May 25, 2013
Researchers Working To Map The Weather On Hot Jupiter Exoplanets
[ Watch the Video: Big Weather on Hot Jupiters ]
redOrbit Staff & Wire Reports - Your Universe Online
The class of new worlds dubbed as “hot Jupiters” definitely live up to their name, according to new research that has recorded temperatures as high as 2400 degrees Kelvin (or more than 3800 degrees Fahrenheit) on one of these massive, close-orbiting exoplanets.
According to NASA, those temperature readings were observed on a gas giant named HAT-P-2b by Nikole Lewis, a NASA Sagan Exoplanet Fellow working at MIT. Lewis said that daytime temperatures on the planet have reached 2400K, while the nightside of HAT-P-2b drops slightly below 1200K.
That would mean that, even at night, HAT-P-2b is still 10 times hotter than Jupiter.
Hot Jupiters are among the hundreds of new planets that have been discovered by the US space agency´s Kepler spacecraft, and unlike the actual Jupiter and the other large planets in our solar system, they tend to orbit very closely to their planet stars. Their orbits are often a fraction the size of Mercury´s.
In an attempt to confirm what the weather might be like on such a planet, Heather Knutson of the California Institute of Technology´s Division of Geological & Planetary Sciences and Nick Cowan of the Northwestern University Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA) came up with a method that allowed them to create the first weather map of a hot Jupiter back in 2007.
Knutson explained that the majority of these exoplanets are “tidally locked to their stars,” meaning that they have “a permanent dayside and a permanent night side.”
“As we watch them orbit from our vantage point on Earth, the planets exhibit phases — e.g., crescent, gibbous and full. By measuring the infrared brightness of the planet as a function of its phase, we can make a rudimentary map of temperature vs. longitude,” she added.
The only infrared observatory sensitive enough to perform that research is the Spitzer Space Telescope, and over the past six years it has helped map nearly a dozen hot Jupiters — including HAT-P-2b.
“These exoplanet maps may seem crude compared to what we´re accustomed to on Earth, but they are a fantastic accomplishment considering that the planets are trillions of miles away,” NASA officials explained. “The maps show huge day-night temperature differences typically exceeding 1000 degrees. Researchers believe these thermal gradients drive ferocious winds blowing thousands of miles per hour.”
Unfortunately, without regular images, researchers are unable to report what these types of windy conditions would look like. However, over the years, experts have managed to create computer simulations which reproduce the types of storms and cloud belts found in the atmosphere of Jupiter.
“If you take those models and turn up the heat, and slow down the rotation to match the tidally-locked spin of a hot Jupiter, weather patterns become super-sized,” the US space agency said. For example, they speculate that the planet´s Great Red Spot could “grow as large as a quarter the size of the planet and manifest itself in both the northern and southern hemispheres” on a hot Jupiter exoplanet.
Furthermore, the researchers believe that the heat would make it impossible for ordinary water and methane clouds to form. In their place, Knutson believes that hot Jupiters might have clouds composed of silicates.
“Silicates are predicted to condense in such an environment,” she said. “We're already getting some hints that clouds might be common on these planets, but we don´t yet know if they´re made of rock.”