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29th of June 2017
Quasar Twinkling
by Mark Walker & Helen Sim
Gas filaments surrounding stars like the strands of a pompom may be the answer to a 30-year old mystery: why quasars twinkle. Dr Mark Walker (Manly Astrophysics) and collaborators at Caltech, Manly Astrophysics and CSIRO published this solution this week in The Astrophysical Journal. Their evidence comes from research done with CSIRO's Australia Telescope Compact Array radio telescope in eastern Australia. The team was studying quasars – powerful, distant galaxies – when they saw one called PKS 1322–110 start to dim and brighten wildly at radio wavelengths over just a few hours. Quasar radio twinkling was recognized in the 1980s. Most often it is gentle – small, slow changes in radio brightness. Violent twinkling is rare and unpredictable. Stars in the night sky twinkle when currents of air in our atmosphere focus and defocus their light. In the same way, quasars twinkle when streams of warm gas in interstellar space focus and defocus their radio signals. But until now it was a mystery what those streams were and where they lay. The team found that PKS 1322-110, like two other quasars which have displayed wild twinkling, lay close (on the sky) to hot stars. The team suggests that a throng of warm gas filaments surrounding the hot stars is the cause of the violent twinkling.
See the full Press Release for more details, and a link to the published paper.

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