Hubble sees a new atmosphere form on a rocky exoplanet

Planet GJ 1132 b seems to have started as a gaseous world with a thick blanket of atmosphere. Beginning at several times the Earth’s radius, the so-called “sub-Neptune” lost its prime atmosphere of hydrogen and helium, which was removed by the intense radiation from its hot, young star. In a short time, it was reduced to a bare heart about the size of the Earth.

To the surprise of astronauts, new ideas from Hubble [1] has discovered a secondary atmosphere that has replaced the first atmosphere on the planet. It is rich in hydrogen, hydrogen cyanide, methane and ammonia, and also contains hydrocarbon bark. Astronomers claim that hydrogen from the original atmosphere was introduced into the planet’s molten magma and is now slowly released by volcanism to create fresh air. This second atmosphere, which continues to leak into space, is regularly replenished from a hydrogen reservoir in the healthy magma.

“This second feeling comes from the surface and interior of the planet, so it’s a window on the geology of another world,” explained team member Paul Rimmer from Cambridge University, UK. “A lot more work needs to be done to look through it, but finding this window is very important.”

“We initially thought these radiation-filled planets would be very thin because we believed they lost their atmospheres,” said a member of the Raissa Estrela team of the Jet Propulsion Laboratory at the California Institute of Technology in Pasadena, California, USA. But we looked at the preconceived notions of this planet with Hubble and realized that there is a feeling. “

“How many terrestrial planets don’t start as boundaries? Some can start as sub-Neptunes, and they become terrestrial areas through a device where light evacuates the private atmosphere. This process works early in life planet, when the star is warmer, “said team leader Mark Swain of the Propulsion Laboratory. “Then the star cools and the planet just sits there. So you have this equipment that can cook the atmosphere in the first 100 million years, and then settle And if you can refresh the atmosphere, maybe you can keep it. “

In some ways, GJ 1132 b has several parallels to Earth, but in some ways it is also quite different. Each has an equal density, equal sizes, and equal ages, about 4.5 billion years old. They both started feeling full of hydrogen, and both were hot before they cooled down. The team’s work even suggests an atmospheric pressure similar to GJ 1132 b and the Earth at the surface.

However, the history of the creation of the planets is quite different. The Earth is not believed to be the remaining heart of sub-Neptune. And the Earth rises at a comfortable distance from our yellow sun. GJ 1132 b is so close to its host red dwarf star that it completes the star’s orbit once every day and a half. This close range keeps GJ 1132 b locked fast, always showing the same face as its star – just as our moon holds one hemisphere permanently in front of the Earth. .

“The question is, what keeps the healthy hot enough to stay the liquidity and power of volcanism?” asked Swain. “This system is unique because it has the opportunity to do a lot of tidal heating.”

Tidal warming occurs through freezing, when energy from the orbit and orbit of a planet is distributed as heat within the planet. GJ 1132 b is in elliptical orbit, and has the strongest tidal forces when it is closer to or farther from the host star. At least one other planet in the host star system will also be drawing attention to the planet. The effect is that the planet is compressed or stretched by this gravity “pumping”. Heating that tide keeps the liquid melting for a long time. A nearby example in our own Solar System is the Jovian moon, Io, which has a continuous volcanism as a result of a tidal tug-of-war between Jupiter and the nearby Jovian branches.

The team thinks the bark of GJ 1132 b is very thin, probably just hundreds of feet thick. That is far too important to support anything that looks like volcanic mountains. Its flat ground can also be broken as an egg by a tidal wave. Hydrogen and other gases could be released through these cracks.

“Perhaps this feeling, if narrow – meaning if surface pressure is similar to Earth – means you can see straight down to the ground at infrared waves. That means if astronauts use James Webb ‘s space telescope to look at this planet has the potential to see not the spectrum of the atmosphere, but the spectrum of the surface, “Swain explained. “And if magma or volcanic pools go on, those areas will get hotter. That would generate more emissions, so they might be looking at the real geological activity – which is exciting!”

This result is important because it allows exoplanet scientists to figure out something about the geology of a planet from its atmosphere, “Rimmer said.” It is also important to understand where the rocky planets are in the System Our own solar system – Mercury, Venus, Earth and Mars, fits into the bigger picture of a comparable planet, in terms of the amount of hydrogen available against oxygen in the atmosphere. “

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[1] The comments were made as part of the Hubble # 14758 observation program (PI: Zach Berta-Thomson).

The Hubble Space Telescope is a project of international collaboration between ESA and NASA.

The team ‘s findings will be published in an interesting journal of The Astronomical Journal.

The international team of astronauts in this study is made up of MR Swain, R. Estrela, GM Roudier, C. Sotin, P. Rimmer, A. Valio, R. West, K. Pearson, N. Huber- Feely, and RT Zellem.

Image credit: NASA, ESA, and R. Hurt (IPAC / Caltech)