Astronomers finally detect a rocky planet with an atmosphere

Astronomers finally detect a rocky planet with an atmosphere

Astronomers have been searching for years for rocky planets outside our solar system with atmospheres – properties considered essential for any possibility of harboring life. Well, they finally seem to have found one. But this hellish planet – apparently with a surface of molten rock – offers no hope of habitation.

Researchers said on Wednesday that the planet is a “super-Earth” – a rocky world much larger than our planet but smaller than Neptune – and that it orbits very close to a star that is fainter and slightly less massive than our sun, quickly completing orbit every 18 hours or so.

Infrared observations using two instruments aboard the James Webb Space Telescope indicate the presence of a large atmosphere – if not hospitable, perhaps replenished continuously by gases released from a vast ocean of magma.

“The atmosphere is likely to be rich in carbon dioxide or carbon monoxide, but can also have other gases such as water vapor and sulfur dioxide. Current observations cannot determine the exact composition of the atmosphere,” said planetary scientist Renyu Hu of NASA’s Jet Propulsion Laboratory and Caltech. , lead author of the study published in the journal Nature.

Webb’s data also do not clearly explain the thickness of the atmosphere. Hu said it could be as thick as Earth or thicker than Venus, whose toxic atmosphere is the densest in our solar system.

The planet, called 55 Cancri e or Janssen, is about 8.8 times larger than Earth, with a diameter about twice that of our planet. It orbits its star at a distance of one-25th the distance between our solar system’s innermost planet Mercury and the sun. As a result, its surface temperature is about 3,140 degrees Fahrenheit (1,725 degrees Celsius/2,000 degrees Kelvin).

“Indeed, this is one of the most famous rocky exoplanets,” said astrophysicist and study co-author Brice-Olivier Demory of the Center for Space and Habitability of the University of Bern in Switzerland, using the term for planets outside our solar system. “There’s probably a better place for a vacation spot in our galaxy.”

The planet may be tidally locked, meaning it always has the same side facing its star, just as the moon faces Earth. This planet is located in our Milky Way galaxy about 41 light years from Earth, in the constellation Cancer. A light year is the distance light travels in a year, 5.9 trillion miles (9.5 trillion km). Four other planets, all gas giants, are known to orbit their host stars.

The star is gravitationally bound to other stars in the binary system. The other is a red dwarf, the smallest type of normal star. The distance between these companions is 1,000 times the distance between the Earth and the sun, and light takes six days to travel from one to the other.

After all their searching, the rocky exoplanet that scientists finally found evidence of an atmosphere for turns out to be one that probably shouldn’t exist. Being so close to its star, any atmosphere should be stripped away by stellar radiation and wind. But gases dissolved in the vast ocean of lava thought to cover the planet may continue to bubble up to replenish the atmosphere, Hu said.

“This planet is uninhabitable,” Hu said because it is too hot to have liquid water, which is considered a prerequisite for life.

All previous exoplanets found to have atmospheres were gas planets, not rocky planets. As Webb pushes the boundaries of exoplanet exploration, the discovery of rocky rocks with atmospheres represents progress.

On Earth, the atmosphere warms the planet, contains the oxygen that humans breathe, protects against solar radiation and creates the pressure necessary for liquid water to remain on the planet’s surface.

“On Earth, the atmosphere is key to life,” Demory said. “These results at 55 Cnc e give hope that Webb can conduct similar investigations of planets much cooler than 55 Cnc e, which could support liquid water on their surfaces. But we’re not there yet.”