How do water and hydrogen interact in planetary evolution? This is what a recent study published in The Astrophysical Journal Letters hopes to address as a team of researchers investigated the atmospheric interiors of planets and how these aid in their formation and evolution. This study has the potential to help astronomers better understand the intricate processes responsible for planetary formation and evolution, much of which is still not understood.
“We usually think of basic physics and chemistry as being known already,” said Dr. Lars Stixrude, who is a professor in the Department of Earth, Planetary, and Space Sciences at UCLA and a co-author on the study. “We know when things are going to melt and when they're going to dissolve and when they're going to freeze. But when it comes to the deep insides of planets, we just don't know. There’s no textbook where we can look these things up, and we have to predict them.”
For the study, the researchers used a series of computer models to simulate the interaction between water and hydrogen at various temperatures and pressures with the goal of ascertaining how their interaction results in the formation and evolution of planetary atmospheres. In the end, the researchers found that along with temperature and pressure increasing together, they also observed fluid structure changes occurring at 30 gigapascals (30,000,000,000 pascals) and 3000 Kelvin (4,940 degrees Fahrenheit/2,727 degrees Celsius). For context, Earth’s atmosphere experiences 101,325 pascals and its average atmospheric temperature is 59 degrees Fahrenheit (15 degrees Celsius).
The researchers note these findings could help better understand exoplanets with hydrogen atmospheres, most notably K2-18 b and TOI-270 d, which are both hypothesized to be habitable exoplanets with hydrogen atmospheres resting above liquid water oceans.
Artist's illustration of K2-18 b. (Credit: ESA/Hubble, M. Kornmesser)
“If water and hydrogen are indeed substantially mixed throughout a planet’s interior, the structure and thermal evolution of Earth- and Neptune-like exoplanets can be substantially different from the standard models typically used in the field,” said Dr. Hilke Schlichting, who is a professor & associate dean for research in the Department of Earth, Planetary, and Space Sciences at UCLA and a co-author on the study. “On the other hand, planets that are colder could have a separate layer enriched in water, possibly in liquid form.”
What new discoveries into planetary atmospheres, formation, and evolution will researchers make in the coming years and decades? Only time will tell, and this is why we science!
As always, keep doing science & keep looking up!
Sources: The Astrophysical Journal Letters, EurekAlert!, UCLA Newsroom
