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James Webb Space Telescope The data reveal that WASP-107 b has significantly less methane than expected and a surprisingly large core, providing key insights into its atmospheric chemistry and internal dynamics.

A surprisingly small amount of methane and a super-large core lurk in the cotton candy-like planet WASP-107 b.

The findings, based on data obtained from the James Webb Space Telescope, mark the first measurements of an exoplanetthe main mass and will likely support future studies of planetary atmospheres and interiors, a key aspect in the search for habitable worlds outside our solar system.

“Looking inside a planet hundreds of light years away sounds almost impossible, but when you know the mass, radius, atmospheric composition and heat of its interior, you have all the pieces you need to get an idea of ​​what’s inside and how heavy that core is ” said lead author David Singh, Bloomberg Distinguished Professor of Earth and Planetary Sciences at Johns Hopkins University. “This is already something we can do for many different gas planets in different systems.”

Recently published in Naturethe study shows that the planet has a thousand times less methane than expected and a core that is 12 times more massive than Earth’s.

Artist’s concept of WASP-107 b, a warm Neptune exoplanet about 200 light-years away. Credit: Roberto Molar Candanosa/Johns Hopkins University

Planetary composition and habitability potential

A giant planet enveloped in a scorching atmosphere as fluffy as cotton, WASP-107 b orbits a star about 200 light-years away. It is puffy due to its construction: a Jupitera world only one-tenth the mass of this planet.

Although it has methane – a building block of life on Earth – the planet is not considered habitable due to its proximity to its parent star and lack of a solid surface. But it may contain important clues about the late stage of planetary evolution.

Methane Mysteries and Chemical Dynamics

In a separate study published in Natureother scientists also spotted methane with the Webb telescope and provided similar insights into the planet’s size and density.

“We want to look at planets more like the gas giants in our own solar system that have a lot of methane in their atmospheres,” Singh said. “This is where the WASP-107 b story got really interesting because we didn’t know why the methane levels were so low.”

The new measurements of methane suggest that the molecule transforms into other compounds as it flows up from the planet’s interior, interacting with a mix of other chemicals and starlight in the upper atmosphere. The team also measured sulfur dioxide, water vapor, carbon dioxide and carbon monoxide – and found that WASP-107 b has more heavy elements than Uranus and Neptune.

Observational studies and prospective studies

Profiling the planet’s chemistry is beginning to reveal key pieces of the puzzle of how planetary atmospheres behave under extreme conditions, Singh said. His team will conduct similar observations next year of an additional 25 planets with the Webb telescope.

“We have never been able to study this mixing process in an exoplanet atmosphere in detail, so this will add a lot to understanding how these dynamic chemical reactions occur,” Singh said. “This is something we definitely need as we start looking at rocky planets and biomarker signatures.”

Internal heat sources and atmospheric effects

Scientists have speculated that the planet’s excessively large radius is the result of a heat source inside, said Zafar Rustamkulov, a Johns Hopkins planetary sciences doctoral student who led the study. By combining atmospheric and internal physics models with Webb’s data on WASP-107 b, the team accounts for how the planet’s thermodynamics affects its observed atmosphere.

“The planet has a hot core, and that heat source changes the chemistry of the gases more deeply, but also drives this strong, convective mixing bubbling up from the interior,” Rustamkulov said. “We think this heat causes a change in the chemistry of the gases, specifically destroying methane and creating increased amounts of carbon dioxide and carbon monoxide.”

Current investigations and future experiments

The new findings also represent the clearest link scientists have been able to make between the interior of an exoplanet and the upper part of its atmosphere, Rustamkulov said. Last year, the Webb telescope spotted sulfur dioxide about 700 light-years away in a different exoplanet called WASP-39, providing the first evidence of an atmospheric compound created by reactions triggered by starlight.

The Johns Hopkins team is now focusing on what might keep the core hot and expects that there may be forces at play similar to those that cause tides in Earth’s oceans. They plan to test whether the planet is being stretched and pulled by its star and how this might explain the high heat of the core.

References:

“Neptune’s Warm Methane Reveals Major Mass and Vigorous Atmospheric Mixing” by David K. Singh, Zafar Rustamkulov, Daniel P. Thorngren, Joanna K. Barstow, Pascal Tremblin, Catarina Alves de Oliveira, Tracy L. Beck, Stefan M. Birkman, Ryan C. Challener, Nicolas Crouzet, Néstor Espinoza, Pierre Ferruit, Giovanna Giardino, Amélie Gressier, Elspeth KH Lee, Nikole K. Lewis, Roberto Maiolino, Elena Manjavacas, Bernard J. Rauscher, Marco Sirianni, and Jeff A. Valenti, May 20 2024, Nature.
DOI: 10.1038/s41586-024-07395-z

“High internal heat flow and a large core in a warm Neptunian exoplanet” by Louis Welbanks, Taylor J. Bell, Thomas G. Beatty, Michael R. Line, Kazumasa Ono, Jonathan J. Fortney, Everett Schlavin, Thomas P. Green, Emily Rauscher, Peter McGill, Matthew Murphy, Vivienne Parmentier, Yao Tang, Isaac Edelman, Sagnik Mukherjee, Lindsey S. Weiser, Pierre-Olivier Lagage, Ahren Dyrek, and Kenneth E. Arnold, 20 May 2024, Nature.
DOI: 10.1038/s41586-024-07514-w

Other study authors include Daniel P. Thorngren and Elena Manjavacas of Johns Hopkins University; Joanna K. Barstow of the Open University; Pascal Tremblin of Université Paris-Saclay; Catarina Alves de Oliveira, Stefan M. Birkman and Pierre Feruit by European Space Agency; Tracy L. Beck, Nestor Espinoza, Amelie Gresier, Marco Siriani, and Jeff A. Valenti of the Space Telescope Science Institute; Ryan C. Challener of Cornell University; Nicolas Crouzet, Giovanna Giardino and Nikole K. Lewis of Leiden University; Elspeth KH Lee; Roberto Maiolino of the University of Cambridge; and Bernard J. Rauscher from NASA Goddard Space Flight Center.

This research is based on data obtained from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy Inc. under NASA contract NAS 5-03127.