Astronomers Discover Most Pristine Star Ever Found

The ancient star may hold clues to the dawn of stars and galaxies in the early universe.

Apr. 5, 2026 at 2:07pm

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Astronomers have identified the most pristine known star, SDSS J0715-7334, a relic that may trace back to the universe's second generation of stars. The star has less than 0.005 percent of the Sun's metal content, making it about twice as metal-poor as the previous record holder. This suggests the star was born from material touched by only the earliest stellar deaths, providing a rare glimpse into the young universe.

Why it matters

Pristine stars like SDSS J0715-7334 are considered 'windows into the dawn of stars and galaxies in the universe.' By studying their chemical composition, astronomers can learn about the conditions and processes that shaped the first generations of stars and galaxies after the Big Bang.

The details

The discovery began with data from the Sloan Digital Sky Survey, which the research team used to identify stars with extremely low heavy-element content. They then used the Magellan telescopes in Chile to gather high-resolution spectra that confirmed the star's unusual composition. Analysis showed the star has less than 0.005 percent of the Sun's metal content, making it about twice as metal-poor as the previous record holder. The star's low carbon and iron levels also suggest it was formed through dust cooling rather than the more common atomic fine structure cooling process.

  • The discovery was made in data from the fifth-generation Sloan Digital Sky Survey (SDSS-V).
  • The team used the Magellan telescopes at Carnegie Science's Las Campanas Observatory in Chile to gather the high-resolution spectra that confirmed the star's unusual composition.

The players

Alexander Ji

A professor at the University of Chicago who led the research team that discovered the pristine star.

Juna Kollmeier

An astrophysicist at Carnegie Science who leads the SDSS-V survey, which helped identify the candidate star.

Michael Blanton

The Director and Crawford H. Greenewalt Chair of the Carnegie Science Observatories, which operates the Magellan telescopes used in the discovery.

SDSS-V

The fifth-generation Sloan Digital Sky Survey, which takes millions of optical and infrared spectra across the sky and helped flag the candidate star.

Magellan Telescopes

The twin telescopes at Carnegie Science's Las Campanas Observatory in Chile that were used to gather the high-resolution spectra confirming the star's unusual composition.

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What they’re saying

“These pristine stars are windows into the dawn of stars and galaxies in the universe.”

— Alexander Ji, Professor, University of Chicago

“Since these stars are rare, surveys like SDSS-V are designed to have the statistical power to find these needles in the stellar haystack and test our theories of star formation and explosion.”

— Juna Kollmeier, Astrophysicist, Carnegie Science

“The ecosystem of telescopes at Las Campanas was critical to nearly every aspect of this breakthrough work.”

— Michael Blanton, Director, Carnegie Science Observatories

What’s next

The researchers note that more stars this metal-poor, found in different environments, will be needed to further test ideas about how the first stars formed.

The takeaway

The discovery of the most pristine star known, SDSS J0715-7334, provides a rare local record of the early universe and strengthens the case that dust helped later low-mass stars form, even in environments beyond the Milky Way. This ancient star offers a unique window into the dawn of stars and galaxies in the cosmos.