A NASA-led team has found evidence that the over sized planet WASP-18b also called Hot Jupiter is wrapped in a smothering stratosphere loaded with carbon monoxide and devoid of water. The findings come from a new analysis of observations made by the Hubble and Spitzer space telescopes.
In the research, the scientists investigated the data collected for WASP-18b which is located 325 light years from earth to find exoplanets with stratospheres. The big planet has the mass of 10 Jupiters, has been observed continuously, and then astronomers accumulate a relatively large trove of data. During the study, the scientists have analyzed five eclipses captured by Hubble and two from Spitzer.
“The composition of WASP-18b defies all expectations,” said Kyle Sheppard of NASA’s Goddard Space Flight Center in Greenbelt, Maryland, lead author of the paper published in the Astrophysical Journal Letters. “We don’t know of any other extrasolar planet where carbon monoxide so completely dominates the upper atmosphere.” Kyle further stated.
As per the finding, the stratosphere layer formation is attributed to sunscreen like molecules, and it absorbs UV and other harmful radiation that comes from the stars. The new finding suggests the WASP-18b is a massive planet that orbits very close to its host star, has an unusual composition. Compared to other hot Jupiters, this planet’s atmosphere likely would contain 300 times more metals or elements heavier than hydrogen and helium. The findings suggest that it may not have formed the way other hot Jupiters did.
Nikku Madhusudhan a co-author of the study from the University of Cambridge said: “The only consistent explanation for the data is an overabundance of carbon monoxide and very little water vapor in the atmosphere of WASP-18b, in addition to the presence of a stratosphere.” He further stated that “This rare combination of factors opens a new window into our understanding of physicochemical processes in the explanatory atmosphere.”