What is the most pristine star in the known universe? Researchers using data from the Sloan Digital Sky Survey-V (SDSS-V) and observations from the Magellan telescopes at Carnegie Science’s Las Campanas Observatory in Chile may have just spotted it.
Publish their findings in Natural astronomyThe research team, consisting of Alexander Ji of the University of Chicago and Juna Kollmeier, a Carnegie astrophysicist, examined data from the second generation of the SDSS (now in its fifth generation) and believes the most pristine star is SDSS J0715-7334. It is about 80,000 light years from Earth and may have been pulled into the Milky Way over time. The team notes that the star likely formed a few billion years after the birth of the universe.
“These pristine stars are windows into the dawn of the universe’s stars and galaxies,” Ji said in a press release.
Red giant SDSS J0915-7334.
(Image credit: Navid Marvi/Carnegie Science)
What are pristine stars?
It’s a common theory that after the Big Bang, the universe was made up of hot, soft particles that eventually expanded and cooled. During this time, patches of neutral hydrogen gas formed. Some of these areas became heavy and dense, eventually causing the material to collapse in on itself over hundreds of millions of years due to the gravity of the gases. These dense areas would then form the first stars, composed of pristine hydrogen and helium, according to the study.
The authors note that these stars likely burned hot and fast, dying young. However, before they died, the stars probably produced new elements and blasted them out into the vastness of space, creating new stars containing many of these elements.
“All of the heaviest elements in the universe, which astronomers call metals, were produced by stellar processes – from fusion reactions occurring within stars to supernova explosions to collisions between very dense stars,” Ji said in the press release. “So finding a star with very little metal indicated to this group of students that they were going to discover something very special.”
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Why finding pristine stars is important
Researchers look for these ancient stars, especially those of the second and third generations, because they help reveal more information about how the universe began and developed its structure.
“We have to look into our cosmic backyard to find these objects, because we cannot yet observe individual stars on the cusp of star formation. Because 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,” Kollmeier said in the press release.
Identifying Blank Stars
Data collected over five generations of the SDSS has already provided a wealth of information, including millions of optical and infrared spectra across the sky. From this data, Ji and his team identified stars containing very few heavy elements.
Once identified, the team then used the Magellan Telescope at Carnegie Science’s Las Campanas Observatory (Las Campanas) to capture high-resolution spectra of the stars. The results indicated that SDSS J0715-7334 was the most intact.
“The Las Campanas telescope ecosystem has been essential to nearly every aspect of this groundbreaking work, from the Pontus data collected as part of the SDSS-V Milky Way mapping efforts to the Magellan observations that showed exactly how special SDSS J0715-7334 truly is,” Michael Blanton, director and Crawford H. Greenewalt president of the Carnegie Science Observatories, said in the press release.
As Ji and the team gather more information about these stars using advanced equipment and data from Las Campanas and the SDSS, he hopes to inspire the next generation of astronomers to look at the sky.
“Training the next generation of astronomers is essential to the future of our field. And generating enthusiasm for the practice of science by undertaking projects like this is a great way to ensure that curious young learners can see themselves in astrophysics,” Ji concluded in the press release.
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