The next catalog of Gaia space telescope
dedicated to astrometry, which maps our galactic neighborhood, should offer a list of stars that probably host at least one exoplanet
. The method is complex, but several thousand systems would potentially be affected.
The technique requires maximum precision and a lot of readings… Gaia’s specialty!
Gaia searches for stars, and more stars
It will be necessary to wait until the second quarter for the third “definitive” catalog of the Gaia mission to be published. It will contain precise information on more than 1.8 billion stars, including for the majority of them their light spectrum (intensity, color, type), their position, their displacement… A veritable gold mine of 5 petabytes of data, centered on the first 34 months of scientific mission. Here is “only” three years of data, while the telescope has been at the L2 Lagrange Point for nine years! The rest is preciously stored on Earth.
By focusing on stars, it is sometimes possible to determine whether they host exoplanets without having to use either the transit method, parallax or direct imaging. With the precise position of the star, a massive exoplanet will influence its trajectory, which will thus resemble a wave. A tiny wave, observed tens or hundreds of light years away, as Gaia does. Only a few other extraordinary telescopes like Hubble or the VLT can achieve the same, at the cost of very long observations.
A moving sun, a planet in ambush
To test the method of detecting exoplanets via astrometry, the scientists observed Gaia’s readings of the star HD81040, located about 115 light-years from our Sun. Around the latter, a “Super-Jupiter” type exoplanet orbits in approximately 1,000 days, it was discovered in 2006… and it is a very good candidate for testing the method. And that’s even though DR4’s 34-month study only covers a 900-day period where HD81040 appears on the data (not every day, of course, Gaia is constantly spinning to observe the entire observable sky).
The study of the data is categorical, the analysis of the astrometry and the measurement of its displacement over time clearly shows the presence of a massive exoplanet. Only the period is distorted, for a good reason: this “Super-Jupiter” did not have time to make a complete orbit around its star.
See catalog size
With precise astrometry and the ever more extensive and refined catalog of Gaia, it will in theory be possible to extract thousands of candidate stars probably hosting massive exoplanets… although this is not the main mission of the telescope!
This will require the use of predictive algorithms, which will have to be modified according to the validation (or not) of the candidates with other telescopes or other detection methods. Enough to explode another catalog which nevertheless fills up very quickly, that of known exoplanets. There are “only” 4,905 at the start of 2022…
On the same subject :
Thanks to the CHEOPS telescope, ESA discovers that this planet is shaped like a rugby ball
Source: ESA
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