Washington: Using the NASA Hubble Space Telescope, a team of scientists including an Indian-origin researcher has made the most detailed map ever of the temperature of an exoplanet’s atmosphere and traced the amount of water it contains.
The planet targeted for both the investigations was the hot-Jupiter exoplanet WASP-43b. WASP-43b is a planet the size of Jupiter but with double the mass and an orbit much closer to its parent star than any planet in the solar system.
It has one of the shortest years ever measured for an exoplanet of its size – lasting just 19 hours. “These maps can be used to constrain circulation models that predict how heat is transported from an exoplanet’s hot day side to its cool night side,” explained Kevin Stevenson from University of Chicago.
While one study mapped the temperature at different layers in the planet’s atmosphere, the other traced the amount and distribution of water vapour within it.
The Hubble observations show that the exoplanet has winds that howl at the speed of sound from a day side that is hot enough to melt iron – soaring above 1,500 degrees Celsius – to the pitch-black night side that sees temperatures plunge to a comparatively cool 500 degrees Celsius.
Finding the proportions of the different elements in planetary atmospheres provides vital clues to understanding how planets formed. “Because there is no planet with these tortured conditions in the solar system, characterising the atmosphere of such a bizarre world provides a unique laboratory with which to acquire a better understanding of planet formation and planetary physics,” noted Nikku Madhusudhan from Cambridge University.
According to team member Laura Kreidberg of the University of Chicago, the planet is so hot that all the water in its atmosphere is vapourised rather than condensed into the icy clouds we find on Jupiter.
In WASP-43b the team found the same amount of water as we would expect for an object with the same chemical composition as the Sun.
“This tells us something fundamental about how the planet formed,” added Kreidberg. The results were presented in two new papers in the journal Science Express and The Astrophysical Journal Letters.