NASA used the James Webb Space Telescope to detect an atmospheric asymmetry on the extrasolar planet WASP-107b. This unprecedented observation reveals differences in temperature and cloud properties between the eastern and western sides of the planet, which is important for understanding the dynamics of exoplanet atmospheres
A breakthrough discovery in the atmosphere of the planets
Researchers from the University of Arizona, along with an international group of scientists, observed the atmosphere of a uniquely hot and bloated extrasolar planet using NASA's James Webb Space Telescope. The planet, which is about the size of Jupiter but only one-tenth the mass, was found to have an east-west asymmetry in its atmosphere, meaning that there are significant differences between the two ends of its atmosphere.
The findings were published today (September 24) in the journal Nature Astronomy.
Revealing the East-West asymmetry from space
"This is the first time that the east-west asymmetry of an extrasolar planet has been observed crossing its star from space," said lead study author Matthew Murphy, a research student at the University of Arizona's Stewart Observatory. A transit occurs when a planet passes in front of its star, such as a moon crossing the sun during a solar eclipse.
"I think that observations from space have many advantages compared to observations made from Earth," Murphy added.
The study of atmospheric dynamics
East-west asymmetry of an extrasolar planet refers to differences in atmospheric properties such as temperature or cloud properties, observed between the eastern and western hemispheres of the planet. Identifying the existence of the asymmetry is important for understanding the climate, atmospheric dynamics and weather patterns of extrasolar planets - planets outside our solar system.
The planet WASP-107b is tidally fixed to its star. That is, it always presents the same side to the star it orbits. One side of the planet always faces the star, while the other side is always away from it, creating a permanent day side and a permanent night side of the planet.
Advanced techniques with the James Webb Space Telescope
Murphy and his team used a transition spectroscopy technique with the James Webb Space Telescope. It's the main tool astronomers use to understand what the atmospheres of other planets are made of, Murphy explained. The telescope took a series of images as the star crossed its host star, encoding information about the star's atmosphere. Thanks to the new techniques and the unprecedented precision of the James Webb telescope, the researchers were able to separate the signals from the eastern and western sides of the atmosphere and examine certain processes occurring in it in a more focused way.
"Photographing these views tells us a lot about the gases in the planet's atmosphere, the clouds, the chemical structure and how everything changes depending on the amount of sunlight it receives," said Murphy.
The planet WASP-107b is unique in that it has a very low density and relatively low gravity, leading to a puffier atmosphere than other exoplanets of the same mass.
"We don't have anything like it in our solar system. This is unique, even among the population of extrasolar planets," Murphy added.
The temperature of the planet WASP-107b is about 470 degrees Celsius - a temperature that is intermediate between the planets of our solar system and the hottest planets known.
"Traditionally, our observational methods don't work so well for such intermediate planets, so there are a lot of open and exciting questions that we can begin to answer," Murphy said. "For example, some of our models showed that a planet like WASP-107b shouldn't show this asymmetry at all - so we're already learning something new."
Continue the study of the extrasolar planets
Researchers have been studying extrasolar planets for nearly two decades, and many observations from Earth and space have helped astronomers guess what the atmospheres of these planets look like, said Thomas Beatty, co-author of the study and associate professor of astronomy at the University of Wisconsin-Madison.
"But this is really the first time we've seen such asymmetries directly in the form of transition spectroscopy from space, which is the main method by which we understand what the atmospheres of extrasolar planets are made of - it's really amazing," said Beatty.
Murphy and his team are currently working on further analysis of the observational information they have and plan to conduct additional observations to better understand what causes this asymmetry.
"Almost all the extrasolar planets cannot be directly observed, and it is certainly impossible to know what is happening on one side compared to the other," concluded Murphy. "This is the first time we're able to take a more focused look at what's going on in the atmosphere of an extrasolar planet."
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One response
Something in the article doesn't work for me. If it is a planet with one side always facing its sun (star) and the other side it is not entirely expected that there will be permanent differences. The side facing the sun is expected to always be warmer. like day and night.
It is surprising that science does not predict this and the models do not predict this...