The nearby juvenile star bombards them with intense radiation. It probably “bakes” any surface oceans, lakes or rivers, which is a disaster if you’re looking for places where life can arise or exist.
That’s because life needs water, and the planets around these stars are among the most likely to harbor life. But it doesn’t look so hopeful if the radiation evaporates the water.
Researchers at the University of Cambridge in the UK created a complex model that describes a world with most of its water locked deep below the surface, not in pools or oceans, but in rocks.
Technically, it is trapped in minerals deep below the surface. If conditions are right, worlds around these most common stars in the galaxy could have enough water in them to equal several Earth oceans.
Cambridge PhD student Clare Guimond, along with two other researchers, came up with the model, which describes newborns around M-type worlds orbiting red dwarf stars.
“We wanted to investigate whether, after such a tumultuous upbringing, these planets could rehabilitate themselves and continue to host surface water,” she said.
Her team’s work shows that these planets could be a very good way to replace liquid surface water that was chased away in the host star’s early life.
“The model gives us an upper limit on how much water a planet can carry at depth, based on these minerals and their ability to take water into their structure.”
Sequestration of water on a forming world
M-type red dwarfs are the most common stars in the galaxy. This makes them good subjects for studying the variables of planetary formation. They form just like other stars do.
Once they are young, they also tend to be explosive and temperamental, just like other stars. However, they remain colic much longer than other stars. That does not bode well for the surfaces of any nearby planets (or protoplanets).
If it is not baked away, the water migrates underground. But would that happen to any rocky planet? What size world would it take to do this?
The team found that a planet’s size and amount of water-bearing minerals determine how much water it can “store”.
Most end up in the upper mantle. The rocky layer lies directly below the crust. It is usually rich in so-called “anhydrous minerals.”
Volcanoes feed off this layer, and their eruptions can eventually bring steam and vapor back to the surface through eruptions.
The new research showed that larger planets – about two to three times the size of Earth – typically have drier rocky mantles. This is because the water-rich upper mantle makes up a smaller part of its total mass.
Hidden Water and Planetary Science
This new model helps planetary scientists understand not only the conditions at Earth’s birth, but also the water-rich objects that aggregate to form planets. But it is actually more aimed at the formation environment of larger rocky planets around M-type red dwarfs.
Thanks to the extreme youth of their star, these worlds likely experienced chaotic climatic conditions for long periods. They could have worked to send liquid water deep underground. Once their stars settled down, the water could emerge in different ways.
The model could also explain how Venus could have gone from being a barren hellscape to an aqua world early on. The question of Venus’ water is of course still hotly debated.
But if it had liquid pools and oceans four billion years ago, how did they happen?
“If that happened, Venus must have found a way to cool itself and recover surface water after being born around a burning sun,” said Guimond’s research partner Oliver Shorttle.
“It’s possible that it tapped into its internal water to do this.”
Implications for Exoplanet Searches
Finally, the current research may provide new directions in the search for habitable exoplanets in the rest of the galaxy. “This can help refine our triaging of which planets to study first,” Shorttle said.
“When we’re looking for the planets that can best hold water, you’re not likely to have one significantly more massive or wildly smaller than Earth.”
The factors in Guimond’s model also have implications for the formation and mineralogy of rocky planets. More specifically, it can explain what is hidden inside a planet, especially between the surface and the mantle.
Future research will likely look at the habitability and climate of both rock-rich and surface water-rich worlds.
This article was originally published by Universe Today. Read the original article.