The James Webb Space Telescope observed exoplanet WASP-80 b as it passed in front of and behind its host star, revealing spectra indicating an atmosphere containing methane gas and water vapor. Although water vapor has been detected on more than a dozen planets to date, until recently methane (a molecule abundant in the atmospheres of Jupiter, Saturn, Uranus, and Neptune in our solar system) was an elusive molecule to find in the atmospheres of transiting exoplanets. when examined using space spectroscopy.

Taylor Bell of the Bay Area Environmental Research Institute (BAERI) at NASA’s Ames Research Center in Silicon Valley, California, and Louis Wellbanks of Arizona State University tell us more about the importance of detecting methane in exoplanet atmospheres and Webb’ He discusses how ‘s observations help this definition. These findings of this long-sought molecule were recently published Nature.

“With a temperature of about 825 Kelvin (about 1,025 degrees Fahrenheit), WASP-80 b is the planet scientists call ‘hot Jupiter’; it is similar in size and mass to our solar system’s Jupiter, but with temperatures between Fahrenheit and Fahrenheit. HD 209458 The temperature of hot Jupiters, such as b (the first discovered transiting exoplanet), is around 1450 K (2150 F), and the temperature of cold Jupiters, like ours, is around 125 K (235 F).

“WASP-80 b orbits its red dwarf star every three days and is located 163 light-years away in the constellation Auriga. Because the planet is so close to its star and both are so far away from us, we cannot see the planet directly, even with the most advanced telescopes like the Webb. Instead, the researchers They study the combined light from the star and planet using the transit method (used to detect most known exoplanets) and the eclipse method.”

“We observed the system using the transit method as the planet moved in front of its star from our vantage point, causing the starlight we see to dim slightly. This is like someone walking in front of a lamp and the light dims.”

“During this time, the thin ring of the planet’s atmosphere around the day-night boundary is illuminated by the star, and in certain colors of light where molecules in the planet’s atmosphere absorb light, the atmosphere appears thicker and blocks more of the starlight, causing deeper dimming compared to other wavelengths where the atmosphere appears transparent.” “This method helps scientists like us understand what a planet’s atmosphere is made of by seeing what color light is blocked.”

“Meanwhile, using the eclipse method, we watched from our perspective as the planet passed behind its star, which caused another small decrease in the total illumination we received. All objects are illuminated by a type of light emitted by something called thermal radiation, which is characterized by the intensity and color of light that depends on how hot the object is.” “It emits a lot of light.”

“Shortly before and after the eclipse, the warm daytime side of the planet was facing us and by measuring the light falloff during the eclipse, we were able to measure the infrared light emitted by the planet. For eclipse spectra, absorption by molecules in a planet’s atmosphere usually shows up as a decrease in the light emitted by the planet at certain wavelengths. “Because the planet is much smaller and cooler than its host star, the eclipse depth is much smaller than the transit depth.”

“The first observations we made had to be converted into what we call a spectrum; It is essentially a measurement of how much light of different colors (or wavelengths) is blocked or emitted by a planet’s atmosphere. There are many different tools for converting raw observations into useful spectra; “Therefore, we used two different approaches to ensure that our findings were robust to different assumptions.”

“We then interpreted this spectrum using two types of models to simulate what the planet’s atmosphere would look like under such extreme conditions. The first type of model is completely flexible and tries to find the millions of combinations of methane content, water, and temperature that best fit our data. The second type, called ‘consistent models’, explores millions of combinations but uses our current knowledge of physics and chemistry to determine the levels of methane and water to expect.”

“Both models lead to the same conclusion: precise detection of methane.”

“To test our findings, we used robust statistical methods to estimate the probability that our detection was due to random noise. We consider what is called “5 sigma detection” in our industry to be the “gold standard,” meaning the chance of detection due to random noise is 1 in 1.7 million. “It exceeds the 5 sigma ‘gold standard’ by setting the probability of false detection in the spectrum and eclipse spectrum to 1 in 942 million for each observation, strengthening our confidence in both detections.”

“With such a confident detection, we have not only found an elusive molecule, but we can also begin to explore what this chemistry tells us about the birth, growth and evolution of the planet. For example, by measuring the amount of methane and water on the planet, we can infer the ratio of carbon atoms to oxygen atoms.” “

“This ratio is expected to vary depending on where and when the planets formed in their systems. “So examining this carbon/oxygen ratio could provide clues as to whether a planet formed closer to or further away from its star before slowly drifting inward.”

“Another thing that excites us about this discovery is that it finally opens up the opportunity to compare planets outside our solar system with planets within it. NASA has a history of sending spacecraft to the gas giants in our solar system to measure the amount of methane and other gases. Now we’ve measured the same gas on an exoplanet, making the apples a bit bigger.” “We can start comparing apples to apples and see if the prospects for the solar system match what we’ve seen beyond that.”

“Ultimately, as we look to future discoveries with Webb, this result shows us that we are on the verge of more exciting discoveries. Additional MIRI and NIRCam observations of WASP-80 b with Webb will allow us to investigate the properties of the atmosphere at different wavelengths of light. Our findings lead us to investigate the properties of carbon monoxide and carbon “It leads us to believe that we may be able to observe other carbon-rich molecules, such as carbon dioxide, which will allow us to paint a more complete picture of the conditions in this planet’s atmosphere.”

“Moreover, as we find methane and other gases on exoplanets, we will continue to expand our knowledge of how chemistry and physics work in environments different from those on Earth, and perhaps soon on other planets, reminding us of what we have.” . here at home What is clear is that the journey of discovery with the James Webb Space Telescope is full of potential surprises.”