Astronomers Utilize Webb Telescope to Explore Rocky Exoplanets' Atmospheres

In a groundbreaking initiative, astronomers are expanding their investigation into rocky exoplanets with atmospheres, utilizing the capabilities of NASA’s James Webb Space Telescope (JWST) and the Hubble Space Telescope. This effort focuses on two recently added targets—LHS 1140 b and LTT 1445 Ab—both orbiting red dwarf stars, which are smaller and cooler than our Sun, yet more prevalent in the universe. The JWST is set to analyze these celestial bodies for signs of atmospheric composition, specifically seeking carbon dioxide, a key indicator of potential habitability.

This project, led by astronomer Néstor Espinoza from the Space Telescope Science Institute, marks a significant shift in exoplanet research. Historically, atmospheric studies have predominantly focused on gas giants, leaving a gap in our understanding of rocky planets that could potentially host life. As of now, the research initiative includes four targets, with plans to investigate up to a dozen exoplanets in total.

Espinoza stated, “The answer for 'Are we special ... or not?' can start to be answered if we begin uncovering atmospheres of these rocky exoplanets around M-dwarfs.” The concept is that if these M-dwarfs harbor atmospheres, the implications for the potential emergence of life in such environments could be significant. Previous studies suggest that LHS 1140 b might possess an ocean half the size of the Atlantic and possibly a nitrogen-rich atmosphere, making it a promising candidate for further investigation.

The JWST will employ a novel secondary eclipse technique to study these planets. Unlike traditional methods that measure the starlight filtering through an atmosphere, this technique allows astronomers to isolate the light from the planet itself when it passes behind its host star. This approach mitigates the issue of stellar contamination from red dwarf stars, which can emit harmful radiation, potentially stripping planets of their atmospheres.

The two newly included exoplanets, LHS 1140 b and LTT 1445 Ab, are approximately 49 and 22 light-years away from Earth, respectively. Both planets were discovered within the last eight years and present unique characteristics that make them ideal for atmospheric studies. For instance, LTT 1445 Ab is part of a multi-star system, providing intriguing dynamics for analysis.

Jennifer Lotz, director of operations at the Space Telescope Science Institute, initiated this rocky exoplanet survey using discretionary time on the JWST, similar to past revolutionary projects like the Hubble Deep Field. The observations are anticipated to commence imminently, with preliminary findings expected to inform future research proposals.

While the hunt for rocky exoplanets with atmospheres continues, the scientific community remains optimistic. As Ryan MacDonald, a coauthor of the study, noted, “We’ll need more JWST observations to verify an atmosphere, but LHS 1140 b is looking like one of the most promising potentially habitable super-Earths.”

In summary, this innovative research could redefine our understanding of the cosmos, particularly concerning the characteristics that make certain exoplanets more likely to support life. The results may provide crucial insights into the atmospheric properties of rocky worlds orbiting M-dwarfs, potentially reshaping the search for extraterrestrial life in our galaxy.