[Baps] seminar today at MIT by James Bryson on the early solar system

[Benjamin Weiss]

Hi all,

James Bryson (University of Cambridge) will be giving this EAPS 
Department Lecture Series seminar today at 4 pm in MIT building 54-915. 
Refreshments at 3:45.

*Constraints on the timescales and distances of solid migration in the 
solar nebula from meteorite palaeomagnetism*

Solid objects ranging in size from the oldest mm-scale grains to 
km-scale asteroids and even the terrestrial planets are thought to have 
migrated throughout the early solar system. Although these migrations 
have been proposed to have played key roles in generating the present 
day architecture of the solar system and forming planetary bodies, their 
timescales and distances are poorly constrained. One reason for this 
limited understanding stems from difficulties in recovering the 
formation distances of meteorite components and parent bodies from 
laboratory measurements. Models of our protoplanetary disk indicate that 
the magnetic field it supported decreased in intensity by orders of 
magnitude over distances of tens of AU from the Sun. Hence, the 
intensity of ancient magnetic fields recovered from magnetic 
measurements of material old enough to have recorded a magnetic 
remanence of this field could be used as a novel method of constraining 
its formation distance. I will present paleomagnetic results from two 
ancient meteorites that indicate the distal formation (>10 AU) of their 
parent bodies. I will use the distances I recover to support at least 
one major planetary migration event during the history of our solar 
system, the efficient outward transport of mm-sized solids from the 
innermost solar system to >10 AU within ~3 Myr, and propose an 
explanation for a key trend in the oxygen isotope composition of 
carbonaceous chondrites that indicates the inward migration of distal 
ice to the carbonaceous chondrite reservoir within the first ~3 - 4 Myr 
of the solar system. Finally, I will use all of these observations to 
place new constraints on the timescale of the formation of Saturn's core 
and the accumulation of its gaseous envelope.


Thanks

Ben Weiss

benweiss.mit.edu

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