If there’s any chemical in the rest of the world that excites the search for biosignatures, it’s methane. This is not a complete dunk as it includes both biotic and abiotic sources.
But finding it in an exoplanet’s atmosphere means the planet is worth closer scrutiny.
Methane attracts scientific attention primarily because of its short duration in planetary atmospheres. Methane, at least in Earth’s atmosphere, cannot withstand starlight for long. It succumbs to photodissociation and must be continuously replenished to maintain its presence in the atmosphere.
If methane is present in large quantities on a rocky planet, the source must be large and likely biological. On Earth, huge amounts of methane are produced by biological activities.
Metabolically, methane is not difficult to produce.
Methane is common in the solar system, but not necessarily abundant. As far as scientists know, it’s all non-living. Processes like serpentinization could explain it.
serpentinization is a natural, abiotic process involving water, carbon dioxide, and minerals olivine. Olivine is common on Earth and is the main component of our planet’s upper mantle. It has also been found on the Moon, Mars, and some asteroids.
Recently, the James Webb Space Telescope detected methane in the atmosphere of WASP-80b, a gas giant planet with about half the mass of Jupiter. WASP-80b orbits her K-type main sequence star, which is approximately 1.5 billion years old. WASP 80 is about 162 light-years away, and WASP-80b is the only planet ever detected around this star.
![Atmospheric composition graph](https://www.sciencealert.com/images/2023/11/WASP80b-methane-and-water-JWST1-642x432.png)
WASP-80b is a gas giant planet, which rules out the possibility of life except in extreme science fiction scenarios. However, WASP-80b is not a rocky planet, so serpentinization of olivine, the best known abiotic source of methane, is also ruled out. But it’s still interesting to find out.
Part of the reason is that we can now compare exoplanets to the methane-laden atmospheres of Uranus and Neptune in our solar system. It can only help us to better understand future methane detection.
A new paper published in the journal Nature reports on this finding. the title is””Methane in the atmosphere of the warm exoplanet WASP-80b.The lead author is Taylor Bell, a postdoctoral fellow at the Bay Area Environmental Research Institute.
WASP-80b is a warm Jupiter. Its temperature is approximately 550 degrees Celsius (1,025 degrees Fahrenheit, 825 degrees Fahrenheit). In other words, it’s between hot Jupiter. HD 209458b (the first transiting exoplanet discovered) and cold Jupiter, the largest planet in the solar system. The temperature of our planet Jupiter is approximately 112 degrees Celsius (235 °F; 125 K).
Temperature is an important point. Methane detections in exoplanet atmospheres are lacking, so at this stage in the game, each detection plays a critical role in developing atmospheric theory and guiding follow-up studies.
WASP-80b’s temperature places the planet in an “interesting transition region where equilibrium chemistry models predict that there should be detectable CH4 and CO/CO2 signatures in the planet’s transmission and emission spectra,” the study’s authors said. are explaining.
WASP-80b is very close to the red dwarf star, taking only three days to orbit it. This planet is so far away and so close to its star that even the powerful JWST can’t actually see it. Instead, astronomers used her JWST to study the combination of light from stars and planets during solar transits and eclipses.
Unlike JWST, telescopes like Hubble and Spitzer, which can observe in the infrared, have not detected as much methane in exoplanet atmospheres. The lack of detection led scientists to develop theoretical explanations for how atmospheric methane is depleted. High metal content, high internal heat flux, and other reasons were investigated as methane depletion mechanisms.
JWST is now detecting methane, which raises important questions.
“However, WASP-80b’s conclusive detection of atmospheric methane by low-resolution JWST spectroscopy may be affected by the extent to which past non-detections were influenced by the sparse wavelength coverage and accuracy achievable with HST and Spitzer. “This raises the question,” the authors write. write.
So if astronomers continue to detect methane in the atmospheres of more exoplanets, we may need to change the way we think about methane as a biosignature.
“As methane and other gases are discovered on exoplanets, we continue to learn more about how chemistry and physics work under conditions different from those on Earth, and perhaps soon “We will deepen our knowledge on other planets that remind us of what we have here. Go home,” the authors wrote in their paper. NASA blog post.
Researchers explain that finding exoplanets with methane in their atmospheres can also help us understand our solar system.
“NASA has a history of sending spacecraft to the solar system’s gas giant planets to measure the amount of methane and other molecules in their atmospheres,” the authors write.
“Now, by measuring the same gas inside exoplanets, we can start comparing ‘apples to apples’ and see whether our expectations from our solar system match what we see outside our solar system. ”
![On the left is a featureless blue planet, Uranus, on the right is the sphere of Neptune with some features.](https://www.sciencealert.com/images/2023/11/UranusLeftComparedToNeptuneRight-642x321.jpg)
The researchers also say that measuring methane along with water can help reveal where and how planets formed.
“For example, by measuring the amounts of methane and water on Earth, we can infer the ratio of carbon to oxygen atoms,” the researchers wrote.
“This ratio is expected to vary depending on when and where the planets form in the system.” Astronomers will use this data to determine whether the planets formed near their star or far away. You can determine whether it has moved inward since it was removed.
JWST is probably not complete in WASP-80b. This data comes from his NIRCam instrument on the space telescope. Her future MIRI and NIRCam observations, which will probe the planet at different wavelengths, should also detect other carbon molecules such as carbon monoxide and carbon dioxide.
“With this discovery, we will be able to observe other carbon-rich molecules such as carbon monoxide and carbon dioxide, and it is thought that this will enable us to gain a more comprehensive understanding of the state of this planet’s atmosphere.” The researchers explain.
Methane has attracted a lot of attention because of its connections to biology, but this study shows a different side of methane. This helps us understand where and how some planets formed and whether they moved.
Detecting methane on exoplanets helps improve our overall understanding of exoplanet atmospheres. They can also help us understand our own solar system, where many questions still remain.
JWST is poised to play an important role in building knowledge about methane and the atmosphere.
“One thing is clear: the James Webb Space Telescope’s voyage of discovery is full of potential surprises,” the authors say.
This article was first published today’s universe.read original article.