Stars sing their history: Starquakes reveal secrets of ancient galaxy

Starquakes are giant vibrations inside stars like our Sun. (Representative Image: NASA)

Did you ever imagine stars in space composing music? Scientists say that these celestial "songs" can tell us the secret history of the stars and galaxies.

Earthquakes Resonate Through the Cluster

Massive vibrations in stars like our Sun are referred to as earthquakes. They are caused by gas bubbles bursting near the surface of a star. Ripples move deep in the star's body. Small changes in the star's light make us able to detect them.

These star cluster vibrations in the M67 were the focus of recent research published in Nature. The group is about 3,000 light-years from Earth. Researchers studied stars when they were in their massive phase with NASA's Kepler satellite telescope. It's a rare look at how stars evolve as they age.

Repeating One Note

Astronomers found that stars in M67 underwent a harmonious pause. With time, their vibrations were "trapped" playing the same note. When the outer layer breaks deep inside the star, this strange stall takes place.

The outer envelope constitutes approximately 80% of the mass of the star. This extremely turbulent layer affects the behavior of sound waves. Scientists discovered that the cause of this musical freeze is a change in the speed of sound. The frequency with which this happens depends on the composition and mass of the star.

Measurement of "small spacings" yielded one clue. A star's sound has these tightly grouped frequencies. These indicate the amount of hydrogen remaining in younger stars' cores. It was thought that such signals taught us little new about red giants.

Surprisingly enough, these gaps were affected by changes in the hydrogen-burning shell. The gaps expanded as the shell increased in thickness. They became smaller when it decreased in size. Then, akin to a music track stuck in repeat, they suddenly ceased to change.

Cosmological histories courses can gain from hearing the Galaxy's Past Clusters, like M67. Within such clusters, all of the stars form at approximately the same time. This means that they are similar in terms of age and makeup.

Similar to earthquakes, starquakes reveal what's below. Larger stars create slow, deep vibrations. Smaller stars create higher-pitched sounds. The age and internal constitution of a star can be estimated from these vibrations.

The study now assists in more accurate stellar age calculation. This may be of use in tracing the development and history of our galaxy. Smaller galaxies have been consumed by the Milky Way, which has grown. Part of the long story is revealed by each region.

Furthermore, stars such as those found in M67 also suggest what our Sun may experience in the future. It will also undergo the massive phase as it matures. We can preview its distant future by hearing older stars.

Scientists can now have an added incentive to look over older data due to this new method. It is now possible for astronomers to "hear" again—with enhanced ears—through knowing what acoustic patterns to pay attention to.