Lava worlds, huge exoplanets with bright skies and raging volcanic seas called magma oceans, are nothing like the planets in our solar system.

To date, approximately 50% of all exposed rocky exoplanets have been found to be able to retain magma on their surfaces, likely because these planets are so close to their host star that they orbit in less than 10 days. Being so close, the planet is bombarded by harsh weather, raising its surface temperature to extremes, making it nearly uninhabitable for life as we know it today.

Now, in a new study, scientists have shown that these vast molten oceans have a major impact on the observed properties of hot rocky Super-Earths, such as their size and evolutionary paths.

Recently published works Astrophysical JournalHe found that, due to the highly compressible nature of lava, magma oceans can cause lava-rich planets without atmospheres to be slightly denser than solid planets of the same size, and can also affect the structure of mantles, the thick inner layer surrounding the Earth. core planets

Even so, characterizing the basic workings of lava planets can be a difficult task because these objects have not been adequately studied, said Kirsten Boley, the study’s lead author and a graduate student in astronomy at Ohio State University.

“Lava worlds are very strange, very interesting things, and we are more biased in finding them because of the way we detect exoplanets,” said Bowley, whose research focuses on understanding what the key components are that make exoplanets unique and how to tune those elements. or, in the case of lava worlds, their temperature can completely transform them.

One of the most famous of these mysterious burning worlds is 55 Cancri e, an exoplanet about 41 light-years away that scientists say is home to bright skies and turbulent lava seas.

Although there are extremely volcanically active objects in our solar system, such as Jupiter’s moon Io, there are no actual lava planets in our region of space that scientists can study up close and personal. But examining how the composition of igneous oceans affected the evolution of other planets — such as how long they remained molten and why they eventually cooled — could offer clues to Earth’s own fiery past, Boley said.

“When planets first form, especially rocky terrestrial planets, they go through the magma ocean stage as they cool,” Boley said. “So lava worlds can give us a glimpse of what might have happened in the evolution of almost any terrestrial planet.”

Using Exoplex’s built-in exoplanet simulation software and data collected from previous studies to create a module containing information about various types of magma compositions, the researchers modeled various evolutionary scenarios for a terrestrial planet with surface temperatures between 2,600 and 3,860 degrees Fahrenheit. The melting point at which the planet’s solid mantle will turn into liquid.

From the models they created, the team was able to discern that the mantles of magmatic ocean planets can take one of three forms: the first, when the entire mantle is completely molten, the second, when the magma ocean is at the surface, and the second. The third sandwich model consists of a magma ocean at the surface, a layer of solid rock in the middle, and another layer of molten magma closest to the planet’s core.

The results show that the second and third forms are slightly more common than fully molten planets. Depending on the composition of their igneous oceans, some atmosphereless exoplanets are better than others at trapping volatile elements (compounds such as oxygen and carbon that were needed to form the first atmospheres) over billions of years.

For example, the study notes that a basal magma-class planet that is 4 times larger than Earth could hold more than 130 times the mass of water found in Earth’s oceans today and nearly 1,000 times the amount of carbon currently present on Earth. surface of the planet. and shell.

“When we talk about the evolution of a planet and its potential to have a variety of elements necessary to support life, the ability to trap many volatile elements in their mantle may have larger impacts on habitability,” Boley said.

Lava planets are still a long way from being sufficiently habitable, but it’s important to understand the processes that helped these worlds get to that point. Still, this study makes clear that measuring the density of these worlds when comparing them to solid exoplanets is not the best way to characterize these worlds because a magma ocean does not significantly increase or decrease the density of its planet, Boley said.

Instead, their research suggests that scientists should focus on other terrestrial parameters, such as fluctuations in the planet’s surface gravity, to test their theories about how hot lava worlds work, especially if future researchers plan to use their data to help studies of larger planets.

“This study, a combination of earth sciences and astronomy, fundamentally raises interesting new questions about lava worlds,” Boley said. Source