Astronomers have made a significant discovery regarding the exoplanet TRAPPIST-1e, located just 40 light-years from Earth. Recent observations from the James Webb Space Telescope (JWST) suggest that this Earth-sized planet may possess a life-supporting atmosphere. If confirmed, this finding would bring scientists closer to identifying a second Earth.
The observations indicate that TRAPPIST-1e could have a gaseous envelope that might allow for the presence of liquid water on its surface. While the initial data is ambiguous, it represents the closest evidence yet in the ongoing search for habitable worlds beyond our Solar System. Astronomer Sara Seager of the Massachusetts Institute of Technology (MIT), who co-authored one of the studies on these findings, stated, “TRAPPIST-1e remains one of our most compelling habitable-zone planets, and these new results take us a step closer to knowing what kind of world it is.”
The quest for habitable exoplanets often uses Earth as a benchmark. Its unique capacity to support life hinges on the presence of liquid water, which is essential for biochemical processes. To sustain liquid water, a planet must orbit within a specific distance from its host star—an area known as the habitable zone—where temperatures allow water to remain in liquid form rather than freezing or evaporating.
The TRAPPIST-1 system, discovered in 2016, has generated excitement among scientists due to its seven rocky exoplanets, several of which reside in the habitable zone of their red dwarf star. However, red dwarfs present unique challenges. They are cooler than stars like the Sun, resulting in a habitable zone that is much closer to the star. Additionally, these stars are often more active, with flare activity that may strip nearby planets of their atmospheres.
While previous studies of TRAPPIST-1d, another planet in the system’s habitable zone, found no evidence of an atmosphere, TRAPPIST-1e appears to be positioned at a more favorable distance. A research team led by astronomer Néstor Espinoza from the Space Telescope Science Institute (STScI) and Natalie Allen from Johns Hopkins University utilized JWST to analyze starlight as TRAPPIST-1e transited in front of its host star. They aimed to detect variations that could indicate the presence and composition of an atmosphere.
A second research team, headed by astrophysicist Ana Glidden from MIT, worked to interpret the data collected from four transits of TRAPPIST-1e. The analysis was complicated by the need to account for potential contamination from the star’s activity.
The results revealed two possible scenarios. According to Ryan MacDonald, an astrophysicist at the University of St Andrews, “The most exciting possibility is that TRAPPIST-1e could have a so-called secondary atmosphere containing heavy gases like nitrogen. But our initial observations cannot yet rule out a bare rock with no atmosphere.”
If TRAPPIST-1e does possess an atmosphere, the research team has initiated steps to identify its composition. As starlight passes through a planet’s atmosphere, certain wavelengths can be absorbed and re-emitted by the gases present. By examining variations in the spectrum, scientists can deduce the presence of specific atoms and molecules.
Currently, the preliminary findings lean away from the presence of a high concentration of carbon dioxide, which would be consistent with atmospheres similar to those of Venus and Mars. The data instead suggest an atmosphere rich in molecular nitrogen, with trace amounts of carbon dioxide and methane. This is particularly intriguing, as Earth’s atmosphere is approximately 78 percent molecular nitrogen.
If validated, this discovery could position TRAPPIST-1e as the most Earth-like exoplanet identified to date. Although further confirmation is necessary, additional JWST observations are planned to determine the nature of the atmosphere definitively. Glidden expressed enthusiasm for the ongoing research, stating, “We are really still in the early stages of learning what kind of amazing science we can do with Webb.”
The research findings are detailed in two studies published in The Astrophysical Journal Letters. As scientists continue to explore the potential for life on other planets, the possibility of discovering a second Earth remains an exciting frontier in modern astronomy.
