The James Webb Space Telescope has just achieved a historic first by capturing direct images of carbon dioxide in the atmosphere of an exoplanet. This discovery opens a new window into understanding planetary systems.
Located 130 light-years away, the HR 8799 system hosts four giant planets that have long intrigued scientists. Webb's observations confirm that these worlds formed similarly to Jupiter and Saturn, through the accretion of solid cores. This method of formation, known as 'core accretion,' is a valuable clue for understanding the diversity of planetary systems.
Infrared view of the multi-planetary system HR 8799 by the Webb telescope. The colors represent different wavelengths captured by the NIRCam instrument.
Credit: NASA, ESA, CSA, STScI, W. Balmer (JHU), L. Pueyo (STScI), M. Perrin (STScI) The data reveal a significant presence of heavy elements like carbon and oxygen in these planets' atmospheres. This composition suggests gradual formation, unlike other models where planets are born through the rapid collapse of a gas disk. Researchers emphasize the importance of these findings for comparing our Solar System to other stellar systems.
The team also studied the 51 Eridani system, located 96 light-years away. The observations, published in
The Astrophysical Journal, show similarities with HR 8799. These discoveries are made possible by Webb's coronagraphs, which block the light from stars to reveal surrounding planets.
Image of exoplanet 51 Eridani b by Webb, showing details at 4.1 microns.
Credit: NASA, ESA, CSA, STScI, W. Balmer (JHU), L. Pueyo (STScI), M. Perrin (STScI)
The direct detection of carbon dioxide marks a turning point in exoplanet research. Until now, atmospheric composition was mainly inferred from starlight filtered by planets. Webb now enables direct analysis, providing more precise data on the chemistry of these worlds.
Researchers plan to extend these observations to other systems to better understand the formation of giant planets. These studies could shed light on the conditions necessary for the emergence of Earth-like planets. Webb's ability to observe planets close to their stars opens new perspectives in the search for extraterrestrial life.
How does the Webb telescope detect carbon dioxide on exoplanets?
The James Webb Space Telescope uses infrared-sensitive instruments to analyze light emitted or reflected by exoplanets. These instruments, such as NIRCam, can identify specific molecular signatures like carbon dioxide in planetary atmospheres.
Webb's coronagraphs play a key role by blocking the intense light from host stars, revealing surrounding planets. This technique is similar to that used during a solar eclipse to observe the Sun's corona.
By targeting specific wavelengths, scientists can isolate the chemical signatures of atmospheric gases. Carbon dioxide, for example, absorbs certain infrared wavelengths, enabling its detection and analysis.
This method paves the way for detailed studies of exoplanet atmospheres, offering clues about their formation, evolution, and potential habitability.
Why is the formation of giant planets important for understanding our Solar System?
Giant planets like Jupiter and Saturn played a crucial role in the formation and evolution of our Solar System. Studying them helps us understand the processes that shaped terrestrial planets, including Earth.
Giant planets can influence the orbits and composition of other celestial bodies. Their presence may protect inner planets from comet impacts or, conversely, expose them to more collisions.
By comparing exoplanetary systems to our Solar System, scientists can determine whether our configuration is common or unique. This helps contextualize Earth's place in the Universe and assess the chances of finding similar environments elsewhere.
Webb's discoveries about HR 8799 and 51 Eridani provide tangible evidence that the formation mechanisms of giant planets are diverse, enriching our understanding of planetary system dynamics.