Researchers from the University of Cambridge have developed a method to use radio signals to determine the mass of the first stars that emerged shortly after the Big Bang, around 13 billion years ago. The study, published in Nature Astronomy, opens new possibilities for exploring the early Universe and the formation of the first galaxies.

The 21-Centimeter Signal: A Key to the Past

The focus is on the so-called 21-centimeter signal — a faint radio emission produced by hydrogen atoms in the early Universe. This signal carries information about how the first stars, known as Population III stars, and early black holes influenced their surroundings. According to Professor Anastasia Fialkov of Cambridge’s Institute of Astronomy, analyzing this emission allows scientists to peer into the "cosmic dawn" — the era when the first stars began to light up the Universe and disperse the primordial darkness.

"This is a unique opportunity to trace how the first light emerged in the Universe," said Fialkov.

Modeling the First Stars

The researchers developed a theoretical model that links the mass of Population III stars to the properties of the 21-centimeter signal. Unlike telescopes like James Webb, which capture images of distant galaxies, radio telescopes collect statistical data from faint signals. This approach enables the study of entire populations of early stars rather than individual ones.

Particular attention was given to binary star systems, where one star has become a black hole or neutron star while the other remains active. These systems emit powerful X-rays that heat surrounding hydrogen and alter the 21-centimeter signal. Earlier studies had underestimated the impact of such systems, leading to less accurate estimates of the masses of the first stars.

Significance for Astronomy

"Radio astronomy can reveal the mass of the first stars and show how different they were from stars we see today," explained co-author Dr. Eloy de Lera Acedo. This information helps scientists understand how the first stars and galaxies formed and what physical processes governed the early evolution of the Universe.

The findings will serve as a foundation for future observations using advanced radio telescopes like the Square Kilometre Array (SKA). These instruments will detect faint signals with greater precision, revealing new details about the cosmic dawn.

Research Outlook

The study highlights the unique role of radio astronomy in probing the early Universe. Researchers plan to continue analyzing the 21-centimeter signal to refine our understanding of the first stars and their influence on galaxy formation. In the long term, this data could help answer fundamental questions about the origin of stars, black holes, and possibly even life itself in the Universe.