The first super-Earth discovered by astronomers has been emitting strange signals for almost two decades, and scientists may have finally figured out why. A new study shows that volcanoes on this netherworld periodically erupt and release hot gas that forms the atmosphere, but the atmosphere burns away, leaving the planet bald again. Testing this theory will involve training the James Webb Space Telescope (JWST) on the strange exoplanet.

Planet 55 Cancri e is a rocky world approximately eight times larger than our planet and was discovered in 2004 about 40 light-years from Earth.

The planet is so close to its parent star that it makes a complete revolution in just 17 hours, less than 2% of the distance between Earth and the Sun. This creates rather unexplained extreme conditions on the planet. Perhaps the most mysterious aspect of the planet is the nature of its transit signal, as outlined in a paper accepted into the Astrophysical Journal Letters in September. This is the light seen from Earth when 55 Cancri e passes the surface of its parent star, creating a small eclipse, and the light seen when the planet passes behind its star.

Sometimes the planet itself emits no visible light when it passes behind the star 55 Cancri e, while other times the planet emits a strong visible light signal. There is always a signal in infrared light, even though the signal strength varies.

Observations of this infrared light by the Spitzer Space Telescope showed that the dayside of the planet is subject to extremely scorching temperatures exceeding 4,400 degrees Fahrenheit (2,427 degrees Celsius), while the night side has a cooler but still hellish temperature of about 2,060 degrees Fahrenheit. (1127C).

In the new study, the authors suggest that the planet’s proximity to its star causes gas to be expelled, meaning giant volcanoes and thermal springs are opening up, releasing hot, carbon-rich elements into the atmosphere. However, the planet cannot remain in this atmosphere for long due to the intense heat, and this gas will eventually evaporate, leaving the planet exposed until outgassing begins again.

Unlike most planets, 55 Cancri e’s atmosphere is unstable. As the gas extraction process works to increase the atmosphere, excessive radiation from the star and the solar wind blow it away. However, these two processes are not balanced, resulting in a situation where the planet sometimes has an atmosphere and sometimes does not.

Researchers believe this imbalance in the planet’s atmosphere could explain the strange transit signals. When a planet is in its “bald” stage, where it has no atmosphere, visible light does not escape the planet’s atmosphere because it is absent, but the planet’s hot surface still emits infrared light. As the atmosphere expands, both visible light and all radiation from the surface are detected in the transit signal.

While this is just a hypothesis, JWST offers a way to test it. By measuring the pressure and temperature of the planet’s atmosphere, scientists were able to determine whether an atmosphere was always present. Source