Science and Nature

Scientists may have discovered the first evidence for tectonic activity on exoplanet

Scientists may have discovered the first evidence for tectonic activity on exoplanet thumbnail

This illustration shows the possible interior dynamics of the hot super-Earth LHS 3844b. (Image: Thibaut Roger / University of Bern)

Since its discovery in 2018 by the National Aeronautics and Space Administration’s (NASA) Transiting Exoplanet Survey Satellite (TESS), astronomers have been studying the exoplanet named LHS 3844b. A recent study at the University of Bern, Switzerland using the data collected by TESS reveals that one side of the planet is tectonically active and volcanoes could be lighting up its night sky.

The LHS 3844b is an exoplanet that is tidally locked to its star which means that one side of it is permanently facing the star while the other faces the space. The side that faces the Sun records temperatures up to 770 degrees Celsius while the other records temperatures below 250 degrees Celsius.

As per the study published in Astrophysical Journal Letters, astronomers believe that the severe temperatures on the planet could affect the planet’s interior. To test this, they ran simulations with different strengths of material and internal heating sources, such as heat from the planet’s core and the decay of radioactive elements.

“Most simulations showed that there was only upwards flow on one side of the planet and downwards flow on the other,” lead author Dr Tobias Meier, an astronomer in the Center for Space and Habitability at Bern, said in a statement from the university. “Material therefore flowed from one hemisphere to the other. Surprisingly, the direction was not always the same.”

The co-author of the study working at the Center for Space and Habitability at the University of Bern, Dr Dan Browner pointed out that based on what happens on Earth, the material on the hot side of the planet was expected to be lighter, flowing upwards and vice versa on the dark side.

Browner explained the consequences of different flow of material on the exoplanet. “Yet, some of the simulations also showed the opposite flow direction. This initially counter-intuitive result is due to the change in viscosity with temperature: cold material is stiffer and therefore doesn’t want to bend, break or subduct into the interior. Warm material, however, is less viscous — so even solid rock becomes more mobile when heated — and can readily flow towards the planet’s interior,” he said.

“Such material flow could have bizarre consequences. On whichever side of the planet the material flows upwards, one would expect a large amount of volcanism on that particular side,” he added.

He compared the volcanic activity on the exoplanet with that of Hawaii and Iceland as well due to deep upwelling flows. He also believes that LHS 3844b may have a whole hemisphere filled with countless volcanoes and the other one with almost none.

On the other hand, Dr Mier feels that it would require more observations to verify such a conclusion. If their observations are correct, a higher-resolution map of the surface temperature can reveal that the planet has “enhanced outgassing from volcanism, or detection of volcanic gases”.

The LHS 3844b is 1.3 times Earth in size and has 2.25 times the mass. It takes just 11 hours for the planet to complete its orbit around its Sun which is a red-dwarf star almost one-fifth size of our Sun.

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