"In this star, most chemical elements are depleted by factors 10,000 to 100,000 compared to the Sun. Additionally, the composition is distinctive. Whereas most heavy-element-depleted stars show a large enhancement in carbon, this star does not. This makes this star the second of its kind and an important messenger from the early Universe", says Dr. Else Starkenburg.

To find these oldest messengers among the much larger population of younger stars is no easy task. Just after the Big Bang, the Universe was filled with hydrogen and helium and a bit of lithium. No heavier elements were around, as these are only synthesised in the hot interior of stars - and those did not yet existt.

Our Sun has about 2% of heavier elements in its atmosphere, as can be seen from a spectrum of its light. Because of this, astrophysicists can conclude that the Sun has emerged as part of a later generation of stars - and "recycled" in its atmosphere are the products of some stars that lived long before the Sun and no longer exists.

In searching for the oldest stars, astronomers look for stars with more pristine atmospheres than our Sun. The more pristine the atmosphere, the earlier the star was born. Studying stars of different ages allows us to understand the history of the Galaxy - an area of research that therefore is also called Galactic archaeology.