of 2 km radius.
Results. In the widely accepted scenario, where the dispersal of the planetesimal disk occurred at the time of the Late Heavy Bombardment about 4 Gy ago, comet-sized planetesimals have a very low probability of surviving destructive collisions in the disk. On the extreme assumption that the disk was dispersed directly upon gas removal, a significant fraction of the planetesimals might have remained intact. However, these survivors would still bear the marks of many nondestructive impacts.
Conclusions. The Nice model of solar system evolution predicts that typical km-sized comet nuclei are predominantly fragments resulting from collisions experienced by larger parent bodies. An important goal for future research is to investigate whether the observed properties of comet nuclei are compatible with such a collisional origin.
Key words: comets: general / Kuiper belt: general / protoplanetary disks / Oort Cloud
© ESO, 2015
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.