Astronomers have discovered that among the brightest stars, there are faint stars. This means that early galaxies may actually contain a much larger mass than we thought. The research team came to this conclusion using the James Webb Space Telescope (JWST) to study nine early galaxies that underwent an intense star formation phase.

According to "space," researchers combined these data with observations from the Very Large Telescope (VLT) on Earth, which for the first time measured the density of small and faint stars in these galaxies. They found that the proportion of small stars in these galaxies is much higher than in modern galaxies like our Milky Way, surprising scientists who had assumed that the proportions of small and faint stars are similar.

"This means that the galaxy as a whole is much larger than previous estimates suggested," said Chloe Chin, a team member from Leiden University in the Netherlands.

Details of the new discovery about faint stars

Astronomers study galaxies and calculate their star density rates using the total light or spectrum emitted by these cosmic cities. The problem is that as the mass of a star increases, its brightness also increases, so it dominates the galaxy's overall spectrum while smaller stars disappear.

The James Webb Space Telescope's sensitivity has finally given astronomers the opportunity to highlight these small stars and give them a chance to shine. "Until recently, this kind of measurement was simply not possible," said Martijn Slob, a team member from Leiden University. "We needed not only a telescope that could collect enough light but also spectra with exceptional quality and new analysis techniques to accurately discern the subtle features of small stars."

The team's discovery sheds light on our understanding of young galaxies in the early universe. Scientists had always assumed that stars of different masses were born in equal proportions throughout cosmic history, but it now appears that this is not the case.

"This result shows that significantly more mass than previously thought is hidden in small stars," said Mariska Kriek, the team leader from Leiden University. "This has implications across various fields of astronomy. Since many planets orbit around small stars, it could mean that there are more planets formed in the early universe than we previously assumed."

The team now plans to apply this method to more of the first galaxies in the universe, hoping to expand their research to include the very first stars in the cosmos. The results were published in the journal "Nature Astronomy."