The artist’s concept shows what the exoplanet K2-18 B looks like based on scientific data. |Photo source: Reuters
Story so far: On April 16, an international research team uploaded a paper that reported that distant exoplanet K2-18B could be habitable. Astronomers were cautiously excited about this statement. While finding places in the universe where life can be concealed is a crucial pursuit in the field, experts (including the teams that make the discovery) are cautious, as many similar claims must be withdrawn after careful examination.
What is K2-18B?
K2-18B is an external star – a planet outside the solar system. It is located within the range of 124 light bulbs from the Leo sign, rotating Star K2-18. It is 5.2 times wider than the Earth, about nine times its size, indicating that it may be rich in hydrogen. The amount of stellar radiation it obtains from stars is comparable to what the Earth obtains from the Sun. It was discovered by the Kepler Telescope in 2015. In 2019, Hubble Space Telescope discovered signs of water vapor in its atmosphere. Four years later, the James Webb Space Telescope (JWST) also detected signs of carbon dioxide and methane. Scientists previously showed in modeling studies that if (not only) there is a sea of ​​liquid water on the surface of a planet, methane and carbon dioxide can be found in an atmosphere filled with hydrogen, without ammonia.
What kind of planet is K2-18b?
According to the new work, K2-18B may be the Hycean world: covered with a sea of ​​hydrogen-inflatable. JWST aims to study such planets better than other telescopes, although K2-18B itself is not identified as Hycean. Some computer models show that it may also have stratosphere, some carbon oxides and cyanide in the intermediate atmosphere. The researchers also said that when the concentration of greenhouse gases in the atmosphere prevents any heat from escaping the surface, its surface conditions may approach an out-of-control greenhouse threshold. That’s why Venus is hell.
Also Read: How Scientists Explore the Appearance of Alien
In the new paper, the team reports the presence of two compounds in the atmosphere of K2-18b: dimethyl sulfide (DMS) or dimethyl disulfide (DMDS). Scientists suggest that DMS may be a biomarker on exoplanets, a marker of life. DMS on Earth is mainly made in the ocean. Phytoplankton produces a molecule called dimethylsulfonic acid dimethylsulfonic acid. When they die, the enzyme breaks down the molecules to release the DMS. When bacteria break down plant matter, it also emits. In 2015, researchers reported that 76% of soil bacteria contained a gene that allowed them to produce DMS.
Is K2-18B really habitable?
Experts say the only way to find an alien life is to detect it directly. That’s why NASA begins learning about Jupiter’s Europa’s Clippers mission in 2024. Trying to find conditions that are suitable for life (this is only life that we know about), and the presence of specific molecules from afar can only imply habitable conditions.
Many of the uncertainties in these studies also come from the tools of astronomers and the accuracy of the models they use to simulate the conditions of outer space. Chemical processes unknown to date may be able to create molecular scientists consider biomarkers. Or JWST’s inability to detect certain compounds may mean that they exist at concentrations below their detection threshold.
In 2023, the team reported tips for finding DMS on K2-18B. Now it says that this compound may actually be 1,000 times larger than the number on Earth. Since DMS is transient, it may be constantly generated on the surface. However, the paper only reports significant detection of DMS or DMD, rather than DMS alone.
Scientists have also been modeling the physical condition of K2-18B to examine alternative explanations of its chemistry. A 2023 study said: “Most SST world observation targets are unlikely to maintain liquid water oceans.” In 2024, a U.S. team published a paper saying JWST observations could be explained by K2-18B as “gas-rich mini-news” that “doesn’t require biosphere or other unknown methane to explain the data.” In January, an international team reported that a “full reanalysis” of the K2-18B data collected by JWST confirmed the presence of methane, but “no statistical significance or reliable evidence of carbon dioxide or DMS.” This conclusion doubts whether K2-18b is the world of sea science.
Several false alarms (including Trappist-1 system, exoplanet WASP-12B) professors and scientists scrutinize such claims carefully.
publishing – April 20, 2025 02:08 AM IST
