The James Webb Telescope reveals the secrets of the formation of our solar system – Futura

To explain the structure of our solar system and the processes that led to the formation of its planets, scientists have long hypothesized that icy materials that formed in the cold outer region of our star system must have migrated there at some point to the Sun brings water to the inner rocky planets like Earth. James Webb Space Telescope observations of protoplanetary disks in which planets form around a star appear to confirm this hypothesis.

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[EN VIDÉO] The planets of the solar system were born from cataclysms. The Earth and the other planets that revolve around the Sun were born in turmoil.

According to the most common models, our solar system began to form about 4.6 billion years ago from a huge cloud of gas composed mostly of hydrogen and helium. Small fluctuations in the density of the cloud caused it to collapse: this is called gravitational collapse. As the cloud contracted, its rotation speed gradually increased as most of the matter clumped together toward the center, forming the young sun; The rest formed the protoplanetary disk that orbited the young star and consisted of gas and dust. As they met, the latter began to aggregate into larger blocks, which, with successive collisions, gradually enlarged into planetesimals – embryonic planets developing in a protoplanetary disk.

Complex dynamics in the protoplanetary disk

The heat in the region close to the Sun, called the inner solar system, prevents molecules and light elements such as water from condensing. The planets that form in this region therefore consist mainly of heavier components such as iron or silicate rock: the planetesimals close to the Sun form small and dense rocky planets that become the four telluric planets that we know today. hui (Mercury, Venus, Earth and Mars). In the outer solar system, however, it is cold enough for molecules and volatile elements to remain in a solid state. The planetesimals that form there gradually aggregate hydrogen and helium from the protoplanetary disk, the lightest but also most abundant elements. They thus form gas planets (Jupiter, Saturn, Uranus and Neptune), which are much heavier and more impressive than the telluric planets, but also much less dense. This global model describes well what we observe in our current solar system, with one exception: If water in the inner solar system could not condense during the formation of the planets, how could oceans on the surface of our solar system have condensed? Planet?

This animation shows the evolution of a protoplanetary disk around a star. When planets form, holes are created in which gas and dust accumulate. © ExploreAstro

To explain the presence of water on certain terrestrial planets (such as Earth or even Mars), scientists have long suspected that during the contraction of the protoplanetary disk, small ice-covered blocks – composed of light elements such as water – are formed in the solid state – originally formed in the outer regions of the solar system, migrated towards the Sun and allowed the accumulation of water in the inner region and the planetesimals found there. Although this hypothesis seems plausible, it is impossible to go back in time to verify it.

Protoplanetary disks studied by the James Webb Space Telescope

The James Webb Space Telescope, launched in 2021, was developed, among other things, to observe the formation of stars and planetary systems. By analyzing the data collected by his Miri spectro-imager (Mid InfraRed instrument, which allows, for example, the analysis of the chemical composition of the atmospheres of exoplanets or protoplanetary disks) when he observed four protoplanetary disks in the constellation Taurus, a Team of scientists have made a discovery that is crucial to our understanding of how planetary systems form. They present their results in the scientific journal The Astrophysical Journal Letters.

The observed protoplanetary disks – two compact and two more extensive ones – surround very young stars (2 to 3 million years old) that belong to the same family as our Sun. According to scientists, the hypothesis of the migration of light and icy elements into the interior of the protoplanetary disk seems to work better for compact protoplanetary disks than for more extensive protoplanetary disks: the latter are more likely to have areas where there tends to be greater pressure to capture the frozen material and its Significantly slow down the hike towards the center. Based on this premise, the authors concluded that observing more water in the internal regions of compact discs than in expanded discs would support this hypothesis.

And that’s exactly what James-Webb observed: By analyzing his data, the research team discovered an excess of water in the inner regions of the two compact protoplanetary disks compared to the inner regions of the expanded disks. According to their results, icy materials tend to become trapped in the highest pressure zones of extended disks, preventing them from reaching the inner region. Researchers also believe that the planet Jupiter, the most massive planet in our solar system, may have played this role in the planets’ formation by preventing water accumulation in the inner solar system and on the relatively water-poor terrestrial planets. Although the James Webb Space Telescope was originally designed to observe the far corners of the universe, it can also allow us to learn more about our own solar system!

Originally posted 2023-11-12 10:34:35.


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