RR Lyrae variables are at least 10 billion years old and their brightness can vary by 200 percent over half a day, which is hard to study from Earth due to our day-night cycle.
“Unlike our Sun, RR Lyrae stars shrink and swell, causing their temperatures and brightness to rhythmically change like the frequencies or notes in a song,” Dr Lindner explained.
While some of these stars pulsate with a single frequency, observations confirm that others pulsate with multiple frequencies.
Several of these stars, including the RR Lyrae variable star KIC 5520878, pulsate with two principal frequencies, which are nearly in the golden ratio. Astronomers call these stars ‘golden’ RR Lyrae variables.
“We call these stars ‘golden’ because the ratio of two of their frequency components is near the golden mean, which is an irrational number famous in art, architecture, and mathematics,” Dr Lindner said.