Category: population III stars

What Was It Like When The First Stars Began Il…

What Was It Like When The First Stars Began Illuminating The Universe?

“After the Big Bang, the Universe was dark for millions upon millions of years; after the glow of the Big Bang fades away, there’s nothing that human eyes could see. But when the first wave of star formation happens, growing in a cosmic crescendo across the visible Universe, starlight struggles to get out. The fog of neutral atoms permeating all of space absorbs most of it, but gets ionized in the process. Some of this reionized matter will become neutral again, emitting light when it does, including the 21-cm line over timescales of ~10 million years.

But it takes far more than the very first stars to truly turn on the lights in the Universe. For that, we need more than just the first stars; we need them to live, burn through their fuel, die, and give rise to so much more. The first stars aren’t the end; they’re the beginning of the cosmic story that gives rise to us.”

We like to think of the Universe evolving as a story that follows a particular order: first we had the Big Bang, then things expanded and cooled, then gravitation pulled things into clumps, we formed stars, they lived and died, and now here we are. But in reality, things are messier than that! The very first stars didn’t immediately spread light throughout the Universe, but instead had a cosmic ocean of neutral atoms to contend with: one that they weren’t energetic enough or numerous enough to break through. The first stars in the Universe fought a battle against the clumping, neutral, atomic-based matter that surrounded them… and lost.

Come get the valiant but ultimately unsuccessful story of the first stars in the Universe, and learn why “letting there be light” didn’t illuminate the Universe!

Ask Ethan: Why Were The First Stars Much Large…

Ask Ethan: Why Were The First Stars Much Larger Than Even Today’s Biggest Ones?

“I do not understand why a star’s metallicity has an impact on its size. Why? I am asking this because in one of your articles, you were saying that in the beginning of the universe, stars with mass almost 1000 [times] the sun’s mass probably existed because they were almost 100% hydrogen and helium.”

There’s a bit of a puzzle in the Universe: the stars we form today are about 40% the mass of the Sun, on average, and the most massive one we’ve ever discovered is about 260 times the mass of our Sun. In the very early Universe, however, before any other, prior generations of stars formed, we expect the average stellar mass will be 10 times the Sun’s mass, with the largest stars reaching upwards of 1000 solar masses. If the only difference is the amount of heavy elements, then why, if metals help with cooling and enable stars to form more easily, would the first stars be biased towards higher masses? 

It seems counterintuitive, but science has the answer to it. And with the answer, we might just have the explanation for how those pesky quasars, AGNs, and supermassive black holes formed so fast!