Sometimes the biggest challenge in coming up with new astronomical results is enormity. Perhaps that is why the release of the most recent complete package of data from the Gaia satellite, last Monday (13), has passed with some discretion. But make no mistake. We are facing results that will have an extraordinary impact on all fields of astronomy in the coming decades. Just to start unpacking this, keep in mind that the new catalog contains individualized data on 1.8 billion stars in our Milky Way galaxy.
That’s it, billion, with “b”. The entire galaxy must have something like 200 billion stars, so it’s no exaggeration to say that the European Space Agency’s Gaia project alone has mapped about 1% of the Milky Way’s total stars. With this census comes an unprecedented understanding of the galactic structure, with its spiral arms and central bar – something very difficult to visualize without systematic, three-dimensional mapping like this, given that we are inside it, some 26,000 km from Earth. center.
For 1.5 billion of these stars we now have effective ratings indicating what kind of star they are. Are they M-type red dwarfs smaller than the Sun? Solar-type stars, G? Stars more massive than the Sun, type O or B?
For 220 million of them, there are now low-resolution spectra, that is, observations of the light from these stars broken down into their constituent colors – which allows for information on composition and age to be derived. As for high-resolution spectra, Gaia has brought 1 million of them, which allow us to investigate these stars in even more detail.
Variable stars, which change their brightness over time, number 10 million in the new catalogue. And identified binary star systems are 813 thousand.
Launched in 2013 and then installed in an orbit that keeps it constantly 1.5 million km from Earth (by the way, in the same region where the James Webb Space Telescope now “lives”), Gaia aims to make complete scans from the sky. With this, it is not limited to the observation of stars, but also records objects inside the Solar System and far beyond our galaxy. Some figures: the new data package has information on 2.9 million galaxies, 1.9 million quasars (active galactic nuclei) and 156,000 asteroids orbiting the Sun.
This is the third major data package from Gaia, DR3, which includes the first 34 months of observations of the satellite, and its details were brought out in dozens of scientific articles, making up a special issue of the journal Astronomy & Astrophysics. The next one, DR4, will be based on 66 months and should include thousands of exoplanets, also revolutionizing this area of ​​study. The satellite team is waiting for confirmation that the mission will be extended to 2025, which seems like a slog at this point. Astronomy will never be the same after Gaia.
This column is published on Mondays, in Folha Corrida.
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