The James Webb Space Telescope (JWST) has identified signs of heavy water in the atmosphere of exoplanet WASP-39b, located approximately 700 light-years from Earth. This finding offers scientists new perspectives on planetary formation processes and may aid in the search for potentially habitable worlds.
The JWST focused on analyzing the atmosphere of WASP-39b, searching for variations of the water molecule. Specifically, the research concentrated on heavy water, known as HDO, which is a variation of H2O where one of the hydrogen atoms has been replaced by deuterium, a heavier form of the element. The team calculated the ratio of deuterium to hydrogen (D/H), a crucial piece of data for inferring the origin and evolution of this planet.
During the investigation, various elements were evaluated, including atmospheric temperature, the presence of clouds, the diversity of molecules present, and the atmosphere's ability to filter light at specific wavelengths. Researchers emphasize that WASP-39b is one of the most studied exoplanets currently and possesses the most detailed atmospheric spectrum ever recorded for a body outside the Solar System.
The study results indicated that the proportion of deuterium found on this planet is higher than that observed in the gas giants of our own Solar System. Two hypotheses have been raised to explain this difference. One suggests that ordinary water may have been lost to space, since heavier molecules containing deuterium tend to remain in the atmosphere while lighter ones escape more easily.
The second possibility points out that the planet may have originated in a colder, more distant region of its stellar system, incorporating water-rich materials before migrating close to its host star. However, scientists stress that deeper chemical models are necessary to confirm which of these scenarios best fits the collected data.
Despite the discovery involving water, it is important to note that WASP-39b is not considered a viable candidate for life. It is an extremely hot gas giant, exhibiting temperatures close to 1,000 °C. However, the relevance of this study lies in the method employed. The HDO signature may establish itself as a valuable tool for examining other planets, including rocky worlds with characteristics more similar to Earth.
Researchers concluded that HDO remains the most accessible indicator due to its unique spectral characteristics, and its future detection may be possible on temperate rocky exoplanets, serving as a potential marker of habitability. Thus, James Webb is expanding the scientific capacity to analyze distant atmospheres and identify chemical clues that help answer astronomy's fundamental question: are we alone in the Universe.
A study conducted using the James Webb Space Telescope has drawn the attention of the scientific community to two very different worlds—Pluto and Titan. Both objects exhibit the same mysterious infrared signal, which indicates the presence of unexplained chemistry.
Despite obvious differences—Titan, Saturn's moon, possesses a dense atmosphere, seas of liquid methane, and dunes of organic particles, whereas the dwarf planet is an extremely cold environment with a thin atmospheric layer—observations by James Webb showed identical light absorption in a specific infrared range on both bodies. This result suggests the presence of an unknown compound.
Bruno Bézar, a planetary scientist from the Paris Observatory and lead researcher, noted that the situation is 'quite mysterious; we cannot say what it is.' The initial clue emerged from analyzing data from Titan collected by the telescope in 2022, where researchers used spectroscopy to identify materials based on how they absorb light. However, the detected pattern does not correspond to any cataloged compound.
To rule out equipment errors, scientists compared data obtained using the NIRSpec and MIRI instruments installed on James Webb. Both instruments recorded the same characteristic, confirming that the signal was not a measurement error. The team then analyzed data from Pluto, obtained in 2023, and again found the same pattern. One hypothesis relates to alkenes—a family of hydrocarbons that exhibit similar behavior in the observed infrared range.
It is believed that this compound may arise from chemical processes involving nitrogen and methane. Under ultraviolet radiation, these elements can generate more complex organic molecules that then reach the surface. Key indicators of this hypothesis include the appearance of the signal on Titan's surface, its decrease in intensity at the edges of observations, the fact that Pluto's atmosphere alone does not explain the phenomenon, and the absence of such a characteristic on Ganymede.
New observations from James Webb will help scientists map the distribution of this signal on Titan and determine if it is related to specific areas, such as regions of large organic dunes. The NASA Dragonfly mission may also contribute to this study; this craft, scheduled to arrive at Titan in the 2030s, will be equipped with instruments capable of directly analyzing molecules on the surface.
According to Bruno Bézar, the research could potentially reveal the mechanisms of complex chemical process development in various worlds of the Solar System.
