What will our Sun look like in a few billion years? Observations of the star HIP 102152 are giving us some clues. HIP 102152 is the oldest known "solar twin", a star that is almost identical to the Sun, except in age. It clocks in at 8.2 billion years old, making it almost 4 billion years older than our Sun.
Observations of HIP 102152 taken with the European Southern Observatory's Very Large Telescope are helping to solve a long-standing mystery about the Sun. While studying the composition of the Sun, astronomers found that the Sun contains much less lithium than expected. Lithium is one of a few elements thought to be created shortly after the Big Bang. Some stars, such as our Sun, contain much less lithium than expected, based on how much was created in the Big Bang.
New research involving solar twins suggests that the amount of lithium in sun-like stars is simply a reflection of their age. HIP 102152 contains even less lithium than the Sun, and the study of a young solar twin revealed it to have more lithium than the Sun. This provides strong evidence for sun-like stars destroying their lithium as they age.
HIP 102152 and the Sun share another striking similarity: they are both deficient in elements contained in rocky planets and meteorites, presumably because they were used to form such objects instead of becoming part of the star. This suggests HIP 102152 may have terrestrial planets, just like the Sun! In the future, perhaps Solar twins can give us the opportunity to see if other sun-like stars have planetary systems just like ours, or if our solar system is unique.