The center of our Milky Way is something like a sunset at Santorini Castle. Everyone wants to photograph it. Well, in this case, all astronomers. The reason, basically, is that it has a large concentration of stars, so there is a lot of material to dig around and find possible exoplanets. Unfortunately, most of the photos that have been taken so far did not have the ideal resolution for this type of search. However, thanks to the Euclid Telescope, designed by ESA to study dark matter and dark energynow we have the largest and most detailed photo of this point of our galaxy that has ever been done.
There is light beyond the darkness. Studying billions of distant galaxies allows Euclid to see how the Universe has expanded and, in the process, determine the possible presence of dark matter. But in this case it has not been used for that. The astronomers have taken advantage their ability to focus on large areas of sky sharply and have taken 9 photographs of regions larger than a full Moon. With all of them they have made a mosaic in which more than 60 million stars, as well as nebulae and star clusters, can be observed more clearly than ever.
A catalog of microlenses. The goal of this photograph is to detect gravitational microlensing. These are formed when two stars align in front of an observer (the telescope) in such a way that the gravity of the nearest star bends the light of the one behind it, acting as a kind of magnifying glass. If the nearest star also has a planet orbiting around it, its own gravity also contributes to that process. Therefore, light bends in an asymmetrical way, which serves as an indicator for the search for exoplanets. Logically, to study this phenomenon, catalogs with many stars are needed. Nothing like one this precise.
It takes time. It takes at least 20 days to detect such irregularities in the bent light. So a single glimpse of Euclid won’t do that. However, this very precise catalog will be used so that, when launched into space the Nancy Grace Roman telescopethis has a starting point from which to start working. By comparing the same area, not only can microlenses be detected, you can also see how they have varied over time. This makes it possible to detect exoplanets and, by seeing how fast they move, calculate their mass.
Previous steps. Catalogs like this have already been made before, although much less precise. In fact, 300 exoplanets have been detected using the microlensing method. The problem is that ground-based telescopes have always been used; which, having the Earth’s atmosphere in the middle, take the images with less sharpness. For example, the telescopes at the Keck Observatory have been widely used. However, what Euclid has photographed in 26 hours would have taken these telescopes more than 2,000 hours of observation.
However, Euclid will start from some of those previous steps. For example, thanks to data taken by the Keck observatory and the Hubble Space Telescope (this one is in space, but analyzes smaller areas of sky), it has been possible to calculate the mass of two already known icy exoplanets. The changes in the location of the stars have been seen and the calculations have been made.
In summary. Euclid has made the most complete catalog of stars in the center of our galaxy in history. But in reality, their success is largely based on teamwork. A work that is already carried out with the Keck observatory and Hubble, but also with the telescopes that are to come. Especially the Nancy Grace Roman.
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