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A PULSATING star鈥檚 song could be the result of fractals at play.
Pressure changes inside a star can shuffle between layers of gas. Observers see the star appearing to 鈥渂reathe鈥� as its brightness fluctuates. The star鈥檚 oscillations form a sort of melody with harmonies on top: our sun has a simple tune, variable stars a complex one.
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William Ditto and his colleagues at the University of Hawaii, Manoa, compared the two strongest tones made by the variable star KIC 5520878, using observations by NASA鈥檚 Kepler space telescope. They noticed that the frequency of the secondary note divided by the primary, or lowest, note gives a value near the 鈥済olden ratio鈥� 鈥� 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 鈥済olden鈥� ratios also showed fractal patterns, while two non-golden stars did not (). This could mean the golden songs could reveal insights into stellar physics.
This article appeared in print under the headline 鈥淪tar鈥檚 golden song has a fractal theme鈥�