An international team led by Brazilian astronomers used ESO’s Very Large Telescope (VLT) to identify and study a star almost identical to the Sun that, however, is much older. This star, called HIP 102152 and about 250 light years away from Earth, is giving astronomers a chance to see the possible future of the Sun but also to solve the mystery of its lithium content.
Astronomers have been looking for the Sun’s twins for a long time in order to make a comparison with it but so far only very few of them were discovered. The international team that carried out this new research has studied two of them: one called 18 Scorpii and HIP 102152. The analyzes of these two stars have established that 18 Scorpii is about 2.9 billion years old, therefore younger then the Sun. Instead, HIP 102152 is about 8.2 billion years old, much older than the Sun’s 4.6 billion years.
HIP 102152 is particularly interesting because it can give us an idea of the possible future of the Sun but it can also help us to understand if the Sun has a typical chemical composition. In particular, the astronomers focused on the analysis of lithium to see if the low lithium content in the Sun is normal.
Lithium is one of the lightest elements. in fact in the periodic table it comes after hydrogen and helium and is one of the elements created just after the Big Bang. The Sun is composed of lithium for about 1% while its younger twins have a much larger amount. Astronomers theorized that there’s a correlation between the age of a star and the amount of lithium contained in it but so far it wasn’t possible to prove it.
The analysis of the star HIP 102152 shows that it contains a very small amount of lithium. Astronomers infer that somehow the lithium in these stars is somehow destroyed over time so the amount present in the Sun is normal for its age.
The research on the Sun and its twins will continue to examine other possible explanations. This research also revealed another interesting characteristic of the star HIP 102152: like in the Sun, there’s a scarcity of elements that on the contrary are rather abundant on Earth and in meteorites. This analogy is a clue that this star may have one or more rocky planets as well. This is far from certain but I can’t help wondering if there might be an Earth’s twin.
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