Give it Time and A Humble Pebble Could Turn into a Massive Planet

The pebble accretion theory could be summed up into one simple sentence: give it time and a humble pebble could turn into a massive planet. Yet, many experiments and computer-generated simulations have been carried out before scientists at the Southwest Research Institute could use this model to explain the formation of giant gas planets.

The questions related to the formation of massive gas planets like Jupiter and Saturn has always posed difficulties to scientists. Previous researchers relied on the core accretion model claiming that the icy and rocky core of the planet was the first to take form and then, the planet’s dimensions grew due to the interstellar dust and gas surrounding them.

No matter how pertinent and valid this model appeared, there were still many questions that remained unanswered, scientists explained. First of all, they couldn’t understand how this core was formed in the first place. Second of all, the initial core had to have the size of Uranus in order to allow gas formations to reach their current dimensions in a short period of time. However, calculations show that these gaseous celestial bodies took less time to form.

After many trials, researchers have finally come up with a new model, the pebble accretion model, which solves all these mysteries. Based on this new theory, gas planets could be formed in a much smaller period of time, if their core contained one foot-wide pebbles.

These small pebbles would have to be collected at very slow speed in order for the planets to have time to gravitationally interact with each other.

The surrounding gas and dust functioned as a propelling force, according to the pebble accretion model, pushing the rocks towards the core of the new planet.

Computer simulations that researchers have made have revealed that pebbles have to get to the core of the planet at a very low speed; otherwise, the entire formation process would be ruined. Calculations have revealed that thousands of icy Earths would have been formed in the Universe, had the pebbles travelled at a much faster speed.

The fact that there are only a few massive gas formations in the Universe proves that rocks moved slowly allowing the new planets to fling competing celestial bodies away from the pebbles.

When reproduced this way, the pebble accretion model has led to the formation of a Solar System that is identical to ours. According to Dr. Hal Levison from the aforementioned institute the generated system contained two gas planets, two ice planets similar to Uranus and Neptune and a belt similar to Kuiper.

The new discovery has already been accounted for as a valid explanation for the formation of gas giants and it could soon lead to many interesting findings.

The current study was published in the journal Nature.

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