Webb Telescope Unveils Surprising Atmospheric Asymmetry on Cool, Puffy Exoplanet

Artist's illustration of the exoplanet WASP-107 b based on transit observations from NASA's James Webb Space Telescope as well as other space- and ground-based telescopes, led by Matthew Murphy of the University of Arizona and a team of researchers around the world.

Artist's illustration of the exoplanet WASP-107 b based on transit observations from NASA's James Webb Space Telescope as well as other space- and ground-based telescopes, led by Matthew Murphy of the University of Arizona and a team of researchers around the world.

Summary: Using NASA’s James Webb Space Telescope, astronomers have discovered significant east-west atmospheric asymmetry in the cool, low-density exoplanet WASP-107b, challenging existing atmospheric models for planets in this temperature range.

Estimated reading time: 5 minutes

In a groundbreaking observation, astronomers have detected an unexpected atmospheric asymmetry in the exoplanet WASP-107b. This finding, published in Nature Astronomy, marks the first time such an asymmetry has been observed in a relatively cool exoplanet during its transit across its host star from space.

A Unique Exoplanet Under the Microscope

WASP-107b is an extraordinary celestial body. Despite being roughly the size of Jupiter, it has only about a tenth of Jupiter’s mass, resulting in an extremely low density of 0.126 g cm−3. This unique composition makes WASP-107b’s atmosphere more inflated than other exoplanets of similar mass.

Matthew Murphy, the lead study author and a graduate student at the University of Arizona’s Steward Observatory, emphasizes the planet’s distinctiveness: “We don’t have anything like it in our own solar system. It is unique, even among the exoplanet population.”

With an equilibrium temperature of approximately 770 K (about 890 degrees Fahrenheit), WASP-107b occupies an intermediate temperature range between the planets in our solar system and the hottest known exoplanets. This temperature places it in a category that has been challenging to study with traditional observing techniques.

Unprecedented Observations with JWST

The research team utilized the James Webb Space Telescope’s NIRCam instrument to obtain transmission spectra of WASP-107b between 2.5 and 4.0 μm. This advanced technology allowed for a more detailed examination of the planet’s atmosphere than ever before.

“This is the first time the east-west asymmetry of any exoplanet has ever been observed as it transits its star, from space,” Murphy stated. He added, “I think observations made from space have a lot of different advantages versus observations that are made from the ground.”

The team’s analysis revealed a morning-to-evening temperature difference of approximately 100 K, with a hotter evening limb. This finding was unexpected, as atmospheric models for planets in this temperature range did not predict substantial spatial heterogeneity.

Implications and Future Research

The discovery of atmospheric asymmetry in WASP-107b raises important questions about our understanding of exoplanet atmospheres. Thomas Beatty, study co-author and assistant professor of astronomy at the University of Wisconsin-Madison, highlighted the significance of these observations:

“But this is really the first time that we’ve seen these types of asymmetries directly in the form of transmission spectroscopy from space, which is the primary way in which we understand what exoplanet atmospheres are made of – it’s actually amazing.”

This research opens up new avenues for studying exoplanet atmospheres, particularly for cooler planets that have been challenging to observe in detail. Murphy and his team plan to conduct additional observations to better understand the drivers of this asymmetry.

“For the first time, we’re able to take a much more localized view of what’s going on in an exoplanet’s atmosphere,” Murphy explained.

As astronomers continue to study WASP-107b and other similar exoplanets, they hope to determine whether this planet is an outlier or if current models have underestimated the presence of limb asymmetry in cooler exoplanets. This research could lead to significant revisions in our understanding of exoplanet atmospheres and their dynamics.

Quiz:

  1. What is the approximate equilibrium temperature of WASP-107b? a) 2000 K b) 770 K c) 300 K
  2. What instrument on the James Webb Space Telescope was used for this study? a) MIRI b) NIRSpec c) NIRCam
  3. What unexpected feature was observed in WASP-107b’s atmosphere? a) East-west asymmetry b) Uniform temperature distribution c) Absence of an atmosphere

Answers:

  1. b) 770 K
  2. c) NIRCam
  3. a) East-west asymmetry

Further Reading:

  1. NASA James Webb Space Telescope: https://www.jwst.nasa.gov/
  2. Nature Astronomy Journal: https://www.nature.com/natastron/
  3. Exoplanet Exploration – NASA: https://exoplanets.nasa.gov/

Glossary of Terms:

  1. Exoplanet: A planet that orbits a star outside our solar system.
  2. Transmission spectroscopy: A technique used to study the composition of a planet’s atmosphere as it transits its host star.
  3. Limb asymmetry: Differences in atmospheric characteristics between the eastern and western edges of a planet.
  4. Tidally locked: When a planet always shows the same face to its star due to gravitational forces.
  5. Equilibrium temperature: The theoretical temperature a planet would have if it were a perfect blackbody absorbing and emitting radiation.
  6. NIRCam: Near-Infrared Camera, one of the primary instruments on the James Webb Space Telescope.

Enjoy this story? Get our newsletter! https://scienceblog.substack.com


Substack subscription form sign up