Astronomers Say, Exoplanet Grows New Layer of Atmosphere :
Utilizing the advanced capabilities of JWST, scientists have made a captivating discovery regarding a scorching lava planet dubbed 55 Cancri e: it developed a second atmosphere after its original one was obliterated by its star.
Situated approximately 41 light-years away from our solar system, 55 Cancri e boasts dimensions nearly twice that of Earth and a mass roughly nine times greater. Classified as a "super-Earth" among the myriad of exoplanets documented, this intriguing world transcends the familiar, falling into a category all its own.
Astronomers have theorized that the exceptional density of the exoplanet implies a predominantly carbon-based composition, possibly crystallized into diamond form under immense pressure. Additionally, its orbit around the sun-like star, 55 Cancri A, is remarkably close—just 1.4 million miles (2.3 million kilometers)—a mere fraction of the distance between Earth and the sun.
This proximity subjects 55 Cancri e to intense radiation, a force that previously stripped away its primary atmosphere, a fate shared by other rocky planets in close proximity to their stars. However, recent findings unveil the presence of a dense envelope of gases encasing the planet, indicating the emergence of a secondary atmosphere. Researchers speculate on the mechanism behind this phenomenon.
"Astronomers meticulously dissected the thermal emanations originating from this rocky celestial body, uncovering compelling evidence pointing towards the existence of a significant atmospheric layer," Renyu Hu, a distinguished researcher hailing from the esteemed halls of the California Institute of Technology (Caltech) and an indispensable figure within the investigative cohort, elucidated.
"The compelling inference suggests that this alternative atmosphere is likely born from the internal outgassing processes within the rugged core of 55 Cancri e, marking a seminal milestone in our quest to unravel the mysteries of rocky exoplanets."
Indeed, this revelation sparks excitement within the scientific community, offering fresh insights into the dynamic interplay between exoplanets and their host stars.
Mysteries of 55 Cancri e: Defiance Against Its Star
Discovered in 2004 through the radial velocity exoplanet discovery method, 55 Cancri e, initially named Janssen, emerged as the first super-Earth detected orbiting a main sequence star. With a swift 0.7 Earth-day orbit and a composition rich in carbon, its mysteries began to unfold. In 2016, a pivotal moment arrived when the Hubble Space Telescope conducted the inaugural atmospheric investigation of an exoplanet, revealing the presence of hydrogen and helium within the confines of 55 Cancri e's atmosphere.
Upon further investigation, scientists uncovered details about its rapid 0.7 Earth-day orbit and carbon-rich composition.
Subsequently, in 2016, the Hubble Space Telescope conducted the inaugural atmospheric examination of an exoplanet, revealing the presence of hydrogen and helium within the atmosphere of 55 Cancri e.
Two plausible scenarios emerge to elucidate the atmospheric composition of 55 Cancri e.
One hypothesis suggests that this super-Earth may harbor a vaporous silicate atmosphere, thinly veiling its lava-covered surface. Comprised of volatile elements and chemical compounds such as carbon, nitrogen, hydrogen, and sulfur, this atmosphere could be susceptible to erosion by the intense irradiation emanating from its host star.
To ascertain the validity of these hypotheses, Hu and fellow researchers scrutinized observations from the JWST during the occurrence of a secondary eclipse, wherein 55 Cancri e traversed behind its host star, 55 Cancri A.
Analysis of data from two such secondary eclipses effectively dismissed the notion of the planet being a barren expanse of lava devoid of a significant atmosphere.
Indeed, the findings solidified the understanding that 55 Cancri e is indeed a fiery landscape cloaked in molten lava. Furthermore, the research team posits that this molten terrain played a pivotal role in facilitating the development of its secondary atmosphere.
"55 Cancri e is positioned in such proximity to its host star that it undergoes intense heating through radiation," explained Hu. "This relentless heat maintains extraordinarily high temperatures across the planet's surface."
"At such extreme temperatures, virtually everything on the planet transitions into a molten state. Whether it's rock or any other material, it liquefies into molten lava, consequently facilitating the outgassing process crucial for the sustenance of a secondary atmosphere," Hu elaborated.
The researcher additionally noted that the original atmosphere of 55 Cancri e, presumably established since its inception around its star, likely comprised predominantly of hydrogen and helium. However, the precise composition of the secondary atmosphere that supplanted the initial one remains uncertain.
"The composition of the secondary atmosphere hinges upon the makeup of the underlying rock," Hu explained. "Should the rock exhibit a highly reducing nature, characterized by compounds prone to gaining electrons and hydrogen, it could foster the formation of a hydrogen-helium atmosphere akin to the primary one.
Conversely, if the rock bears semblance to Earth's mantle, gases such as water, carbon monoxide, and carbon dioxide would likely dominate the secondary atmosphere."
Hu further added that although the observations conducted by the JWST regarding 55 Cancri e do not definitively ascertain the composition of the planet's atmosphere, models employed to interpret these measurements tend to support the presence of a significant quantity of carbon dioxide and carbon monoxide.
Can 55 Cancri e truly generate a secondary atmosphere?
While 55 Cancri e stands out as one of the hottest rocky planets observed orbiting in such close proximity to its host star, it's not the only one of its kind, as Hu highlights. Consequently, the question arises: could other similarly scorching terrestrial worlds have also developed secondary atmospheres? The answer, according to the team, remains uncertain.
This uniqueness stems from a particular aspect of 55 Cancri e.
"At 1.8 times the size of Earth, it's a substantial rocky body — a factor that aids in the retention of volatile substances despite the intense stellar irradiation," Hu clarified. "In contrast, we anticipate that a much smaller rocky planet orbiting closely around its star could exhaust its entire volatile reservoir, resulting in a complete loss of atmosphere."
Thus, it becomes evident that the ability of a planet to maintain its atmosphere and develop a secondary one hinges not only on the distance from its star but also on its size. Hu emphasized that in both respects, 55 Cancri e appears to be optimally positioned for the replacement of a lost primary atmosphere with a secondary one.
