WASHINGTON – Astronomers have searched for years for rocky planets outside our solar system that have atmospheres, a trait considered essential for any possibility of harboring life. It looks like they’ve finally located a location. However, it has a surface of molten rock, which offers no hope of habitability.
The planet is a “super-Earth” — a rocky world much larger than our planet but smaller than Neptune — that orbits perilously close to a faint star slightly less massive than our Sun, rapidly completing its orbit every 18 hours or so, researchers said Wednesday.
Infrared observations using two instruments aboard the James Webb Space Telescope have indicated the presence of a significant — albeit inhospitable — atmosphere, perhaps constantly replenished by gases emanating from a vast ocean of magma.
“The atmosphere is likely rich in carbon dioxide or carbon monoxide, but it could also contain other gases such as water vapor and sulfur dioxide,” said planetary scientist Renyu Hu of NASA’s Jet Propulsion Laboratory and the California Institute of Technology. Determine the precise composition of the atmosphere. , lead author of the study published in the journal Nature.
Webb’s data also did not show the thickness of the atmosphere. He said it could be as thick as Earth or even 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 more massive than Earth, and has a diameter about twice that of our planet. It orbits its star at a distance of 25 of the distance between the planet Mercury and the Sun, and is the deepest planet in our solar system. As a result, its surface temperature is about 3140 degrees Fahrenheit.
“In fact, this is one of the hottest rocky planets known,” said astrophysicist and study co-author Brice-Olivier Demaury of the Center for Space and Habitability of the University of Bern in Switzerland. “There are probably better places to vacation in our galaxy.”
The planet is likely tidally locked, meaning it always faces the same side as its star, much as the Moon does toward Earth. The 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, which is 5.9 trillion miles. Four other planets, all gas giants, are known to orbit their host star.
This star is gravitationally bound to another star in a binary system. The other is a red dwarf, which is the smallest type of regular star. The distance between these companions is 1,000 times the distance between the Earth and the Sun, and it takes six days for light to travel from one to the other.
There are probably better vacation spots in our galaxy.
– Brice Olivier Demaury, University of Bern
After all the searching, it turns out that the rocky exoplanet, which scientists have finally found evidence of having an atmosphere, is a planet that probably shouldn’t have one. Because it is so close to its star, any atmosphere must be stripped from it by stellar radiation and winds. Dissolved gases in the vast lava ocean believed to cover the planet may continue to boil off to replenish the atmosphere, Hu said.
“The planet cannot be habitable,” Hu said, because it is so hot that there is no liquid water, a basic condition for life.
All previous exoplanets that were discovered to have atmospheres were gaseous, not rocky. While Webb pushes the boundaries of exoplanet exploration, the discovery of a rocky planet with an atmosphere represents progress.
On Earth, the atmosphere warms the planet, contains the oxygen that people breathe, protects from solar radiation and creates the pressure necessary for liquid water to remain on the planet’s surface.
“On Earth, the atmosphere is the key to life,” Demory said. “This result on 55 Cnc e raises hope that Webb can perform similar investigations on planets much cooler than 55 Cnc e, which could support the presence of liquid water on their surfaces. But we are not there yet.”
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