The atmospheres of gas giant planets throughout the Milky Way galaxy may be very different from those in our solar system, the James Webb Space Telescope has discovered.
Remote observations exoplanet HD149026b, also known as Smertrios, revealed that the planet’s atmosphere is rich in what scientists call heavy elements, essentially anything but hydrogen and helium. In Smertrios’ environment, the James Webb Space Telescope high concentrations of carbon and oxygen were detected.
The results surprised astronomers. In gas giant our planets solar systemjust like Jupiter, Saturn, Uranus and Neptune, scientists see a clear correlation between the mass of the planet and the amount of heavy elements in the atmosphere. The larger the planet, the lower the concentration of these elements in its atmosphere.
Related: The James Webb Space Telescope found no atmosphere on the Earth-like TRAPPIST-1 exoplanet
“The giant planets of our solar system show an almost perfect relationship between both overall composition and atmospheric composition and mass,” said Jacob Bean, a professor of astronomy and astrophysics at the University of Chicago and lead author of a new paper describing the observations, said. in a statement (opens in new tab).
Astronomers have seen more diverse atmospheric compositions on gas giant exoplanets before, but the composition of HD149026b’s atmosphere is off the charts.
“[The planet is] the mass of Saturn, but its atmosphere appears to have 27 times the amount of heavy elements associated with its hydrogen and helium that we see on Saturn,” study co-author Jonathan Lunine, a professor of Physical Sciences Department at Cornell University, said in the statement.
HD149026b, or Smertrios, is a so-called hot Jupiter, a Jupiter-like planet that orbits very close to its parent star. In the case of Smertrios, this distance is so short that the planetary year lasts only three Earth days. As a result of this proximity to the star, the temperature in Smertrios’ atmosphere reaches a scorching 2,700 degrees Fahrenheit (1,425 degrees Celsius), which is three times higher than the surface temperature of the solar system’s hottest planet, Venus. However, that does not explain the unusual composition of the planet’s atmosphere
“Every giant planet appears to be different, and we’re starting to see those differences thanks to JWST,” Lunine said. “In this paper, we determined how many molecules are related to the main gas component, which is hydrogen, the most common element in the universe. That tells us a lot about how this planet formed.”
By measuring the composition of a planet’s atmosphere, scientists can gain insight into the chemistry of its parent star and the material from which it formed millions or billions of years ago. The planetary disk that gave birth to Smertrios likely had more carbon compared to oxygen than the disk that gave birth to our solar system, the study found. The researchers plan to study Jupiter’s hotter planets in the coming year, with the hope of finding “statistical trends” behind the variation in their chemical compositions.
“The origin of this diversity is a major mystery in our understanding of planet formation,” Bean said. “Our hope is that further observations of the atmospheres of extrasolar planets with JWST will better quantify this variability and yield constraints on the more complex trends that may exist. We have shown definitively that the atmospheric compositions of the giant extrasolar planets do not follow the same trend as that of the solar system planets,” he added.
The studying (opens in new tab) was published in the journal Nature on Monday, March 27.
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