Researchers at NASA's Jet Propulsion Laboratory in Pasadena, Calif., Are cooking a foreign atmosphere here on Earth, JPL Scientists have used a high-temperature "furnace" to heat a mixture of hydrogen and carbon monoxide to more than 2000 degrees Fahrenheit (1,100 degrees Celsius) on the molten lava temperature. The goal was to simulate conditions that can be found in the atmosphere of a special class of planets (planets outside our solar system) called "hot Jupiters".
Hot Jupiters are gas giants that orbit very close to their parent star, as opposed to all the planets in our solar system. While Earth takes 365 days to rotate the sun, Hot Jupiters orbit their stars in less than 10 days. Their proximity to the star means that their temperatures can range from 1,000 to 5,000 degrees Celsius (530 to 2,800 degrees Celsius) or even warmer. For comparison, a hot day on the surface of Mercury (which takes 88 days to the solar orbit) reaches about 800 degrees Fahrenheit (430 degrees Celsius).
"Although it is impossible to accurately simulate these difficult environments in the laboratory, we can get very close," said JPL Chief Scientist Murthy Godifati, who leads the team that conducted the new study, published last month in the Astrophysical Journal.
The team began with a simple chemical mixture of hydrogen gas and mainly 0.3% carbon monoxide gas. These molecules are most common in the universe and early solar systems, and they can create a reasonable atmosphere of hot Jupiter. The team then heated the mixture between 620 and 2,240 ° C (330 and 1,230 ° C).
The team also exposed the laboratory to a high-dose ultraviolet radiation – similar to what the warm Jupiter would have experienced so close to its parent star. UV light has proven to be a powerful component. She was largely responsible for some of the surprising results of the research on the chemistry that might occur in these fine atmosphere.
Hot Jupiters are great according to the planet's standards, and they radiate more light than cool planets. These factors allowed astronomers to gather more information about their atmosphere than most other star types. These observations reveal that many atmospheric temperatures are atoms at high altitudes. Although the clouds may explain the opacity, they become less and less sustainable as the pressure decreases, and the opacity was observed where the atmospheric pressure is very low.
Scientists have sought explanations other than clouds, and aerosols – solid particles suspended in the atmosphere – can be one. However, according to JPL researchers, scientists were not previously aware of how aerosols might develop into hot-air atmosphere. In the new experiment, adding UV light to a hot chemical mix did the trick.
"This result changes the way we interpret Jupiter's hot atmosphere," said Benjamin Fleury, a research scientist at JPL and lead author of the study. "We want to understand the properties of these aerosols, we want to better understand how they create, how they absorb light and how they react to changes in the environment." All this information can help astronomers understand what they see when they look at these stars.
The study yielded another surprise: chemical reactions produced significant amounts of carbon dioxide and water. While water vapor is found in warm atmospheric atmosphere, scientists expect most of this expensive molecule only when there is more oxygen than carbon. The new study shows that water can form when carbon and oxygen are in equal amounts. (Carbon monoxide contains one carbon atom and one oxygen atom). While some carbon dioxide (one carbon and two oxygen atoms) were created without the addition of UV radiation, the reactions increased with the addition of simulated star light.
"These new results are designed to immediately interpret what we see in warm atmospheric justice," said JPL Chief Scientist Mark Swain, a research fellow. "We assumed that temperature controls chemistry in these atmospheres, but it shows that we need to look at how radiation plays a role."
With next-generation tools, such as the NASA's SpaceWatch, which will be launched in 2021, scientists may produce the first detailed chemical profiles of exoplanet atmospheres, and some of the first topics may be hot Jupiter. Learn how other solar systems are created and how they are similar or different to ours.
For JPL researchers, work has only begun. Unlike a typical furnace, their seal the gas tightly to prevent leaks or contamination, and this allows researchers to control the pressure of the gas as the temperature rises. With this hardware, they can now simulate exoplanet atmospheres at even higher temperatures: close to 3000 degrees Fahrenheit (1,600 degrees Celsius).
"It was an ongoing challenge to understand how to design and operate the system successfully, since most standard components such as glass or aluminum melt at these temperatures," said JPL scientist Bryana Henderson, a research author of the study. "We are still learning how to push these boundaries while safely handling these chemical processes in the laboratory, but ultimately, the exciting results from these experiments are worth all the extra effort."
Publication: Banghi Fleury, et al., "Photochemistry in the Exophthalmic Atmosphere of H2", ApJ, 2019, doi: 10.3847 / 1538-4357 / aaf79f