The song of the spheres – or, as BBC puts it, the music of the stars – is getting easier for astronomers to hear:
Bill Chaplin of the University of Birmingham told the annual meeting of the American Association for the Advancement of Science that astroseismology was, in essence, listening to the “music of the stars”.
Such precision light-level measurements also work for astroseismology, because as sound waves resonate within a star, they slightly change both the brightness and the colour of light that is emitted.
Researchers can deduce the acoustic oscillations that gave rise to the ripples on the light that Kepler sees.
Like a musical instrument, the lower the pitch, the bigger the star. That means that the sounds are thousands of times lower than we can hear.
But there are also overtones – multiples of those low frequencies – just like instruments, and these give an indication of the depth at which the sound waves originate, and the amount of hydrogen or helium they are passing through.
Since stars fuse more and more hydrogen into helium as they grow older, these amounts give astroseismologists a five-fold increase in the precision of their age estimates for stars.