Bizarre mystery of ‘missing’ planets in space may be solved

(ORDO NEWS) — Today, the number of confirmed exoplanets is 5197 in 3888 planetary systems, with 8992 more candidates awaiting confirmation.

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

Another statistically significant population was the rocky planets, which measure about 1.4 Earth radii (also known as “super-Earths”).

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

Of the more than 2,600 planets discovered by Kepler, there is an apparent rarity of exoplanets with a radius of about 1.8 times Earth’s. – which they call “radius valley”.

Bizarre mystery of missing planets in space may be solved 2
An illustration showing the shortage of exoplanets roughly 1.8 times the size of Earth that NASA has observed. spacecraft Kepler

The second mystery, known as “peas in a pod,” has to do with similarly sized nearby planets found in hundreds of planetary systems with harmonious orbits.

In research from Rice University’s Cycles of Life-Essential Volatile Elements in Rocky Planets (CLEVER) project, an international team of astrophysicists proposes a new model that explains the interaction of forces acting on newborn planets. this could explain these two mysteries.

The study was led by André Isidoro, a Welsh postdoctoral fellow at NASA-funded Rice CLEVER Planets. He was joined by fellow CLEVER Planets researchers Rajdeep Dasgupta and Andrea Isella, Hilke Schlichting of the University of California, Los Angeles (UCLA), and Christian Zimmermann and Bertram Biesch of the Max Planck Institute for Astronomy (MPIA).

As they described in their research paper, which was recently published in the Astrophysical Journal Letters , the team used a supercomputer to run a planetary migration model that simulated the first 50 million years of the planetary system’s development.

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 orbital chains.

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.

While planetary migration models have been used to study planetary systems that have retained orbital resonances, these discoveries represent a first for astronomers.

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

“We can also show that the planet formation model, which includes giant impacts, is consistent with exoplanets like peas in a pod.”

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

In a paper published Nov. 21, 2021 in the journal Nature Astronomy, they used N-body simulations to show how this pea-in-a-pod system could maintain its harmonious orbital structure despite collisions caused by planetary migration.

This allows ed them to impose limits on the upper limit of collisions and the mass of objects involved.

Their results show that the TRAPPIST-1 collisions were comparable to the impact that created the Earth-Moon system.

Isidoro said: “The migration of young planets to their stars creates overpopulation and often leads to catastrophic collisions that deprive the planets of their hydrogen-rich atmospheres.”

“That means giant hits. , like the one that formed our Moon, are probably a common result of the formation of the planets.”

This latest study suggests that planets come in two varieties: dry and rocky, which are 50% larger than Earth. (super-Earths) and planets that are rich in water ice about 2.5 times the size of Earth (mini-Neptunes).

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

According to Isidoro, those results are consistent with new observations that suggest super-Earths and mini-Neptunes are not exclusively dry and rocky planets.

These results open up opportunities for exoplanet researchers who will rely on the James Webb Space Telescope to make detailed observations of exoplanet systems.

Using an advanced suite of optics, infrared imaging, coronagraphs and spectrometers, Webb and other next-generation telescopes will characterize exoplanet atmospheres and surfaces like never before.

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