For the first time, astronomers have uncovered evidence of a substantial atmosphere surrounding a rocky world beyond our Solar System. Although not suitable for human habitation, this remarkable finding marks a significant advancement in planetary astronomy and our understanding of exoplanetary diversity.
The world in question, known as Janssen or 55 Cancri E, is classified as a super-Earth exoplanet. Situated in close proximity to its host star, Janssen’s surface is believed to be engulfed in a vast ocean of molten lava, rendering it inhospitable to life as we know it.
Janssen orbits a star named Copernicus, or 55 Cancri A, one of the binary pair of dwarf stars located approximately 41 light-years away from Earth. Since its discovery in 2004, astronomers have been captivated by the peculiar characteristics of Janssen, which boasts a mass nearly nine times that of Earth and orbits its host star every 18 hours.
Despite its extreme temperatures exceeding 2,573 Kelvin on the dayside, previous observations hinted at the presence of an atmosphere containing hydrogen and helium. However, recent investigations led by planetary scientist Renyu Hu at NASA’s Jet Propulsion Laboratory and the California Institute of Technology, utilizing data from the James Webb Space Telescope (JWST), have revealed new insights into Janssen’s atmospheric composition.
By meticulously observing the star during secondary eclipses, the research team discerned the thermal emissions from Janssen alone, unveiling a thick and volatile atmosphere rich in carbon monoxide or carbon dioxide. This finding challenges previous assumptions and suggests that the atmosphere may have originated from outgassing processes within the exoplanet’s magma ocean, akin to the atmosphere of Jupiter’s moon Io.
While uncertainties persist, these revelations shed light on the dynamic interplay between exoplanetary atmospheres and their host stars. Continued observations with the JWST and other observatories hold the promise of unraveling further mysteries surrounding the evolution and composition of distant worlds.
The findings, published in the journal Nature, underscore the ongoing quest to comprehend the diversity and complexity of exoplanetary systems within our Milky Way galaxy.
Edited by Dr. Brijendra Kumar Mishra, (Disaster Risk Reduction Expert)