Using the James Webb Space Telescope, researchers found that HD189733b, an exoplanet known for its extreme weather, also contains hydrogen sulfide in its atmosphere, suggesting it has a sulfurous smell similar to rotten eggs. The discovery provides new insights into the role of sulfur in the formation and atmospheric composition of gas giant planets outside our solar system.
An exoplanet notorious for its deadly weather hides another bizarre feature - it smells like rotten eggs. That's the conclusion of a new Johns Hopkins University study of data from the James Webb Space Telescope.
The atmosphere of the Jupiter-sized gas giant HD189733b contains trace amounts of hydrogen sulfide, a molecule that not only emits a foul odor but could also provide scientists with new clues about how sulfur, a planet-building element, might affect the interiors and atmospheres of gaseous worlds outside our solar system.
The findings were published today (July 8) in the journal Nature.
"Hydrogen sulfide is a major molecule that we didn't know existed. We predicted its existence and knew it was on Jupiter, but we haven't actually detected it outside the solar system," said Guangwei Fu, an astrophysicist at Johns Hopkins University who led the study. "We're not looking for life on this planet because it's too hot, but finding hydrogen sulfide is a stepping stone to discovering this molecule on other planets and also allowing us to learn more about how different types of planets formed."
In addition to detecting hydrogen sulfide and measuring the total amount of sulfur in HD189733b's atmosphere, Fu's team also made precise measurements of the planet's main sources of oxygen and carbon - water, carbon dioxide and carbon monoxide.
"Sulfur is an important element in building more complex molecules, along with carbon, nitrogen, oxygen and phosphate, and scientists need to study it more to fully understand how planets formed and what they are made of," Fu said.
Fu said that HD189733b is only 64 light-years away from Earth and is the closest "hot Jupiter" that astronomers can observe passing in front of its star. Since its discovery in 2005, it has become a benchmark planet for detailed studies of exoplanet atmospheres.
The planet is 13 times closer to its star than Mercury is to the sun, and only takes about two Earth days to complete one orbit. It has scorching temperatures of up to 1,700 degrees Fahrenheit and severe weather, including raining glass and 5,000 mph crosswinds.
The Webb telescope has detected water, carbon dioxide, methane and other important molecules in other exoplanets, providing scientists with another new tool to track hydrogen sulfide and measure sulfur in gaseous planets outside our solar system.
"Suppose we studied another 100 hot Jupiters and they were all sulfur-strengthened. What does that mean, how were they born, and how did their formation differ compared to our own Jupiter?" Fu said.
The new data also rule out the presence of methane in HD189733b using Webb's unprecedented precision and infrared wavelength observations, refuting previous claims about the abundance of methane molecules in the atmosphere. Previously, academics had thought the planet was too hot to have high concentrations of methane, but now we know it doesn't.
The team also measured the amount of heavy metals on Jupiter, a finding that helps scientists answer the question of how a planet's metallicity is related to its mass.
The less massive icy giants like Neptune and Uranus contain more metals than the gas giants like Jupiter and Saturn, the largest planets in the solar system. The higher metal content suggests that Neptune and Uranus accumulated more ice, rock and other heavy elements early in their formation rather than gases like hydrogen and helium. Fu said scientists are testing whether this correlation also applies to exoplanets.
"This Jupiter-mass planet is very close to Earth and has been well studied. Now we have this new measurement showing that its metal concentration does provide a very important anchor for studying how a planet's composition changes with its mass and radius," Fu said. "These findings support our understanding of how planets form by creating more solid material after the initial core is formed, which then naturally enhances the heavy metal content."
In the coming months, Fu's team plans to track sulfur in more exoplanets and figure out how high concentrations of sulfur might affect the extent to which they formed near their parent stars: "We want to know how these types of planets got there, and understanding the composition of their atmospheres will help us answer that question."
Compiled from /ScitechDaily