Do Trojan planets exist?

A study on the so-called Trojan planets has been published. These objects could form in the same orbits as gas giants. However, over time, their orbits become unstable due to tidal forces.

Can whole planets form instead of Trojan asteroids? Source: NASA/JPL-Caltech

Trojan planets could exist

There may be several planets in the same orbit around a star. This follows from the existence of Lagrange points L4 and L5. When a large body rotates around a star, then in its orbit at 60 degrees in front and 60 degrees behind, there are points where the gravity of all bodies are balanced.

In the solar system, such points are called Trojan and there are many asteroids in them. Those who fly in front and behind Jupiter have the names of heroes of the Trojan War, from where all such objects got their name.

Lagrange points of the system. Source:

Theoretically, nothing prevents a much larger body from forming in the orbit of some gas giant. It can reach the size of Mercury, or even the Earth. However, so far, nothing like this has been found among 5,000 confirmed exoplanets.

Destructive effect of tidal forces

A new study is devoted to the question of why there are no objects at Lagrange points among open bodies. The first part of the answer is that we mostly see either objects very close to the star, or having a significant gravitational effect. Trojan planets by their nature cannot be either the first or the second.

The second part of the answer contains a simulation of a planetary system containing a Trojan planet. You can read more about it in the Icarus magazine. Scientists have found that the tidal forces of the gas giant for millions of years affect the orbit of the body at the Lagrange point. It begins to move along a trajectory that increasingly resembles the shape of a banana.

This ends with the Trojan planet being thrown out of the system. Therefore, if such objects can be found, then it is necessary to look for them in young systems. As other studies have shown, they may be suitable for life much better and for completely different reasons.

According to

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