2023-05-13 18:00:00
The results of the Gaia satellite allow us to refine our knowledge of the formation of our galaxy. The oldest stars date back only 800 million years following the Big Bang. Better: collisions with dwarf galaxies and even galaxy absorptions are now documented. Welcome to the age of cosmic archaeology.
This article is taken from the monthly Sciences et Avenir – La Recherche n°915, dated May 2023.
These astronomers present themselves as “galactic archaeologists”. They set out to reconstruct the evolution of our entire galaxy, the Milky Way, which contains some 200 billion stars… and whose beginnings date back to the beginning of the Universe itself, more than 13 billion years! To search its recesses and identify the fossil traces of events that shaped its existence, they use instruments of incredible precision, such as the Sloan Digital Sky Survey telescope, located at the Apache Point observatory in the United States.
But above all, the Gaia satellite of the European Space Agency (ESA), which orbits 1.5 million kilometers from the Earth and “revolutionized for some years the science of galactic archeology “, observes Georges Kordopatis, from the observatory of the Côte-d’Azur. By inspecting nearly 70 million stars every day, he has made it possible to establish prodigiously detailed maps, to discern numerous substructures and to reveal hitherto unsuspected phenomena.
“We now have a much clearer view of how our galaxy has developed over its history, samazes Carine Babusiaux, from the Institute of Planetology and Astrophysics of Grenoble. A much more complex and eventful evolution than we imagined, under the effect of processes still taking place today. “Astronomers realized for regarding a century that our galaxy was dominated by a huge spinning disk some 100,000 light-years in diameter. Then, from the 1950s, they realized that this disk was made up of several main “arms” where the density of stars is particularly high and which spiral around a bulge, even if their number (four or more) remains uncertain to this day.
The Sun lies within an arc of […]
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