Free Astronomy Magazine May-June 2018

31 MAY-JUNE 2018 SPACE CHRONICLES tem,” explained lead investigator Hannah Wakeford of the Space Tel- escope Science Institute in Balti- more, Maryland, and the University of Exeter in Devon, United King- dom. “But exoplanets are showing us that planet formation is more complicated and more confusing than we thought it was. And that’s fantastic!” Wakeford and her team were able to analyze the atmospheric compo- nents of this exoplanet, which is similar in mass to Saturn but pro- foundly different in many other ways. By dissecting starlight filter- ing through the planet’s atmos- phere into its component colors, the team found clear evidence for water. This water is detected as va- por in the atmosphere. Using Hubble and Spitzer, the team has captured the most complete spectrum of an exoplanet’s at- mosphere possible with present-day technology. “This spectrum is thus far the most beautiful example we have of what a clear exoplanet atmosphere looks like,” said Wakeford. “WASP-39b shows exo- planets can have much different compositions than those of our solar sys- tem,” said co-author David Sing of the University of Exeter in Devon, United Kingdom. “Hopefully this diversity we see in exoplanets will give us clues in fig- uring out all the different ways a planet can form and evolve.” Located in the constellation Virgo, WASP-39b whips around a quiet, Sun-like star, called WASP-39, once every four days. The exoplanet is currently positioned more than 20 times closer to its star than Earth is to the Sun. It is tidally locked, mean- ing it always shows the same face to its star. Its day-side temperature is a scorch- ing 1,430 degrees Fahrenheit (776.7 degrees Celsius). Powerful winds transport heat from the day-side around the planet, keeping the per- manent night-side al- most as hot. A l - t h o u g h it is called a “hot Saturn,” WASP-39b is not known to have rings. Instead, it has a puffy atmosphere that is free of high-altitude clouds, allow- ing Wakeford and her team to peer down into its depths. Looking ahead, Wakeford hopes to use the James Webb Space Tele- scope — scheduled to launch in 2019 — to get an even more com- plete spectrum of the exoplanet. Webb will be able to give informa- tion about the planet’s atmospheric carbon, which absorbs light at longer, in- frared wave- lengths than Hubble can see. By understand- ing the amount of carbon and oxygen in the at- mosphere, scientists can learn even more about where and how this planet formed. !