Building the Milky Way: A Cosmic Tale of Star Formation and Mergers

#MilkyWay #GalaxyFormation #Astronomy #SpaceScience #Andromeda #GalacticEvolution #StarFormation #CosmicEvents #SpaceExploration #AstroPhysics

What You’re About to Watch: The Evolution and Formation of the Milky Way. In this video, I explore the evolution and formation of the Milky Way. We’ve discussed its various properties in the past, but now it’s time to delve into how this magnificent galaxy came to be over billions of years. We begin by examining the familiar structure of the Milky Way—a spiral galaxy with a flat disk, a halo, and a bulge. The disk contains a mix of young and old stars alongside gas and dust, crucial for star formation. Within the disk, stars move in circular orbits, forming blue spiral arms. Conversely, the galactic halo is spherical, hosting only ancient stars in globular clusters, with almost no gas or dust. The bulge is a mix of both, with star formation occurring primarily in its central regions due to the presence of gas and dust. How did the Milky Way come to have such a structure? The galaxy’s formation began with the collision and merging of small gas clouds and dwarf galaxies. These mergers resulted in a general rotational motion, ultimately flattening into a disk. The gas in the disk condensed to form stars, leading to ordered structures, while the older stars in the halo maintained random, elliptical orbits. Continuing this narrative, we see that dwarf galaxies play a significant role in the Milky Way’s evolution. Over 10 billion years ago, dwarf galaxies containing young stars merged to form globular clusters. These older stars, formed from primordial hydrogen and helium, became the metal-poor clusters we see today. Gradually, these merging processes enriched the galaxy with heavier elements, paving the way for subsequent generations of stars with higher metallicities. Even today, the Milky Way continues to absorb smaller galaxies, like the Ursa Minor and Carina dwarfs and the Large and Small Magellanic Clouds. Gravity leads these galaxies to lose their angular momentum and merge with the Milky Way, contributing to its growth. One of the most captivating aspects of the Milky Way’s future is its impending collision with the Andromeda Galaxy in about 5 billion years. This monumental event will lead to the merging of the two galaxies, forming a massive elliptical galaxy named “Milkomeda.” The collision will trigger rampant star formation, leading to spectacular sights of star clusters and supernovae as the galaxies merge and form one unified structure. Eventually, the resulting galaxy will be dominated by older stars, with no gas left for new star formation. I’ll show you simulation and photographic evidence that support these theories. Deep photographic surveys of distant galaxies reveal their blue, irregular shapes, gradually evolving to form larger, more structured galaxies like ours. Simulations illustrate how the Milky Way-Andromeda collision will unfold, from the initial approach to the final merging into a single colossal galaxy. So, sit back and join me as we unravel the fascinating story of the Milky Way’s formation and evolution. From its early chaotic beginnings to its future collision with Andromeda, this journey through space and time offers a profound understanding of where our galaxy came from and where it is headed.

This is part of my complete intro Astronomy class that I taught at Willam Paterson University and CUNY Hunter.