Despite that conclusion, Thompson says the K2-18b methane discovery is still interesting. That’s because Madhusudhan and his colleagues do not see methane alone. Their analysis shows that the atmosphere of K2-18b also contains carbon dioxide, with both molecules at about 1%. Methane is the most reduced form of carbon – it does not contain oxygen. Carbon dioxide is its most oxidizing form – it contains the most oxygen per carbon of any organic compound. Thompson says seeing both molecules at the same time suggests that the atmosphere may be in a chemical imbalance, a conclusion that scientists could use to gather more information.
For K2-18b, Madhusudhan and his colleagues claim that the source of atmospheric inequality is the oceans that extend across the planet. The team reports the discovery of methane and carbon dioxide with high confidence in statistics, but they also report “discoveries” of ammonia and water, which at first glance may seem strange to a water-rich world. But JWST investigates only the upper echelon of a planet’s atmosphere. The group’s model shows that water floats under hydrogen, and the discovery of ammonia fits the forecast, that the ocean acts as a sinking ground for toxic gases that suck it out of the atmosphere effectively.
NASA; ESA; CSA; R. Crawford / STScI; J. Olmsted / STScI
Reaching this conclusion requires a multi-stage analysis of JWST data, and it is this analysis that has led other scientists to be wary of the team’s interpretation. JWST captures extraterrestrial signals using the so-called transit method workhorse technique of the field. As a planet passes in front of its star, its brightness decreases slightly. The reduction in light depends on the size of the planet and its upper atmosphere composition, so scientists can infer both types of information from such measurements.
Transferring JWST raw data to the gas list is a complicated process. Scientists create spectra from transient events and compare them with computer models that simulate spectrum for different planetary and atmospheric conditions. “We explore millions of combinations of molecules and planetary properties such as temperature and cloud cover until we find something consistent with our observations,” says MacDonald.
However, not all models give the same results. Ideally, researchers address inconsistencies by conducting independent checks on the same data set. But not all JWST data is in the public domain, as some target observations remain private to the group that collected them for a year. For Madhusudhan K2-18b observations and data collaborators will begin release in January next year. Until then, many planetary research communities remain unsure of the team’s results. “The conclusion of the oceans depends on the discovery of methane and its diversity,” says MacDonald. . “If independent groups – starting with crude data – also see the same properties of methane and carbon dioxide and measure the same quantities, we will be more confident that this finding is true.”
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Image Source : physics.aps.org
