Approximately 250 million years after the great explosion that gave rise to the cosmos, the Big Bang, the first stars in the universe began to be born. This is revealed by research carried out by an international team of astronomers and published in the journal Nature . The results of the work have also revealed the most distant oxygen ever detected.
The answer to this great question of when the first stars were born has been provided by the ALMA telescope of the European Southern Observatory (ESO), in Chile, thanks to the observation data of a distant galaxy called MACS1149-JD1 . The researchers detected a very faint glow emitted by its ionized oxygen. By the time infrared light was detected on Earth, its wavelength was more than 10 times longer than when it originated.
With this data, the astronomers deduced that the signal was emitted 13.3 billion years ago (or what is the same, 500 million years after the Big Bang), making it the most distant oxygen ever detected by any telescope so far.
“I was excited to see the distant oxygen signal, a detection that pushes back the boundaries of the observable universe,” says Takuya Hashimoto, a researcher at Osaka Sangyo University and leader of the work.
Aside from this ancient glow of oxygen captured by ALMA, ESO’s Very Large Telescope (VLT) also detected a weaker hydrogen emission signal. The experts were then able to determine the distance to the galaxy, which was consistent with the distance from the oxygen observation, making MACS1149-JD1 the farthest galaxy with an accurate distance measurement and also the galaxy. most secluded ever seen.
“We see this galaxy at a time when the universe was only 500 million years old and yet it already has a population of mature stars. We are therefore able to use this galaxy to study an earlier, completely unknown period of cosmic history “, explains Nicolas Laporte, a researcher at University College London and co-author of the study.
To find out when this early star formation took place, the researchers reconstructed the early history of the galaxy MACS1149-JD1 using infrared data taken with the Hubble and Spitzer space telescopes, finding that the observed brightness of the galaxy can be explained with a model. in which the beginning of star formation starts just 250 million years after the beginning of the universe.
When then did the first galaxies emerge within the so-called cosmic dawn? Apparently there were galaxies that existed before those that we can directly detect today.
“Determining when the cosmic dawn took place is the ‘holy grail’ of cosmology and the study of galaxy formation. With these new observations of MACS1149-JD1 we are getting closer to the possibility of being direct witnesses to the birth of the light of the stars! Since we are all made of processed stellar material, this is really finding our own origins, “concludes Richard Ellis, co-author of the study.
Reference: The onset of star formation 250 million years after the Big Bang, Nature (2018). nature.com/articles/doi:10.1038/s41586-018-0117-z
