A glimpse into the future of the solar system: a star similar to the sun but twice its age

The team members, led by astronomers from Brazil, examined with the huge telescope two twins of the Sun, one star that is considered younger (18 Scorpii) and the elderly HIP 102152 that is likely to be surrounded by rocky planets

An international team of astronomers led by researchers from Brazil used the Very Large Telescope at the European Southern Observatory (ESO) to identify and study our Sun's oldest twin. The star, HIP 102152, 250 light-years from Earth, is more similar to the Sun than any solar twin discovered so far, except that it is almost 4 billion years older.

This old, almost-twin star could provide us with an unusual chance to see what our Sun will look like and behave like when it reaches this age. The sharp observations also provide insights into the relationship between the age of the star and its lithium content, and in addition, the researchers estimate that HIP 102152 may also 'host' rocky planets.

Astronomers have been observing the sun through telescopes for about 400 years, a tiny window of time relative to its age - 4.6 billion years. It is very difficult to study the history and future development of our star, but we can do this by searching for rare stars similar to it in composition, but at different stages of their lives. Astronomers have now identified a star that is the same twin as our sun, but 4 billion years older, almost like watching the reality version of the twin paradox.

George Melendez from the University of São Paulo in Brazil, the lead researcher says: "For decades, astronomers have been looking for solar twins in order to know better about the planet that provides us with life. However, few of them have been found since the first discovery of this type of star in 1997. We were able to obtain excellent spectral measurements using the VLT and can now examine the Sun's twin with great precision to answer the question of whether our Sun is special."

Using the huge telescope, the team members examined two twins of the Sun, one star considered to be younger (18 Scorpii) and the elderly HIP 102152. They used the UVES spectrograph of the Very Large Telescope at the Fresnel Observatory in Chile belonging to the European Southern Observatory (which in turn is affiliated with the European Space Agency), to split the light from these stars into its component colors so that the chemical composition and other properties of the stars could be studied in detail.

They found that HIP 102152, located in the group of Capricornus (or Capricornus), is the oldest known twin of the Sun so far. Its age is estimated at about 8.2 billion years, compared to 4.6 billion years - the age of the sun. On the other hand, 18 Scorpii has been shown to be much younger than the Sun - only 2.9 billion years old.

The study of the Sun's ancient twin, HIP 102152, will allow scientists to predict what might happen to our Sun when it reaches that age, and they have already made one significant discovery: "One question we wanted to answer is whether the composition of the Sun is typical of this type." Melendez says,
"More importantly, why is the lithium content in the star so low?"
Lithium, the third element in the periodic table, was created in the Big Bang along with hydrogen and helium. Astronomers have been grappling with the question for years - why do some stars seem to have a lower lithium content than others?. The new observation of HIP 102152 makes it possible to make progress in solving this mystery by establishing a strong correlation between the age of the Sun-like star and its lithium content.

Our sun contains only about one percent of the lithium content that was in the cloud of material from which it was formed. It turns out that the younger brothers of the Sun contain much larger amounts of lithium, but so far scientists have not been able to prove a clear correlation between the age of the star and the lithium content. Telhwanda Monora of the University of Sao Paulo, the principal investigator of the new study, concludes: "We found that HIP 102152 had very low levels of lithium, clearly showing for the first time that the Sun's old twins do contain less lithium than the Sun and the younger stars of its type. We are now certain that the stars somehow destroy the lithium as they age, and that the lithium content of the Sun appears to be normal for its age."

A final twist in the story is that HIP 102152 has an unusual chemical composition, different from all the other solar twins, but similar to that of the sun itself. Both contain, relatively little, elements common in meteorites and on Earth. This is the most important clue that HIP 102152 may be the central star in a solar system containing rocky Earth-like planets.

to the notice of the researchers