Astronomers using the NASA/ESA/CSA James Webb Space Telescope have detected trace amounts of hydrogen sulfide in the atmosphere of the Jupiter-sized exoplanet HD 189733b.
An artist’s impression of the hot-Jupiter exoplanet HD 189733b. Image credit: Roberto Molar Candanosa / Johns Hopkins University.
HD 189733b is a hot gas giant with a hazy atmosphere mainly composed of hydrogen. It is some 63 light-years away toward the constellation of Vulpecula.
The planet was discovered in 2005 by astronomers using two telescopes at the Haute-Provence Observatory.
HD 189733b is only 1.2 times bigger than Jupiter but in very close orbit around its parent star, HD 189733; it orbits the star once every 2.2 days.
“Hydrogen sulfide is a major molecule that we didn’t know was there. We predicted it would be, and we know it’s in Jupiter, but we hadn’t really detected it outside the Solar System,” said Dr. Guangwei Fu, an astrophysicist at Johns Hopkins University.
“We’re not looking for life on this planet because it’s way too hot, but finding hydrogen sulfide is a stepping stone for finding this molecule on other planets and gaining more understanding of how different types of planets form.”
“In addition to detecting hydrogen sulfide and measuring overall sulfur in HD 189733b’s atmosphere, we precisely measured the main sources of the planet’s oxygen and carbon — water, carbon dioxide, and carbon monoxide.”
“Sulfur is a vital element for building more complex molecules, and — like carbon, nitrogen, oxygen, and phosphate — scientists need to study it more to fully understand how planets are made and what they’re made of.”
As it did by detecting water, carbon dioxide, methane, and other critical molecules in other exoplanets, Webb gives scientists yet another new tool to track hydrogen sulfide and measure sulfur in gas planets outside the Solar System.
“Say we study another 100 hot Jupiters and they’re all sulfur enhanced. What does that mean about how they were born and how they form differently compared to our own Jupiter?” Dr. Fu said.
The new data also ruled out the presence of methane in the atmosphere of HD 189733b with unprecedented precision and infrared wavelength observations from the Webb telescope, countering previous claims about that molecule’s abundance in the atmosphere.
“We had been thinking this planet was too hot to have high concentrations of methane, and now we know that it doesn’t,” Dr. Fu said.
The astronomers also measured levels of heavy metals like those on Jupiter, a finding that could help scientists answer questions about how a planet’s metallicity correlates to its mass.
“Less-massive giant icy planets like Neptune and Uranus contain more metals than those found in gas giants like Jupiter and Saturn, the largest planets in the Solar System,” Dr. Fu said.
“The higher metallicities suggest Neptune and Uranus accumulated more ice, rock, and other heavy elements relative to gases like hydrogen and helium during early periods of formation. Scientists are testing whether that correlation also holds true for exoplanets.”
“This Jupiter-mass planet is very close to Earth and has been very well studied. Now we have this new measurement to show that indeed the metal concentrations it has provide a very important anchor point to this study of how a planet’s composition varies with its mass and radius.”
“The findings support our understanding of how planets form through creating more solid material after initial core formation and then are naturally enhanced with heavy metals.”
The team’s results were published in the journal Nature.
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G. Fu et al. Hydrogen sulfide and metal-enriched atmosphere for a Jupiter-mass exoplanet. Nature, published online July 8, 2024; doi: 10.1038/s41586-024-07760-y
Source : Breaking Science News