Having lost its original atmosphere, this bizarre planet is becoming a new one

Who says you can’t lose your atmosphere to a nearby red dwarf then grow a new one using volcanic activity? Tits resilient planet, located 41 light-years of Earth, seems to thrive again after a difficult meeting with his host star.

The exoplanet GJ 1132 b is both similar and very different from Earth. Of course, it is several times larger than our planet, but the two worlds share similar densities and atmospheric pressures, and both began around 4.5 billion years ago. And like our planet, it started out hot, with an atmosphere rich in hydrogen, then gradually cooled.

The histories of these two planets are distinctly different, however.

While the Earth has always been a terrestrial and rocky world, GJ 1132 b began its life as a gas, Planet similar to Neptune. But as new research shows, a nearby red dwarf erased its original atmosphere rich in hydrogen and helium with powerful radiation, so that GJ 1132 b, having been stripped down to its rocky core, is now technically a terrestrial planet. The new article will appear in an upcoming issue of the Astronomical Journal, but a pre-print is available at arXiv.

The authors of the article reached these conclusions based on direct observations of the exoplanet and theoretical modeling. The telescope of choice was the The Hubble Space Telescope, which enabled the team to spot the “secondary atmosphere,” which consists of molecular hydrogen, hydrogen cyanide, methane, and a smog-like aerosol haze on Earth.

“It’s super exciting because we think the atmosphere we see now has been regenerated, so it could be a secondary atmosphere,” Raissa Estrela, study co-author and planetary at NASA’s Jet Propulsion Laboratory in Southern California, explained in a declaration. “We initially thought that these highly irradiated planets could be quite boring because we thought they had lost their atmosphere. But we looked at the existing observations of this planet with Hubble and we said, ‘Oh no, there’s an atmosphere there.’ “

In terms of explanation, the authors say that much of the current hydrogen on the planet was retained before, after being absorbed into the mantle of molten magma. According to research, volcanic processes are now causing stored hydrogen to leak from below, refueling the new atmosphere.

“This process works early in a planet’s life, when the star is hotter,” JPL scientist Mark Swain said, lead author of the study, in the NASA press release. “Then the star cools down and the planet is just sitting there. So you have this mechanism where you can cook the atmosphere for the first 100 million years and then things calm down. And if you can regenerate the atmosphere, you may be able to keep it.

GJ 1132b, which only takes 1.5 days to make a full orbit of its hungry host star, is likely prone to tidal warming, in which gravitational forces spin the planet from within. The exoplanet, despite its short year, is in an elliptical orbit, resulting in an effect known as “gravitational pumping”. As the GJ 1132b swings back and forth, it alternates between crushing and stretching actions, producing a motor that drives the tidal forces. and, in turn, the preservation of a liquid mantle.

The surface of this exoplanet is probably not very thick, maybe only a few hundred feet deep, according to the authors. The land is probably quite flat, with cracks caused by tidal pumping actions, from which hydrogen escapes regularly.

The new study has implications for the study of similar worlds located elsewhere in the galaxy.

“The detection of an atmosphere on this rocky planet raises the possibility that the many powerfully irradiated super-terrestrial planets, considered to be the evaporated nuclei of sub-neptunes, may, under favorable circumstances, harbor detectable atmospheres,” the authors write. in studying it.

The big question now is, how often does this happen? Is it just a bizarre occurrence? This could be answered by the next James Webb Space Telescope, which, with its infrared capabilities, should be able to easily spot such planets. In addition, JWST could also be used to study GJ 1132 b and provide new data to assert these results.