How do planets, including Earth, form from stellar dust and gas?

Newborn stars usually go through a juvenile stage in which the intense radiation they emit sweeps away the gaseous environment from which they are formed by the gravitational collapse of a nebula. As the gas nebular disappears, The temperature in the surroundings of the stars decreases enough to allow small minerals and, at greater distances, ice and organic matter., it condenses. These materials collide and form aggregates that accumulate around young stars, forming the so-called. protoplanetary discos.

These enormous structures, initially formed by tiny particles of dust and gas that surround young stars, end up forming kilometer-long bodies such as asteroids and comets. From the collisions between these first solid bodies, on much longer time scales, rocky planets like Earth will later emerge.

What concerns us today is exploring, with the revolutionary James Webb Space Telescope, how water travels in these primordial planetary systems.

Frozen water from the ends

In general, there are two types of protoplanetary disks, the so-called compact ones and the extended ones. The JWST Space Telescope He has just revealed the transport processes of water and volatiles inside protoplanetary disks..

Specifically, the article that now sees the light presents JWST-MIRI spectra of four selected protoplanetary disks, two of each type, to test whether water vapor within the ice line is regulated by the drift of solid materials forming inside.

In those clubs they are very dynamic. Small solid rocks are actually amalgamations of small micrometric minerals, ice and organic matter that collide with each other. They form porous aggregates that can easily incorporate ice.

In cold regions outside the club, water tends to condense and form sheets of ice on those tiny rocks. The presence of these frozen mantles means that the particles are able to diffuse better in a medium with high water vapor, as occurs inside compact discs, unlike those discs in which this vapor is scarce.

Water on Earth from a very early age

This is key because The Earth forms near the Sun in a hot environment and, therefore, with relative scarcity of water. However, this mechanism must have worked long enough to hydrate the formative region of our planet and make the Earth. had water from an early age.

The reason for these differences in protoplanetary disks is explained in an elegant and simple way: the capricious paths of water on board the materials that form these disks.

The water specters decipher their secrets.

The enormous resolving power of mid-infrared spectrometer (MIRI) allows obtaining very detailed water spectra. This has revealed an excess of emission in the spectral lines of the materials that make up compact discs compared to extended discs. This excess emission shows that there is a cold component that extends to a distance from these stars, between one and ten times that which separates the Earth from the Sun in our planetary system.

The emission of cold water is due to the sublimation of ice and the diffusion of that vapor through the disk. This implies that these rocky and ice-covered aggregates move more efficiently towards the regions close to the star if there is enough water vapor, something that occurs in compact disks.

Tiny rocks play a fundamental role: they are responsible for transporting large amounts of water and other volatiles to the internal regions of the disk where the embryos of rocky planets form.

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As these materials fall towards the star, they tend to accumulate and create the toroidal rings and empty spaces typical of extended protoplanetary disks. The early formation of giant gas planets, such as Jupiter itself, can play a fundamental role in acting as a barrier for the passage of these materials to more internal regions.

Who would have thought that, thanks to those capricious and intricate paths followed by water aboard tiny rocks, today the Earth would possess the liquid element, capable of transforming it into an oceanic world and oasis of life.