Winter Public Lecture Series in Physics
ABSTRACT:
Over 200 extra-solar planets have been discovered in the last 10 years. Little is yet known, however, about the frequency or characteristics of exo-planets - their numbers, orbital radius and mass distributions in typical stellar systems. This is largely a consequence of the detection biases of the radial velocity and transit techniques - currently the most successful search methods. These have very low efficiency for detection of terrestrial type planets like the cool rocky planets in the solar system. The third technique, gravitational microlensing, first proposed by Einstein, has peak detection efficiency for these systems. The technique is however subject to confusion in multiple planetary systems and ambiguities between stellar binaries and planets. The University's Mt Canopus Observatory has contributed to the detection of 2 extra-solar planets by microlensing - one of only 5.5 Earth masses and the first cool rocky exo-planet ever discovered. Several other systems which may harbour a planet are under investigation. I will review the current situation and future prospects in the field with special emphasis on the gravitational microlensing method.
SPEAKER PROFILE:
John Greenhill was born and
educated in Tasmania. In 1967 he completed his PhD in Physics at the
University of Tasmania on the topic of cosmic ray neutrons in the atmosphere.
As a Research Fellow at the Imperial College, London he set upper limits on
the fraction of anti-matter in high energy comic rays. Back in Hobart where he
was employed as Senior Lecturer in Physics at the University of Tasmania, Dr
Greenhill developed and operated a large area balloon-borne X-ray telescope to
study X-ray binaries. This detector was chosen as the prototype for the
proposed Australian scientific satellite "Mirrabooka". With the
demise of this project he helped upgrade facilities on the Mt Canopus 1-m
telescope and used it for measurement of the optical counterparts of X-ray
sources. In 1996 the Mt Canopus team joined the international PLANET
collaboration searching for extra-solar planets by the microlensing method.
John Greenhill retired in 1997; however he continues his research at the University of Tasmania as an Honorary Fellow in Physics. He is past President of the Tasmanian Branch of the Australian Institute of Physics.
Further information is available
from Dr Elizabeth Chelkowska, ph.
(03)6226-2725, e-mail: Elizabeth.Chelkowska-at-utas.edu.au
. Details appear on the web pages of the
AIP Tasmanian
Branch: http://tas.aip.org.au/
ALL WELCOME