(ORDO NEWS) — Today, telescopes have been able to detect thousands of exoplanets, but there is a big gap in the distribution of their radii for some reason, there are several times fewer celestial bodies with a certain radius than others. Now scientists have come up with a possible explanation.
The number of discovered exoplanets has exceeded 5 thousand, but among them there are so few celestial bodies with a radius of 1.8 of the earth. It seems that scientists have found the answer to this mystery.
To date, the number of confirmed exoplanets is 5,197 in 3,888 planetary systems, with 8,992 more candidates awaiting confirmation.
Most of them belong to the class of massive planets – gas giants the size of Jupiter and Neptune, the radii of which are about 2.5 times greater than that of the Earth.
Another statistically significant population was the rocky planets, which have a radius of about 1.4 Earths (aka “super-Earths”). And here lies the mystery.
If you look at a graph of more than 2,600 planets discovered by the Kepler telescope, you can see the area that scientists have dubbed the “radius valley” – this is a dip in the number of exoplanets with a radius of 1.8 Earth’s.
The second mystery, known as the “peas in a pod problem,” describes similarly sized neighboring planets found in hundreds of planetary systems with harmonious orbits.
Where did the planets go?
In a study conducted by the Life Cycles Essential Volatile Elements on Rocky Planets (CLEVER) project at Rice University, an international team of astrophysicists has presented a new model that takes into account the interaction of forces in systems with newborn planets.
According to astronomers, she can explain these two mysteries.
The authors used a supercomputer to run a planetary migration model that simulated the first 50 million years of a planetary system.
In their model, protoplanetary disks of gas and dust also interact with migrating planets, pulling them closer to their parent stars and locking them into resonant orbits.
Over the course of several million years, the protoplanetary disk disappears, breaking chains and causing orbital instability that results in two or more planets colliding.
This latest study suggests that systems come in two flavors: those made up of dry and rocky planets that are 50 percent larger than Earth (“super-Earths”) and planets rich in water ice about 2.5 times the size of Earth (“mini-Neptunes”).
In addition, the results of the work suggest that part of the planets, twice the size of the Earth, will retain their original atmosphere rich in hydrogen and will be rich in water.
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