Rocky planet with an atmosphere discovered
Using the James Webb telescope, astronomers have found a planet with a surface of molten rock, which release gases to form an atmosphere. By Will Dunham
Astronomers have searched for years for rocky planets beyond our solar system with an atmosphere – a trait considered essential for any possibility of harbouring life. Well, they finally seem to have located one. But this hellish planet, apparently with a surface of molten rock, offers no hope for habitability.
Researchers said on Wednesday, 8 May the planet is a “super-earth” – a rocky world significantly larger than our planet but smaller than Neptune. It orbits perilously close to a star dimmer than our sun, completing an orbit every 18 hours or so.
Infrared observations using two instruments aboard the James Webb space telescope indicated the presence of a substantial – if inhospitable – atmosphere, perhaps continuously replenished by gases released from a vast ocean of magma.
“The atmosphere is likely rich in carbon dioxide or carbon monoxide, but can also
have other gases such as water vapour and sulphur dioxide. The current observations cannot pinpoint the exact atmospheric composition,” 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 make clear 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 more massive than 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, its surface temperature is about 1,725°C. “Indeed, this is one of the hottest known rocky exoplanets,” said astrophysicist and study co-author Brice-olivier
Demory of the University of Bern’s Centre for Space and Habitability in Switzerland, using the term for planets beyond our solar system. “There are likely better places for a vacation spot in our galaxy.”
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 – 9.5 trillion km. 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 one is a red dwarf, the smallest kind of ordinary star.
The distance between these companions is 1,000 times the distance between Earth and the sun, and light takes six days to get from one to the other.
“The planet cannot be habitable,” Hu said, because it is too hot to have liquid water, a prerequisite for life. –