New Discovery Shows Oldest Stars in the Universe May Be Younger Than Previously Thought

New satellite observations have moved the Universe's timeline a little closer. The European Space Agency's (ESA) Planck satellite has revealed that the earliest stars in the Universe started forming later than previously thought.

Distributions of Cosmic Microwave Background (CMB), which is the leftover radiation after the Big Bang, reveal small fluctuations that may provide information about the history, composition and geometry of the Universe. But the period when the first stars started to form, which is the "epoch of reionization," had since been the subject of scientific debate.

"The CMB can tell us when the epoch of reionization started and, in turn, when the first stars formed in the Universe," Jan Tauber, Planck object scientist at ESA, said in a press release.

According to the study, the release of the CMB happened during the time when electrons and protons joined to form hydrogen atoms. This is the first time in the history of the Universe that matter was an electrically neutral state.

Previous studies in 2003 suggested that the earliest stars were born a few hundred years into the history of the Universe. However, there is no evidence that any stars had formed by then, and this would hypothesize the existence of other sources that might have caused the reionization during that period. Other studies estimated 450 million years, others said it was 550 million years.

In 2015, the Planck Collaboration provided new data to address the problem, moving the reionization period later in cosmic history, saying that reionization had been half way done when the Universe was about 550 million years old. The findings were based on Planck's first all-sky maps of CMB polarization taken from its Low-Frequency Instrument (LFI).

But now, a new analysis from Planck's High-Frequency Instrument (HFI), which is the most sensitive to this kind of data, showed that reionization began much later than any previous data suggested - around 700 million years.

Based on the newly discovered age, researchers said that the earliest stars in the Universe could be or might have already been detected by today's technology. Moreover, scientists said that the very first galaxies might have been detected by long exposures, such as the NASA/ESA Hubble Telescope, and it would be easier to spy on these stars using future observatories.