A pulsating star's song could be the result of fractals at play. Pressure changes inside a star can make portions of its surface expand and contract, so observers see it appearing to "breathe" as its brightness fluctuates. The star's oscillations form a sort of melody with harmonies on top: our sun has a simple tune, variable stars have a complex one.
William Ditto and his colleagues at the University of Hawaii, Manoa, compared the two strongest oscillations, or tones, made by the variable star KIC 5520878, using observations by NASA's Kepler space telescope. They noticed that dividing the frequency of the secondary note by that of the primary, or lowest, note gives a value near the "golden ratio" – a number that shows up often in art and nature and is close to 1.618.
They then realised that its frequencies exhibited a fractal pattern: separating the tune into its constituent parts yielded more frequencies at weaker strengths, similar to the way coastlines retain their complexity as you zoom in. Three other pulsing stars with "golden" ratios also showed fractal patterns, while two non-golden stars did not. This could mean the golden songs could reveal insights into stellar physics.
Other physicists who study pulsating stars are doubtful about the significance of the golden ratio finding, however. "The fact that this period ratio (or its reciprocal) lies close to the golden ratio may be a coincidence," says Robert Szabo of Konkoly Observatory in Hungary, "and in my opinion, more evidence is needed to demonstrate that it has a privileged role in the dynamics of [these] stars."
Journal Reference: Physical Review Letters, in press (http://ift.tt/1xXcIjQ)
If you would like to reuse any content from New Scientist, either in print or online, please contact the syndication department first for permission. New Scientist does not own rights to photos, but there are a variety of licensing options available for use of articles and graphics we own the copyright to.
