Skip to main content

Hunting for evidence of the first stars that ever existed

As the universe has aged, the type of stars found within it has changed. Heavy elements like iron are created by the reactions which happen inside stars, and when those stars eventually run out of fuel and explode as supernovae, those heavier elements are spread around and incorporated into the next generation of stars. So over time, stars gradually gained higher levels of these heavier elements, which astronomers refer to as their metallicity.

That means that if you could look back at the very earliest stars, born when the universe was young, they would be quite different from stars today. These early stars are known as Population III stars, formed when the universe was less than 100 million years old, and searching for them has been one of the holy grails of astronomy research.

Related Videos
This artist’s impression shows a field of Population III stars as they would have appeared a mere 100 million years after the Big Bang.
This artist’s impression shows a field of Population III stars as they would have appeared a mere 100 million years after the Big Bang. Astronomers may have discovered the first signs of their ancient chemical remains in the clouds surrounding one of the most distant quasars ever detected. NOIRLab/NSF/AURA/J. da Silva/Spaceengine

Now, astronomers using the Gemini North telescope in Hawai’i may have identified debris from these incredibly early stars for the first time. The researchers looked at a very distant quasar, a bright center of a galaxy, and observed the chemical composition of the clouds around it. They found that this composition was unusual, with a very high ratio of iron to magnesium. This indicates that the material could have been formed from a very early star that experienced a dramatic event called a pair-instability supernova. This theoretical type of supernova is extremely powerful and could happen to these early, low-metallicity stars.

By looking for the remnants of these special supernovae, the researchers had their best chance of identifying material from early stars. “It was obvious to me that the supernova candidate for this would be a pair-instability supernova of a Population III star, in which the entire star explodes without leaving any remnant behind,” said lead author Yuzuru Yoshii of the University of Tokyo in a statement. “I was delighted and somewhat surprised to find that a pair-instability supernova of a star with a mass about 300 times that of the Sun provides a ratio of magnesium to iron that agrees with the low value we derived for the quasar.”

Searching for more of these remnants of early stars could help us find more examples and help us learn about how the universe ended up as we see it today. “We now know what to look for; we have a pathway,” said co-author Timothy Beers of the University of Notre Dame. “If this happened locally in the very early Universe, which it should have done, then we would expect to find evidence for it.”

The research is published in The Astrophysical Journal.

Editors' Recommendations

Hubble captures an open star cluster in a nearby satellite galaxy
Against a backdrop littered with tiny pinpricks of light glint a few, brighter stars. This whole collection is NGC 1858, an open star cluster in the northwest region of the Large Magellanic Cloud, a satellite galaxy of our Milky Way that boasts an abundance of star-forming regions. NGC 1858 is estimated to be around 10 million years old.clock

The Hubble Space Telescope recently captured an image of a beautiful star cluster called NGC 1858, located in an area full of star-forming regions. This area is part of the Large Magellanic Cloud, one of the Milky Way's satellite galaxies, and is located 160,000 light-years away and is thought to be around 10 million years old.

The Large Magellanic Cloud is one of several satellite galaxies to the Milky Way, which are smaller galaxies that are gravitationally bound to our galaxy. Along with its companion, the Small Magellanic Cloud, it orbits around the Milky Way and will eventually collide with our galaxy in billions of years' time.

Read more
See the entire observable universe represented in this interactive map
Visualization of the observable universe, using data from the Sloan Digital Sky Survey.

If you've ever wanted to bask in the cosmic majesty of all that exists or feel the existential horror of your own smallness, a new interactive map will show you the entire observable universe.

You can view the map at mapoftheuniverse.net, where you'll find an overview of the types of objects which are visible and a timescale explaining how what is visible is related to its age due to the speed of light. If you've ever struggled to comprehend the relationship between time and distance in what is observable, this tool is helpful in showing that.

Read more
Hubble Space Telescope captures the earliest stage of star formation
A small, dense cloud of gas and dust called CB 130-3 blots out the center of this image from the NASA/ESA Hubble Space Telescope. CB 130-3 is an object known as a dense core, a compact agglomeration of gas and dust. This particular dense core is in the constellation Serpens and seems to billow across a field of background stars.

This week's image from the Hubble Space Telescope shows a beautiful cloud of dust and gas located in the constellation of Serpens. This cloud is a type of object called a dense core, with enough densely packed material that it could one day be the birthplace of a new star.

The object, called CB 130-3, makes an interesting companion to the protostar image recently shared from the James Webb Space Telescope. This Hubble image shows the earliest phase of star formation, in which dust and gas come together to form a core, while the Webb image shows the next phase of development in which the core is dense enough to attract more material via gravity and starts rotating and giving off jets.

Read more