💫 Our Sun has traveled from the center of the Milky Way

Recent research advances the hypothesis that our star may have undertaken a long journey from the galactic core, in the company of numerous similar stars. This perspective challenges established knowledge about the history of our system and the galaxy itself.

To retrace the solar past, astronomers examine "solar twins," that is, stars whose size, temperature, and chemical composition are very close to those of the Sun. A research team relied on data from the European Space Agency's Gaia satellite, whose exceptionally precise mapping covers billions of stars, to scrutinize nearly 6,600 of these solar twins located in our galactic neighborhood.


The analysis of these stars allowed for the estimation of their ages. The researchers observed that a significant number of them, around 1,550 stars, were 4 to 6 billion years old, a range that includes the Sun and its 4.6 billion years. This concordance indicates that these objects are not scattered randomly but likely share a common origin that can be reconstructed.

The Sun would thus currently be about 10,000 light-years farther from the galactic center than its presumed birthplace, which indicates a significant displacement. According to scientists, our star would have been part of a vast group of stars expelled outward several billion years ago. This phenomenon would be linked to the formation of a rotating bar in the very heart of the Milky Way, which concentrated matter and ejected surrounding stars.

This journey could have had repercussions on the emergence of terrestrial life. Indeed, the inner regions of the galaxy are much denser and more turbulent, with a stronger occurrence of violent nearby events like supernovae. By migrating toward the periphery, the Sun likely found a more peaceful setting, conducive to establishing stable conditions.

Scientists plan to continue this work using future data from Gaia and an in-depth study of the composition of solar twins. The goal is to identify stars born exactly at the same place and time as the Sun, thus revealing true stellar "siblings." These advances will allow for a better understanding of the joint evolution of our galaxy and our Solar System.

Stellar migrations

Stellar migrations correspond to the movements of stars within a galaxy, often under the effect of gravitational forces and internal structures. In the Milky Way, this phenomenon is frequent and can be triggered by interactions with spiral arms, galactic bars, or other stars. These movements redistribute stars over periods of several billion years.

A galactic bar, like the one that exists at the center of our galaxy, is an elongated structure of stars and gas in rotation. Its formation can destabilize the orbits of nearby stars, pulling them outward or inward. This mechanism explains how entire groups of stars, like the Sun and its twins, could have migrated together from the central regions to the periphery.

Stellar migrations influence the evolution of galaxies. They redistribute matter, which affects the formation of new stars and the chemical composition of different zones. For example, migrating stars transport heavy elements, modifying the chemistry of the regions where they settle.