Kurt Liffman (CSIRO Materials Science and Engineering)

Meteorites, Bipolar Jet Flows and Relativistic MHD - Kurt Liffman Colloquium

ATNF Marsfield Lecture Theatre

Abstract

Primitive meteorites are not only samples of asteroids and comets, but are also fossilized samples of the solar nebula - the disk of gas and dust that once surrounded the Sun. Many such meteorites contain small, millimetre-sized, igneous objects called chondrules and "CAIs" surrounded by a dark sedimentary-like substance called "matrix". The matrix has never experienced temperatures in excess of 600 K, but the chondrules and CAIs were formed at temperatures in excess of 1800 K. How such material could have formed in the solar nebula has been a subject of scientific speculation for over two centuries.

Nearly two decades ago, a theory was published which suggested that these and other such objects were formed in or near the interaction region between the inner solar nebula and the early Sun, which also created a high-speed bipolar jet flow. This processed material was ejected by the jet flow from the inner solar nebula to the outer nebula where it agglomerated with the cooler, unprocessed nebula material to form the meteorites that we see today.

Via this mechanism the "Jet Flow Model" predicted that accretion disks around young stars would be reprocessed by bipolar outflows. Happily, this prediction is consistent with the recent observations of crystalline dust in comets, VLTI observations of a radial distribution
of crystalline dust in YSO disks and the high temperature, crystalline materials obtained from Comet Wild 2 by the Stardust mission.

Primitive meteorites may provide detailed information on the mechanism that produces bipolar jet flows. One such deduced mechanism is that jet flows are produced by toroidal magnetic fields at the inner disk edge. The relativistic version shows very little attenuation
of the driving magnetic field, while non-relativistic flows have little or no remnant magnetic field in the far flow. This may provide a model for the formation of radio-loud and radio quiet AGN.