One of the amazing abilities of the James Webb Space Telescope is to not only detect the presence of distant planets, but also to be able to peer into their atmospheres to see what they are made of. With previous telescopes, this was extremely difficult to do because they lacked the powerful instruments needed for this kind of analysis, but scientists using the Webb recently announced that they made a rare detection of methane in an exoplanet atmosphere. have put.
Scientists studied planet WASP-80 b using Webb’s NIRCam instrument, which is known as a camera, but also has a slitless spectroscopy mode that allows it to split incoming light into different wavelengths. Is. By seeing which wavelengths are missing because they have been absorbed by the target, researchers can tell what an object – in this case, a planetary atmosphere – is made of.
Even with Webb’s sensitive instruments, detecting an exoplanet is still difficult. This is because planets are much smaller and dimmer than stars, making them almost impossible to see directly. Instead, researchers often detect them by observing the stars around which they orbit, using techniques such as the transit method which measures the dip in a star’s brightness that occurs when a planet moves in front of it. Is.
“Using the transit method, we observed the system as the planet moved in front of its star from our perspective, causing the starlight visible to us,” said Lewis Wellbanks of Arizona State University, one of the study’s authors. It has decreased a bit.” statement. “It is like when someone passes in front of a lamp and the light dims. During this time, a thin ring of the planet’s atmosphere around the planet’s day/night boundary is illuminated by the star, and in certain colors of light where molecules in the planet’s atmosphere absorb the light, the atmosphere appears thicker. Blocks more of the star’s light, producing a darker haze compared to other wavelengths (where the atmosphere appears transparent). This method helps scientists like us understand what kind of planet’s atmosphere is made up by seeing what colors of light are being blocked.
When the authors used this method on WASP-80b, they found evidence of both water and methane in the planet’s atmosphere. Planets like Jupiter and Saturn in our solar system also have methane in their atmospheres, but these planets are much hotter, with temperatures exceeding 1,000 degrees Fahrenheit. Finding methane in this type of planet, called a hot Jupiter, is exciting because it can help scientists learn about planetary atmospheres and also because it is commonly found in the atmospheres of planets in our solar system. Despite being known, exoplanets are rarely found with atmospheres.
It may also be relevant to the search for life beyond our planet. “Methane is not only an important gas in exploring atmospheric composition and chemistry in giant planets, but in combination with oxygen it is also a potential signature of biology,” Wellbanks said. “One of the key goals of the Habitable Worlds Observatory, NASA’s next major mission after JWST and Roman, is to look for oxygen and methane-like gases in Earth-like planets around Sun-like stars.”
This research has been published in Nature Journal.