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.

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

Georgina Torbet
Georgina is the Digital Trends space writer, covering human space exploration, planetary science, and cosmology. She…
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
Super-sensitive exoplanet-hunting instrument captures its first light data
James Chong, infrastructure technician at Keck Observatory, assisting with the delicate lift of the Zerodur optics bench into the observatory basement where the instrument resides.

Astronomers will soon have a new tool for hunting exoplanets, as the W. M. Keck Observatory's Keck Planet Finder (KPF) instrument recently took its first observations. KPF's "first light" observations captured data from Jupiter, demonstrating how the instrument will be able to detect planets beyond our solar system in the future.

Located at Maunakea in Hawaiʻi, the new instrument detects exoplanets using the radial velocity method. This works by observing a star and looking for a slight wobble, caused by the gravity of planets orbiting around it. This wobble changes the light coming from the star just slightly, in a way that can be used to work out the properties of the planet. The instrument measures spectra, or the wavelengths of light coming from a star, with more massive planets making bigger wobbles.

Read more
Astronomers find remnants of planets around 10 billion-year-old stars
Artist’s impression of the old white dwarfs WDJ2147-4035 and WDJ1922+0233 surrounded by orbiting planetary debris, which will accrete onto the stars and pollute their atmospheres. WDJ2147-4035 is extremely red and dim, while WDJ1922+0233 is unusually blue.

Far away in the depths of the Milky Way lie two small, dim stars that are in the final stage of their life. At over 10 billion years old, white dwarfs WDJ2147-4035 and WDJ1922+0233 are among the oldest stars in our galaxy, and recently, astronomers discovered something special orbiting around them: the remains of planets, making this one of the oldest known rocky planetary systems.

Astronomers used data from GAIA, the Dark Energy Survey, and the X-Shooter instrument at the European Southern Observatory to peer at this system. They identified debris from orbiting planetesimals, which are globs of dust and rock which are created during planetary formation. The researchers used spectroscopy to look at the light coming from the two white dwarf stars and break it down into different wavelengths, which can show what materials the stars and the surrounding matter are made of.

Read more