As researchers persist in their investigation of a far-off star system containing seven rocky exoplanets, the chances of finding a habitable planet seem to be diminishing.

Preliminary results regarding the fourth planet orbiting the TRAPPIST-1 star suggest it expelled its primordial atmosphere into space long ago, and it remains unclear if a new one has developed. Scientists employed NASA’s James Webb Space Telescope to conduct their studies.

Nonetheless, TRAPPIST-1e may still have sufficient greenhouse gases to sustain water, possibly in the form of a global ocean or on the side perpetually facing its red dwarf star.

Among the seven planets circling the star located 40 light-years away, planet E has stood out as a promising life candidate due to its location within the habitable zone, where conditions could permit liquid water if an atmosphere is present.

“TRAPPIST-1 is markedly different from our sun, and consequently, the planetary system that surrounds it is also quite distinct, which poses challenges to both our observational and theoretical models,” stated Nikole Lewis, an astronomy professor at Cornell University involved in the research.

Two scientific papers detailing the preliminary findings have been published in Astrophysical Journal Letters. These follow announcements regarding its neighboring planet, TRAPPIST-1d, which also raised concerns about its potential for harboring life.

The TRAPPIST-1 system was identified approximately eight years prior using NASA’s now-decommissioned Spitzer Space Telescope. The planets, comparable in size to Earth, quickly became a focal point in the quest for life-sustaining worlds.

Astronomers are especially keen to determine if the TRAPPIST planets possess atmospheres, as red dwarf stars are the most prevalent type found in the Milky Way. If planets in such challenging environments can maintain atmospheres despite radiation, it suggests that numerous other worlds might as well.

The findings regarding planet E were derived from just four of 19 intended observations. Early publication may enable other researchers to assess the team’s methods, expand on them, and aid in interpreting the results.

As the research progresses, scientists will experiment with a new technique: comparing signals from TRAPPIST-1e to TRAPPIST-1b, which appears to be an uninhabited, bare rock.

For the initial observations, the team utilized transmission spectroscopy. When a planet transits in front of its star, some starlight passes through its atmosphere, if it has one. Various gases absorb different wavelengths of light, allowing scientists to identify absent spectrum segments to ascertain the chemicals present. However, the method can yield ambiguous outcomes due to sunspots and other stellar activity.

According to the initial data, the team suspects planet E lacks a hydrogen-helium atmosphere, likely obliterated by intense stellar flares from its active star. However, planets can form new atmospheres, as Earth did billions of years ago. Researchers are contemplating whether planet E could have done something similar.

To delve deeper, the team intends to synchronize observations so that planets B and E transit the star concurrently to compare the data. In this case, planet B acts as the control: any shared chemical signatures are likely from the star, while any unique to planet E probably originates from its atmosphere.

A significant inquiry for Webb is whether red dwarfs—commonly referred to as M-type stars—can sustain planets with atmospheres. To tackle this, Webb scientists have initiated a comprehensive survey of rocky planets, first reported by Mashable. Instead of transmission spectroscopy, the “secondary eclipse” technique will be employed, which sidesteps some challenges posed by stellar activity.

“We are genuinely still in the nascent stages of discovering the remarkable science we can achieve with Webb,” remarked Ana Glidden, one of the lead authors from MIT, in a statement. “We’re entering an exciting new era of exploration that we are thrilled to be part of.”