Music x Stars - The Unlikely Pairing

During the Gaia mission, an observatory of the European Space Agency, astronomers used asteroseismology to accurately measure the distance of stars from Earth. Asteroseismology is the study of stellar oscillations, it can be derived from the Greek word "astero" meaning star and "seismology", which refers to the study of vibrations or oscillations. (Time Series and Spectral Analysis in Asteroseismology, By University of Sydney 2018)

Stars make "music" when they expand and contract, and their brightness varies in conjunction. Because scientists discovered these minor brightness changes in captured starlight, they can now 'hear' the song. Astronomers may analyze these minute variations in a star's brightness and convert them into "sound waves" or a "frequency spectrum" of the star's oscillations. These frequencies are then translated into distance measurements.

The frequency spectrum of a star's oscillations, like the sound waves produced by a musical instrument, are determined by the temperature, density, and other physical features of the star's interior. We can infer information about these details from analysing their frequencies. By analysing the "music" or frequency spectrum of the oscillations of thousands of stars, they were able to determine how far away the stars are, some as far as 15,000 light-years. This technique, known as asteroseismic parallax, allows for the measurement of star distances that is independent of the Gaia mission's typical stellar parallax method.

The key difference between the two methods is that stellar parallax, used by the Gaia mission, measures the apparent shift in a star's position over a year as the Earth orbits the Sun, relying on triangulation (forming triangles from known points to find distances) to calculate the distance. This procedure becomes increasingly complex for more distant stars as the parallax angle (difference in position from varied points of sight) gets smaller. In contrast, the asteroseismic parallax technique determines stars' physical attributes by analyzing their "music" or oscillations.

This approach can be used to measure more distant stars, up to 15,000 light-years away, which are difficult to measure with classical parallax. The asteroseismic parallax method is regarded as being better and more effective because it allows for independent verification and enhances the accuracy of Gaia's parallax measurements, particularly for more distant stars, and it can probe the entire sky, whereas Gaia's parallax measurements have some limitations. Additionally, the asteroseismic approach will be critical in enhancing Gaia's parallax, shaping future discoveries.