The first starlight might have lit up the cosmos just 250 million years after the Big Bang—a blink of an eye in cosmic time.
Astrophysicists have been working to pin down exactly when gases compressed to spark nuclear fusion for the first time, producing light and heat and igniting stars. A new study to be published in Nature this week suggests the first stars could have formed earlier rather than later.
The finding comes from two of the most advanced telescopes working today: the internationally funded (ALMA) and the European Southern Observatory's (VLT), both in Chile.
Using ALMA, an international team of astronomers was able to detect a very faint glow emitted by ionized oxygen in a galaxy far, far away known as MACS1149-JD1. As this glow, emitted in infrared light, travelled across the vastness of space, it was affected by the universe's accelerating expansion. As the universe grew, the infrared light from MACS1149-JD1 stretched out to a wavelength ten times longer than when it began its voyage.
The research team was able to infer that the wavelength was emitted 13.3 billion years ago, around 500 million years after the Big Bang. It's the most distant oxygen ever detected by telescope, and its existence likely means that there were stars even earlier.
"I was thrilled to see the signal of the distant oxygen in the ALMA data," said Takuya Hashimoto, lead author of the new paper and a researcher at both
The ALMA data is bolstered by findings from the VLT, which found an even weaker signal of hydrogen emissions from MACS1149-JD1.
For a period of time after the Big Bang, no oxygen existed in the universe. Oxygen only came into existence through the fusion processes at the cores of stars and was only released into the vastness of space when these first stars died. Looking at the hydrogen from 500 million years after the Big Bang, as well as previous infrared data on MACS1149-JD1 taken by the Hubble and Spitzer space telescopes, and star formation seems to begins just 250 million years after the Big Bang.
"Determining when cosmic dawn occurred is akin to the Holy Grail of cosmology and galaxy formation," says Richard Ellis, senior astronomer at University College London."With these new observations of MACS1149-JD1 we are getting closer to directly witnessing the birth of starlight! Since we are all made of processed stellar material, this is really finding our own origins."
The origin of the universe and its first stars are a source of seemingly endless fascination and wonder. Recently, Stephen Hawking's last theory attempted to describe exactly what happened in the immediate aftermath of the Big Bang. It seems that not too long after that, the first stars could have burst into life.