WASHINGTON — Astronomers have searched for years for rocky planets outside our solar system with an atmosphere — a feature considered essential for any ability to harbor life. They seem to have finally found one. However, it has a surface of molten rock, which offers no hope of habitability.
Researchers said Wednesday that the planet is a “super-Earth” — a rocky world significantly larger than our planet but smaller than Neptune — and that it orbits dangerously close to a fainter star and is slightly less massive than our Sun. rapidly completing an orbit around the Earth every 18 years. hour or so.
Infrared observations using two instruments aboard the James Webb Space Telescope indicated the presence of a significant – if inhospitable – atmosphere, perhaps continually replenished by gases released from a vast ocean of magma.
“The atmosphere is likely rich in carbon dioxide or carbon monoxide, but may also contain 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.
The Webb data also did not reveal the thickness of the atmosphere. Hu said it could be as thick as Earth’s, or even thicker than that of Venus, whose toxic atmosphere is the densest in our solar system.
The planet, called 55 Cancri e or Janssen, is about 8.8 times as massive as Earth, with a diameter about twice that of our planet. It orbits its star at one 25th the distance between our solar system’s innermost planet, Mercury, and the Sun. As a result, the surface temperature is approximately 3140 degrees Fahrenheit.
“Indeed, this is one of the best known rocky exoplanets,” said astrophysicist and study co-author Brice-Olivier Demory of the Center for Space and Habitability at the University of Bern in Switzerland, using the term for planets beyond our solar system. “There are probably better places for a vacation spot in our galaxy.”
The planet is likely tidally locked, meaning it constantly faces the same side toward its star, just 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: 5.9 trillion miles. Four other planets, all gas giants, are known to orbit its host star.
That star is gravitationally bound to another star in a binary system. The other is a red dwarf, the smallest type of ordinary star. The distance between these companions is a thousand times the distance between the Earth and the Sun, and light takes six days to travel from one to the other.
There are probably better places for a vacation spot in our galaxy.
–Brice-Olivier Demory, University of Bern
After all their searching, the rocky exoplanet for which scientists finally found evidence of an atmosphere turned out to be one that probably shouldn’t even have one. Because it is so close to its star, any atmosphere should be stripped away by stellar radiation and winds. But gases dissolved in the vast lava ocean thought to cover the planet may continue to bubble up to replenish the atmosphere, Hu said.
“The planet cannot be habitable,” 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 gaseous planets, not rocky planets. As 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 humans breathe, protects against solar radiation and creates the pressure needed for liquid water to remain on the Earth’s surface.
“On Earth, the atmosphere is the key to life,” Demory said. “This result at 55 Cnc e raises hopes that Webb could conduct similar research on planets much cooler than 55 Cnc e, which could support liquid water on their surfaces. But we’re not there yet.”