Analysis of existing JWST data attempts to detect outer planets of Trappist-1

Star system: TRAPPIST-1 | Distance from the Sun: 40.7 light years

The Trappist-1 system, a small star orbited by seven Earth-sized planets, has been a major target for the James Webb Space Telescope. While the inner planets have been studied directly, the potential to detect thermal emission—the heat energy radiated by a planet—from the outer planets remains a significant challenge due to interference from the host star itself.

This analysis compiled existing observations from five separate projects to see if the combined heat signal of the outer planets could be isolated. Despite the high sensitivity of the telescope, the precision of current archived data was not enough to detect this faint heat or determine if these outer worlds are rocky or possess atmospheres.

The findings indicate that current archival observations lack the necessary clarity to distinguish between a surface composed of bare rock and one wrapped in a thick atmosphere. The interference, known as stellar contamination, makes it difficult to cleanly separate the light of the star from the heat of the orbiting planets.

To move forward, the research proposes a new observational strategy. A continuous 60-hour observation window during a specific orbital phase, when the temperature difference between the planets and the star is at its highest, may provide the resolution needed to finally characterize these distant worlds.

Key findings
- Combined emission from outer Trappist-1 planets could not be detected in current archival data.
- Existing observations cannot currently distinguish between bare rock and atmospheric scenarios for these planets.
- Stellar contamination remains a primary hurdle in interpreting transit and emission data from the system.
- A 60-hour continuous observation strategy is proposed to maximize the chance of future detection.

Scientific study

Looking for TRAPPIST-1 external planets' emission in JWST archival data (external link)