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  • Toner Stevenson

Cataclysmic Variable Stars: Searching for ripples in the cosmic Niagara Falls

Presented by Dr Ian Kemp

Monday 2 August 2021


This talk is about “UGSU cataclysmic variables” - one of the most interesting species in the variable star zoo. They are binary systems, in which a red star spills material onto a white dwarf, giving rise to periodic massive eruptions which can brighten the system from magnitude 15 to magnitude 9, easily within the range of a backyard telescope.

These stars are very important systems in astronomy, because they are the precursors of the type 1a supernovae, which are used to measure the Hubble-Lemaître constant, and the accelerating expansion of the universe. The light curves of these systems are fascinating - they show ‘wobbles’ which reveal a lot of what’s going on in the binary system and the accretion disk.

In 2019 Ian Kemp observed a southern sky system called VW Hyi, which was first characterised by astronomers from New Zealand and Australia. In addition to the ‘usual’ variations - known as ’superhumps’, he found hints of a different type of variation, but the data was not conclusive enough to confirm it. So this year, with some partners in crime, Ian is collecting and analysing data on a number of similar systems to look for extra detail in the light curves of these interesting systems. If you are inspired by this talk you can join the hunt - VW Hyi itself is about to go into super-outburst again right about now.


Ian Kemp started his professional life in academic research - with a degree, PhD and postdoc in Materials Science. He then went off to work in Industry and government for a while (25 years) before getting back to research and obtaining a Masters degree in Astronomy. He currently works as a research scientist at the International Centre for Radio Astronomy Research (ICRAR) in Perth - working partly on ‘big data’ (astronomically large data!) and partly on astrophysics research.


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