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Tuesday, July 5, 2022

On the hunt for Exomonds, the next frontier in planetary exploration

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At the edge of our solar system there is a planet with 79 moons. He’s named after a god, Jupiter, and he deserves it. The god of gods in Roman mythology was jealous and vengeful. Reusing its name as a planet, I’m not sure if it’s possible to speak of toponymy off-earth, it’s just that, a planet. The biggest one we have at home, of course, so wearing the name of a god fits like a glove.

Jupiter has so many satellites that some have not yet been officially named, specifically 23 of them. Among the moons of Jupiter that have a name, we find the lesser-known ones Thyone, Adrastea, Isonoe or Kale and also to the famous Europa, Ganymede, the largest in the solar system, or Io the one with the volcanoes. If the mere presence of a moon on Earth fascinates us, we can imagine what the night sky would look like on the surface of our giant neighbor: a sky dotted with natural satellites of various colors and sizes, and with recurring orientations. The idea it’s an important part of the brain’s multiple faculties and since summer nights are short and invite us to look up at the sky, let’s dream what it would be like to have a planet with as many moons as Jupiter or something Saturn with its over 60.

But where do so many moons come from? From what we know so far, the process of forming a satellite around a planet is similar to that of constructing a planet orbiting a star, both growing in the disc that results from the process of forming the larger body. Although on the moons they can also be created by a giant collision, like ours. Or they were captured. This appears to be the origin of Triton, an intriguing satellite orbiting the planet Neptune. newt has an orbit rotating away from the planet and this, together with its Pluto-like chemical composition, suggests that it is an object that may have been bound by Neptune’s gravitational field and originated in what is known as the Kuiper Belt, a collection of smaller bodies beyond the Neptunian orbit.

The fact is that in the solar system there are hundreds of natural satellites, mostly orbiting the giant planets. But outside of our system, we still don’t have any confirmed moons, exomonds, although they could be close to the thousands of exoplanets we’ve discovered in recent years. The search for exomonds continues. The problem is that its detection is complicated.

The most productive technique for detecting exoplanets is that of transit. In this way, most of the planets confirmed so far were discovered (cf Kepler for example). The method is to point a telescope at the star, either on Earth or in space, and wait for something to come by. Obviously it’s easier to measure something passing in front of him if it’s big compared to the body it’s hiding and if it’s in the same plane. Just like it’s more likely that it was your grandma and not a bow tie that spoiled you for more than one highlight while watching your favorite TV show. Although both have always traveled the same distance from the TV and there are on average far more flies than grandmothers, hopefully your grandmother is taller and if not you have a home level pest problem Jurassic Parkeither.

Detection of exoplanets using this transit technique works best when the large object’s orbit is also close to the star, that is, when its orbital periods are short. We have an extreme example in the total occlusion that occurs during a solar eclipse. A planet like Saturn takes 29.4 Earth years to orbit the Sun, that’s its period. Obviously it would be much more difficult to detect the signal of the transit of Saturn from a distant planet than to do it if it were placed at the distance that the Earth is from the Sun, which has a period of one year (terrestrial of course ). Continuing with the grandmother example: If you had a huge house like a famous soccer player (here I assume they are the only ones making enough money in this country to have a big house) and your grandmother died watching TV, if you didn’t see them, let’s remember that it must also be far from you and on the same level as us, let’s not lose the thread when we talk about exoplanets that are located at a great distance from us.

The problem with detecting moons in passing exoplanets is that the moons are to be expected more frequently on these long-period planets, but not because of similarity considerations with the solar system, but because of dynamic effects.

We think that the giant planets have a high probability of forming far away from the star, beyond the ice line. But then you can get closer to the star. As the planet wanders in the protoplanetary disk until it is in the nearest orbit where we discover it through transits, the planet’s gravitational sphere of influence decreases, causing it to lose its moons. The moons become unstable or are either ejected or collide with the planet.

The giant planets that we most easily discover through transits were not born where they are, they have had to migrate, and the fate of the moons of a giant planet that is close to the star depends on the planet’s migration history. When moons are discovered around a planet with a small orbit around its star, it is very likely that the moon was not formed with the planet but was captured in the process of migration.

The first Exomond candidate is orbiting the planet Kepler-1625b would be the size of Neptune and was verified using the Hubble telescope although later analysis of the data seems to rule out their existence. Another candidate is Kepler-1708bi, which would be twice the size of Earth. We continue to search very carefully.

Eva Villaver She is a researcher at the Center for Astrobiology, part of the Higher Council for Scientific Research and the National Institute of Aerospace Technology (CAB/CSIC-INTA).

cosmic emptiness it is a section in which our knowledge of the universe is presented qualitatively and quantitatively. It aims to explain how important it is to understand the cosmos not only from a scientific point of view, but also from a philosophical, social and economic point of view. The name “cosmic vacuum” refers to the fact that the universe is and is mostly empty, with less than one atom per cubic metre, although there are paradoxically trillions of atoms per cubic meter in our environment, inviting us to wonder about our existence and the presence of life in the universe. The section is set up Pablo G. Perez Gonzalezresearchers at the Center for Astrobiology; Patricia Sanchez Blazquez, Full Professor at the Complutense University of Madrid (UCM); Y Eva VillaverResearchers at the Center for Astrobiology.

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Source elpais.com

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