Galactic Shockwave: How a ‘Great Wave’ is Displacing Thousands of Stars

A fascinating “wave” is stirring within our galaxy, influencing billions of stars. This discovery comes from the European Space Agency’s (ESA) Gaia space telescope, which mapped the positions and movements of millions of stars with great precision before its retirement this year.

This galactic wave reaches stars up to 65,000 light-years from the center of the Milky Way, which spans about 100,000 light-years. That’s a significant part of our galaxy. ESA officials suggest that this wave might have been triggered by a past collision with a smaller dwarf galaxy, but more research is needed to confirm this.

The findings were published on July 14 in the journal Astronomy & Astrophysics.

For nearly a dozen years, Gaia tracked the movements of stars. In 2020, it noted that the Milky Way’s disk wobbles like a spinning top. Scientists mapped the wave by observing young giant stars and Cepheids—stars that shine with varying brightness. They believe that gas in the galaxy might also participate in this wave, possibly reflecting patterns from which the stars were born.

ESA likened this galactic wave to “the Wave” you see at sports events, where crowds move in unison from one side of a stadium to the other. It’s a fun way to visualize how this vast movement occurs among stars.

Interestingly, when our galaxy is viewed edge-on, similar wave-like motions become apparent. These vertical movements indicate ripples spreading across the Milky Way’s disk. Eloisa Poggio, an astronomer at the National Institute of Astrophysics in Italy, noted this behavior fits what we expect from a wave. The newly discovered wave may also connect with a smaller, previously known phenomenon called the Radcliffe Wave, which is located about 500 light-years from the Sun and extends for 9,000 light-years. Poggio mentioned these two waves are situated in different areas and require further exploration to determine if they are linked.

As scientists continue to investigate, the implications of this wave could reshape how we understand the structure and dynamics of our galaxy. With ongoing research, we may uncover new insights into the history and evolution of the Milky Way.

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