> > The Cambridge Philosophical Society is holding the third lecture of the Lent > Term at the Bristol-Myers Squibb Lecture Theatre, in the Department of > Chemistry on Monday 12 February 2018 at 6.00 pm. The Speaker is Professor > Richard Harrison, Professor of Earth and Planetary Materials, Department of > Earth Sciences, whose lecture is entitled "Magnetic microscopy of meteorites: > probing the magnetic state of the early solar system". > > Abstract as follows: Microstructural and geochemical studies of meteoritic > metal have been instrumental in shaping our current views of differentiated > asteroids, providing constraints on their cooling rate, their size, the > timing of their differentiation and their fractional crystallisation and > impact histories. The characteristic Widmanstätten microstructure, familiar > to anyone who has looked at a polished and etched section of an iron > meteorite with the naked eye, hides a nanoscale complexity that is revealed > only with high-resolution electron microscopy – a legacy of stranded > diffusion profiles, metastability, martensitic transformations, chemical > segregation and ordering during slow cooling over millions of years on the > parent body. The presence of soft bcc iron has traditionally lead to the > meteoritic metal being dismissed as a reliable carrier of paleomagnetic > information. However, we have shown that, under favourable circumstances, > paleomagnetic information can be recorded and retained on a local scale > within a unique nanoscale intergrowth called the cloudy zone (CZ). > High-resolution X-ray imaging methods enable the magnetic state of the CZ to > be imaged and analysed quantitatively, opening up new avenues of research > into the nanopaleomagnetism of a range of meteorites. Such studies are not > only revealing new insight into the thermochemical properties of asteroids in > the early solar system, but provide us with unique opportunities to learn > about how magnetic fields are generated on planetary bodies in general, and > the underlying physics of the dynamo generation process itself. > > The lecture is free (no booking required) and open to all who are interested > and will be an excellent opportunity to hear an eminent scientist. > > Entrance to the Bristol-Myers Squibb Lecture Theatre, is adjacent to the > Scott Polar Research Institute on Lensfield Road > > If you wish to be removed from this mailing, please email > philo...@hermes.cam.ac.uk <mailto:philo...@hermes.cam.ac.uk> quoting the > reference at the end of the subject line to this email. > -- > Mrs Beverley Larner > Executive Secretary > Cambridge Philosophical Society > 17 Mill Lane > Cambridge CB2 1RZ > > Tel: 01223 334743 > Email: philo...@hermes.cam.ac.uk <mailto:philo...@hermes.cam.ac.uk> > Website: www.cambridgephilosophicalsociety.org > <http://www.cambridgephilosophicalsociety.org/> > > > > > > > > >
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