BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Talks.cam//talks.cam.ac.uk//
X-WR-CALNAME:Talks.cam
BEGIN:VEVENT
SUMMARY:How common are extrasolar late heavy bombardments? - Booth\, M (Ca
 mbridge)
DTSTART:20091109T165000Z
DTEND:20091109T171000Z
UID:TALK21402@talks.cam.ac.uk
CONTACT:Mustapha Amrani
DESCRIPTION:Recent infra-red surveys of FGK stars have shown that 4% of st
 ars exhibit 24 m excess and 16% exhibit 70 m excess indicating the presenc
 e of debris discs. In many cases these discs occur 10s or even 100s of AU 
 from the central star\, analogous to our own Kuiper belt. Studies of the h
 istory of our own Solar System show that the primordial Kuiper belt was on
 ce much more massive than it is now. Interactions between the Kuiper belt 
 and the outer planets caused the outer planets to migrate. The Nice model 
 shows that this migration could have been the cause of the Late Heavy Bomb
 ardment (LHB) on the Moon\, which occurred 3.8 Gya. Here we investigate wh
 ether LHB-like events may have occured in extrasolar systems. We develop a
  model of how the Solar System would have appeared to a distant observer d
 uring its history based on the Nice model. We show that the Solar System w
 ould have been amongst the brightest of systems with debris discs before t
 he LHB at both 24 and 70 m. We find a significant increase in 24 m emissio
 n during the LHB\, which rapidly drops off and becomes undetectable within
  30 Myr\, whereas the 70 m emission remains detectable until 360 Myr after
  the LHB. Comparison with the statistics of debris disc evolution shows th
 at such heavy bombardment events must be rare occurring around less than 1
 2% of Sun-like stars and with this level of incidence we would expect appr
 oximately one of the 413 Sun-like\, field stars so far detected to have a 
 24 m excess to be currently going through an LHB. 
LOCATION:Satellite
END:VEVENT
END:VCALENDAR