Spitzer Space Telescope - Theoretical Research Proposal #40380


Observational signatures of extrasolar Late Heavy Bombardments

Principal Investigator: Edward Thommes
           Institution: Northwestern University

     Technical Contact: Fred Rasio, Northwestern University

Co-Investigators: 
Geoffrey Bryden, JPL                                                  

Science Category: circumstellar/debris disks 
Dollars Approved: 86144 

Abstract:
Spitzer observations have revealed hot dust around some Sun-like stars, at
luminosities about three orders of magnitude higher than predicted by
quasi-steady state disk evolution models. These findings have been interpreted
as the signposts of a system-wide cataclysmic event analogous to the Late Heavy
Bombardment (LHB) experienced by our own Solar System. At the same time, the
frequency of detection of these events is consistent with ALL Solar-type stars
passing through such a phase at some point in their lifetime. We propose to
undertake an in-depth theoretical investigation of the ramifications of this
intriguing result, which seems to be telling us something profound about the
planet formation process---including how our own system fits into the picture.
Using N-body simulations of planets embedded in planetesimal disks, and building
on existing models, we intend to explore the pathways by which a planetary
system can undergo a LHB-like event, and the different ways in which such events
can play out. For each simulated system, we will calculate the dust generated by
planetesimal collisions. In this way, we will generate a library of
time-evolving dust distributions; these will allow us to make direct comparisons
to existing Spitzer data, as well as testable predictions to guide future
observations. Our results will be made available to the astronomy community via
a series of papers to be published over the funding period.