An older, but almost identical star to the Sun has been found in the constellation of Capricornus (The Sea Goat). Mankind has only been studying the Sun for the last 400 years (a very small percentage of its 4.6 Billion year lifespan), but by studying very similar stars at various ages, we have been able to extrapolate a lot of information about our own star. These stars are commonly termed “Solar twins” and now an international team of researchers, led by astronomers in Brazil, have found the oldest solar twin to date with help of ESO’s VLT (Very Large Telescope). Its name is HIP 102152 and it is approximately 4 billion years older than our Sun, effectively making it double in age. This has given astronomers an unprecedented view of what our sun (and planet) will be doing in 4 billion years. It has also cleared up an age-old question about the Lithium content in younger stars, because it is less prevalent in ours. By comparing the chemical compounds in our sun to younger solar twins (such as 18 Scorpii – half the current age of the sun) and matching that data up to the newly discovered HIP 102152, they can confirm earlier theories that lithium content is directly related to the age of a star.
According to TalaWanda Monroe (Universidade de São Paulo and lead author on the new paper), “For decades, astronomers have been searching for solar twins in order to know our own life-giving Sun better. But very few have been found since the first one was discovered in 1997. We have now obtained superb-quality spectra from the VLT and can scrutinise solar twins with extreme precision, to answer the question of whether the Sun is special.” Apart from its age, HIP 102152 appears to comprise many of the same chemical compounds as our sun (lacking in the other solar twins). This suggests the strong possibility that the ancient HIP 102152 may also be host to several terrestrial planets.
This research was presented in “High precision abundances of the old solar twin HIP 102152: insights on Li depletion from the oldest Sun”, by TalaWanda Monroe et al. in the Astrophysical Journal Letters.