Hubble Spots Scorching-Hot Jupiter-Sized Planets Raining Vaporized Rocks

In two new studies, Hubble astronomers have identified freakish weather conditions on two Jupiter-sized exoplanets. On one planet it is raining vaporized rock, while on another its upper atmosphere is getting hotter rather than cooler.

When temperatures here on Earth begin reaching 90 degrees Fahrenheit and above, most of us start seeking out a nice cool place to take refuge. Luckily for us, Earth is located far enough away from the Sun that temps don’t get much higher than that (generally speaking). But on some exoplanets, temperatures can be scorching hot due to their close proximity to their parent star. Astronomers have been studying weather conditions of two Jupiter-size planets where temperatures are hot enough to vaporize most metals, including titanium.

“We still don’t have a good understanding of weather in different planetary environments,” stated David Sing of the Johns Hopkins University in Baltimore, Maryland, and co-author of the two research papers. “When you look at Earth, all our weather predictions are still finely tuned to what we can measure. But when you go to a distant exoplanet, you have limited powers because you haven’t built a general theory about how everything in an atmosphere goes together and responds to extreme conditions. Even though you know the basic chemistry and physics, you don’t know how it’s going to manifest in complex ways.”

In a paper submitted to the journal Nature on April 7th, observations were made by the Hubble Space Telescope of exoplanet WASP-178b. This planet is located approximately 1,300 light-years away from Earth, and its daytime side has an atmosphere that is cloudless and enriched in silicon monoxide gas. Due to the fact that only one side of the planet ever faces its planet star, its blistering atmosphere whirls around to the nighttime side at speeds that exceed 2,000 miles per hour. As the atmosphere whips around to the dark side, the silicon monoxide may actually cool down enough to condense into rock that rains out of clouds, even though at dawn and dusk, the mammoth planet is scorching hot enough to vaporize rock.

Josh Lothringer of the Utah Valley University in Orem, Utah, adds, “We knew we had seen something really interesting with this silicon monoxide feature.”

In a separate paper published in the January 24th issue of Astrophysical Journal Letters, astronomers reported on another sizzling Jupiter-sized planet, KELT-20b, located around 400 light-years from Earth. This extremely hot exoplanet is creating a thermal layer in the atmosphere, due to blasts of ultraviolet light from its parent star, much like Earth’s atmosphere. Here on Earth, the atmosphere absorbs UV light and increases temperatures in a layer between 7 to 31 miles above the surface of Earth. On KELT-20b, the UV radiation from its host star is heating metals in the atmosphere and causing an extremely strong inversion layer.

Guangwei Fu of the University of Maryland, College Park, says, “Until now we never knew how the host star affected a planet’s atmosphere directly. There have been lots of theories, but now we have the first observational data.” Fu added, “The emission spectrum for KELT-20b is quite different from other hot-Jupiters. This is compelling evidence that planets don’t live in isolation but are affected by their host star.”

Lothringer explained, “If we can’t figure out what’s happening on super-hot Jupiters where we have reliable solid observational data, we’re not going to have a chance to figure out what’s happening in weaker spectra from observing terrestrial exoplanets.” He continued, “This is a test of our techniques that allows us to build a general understanding of physical properties such as cloud formation and atmospheric structure.”

Perhaps one day humans will be able to travel to distant planets such as those in the two research papers. If so, we may need to swing by Kepler-13Ab first, where scientists believe it “snows” sunscreen.

Top Image Credit NASA