Galactic Ripples: The Hidden Dynamics of the Milky Way
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Chapter 1: The Cosmic Calm
When you look up at the night sky, it may seem peaceful and still. However, the reality of deep space is far from tranquil. Numerous destructive forces are constantly at play, and we are only beginning to unravel the mysteries of these cosmic phenomena. One recent discovery promises to reshape our understanding of galactic history and sheds light on the structure and dimensions of our galaxy.
Imagine the Milky Way as a serene pond filled with over 100 billion stars. Now, picture a massive stone, equivalent to 400 million suns, being tossed into this pond. The calm surface would be disrupted, sending shockwaves throughout the water. Any object in the vicinity would be affected by these ripples.
Astronomers propose that a similar event may have occurred within our galaxy—not just once, but twice. This cosmic disturbance may have set our stars into a chaotic motion, a dance that could take eons to settle. A groundbreaking study indicates that the Sagittarius dwarf galaxy may have collided with the Milky Way twice over the past several billion years, leading to the peculiar oscillation of stars at varying speeds throughout our galaxy.
Section 1.1: Evidence of Cosmic Collisions
“It appears probable that a second, earlier collision between the two galaxies took place... We observe stars wobbling and moving at different velocities.”
~ Paul McMillan, Study Author
Using data from the European Space Agency’s Gaia space observatory, researchers analyzed the movements of 20 million stars scattered across the Milky Way. They detected a peculiar ripple effect in the motion of these stars, including those on the galaxy's outskirts. This phenomenon has been termed “galactic seismology,” as the team developed a model to explain the wave patterns causing these stellar ripples.
Section 1.2: Understanding the Ripple Effect
Previous research has hinted at the possibility that the collisions between the Sagittarius dwarf galaxy and the Milky Way resulted in this ripple phenomenon. Furthermore, it is suggested that two separate collisions could have influenced the very shape and size of the Milky Way. While the ripples from the last collision may be millions of years old, returning to a previous state on such a vast cosmic scale can take an immense amount of time.
The Sagittarius dwarf galaxy, which is approximately 400 times the mass of our sun, has undergone significant changes. It is believed to have lost about 20% of its mass to the Milky Way due to repeated collisions over billions of years. These interactions have provided invaluable insights into our galaxy's tumultuous past and its implications for the future.
Chapter 2: Insights into Our Galactic History
The comprehensive research findings were published in the Monthly Notices of the Royal Astronomical Society.