KEY POINTS

  • Scientists discovered a star with the lowest iron levels
  • The star could be as old as the universe
  • The star is a dying red giant that will go supernova eventually

A team of scientists came across a star that’s almost as old as the universe. Based on its age and status, the star has already reached the last stages of its life and would eventually go supernova.

The study about the star was conducted by an international team of scientists. It was published in the journal Monthly Notices of the Royal Astronomical Society: Letters.

The star that the scientists discovered has been identified as SMSS J160540.18–144323.1. It is located within the Milky Way galaxy and is about 35,000 light-years from Earth’s neighborhood.

After observing the star, the scientists learned that it has the lowest levels of iron of any known star in the entire galaxy. This finding suggests that SMSS J160540.18–144323.1 belongs to an ancient group of stars that can be traced back to the Big Bang, the major cosmic event that created the universe 13.8 billion years ago.

“This incredibly anemic star, which likely formed just a few hundred million years after the Big Bang, has iron levels 1.5 million times lower than that of the Sun,” lead scientist Thomas Nordlander of the ARC Center of Excellence for All Sky Astrophysics in 3 Dimensions in Australia said in a statement.

“That's like one drop of water in an Olympic swimming pool,” he continued.

As explained by the scientists, a star’s iron content is a good indicator of its age. During the universe’s first couple of years, stars were mainly made up of hydrogen and helium. In larger stars, however, various elements such as silicon and iron are formed through nuclear fusion. Through this process, the atomic nuclei of lighter elements are merged together to create heavier ones.

Once a star goes supernova, the explosion sends its elements across the universe, making them the building blocks of new star formations. Since SMSS J160540.18–144323.1 has a very low iron content, it indicates that it came from a period when other stars did not contain as much metal elements as they do today.

According to the researchers, SMSS J160540.18–144323.1 is a red giant star. This means that it has already reached the end of its life cycle.

Eventually, the fuel powering the star will run out, causing the stellar object to collapse under the weight of its own gravity. Once this happens, the star will trigger a bright supernova event.

Supernova remnant
Supernova remnants are the debris from exploded stars. G292.0+1.8 is a rare type of supernova remnant observed to contain large amounts of oxygen. Because they are one of the primary sources of the heavy elements (that is, everything other than hydrogen and helium) necessary to form planets and people, these oxygen-rich supernova remnants are important to study. The X-ray image of G292+1.8 from Chandra shows a rapidly expanding, intricately structured field left behind by the shattered star. The image is colored red, green, teal and purple in X-rays ranging from the lowest to highest energy levels.Recently the first detection was made of iron debris from the exploded star. Authors constructed a map of this debris, along with that of silicon and sulphur, to understand more about the explosion. They found that these three elements are mainly located in the upper right of the remnant. This is in the opposite direction from the neutron star that was formed in the explosion, and was then kicked towards the lower left of the remnant. This suggests that the origin of this kick is gravitational and fluid forces from an asymmetric explosion. If more than half of the star’s debris is ejected in one direction, then the neutron star is kicked in the other direction so that momentum is conserved. This finding argues against the idea that the copious amounts of neutrinos formed in the supernova explosion were emitted in a lop-sided direction, imparting a kick to the neutron star. NASA/CXC/SAO
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