Did small stars exist in the first generation of stars?

Universe’s First Stars – Smaller Than We Thought? Have you ever looked up at the night sky and wondered what the very first stars of the universe were like? Scientists used to believe that those early stars were huge giants, many hundreds or even thousands of times bigger than our Sun. But now, two new studies say, “Wait a minute! Some of those first stars might have been much smaller.” Let’s explore how scientists found this surprising idea. The Old Belief: Only Giant Stars For many years, astronomers thought that only giant clouds of gas could collapse to form the first stars. Since the early universe mostly had hydrogen and helium, they imagined that the stars born back then were super massive. But now, scientists are saying that small stars may have also formed, right alongside the giant ones. Turbulence and Star Formation One group of scientists, led by astrophysicist Ke-Jung Chen, ran special computer programs called simulations. These simulations showed how early gas clouds behaved when they collapsed. Here’s what they found: • Gas clouds were not calm – they were turbulent (messy and chaotic). • This turbulence broke the big cloud into many smaller clumps. • Some clumps were just about the size of our Sun. This means that the first stars might have reached in size from small stars like our Sun to bigger stars up to 40 times the Sun’s size. So, not just giants – the universe’s first generation of stars may have been a mix of big and small! Primordial Chemistry and Cooling Another team, led by scientist Florian Grussie, looked at chemistry experiments to understand the early space better. They studied a special molecule called helium hydride ion (HeH⁺) – one of the very first molecules ever formed after the Big Bang. Here’s why this is important: • HeH⁺ molecules give off infrared light (like invisible heat). • When they react with hydrogen, they create molecular hydrogen (H₂). • This process helps gas clouds cool down quicker. And when gas clouds cool down, they can collapse more easily to form stars – even small ones. So, thanks to this molecular cooling, even small clouds of gas could form stars in the early universe. What Does This Mean? These two studies tell us something thrilling: • The first stars in the universe were not only giant monsters. • There were also smaller stars, some not much bigger than our Sun. • Turbulence and cooling worked together to make star formation possible in many different sizes. This helps scientists to know how the universe grew and changed after the Big Bang. Why Is This Important for Us? Learning about the first stars is like reading the first chapter of the universe’s story. These stars: • Created the first light in the dark universe. • Made heavy elements that later built planets, galaxies, and even life. • Show us how wonderful and surprising space can be. So next time you look up at the stars, remember – some of the first stars ever might have been minor and humble, just like our Sun!

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Universe’s First Stars – Smaller Than We Thought?

By Hazel September 9, 2025

Have you ever looked up at the night sky and wondered what the very first…