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CATEGORIES:DAMTP Astrophysics Seminars
SUMMARY:Meteorite paleomagnetism: Constraints on the rearr
 angement of the planets and the formation of the f
 irst solids  - James Bryson (Earth Sciences\, Camb
 ridge)
DTSTART;TZID=Europe/London:20171023T140000
DTEND;TZID=Europe/London:20171023T150000
UID:TALK85701AThttp://talks.cam.ac.uk
URL:http://talks.cam.ac.uk/talk/index/85701
DESCRIPTION:It has been suggested that there were at least two
  major planetary rearrangements within the first 1
  Gyr of our solar system. Such events are believed
  to have played a crucial role in shaping the pres
 ent-day architecture our solar system as well as p
 ossibly those of exoplanetary systems. Within our 
 own solar system\, planetary migrations have been 
 proposed to have brought material that formed beyo
 nd the orbit of the gas giants into the inner sola
 r system\, possibly explaining the compositional t
 rends across the asteroid belt as well as the make
 up of the Trojan asteroids. However\, very few rob
 ust\, accurate or quantitative estimates of the he
 liocentric distances of the formation of meteorite
  parent bodies exist. These distance estimates wou
 ld also constrain the range over which the first s
 olids (chondrules and calcium-aluminium-rich inclu
 sions [CAIs]) may have formed or have been recycle
 d throughout the solar system by stellar outflows.
 \nHere\, we present paleomagnetic evidence that th
 e Tagish Lake meteorite does not contain a stable 
 magnetic remanence. Given the ancient aqueous alte
 ration age of this meteorite (<4 Myr after CAI for
 mation)\, this absence suggests that the Tagish La
 ke parent body must have originated from >10 - 20 
 AU where the magnetic field generated by the colla
 pse of the dust and gas within the nebula was %<% 
 0.15 µT. This distance corresponds to radii greate
 r than the orbits of the gas giants prior to the m
 igrations involved in Grand Tack\, suggesting the 
 Tagish Lake parent body represents outer disk bodi
 es that now constitute the Kuiper belt and could t
 herefore feasibly be a comet. Tagish Lake contains
  sparse chondrules and even rare CAIs\, indicating
  that stellar outflows were capable of transportin
 g solid material that formed within 1 AU of the Su
 n and within 1 Myr of CAI formation to distances a
 s far as that of present-day Saturn or Uranus. Fin
 ally\, our results provide a quantitative observat
 ion from the meteorite record that a body formed i
 n the outer solar system and now resides in the in
 ner solar system\, supporting the presence of majo
 r ancient planetary migrations that altered the ar
 chitecture and structure of our solar system. 
LOCATION:MR14\,  Centre for Mathematical Sciences\, Wilberf
 orce Road\, Cambridge
CONTACT:Dr. Yufeng Lin
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