Lava planets may sound like science fiction, but they're very real for astrophysics professor Dr. Lisa Dang, who is studying them as a larger team of international researchers looking to further explore their inner workings.
A lava planet is a type of rocky exoplanet that orbits extremely close to its host star. These planets are tidally locked, meaning the same side is always facing the star. This so-called dayside is hot enough to harbour an ocean of molten rock, while the other side is permanently dark.
Artistic illustration of the internal structure of a lava planet in a cold state, showing a day‑side magma ocean overlain by a mineral atmosphere. The arrows indicate the direction of heat transport within the planet's interior and the thermal radiation emitted from its night side. Credit: Romain Jean-Jacques - https://www.romainjeanjacques.com - @romainjean.jacques
In a recent paper led by Dr. Charles-Édouard Boukaré from York University, Dang and colleagues from educational institutions around the world suggest that lava planets form fully molten with a deep magma ocean covering the entire planet and, over time, the planet's dark side cools down and solidifies.
To test these predictions, the group of researchers led by Dang requested observation time on the James Webb Space Telescope (JWST), a space telescope designed to conduct infrared astronomy at great distances, for five lava planets. Observation time on the JWST is in high demand, but the group's request was approved, and they will receive content over the next year.
"When you take a photo of anything, you get a snapshot of what it looks like at that moment in time, but each snapshot tells a story, and I look forward to the stories the data from the JWST will help us tell about lava planets," Dang says.
For each of the five lava planets, the JWST will provide data throughout each planet's yearly cycle, which is only a few Earth hours. This will enable researchers to view both sides of the planet over one full rotation and make heat maps, which will give them an idea of the inner workings of the planet.
"We will monitor each planet for a full orbit to capture a full rotation," Dang says. "We hope to learn more about their dark side to further understand the interior evolution of these exoplanets."
Dang and her team at Waterloo will take the lead on analyzing the data sets when they start rolling in from the JWST in 2026. The five planets they are observing are of varying ages, so they can learn what these exoplanets look like at different stages of life. As each data set comes in, they will pull it apart, challenge their predictions, and come up with new ones.
They want to know how the planet's heat budget and composition change over the lifespan of the planet and whether the magma oceans ever shrink or solidify as they age. They will also be looking for what molecules are present, what's different between the planets, and what is missing that they hadn't anticipated.
This data will be the most in-depth Dang has ever worked on when it comes to lava planets, and she is eagerly anticipating its arrival and what it could mean for her research.
The paper, "The role of interior dynamics and differentiation on the surface and in the atmosphere of lava planets," was published in Nature Astronomy.
