James Webb Space Telescope Feed Post

Webb Rules Out Thick Carbon Dioxide Atmosphere for Rocky Exoplanet (Light Curve)

TRAPPIST-1 b lacked atmosphere. TRAPPIST-1 c? Much the same. Though thought to be similar to Venus both in size and amount of radiation from its star, Webb found that TRAPPIST-1 c lacks Venus’s thick carbon dioxide-rich atmosphere. If there is an atmosphere, it’s very thin. A refresher: TRAPPIST-1 c is the second planet from its star, the M dwarf TRAPPIST-1. M dwarf stars are intriguing because they are 10 times as common and two times more likely to have rocky planets than stars like our Sun. TRAPPIST-1 has seven! Young M dwarf stars are energetic, emitting X-ray and UV radiation that can strip young planetary atmospheres away. It’s unknown if systems like these had enough water, carbon dioxide, or other ingredients to make atmospheres when the planets formed. Webb is so sensitive that it can search for elements and molecules like oxygen, nitrogen, and carbon dioxide in exoplanet atmospheres. The mystery remains — can planets orbiting small M dwarfs sustain the atmospheres needed to support life as we know it? Get the full report: www.nasa.gov/feature/goddard/2023/webb-rules-out-thick-ca... This image: This light curve shows the change in brightness of the TRAPPIST-1 system as the second planet, TRAPPIST-1 c, moves behind the star. This phenomenon is known as a secondary eclipse. Astronomers used Webb’s Mid-Infrared Instrument (MIRI) to measure the brightness of mid-infrared light. When the planet is beside the star, the light emitted by both the star and the dayside of the planet reach the telescope, and the system appears brighter. When the planet is behind the star, the light emitted by the planet is blocked and only the starlight reaches the telescope, causing the apparent brightness to decrease. Credits: NASA, ESA, CSA, Joseph Olmsted (STScI) Image description: Infographic titled “Rocky Exoplanet TRAPPIST-1 c Secondary Eclipse Light Curve, MIRI Time-Series Photometry (F1500W).” At the top of the infographic is a diagram showing a planet moving behind its star (a secondary eclipse). Below the diagram is a graph showing the change in brightness of 15-micron light emitted by the star-planet system over the course of nearly 2 hours. The diagram and graph are aligned vertically to show the relationship between the geometry of the star-planet system as the planet orbits, and the measurements on the graph. The infographic shows that the brightness of the system decreases slightly as the planet moves behind the star. Image & Description by NASA