Strange mystery of ‘lost’ planets through space may be solved: ScienceAlert

Today, the number of confirmed exoplanets is 5,197 in 3,888 planetary systems, with another 8,992 candidates awaiting confirmation.

The vast majority were particularly massive planets, ranging from Jupiter to the gas giants the size of Neptune, which have a radius of about 2.5 times that of Earth.

Another group that is statistically significant are the rocky planets that measure about 1.4 Earth radii (also known as ‘super-Earths’).

This presents a mystery to astronomers, especially when it comes to the exoplanets discovered by the venerable Kepler space telescope.

Of the more than 2,600 planets discovered by Kepler, there is a distinct dearth of exoplanets with a radius of about 1.8 times the diameter of Earth – referred to as the “Valley of the Radius”.

Planet Size Diagram
Illustration depicting a rarity of exoplanets about 1.8 times the size of Earth observed by NASA’s Kepler spacecraft. (Prof. Isidoro / Rice University)

The second puzzle, known as “Peas in a Pod,” refers to neighboring planets of similar size found in hundreds of planetary systems with harmonious orbits.

In a study led by the Basic Life Cycles of Volatile Elements in Rocky Planets (Clever) Project at Rice University, an international team of astrophysicists presented a new model that explains the interaction of forces acting on newborn planets that could explain these two puzzles.

The research was led by Andre Isidoro, Welch Postdoctoral Fellow in the NASA-funded CLEVER Planets project. He was joined by planetary researchers from Clever Rajdeep Dasgupta and Andrea Isella, Helk Schleichting of UCLA, and Christian Zimmermann and Bertram Beech of the Max Planck Institute for Astronomy (MPIA).

As they describe in their research paper, which recently appeared in Astrophysical Journal LettersThe team used a supercomputer to run a planetary migration model that simulates the first 50 million years of planetary system development.

In their model, protoplanetary disks made of gas and dust also interact with the migrating planets, pulling them close to their parent stars and trapping them in resonant orbital chains.

Within a few million years, the protoplanetary disk disappears, breaking the chains and causing orbital instability that causes two or more planets to collide. While models of planetary migration have been used to study planetary systems that have retained orbital resonance, these results represent a first for astronomers.

As Isidoro said in a statement from Rice University: “I believe we are the first to explain the valley radius using a model of planetary formation and dynamic evolution that consistently explains multiple limitations of observations.

“We are also able to show that a planetary formation model that includes giant impacts is consistent with the pea feature of exoplanets.”

This work builds on previous work by Izidoro and the CLEVER Planets project. Last year, they used a migration model to calculate the maximum perturbation of the seven planetary system at TRAPPIST-1.

In an article published on November 21, 2021 in natural astronomy, they used N-body simulations to show how the “pea in a capsule” system could maintain its symmetrical orbital structure despite collisions caused by planetary migration. This allowed them to place constraints on the upper limit of collision and the mass of the objects involved.

Their results indicate that the collisions in the TRAPPIST-1 system were comparable to the impact that led to the creation of the Earth-Moon system.

“Migration of minor planets toward their host stars creates overcrowding and often results in catastrophic collisions that strip planets of their hydrogen-rich atmosphere,” Isidoro said.

“This means that giant impacts, such as those that formed our moon, are probably a general result of planet formation.”

This latest research indicates that planets come in two different types, consisting of dry, rocky planets 50 percent larger than Earth (super-Earths) and water-ice-rich planets about 2.5 times the size of Earth (mini-Neptunes).

In addition, they suggest that a small portion of planets twice the size of Earth would retain their primordial hydrogen-rich atmosphere and would be rich in water.

According to Isidoro, these findings are consistent with new observations that the super-Earths and minor Neptune are not just dry and rocky planets.

These findings present opportunities for exoplanet researchers, who will rely on the James Webb Space Telescope to make detailed observations of exoplanet systems.

Using its advanced array of optics, infrared imaging, vertebrae, and spectrometers, Webb and other next-generation telescopes will characterize the atmospheres and surfaces of exoplanets like never before.

This article was originally published by Universe Today. Read the original article.

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