Skip to content
Astronomers find what may be the most distant galaxy yet

Astronomers have been jumping at each other in the past lately. Last week, a group using the Hubble Space Telescope announced they had discovered what may be the most distant and oldest star ever seen, dubbed Earendel, which twinkled 12.9 billion years ago, just 900 million years after the Big Bang.

Now another international group of astronomers, pushing the limits of Earth’s largest telescopes, claim to have discovered what appears to be the oldest and most distant collection of starlight ever seen: a reddish spot helpfully named HD1 , which was pouring out prodigious amounts of starlight. energy only 330 million years after the Big Bang. This domain of time is hitherto unexplored. Another blob, HD2 appears almost as far away.

Astronomers can only guess what those blobs are – galaxies or quasars or maybe something else – as they wait for their chance to observe them with the new James Webb Space Telescope. But whoever they are, astronomers say, could shed light on a crucial phase of the cosmos as it evolved from pristine primordial fire to planets, life and us.

“I’m excited as a kid spotting the very first fireworks display of a beautiful and highly anticipated spectacle,” said Fabio Pacucci of the Harvard-Smithsonian Center for Astrophysics. “This may well be one of the first glimmers of light to illuminate the cosmos in a spectacle that ultimately created every star, planet and even flower we see around us today – more than 13 billion years later. .”

Dr Pacucci was part of a team led by Yuichi Harikane from the University of Tokyo that spent 1,200 hours using various ground-based telescopes to search for very old galaxies. Their findings were published Thursday in The Astrophysical Journal and in the Monthly Notices of the Royal Astronomical Society. Their work was also featured in Sky & Telescope magazine earlier this year.

In the expanding universe, the farther an object is from us, the faster it is moving away from us. Just as the sound of an ambulance siren moving away shifts to a lower pitch, this motion shifts light from an object to longer, redder wavelengths. In search of the most distant galaxies, astronomers sifted through some 70,000 objects, and HD1 was the reddest they could find.

“HD1’s red color matched the expected characteristics of a galaxy 13.5 billion light-years away surprisingly well, which gave me a little goosebumps when I found it,” said the Dr. Harikane in a statement released by the Center for Astrophysics.

The gold standard of cosmic distances however is the redshift, obtained by obtaining a spectrum of the object and measuring how much the wavelengths emitted by the characteristic elements have increased or redshifted. . Using the Atacama Large Millimeter/submillimeter Array, or ALMA – a collection of radio telescopes in Chile – Dr. Harikane and his team obtained a tentative redshift for HD1 of 13, meaning that the wavelength of light emitted by an oxygen atom had expanded to 14 times its resting wavelength. The redshift of the other blob has not been determined.

This dated the putative galaxy to just 330 million years after the beginning of time, right in the hunting ground of the Webb Telescope, which will also be able to confirm the redshift measurement.

“If ALMA’s redshift can be confirmed, then it would indeed be a spectacular object,” said Marcia Rieke of the University of Arizona, principal investigator for the Webb Telescope.

According to the story told by astronomers, the road to the universe as we know it began about 100 million years after the Big Bang, when the hydrogen and helium created in the primordial explosion began to condense into the first stars, known as Population 3 stars (Populations 1 and 2, which have large amounts of heavier elements are present in galaxies today). Such stars, composed only of hydrogen and helium, have never been observed, and they would have been much larger and brighter than those in the universe today. They would have burned hot and died quickly in supernova explosions which would then have triggered chemical evolution polluting a pristine universe with elements like oxygen and iron, our stuff.

Dr Pacucci said they first thought HD1 and HD2 were what are called starburst galaxies, which swell new stars. But after further research, they found that HD1 seemed to be producing stars more than 10 times faster than these galaxies usually do.

Another possibility, Dr. Pacucci said, is that this galaxy gave birth to these very first population 3 ultraluminous stars. times the mass of the sun. But astronomers are struggling to explain how a black hole could have gotten so big so early in cosmic time.

Was he born that way – in the chaos of the Big Bang – or was he just incredibly hungry?

“HD1 would represent a giant baby in the early universe delivery room,” said Avi Loeb, co-author of Dr. Pacucci’s paper.


Not all news on the site expresses the point of view of the site, but we transmit this news automatically and translate it through programmatic technology on the site and not from a human editor.