Have We Finally Seen the Universe’s First Stars?

Long before stars illuminated the cosmos, the Universe existed in a vast sea of hydrogen and helium. Only when these gases clumped together under immense pressure did the first stars ignite, forging heavier elements in their fiery cores.

While scientists have long theorized about these early stars—known as Population III stars—no one has ever seen them. However, a new study could change that.

In a preprint submitted to The Astrophysical Journal and uploaded to arXiv, an international team led by Seiji Fujimoto from the University of Texas at Austin describes what may be a galaxy filled with these elusive objects. Named GLIMPSE-16403, this galaxy is not yet confirmed as a Population III host, but its discovery signals that we may be closer than ever to identifying the Universe’s first stars.

Unveiling the Cosmic Dawn

The Cosmic Dawn refers to the first billion years after the Big Bang, when stars and galaxies began forming and illuminating the cosmos. These early Population III stars played a crucial role in shaping the Universe, producing elements heavier than hydrogen and helium through fusion and explosive events.

So far, astronomers have only detected indirect traces of these first-generation stars, never the stars themselves. One challenge is their likely immense size—much larger than today’s stars. Since larger stars burn through their fuel quickly, these ancient giants likely vanished long ago, leaving only the elements they forged behind.

Understanding these early stars is key to unraveling how the Cosmic Dawn unfolded. The James Webb Space Telescope (JWST), the most powerful space telescope ever built, is our best tool for this search. Optimized for detecting faint infrared signals from the distant past, JWST is helping astronomers peer deeper into the early Universe than ever before.

A Breakthrough Candidate

Fujimoto’s team focused their search on galaxies emitting strong hydrogen and helium signals but lacking signs of heavier elements. Their analysis yielded two potential candidates, one of which—GLIMPSE-16403—met all the criteria for a Population III galaxy. Located about 825 million years after the Big Bang, it currently stands as the most promising lead in the search for the first stars.

Further studies will be needed to confirm the nature of the stars within GLIMPSE-16403. Obtaining a detailed spectrum will be challenging due to the immense distance, but this discovery marks a thrilling step forward.

“A century ago, our understanding of the cosmos expanded beyond the Milky Way with the discovery of other galaxies,” the researchers note. “As we reflect on the last hundred years of astronomical breakthroughs, it’s astonishing to think we may soon detect the very first stars that illuminated the Universe.”

Read Original Article: Science Alert

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