Home LATEST NEWS Particularly interesting galactic fossils discovered in the Milky Way

Particularly interesting galactic fossils discovered in the Milky Way


A star cluster with exceptionally low metallicity, that is, the amount of elements other than helium and hydrogen, has been identified. This is an important discovery for the understanding of the formation of galaxies in the Universe, according to the study published in the scientific journal Nature.

This current of stars called C-19 was tracked down by a team of scientists, including researchers from the Strasbourg Astronomical Observatory and the Center for Research on Astronomy at the University of Victoria.

The stars in this group have a metallicity rate that is about 2,500 times lower than that of the Sun, according to the publication. Which means that this group of stars was formed very early, in the first billion years of the age of the Universe., explains Nicolas Martin, co-author of the study and researcher at the Strasbourg Astronomical Observatory.

This cluster is made up of thousands of very old stars and therefore opens a window on the first star creations in the Universe.

A group of stars in blue, which corresponds to a weak metallicity.

Each cluster is a grouping of a few thousand to several million stars. The color of the dots represents the metallicity of the clusters, that is to say their quantity of heavy elements relative to the Sun.

Photo: © N. Martin & Strasbourg Astronomical Observatory; Canada-France-Hawaii Telescope / Coelum; ESA / Gaia / DPAC

Galactic archeology

There are two methods available to science to further understand the mechanisms of the big bang. The first is to study distant galaxies, but we never observe these galaxies with the detail that we can have in our Milky Way, says the astronomer.

The second method is therefore to look at what is closer.

A star in the galaxy.

Thanks to the very precise measurement of the slight displacement of this star, it was possible to show that it belongs to a stellar current of extremely low metallicity.

Photo: SLOAN Digitized Sky Survey image in Aladin software (Strasbourg Astronomical Observatory)

Just as an archaeologist unearths ruins of ancient civilizations or a paleontologist finds dinosaur fossils, researchers try to find the fossils of star clusters or small galaxies that have been absorbed by our own galaxy, observes Nicolas Martin.

The observation of these very first star formations allows to try to better understand how galaxies are formed over time and how they evolve, he adds.

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