Free Astronomy Magazine July-August 2020

36 JULY-AUGUST 2020 SPACE CHRONICLES Hubble makes surprising find in the early Universe N ew results from the NASA/ESA Hubble Space Telescope suggest the formation of the first stars and galaxies in the early Universe took place sooner than previously thought. A European team of as- tronomers have found no evidence of the first generation of stars, known as Population III stars, as far back as when the Universe was just 500 million years old. The exploration of the very first galaxies re- mains a significant challenge in modern astronomy. We do not know when or how the first stars and galaxies in the Universe formed. These questions can be addressed with the Hubble Space Telescope through deep imaging observations. Hubble allows astronomers to view the Universe back to within 500 mil- lion years of the Big Bang. A team of European researchers, led by Rachana Bhatawdekar of the Eu- ropean Space Agency, set out to study the first generation of stars in the early Universe. Known as Popu- by NASA/ESA T his artist’s impression presents the early Universe. [ESA/Hubble, M. Kornmesser] lation III stars, these stars were forged from the primordial material that emerged from the Big Bang. Population III stars must have been made solely out of hydrogen, he- lium and lithium, the only elements that existed before processes in the cores of these stars could create heavier elements, such as oxygen, ni- trogen, carbon and iron. Bhatawdekar and her team probed the early Universe from about 500 million to 1 billion years after the Big Bang by studying the cluster MACSJ0416 and its parallel field with the Hubble Space Telescope (with supporting data from NASA’s Spitzer Space Telescope and the ground-based Very Large Telescope of the European Southern Observa- tory). “We found no evidence of these first-generation Population III stars in this cosmic time interval” said Bhatawdekar of the new results. The result was achieved using the Hubble’s Space Telescope’s Wide