Public Lectures for the Session 2000-2001 held in Room E7 of the Renold Building, UMIST.
Delivered to the Manchester Astronomical Society

21st September 2000

The Zdenek Kopal Memorial lecture: 'Making Movies of Stars'.

Dr. Phil..J.Diamond
Director MERLIN and VLBI, Jodrell Bank, University of Manchester.

Dr Diamond explained that although individual radio telescopes were incapable of giving the angular resolution necessary to study celestial radio objects in detail comparable to optical instruments, by combining the output from dishes placed far apart it was possible to synthesise the very large 'apertures' needed to achieve sub-arc second resolution comparable with the Hubble Space Telescope. Jodrell Bank had for some 20 years, been a pioneer in this technology and 80% of its work now involved Very Long Base Line Interferometry either within the UK, using the six telescopes of the MERLIN network, or via international cooperation with observatories across the globe.

His particular interest was the study of Red Giant (Myra type) stars showing signs of instability pending a future nova stage. By examination of MASER emission from these stars it had been possible, in the case of TX Cam, to compile data from several dozen epochs during a projected observing run that would eventually span 2.5 cycles of its 88 day periodicity. Combining this data had allowed a high resolution 'movie', to be assembled that clearly showed a shell of material being ejected from the star and then rebounding inwards. This data, compared with that from the American Association of Variable Star Observers (AAVSO) showed that phenomena at radio wavelengths was out of phase with optical variability. Studies had shown that at radio wavelengths the behaviour of material ejected by the star was not influenced by gravitational effects but by asymmetrical magnetic fields.

The 250 ft Lovell Telescope at Jodrell was now undergoing refurbishment, pending a £10M grant, that would allow x30 better resolution. This cost was a fraction of that being spent on similar projects in America and elsewhere and was seen as being very good value for money.

Synopsis by Kevin J. Kilburn (Secretary)

Maintained by Michael Oates
Page modified 28 October, 2006